Tumour

Question 1

Describe this XRay? 15yo boy with painful mass. Differential? Top Diagnosis? Prognosis and Prognostic factors?

Answer 1

​EWING SARCOMA

• Differential
  
  • ​ewing
  • osteosarcoma​​
  • less likely
    
    • leukemia
    • rhabdomyosarcoma​​
    • neuroblastoma (<5yo)
• ​Ewing Sarcoma
  
  • 5-25 years of age
  • second most common bone tumor in children
  • ~50% are found in the diaphysis of long bones
• t(11:22) translocation
  
  • found in all cases
  • leads to the formation of a fusion protein (EWS-FLI1)
  • can be identified with PCR and useful to differentitate Ewing sarcoma from other round cell lesions
• Prognosis
  
  • survival
    
    • 60-70% long term survival with isolated extremity disease at presentation and appropriate treatment/tumor response to chemotherapy
    • 40% long term survival with pelvis lesions
    • 15% long term survival if patient presents with metastatic disease
  • poor prognostic factors
    
    • spine and pelvic tumors
    • tumors greater than 100cm3
    • < 90% necrosis with chemotherapy
    • elevated lactic dehydrogenase levels
    • p53 mutation in addition to t(11:22) translocation

Question 2

16yo female with painful thigh. Top Diagnosis? How will she present to you? Radiographic findings typical of this?

Answer 2

Ewing Sarcoma

• Presentation
  
  • pain often accompanied by fever
  • often mimics an infection
• Physical exam
  
  • swelling and local tenderness
• Radiographs
  
  • large destructive lesion in the diaphysis or metaphysis with a moth-eaten appearance
  • Most common diaphyseal lesion
    
    • Common in pelvis
  • lesion may be purely lytic or have variable amounts of reactive new bone formation
  • periosteal reaction may give “onion skin” or “sunburst” appearance
  • Codman’s triangle
  • associated soft tissue mass
• Bone scan
  
  • required as part of staging workup - will show very “hot” lesion
• MRI
  
  • neccessary to identify soft-tissue extension and marrow involvement
  • often shows a large soft tissue component
• CT chest
  
  • is required for appropriate staging to look for pulmonary metastasis

Question 3

12 yo male comes in with fever, and painful left hip. Below is his XR. Diagnosis? Managment? Treatment?

Answer 3

Ewing Sarcoma

• Differential​
  
  • ​infection
  • leukemia
  • osteosarcoma
  • neuroblastoma (if young)
• ​Radiology
  
  • permative, moth eatten appearance
  • ​diffuse, aggressive, lytic lesion with periosteal reaction
  • may be evidence of onion skinning or sunburst
  • ill defined margins, associated soft tissue mass
• ​Further work-up
  
  • ​Labs - ESR, CRP, WBC, CBC and smear, LDH
    
    • ESR is elevated
    • WBC is elevated
    • anemia is common
    • lactic dehydrogenase (LDH)
  • Bone marrow biopsy
    
    • required as part of workup for Ewing’s to rule out metastasis to the marrow
    • also assesses for translocation; translocation in normal marrow has increased risk of relapse
  • Molecular Analysis
    
    • ​CD99
    • PCR can confirm - 11, 22 translocation
  • Bone scan - hot
    
    • _​_assess mets
  • MRI - assess soft tissue mass
    
    • _​_marrow involvement
  • CT chest - assess pulmonary mets
    
    • _​_can help to plan radiation
• ​Consult pediatric oncology and rad onc to discuss imaging
• Treatment is multi-modal​
  
  • preoperative chemotherapy given for 8-12 weeks (3 drugs)
    
    • doxyrubicin (cardiotoxicity)
    • vincristine
    • cyclophosphamide
    • isophosphamide
    • etoposide
  • Restage with MRI to assess response
    
    • ​>90% necrosis is good prognosis
  • Wide surgical resection with limb salvage or amputation
    
    • Positive margins - re-resection and consider radiation
  • OR Radiation if difficult area, but this is falling out of favour due to long term complications
    
    • ​nonresectable tumor
    • wide metastatic disease
  • maintenance chemotherapy for 6-12 months
  • Monitor for recurrent disease every three months for 2 years, then reduce intervals

Question 4

Poor prognostic factors associated with Ewings

Answer 4

• The most important factor is clincially evident metastatic disease
  
  • ​mets to lungs is better than distant boney mets
  • skip lesions better than distant boney mets
• Location
  
  • spine and pelvic tumors (distal tumors have a better prognosis)
• Size
  
  • tumors greater than 100cm3
  • or >8cm
• Age >14 yo
• Male
• LDH >200IU
  
  • CRP/WBC elevation may be associted with mets and higher tumor burden
• < 95% necrosis with chemotherapy
• p53 mutation in addition to t(11:22) translocation
• Relapse at < 2years

Question 5

What is important for staging Ewings?

Answer 5

• All present as stage IIb or III
• plain radiographs and MRI of the primary site
• CT chest - pulmonary mets
• Bone Scan - skip lesions, boney mets
• Bone marrow biopsy
• ESR, CRP, LDH

Question 6

Treatment of Ewings

Answer 6

• preoperative chemotherapy given for 8-12 weeks (3 drugs)
  
  • doxyrubicin (cardiotoxicity)
  • vincristine
  • cyclophosphamide
  • isophosphamide
  • etoposide
• Restage with MRI to assess response
• Wide surgical resection with limb salvage or amputation
  
  • Send to pathology to assess for margins and amount of necrosis
  • >90% necrosis good prognosis
  • positive margins = RT
• OR Radiation if difficult area, but this is falling out of favour due to long term complications
  
  • ​nonresectable tumor
  • wide metastatic disease - should irradiate lungs even when improves with chemo
  • technique
    
    • 2-3 cm margin
    • 60 grey
• maintenance chemotherapy for 6-12 months
• Monitor for recurrent disease every three months for 2 years, then reduce intervals
  
  • Relapse is common
  • treatment associated AML (5 years)
  • treatment associated myelosysplasia
  • sarcoma 2nd to radiation (10 years); 20%
  • carcinoma

Question 7

Complications associated with radiotherapy in children

Answer 7

• limb length discrepany
• joint contracture
• muscle atrophy
• pathological fractures
• secondary malignancy

Question 8

Two class of criteria you can use to decide wether to prophylactically fix this?

Answer 8

Harington Critera

• > 50% destruction of diaphyseal cortices
• > 50-75% destruction of metaphysis (> 2.5 cm)
• Permeative destruction of the subtrochanteric femoral region
• Persistent pain following irradiation

Mirel’s Criteria

Question 9

What is the most common site of metastatic cancer?

Answer 9

thoracic spine

Always make sure to ask about neurological symptoms in any lesion that could be mets

Question 10

A patient with metastatic disease present with confusion, lethary, polyuria, N/V and are severaly dehydrated. What is the diagnosis? What is the treatment?

Answer 10

Hypercalcemia

• Loop diuretics
• fluid resussitation

Question 11

Principles of tumor biopsy

Answer 11

• Prerequisites
  
  • CBC, INR, PTT
  • Imaging
    
    • XR, CT
    • MRI - to look at most appropriate site of lesion
• Indications
  
  • bone tumor
  • Where multiple sites need biospy (because of tumor heterogeneity)
• Call your nearest tumor specialist to confirm you are dong appropriate biopsy, or ask if they would like referal
• Incision
  
  • Keep the incision as small as possible
  • use longitudinal incision in the extremities
  • allows for extension of the incision for definitive management
• Approach
  
  • do not expose neurovascular structures
  • all tissue exposed during the biopsy is considered contaminated with tumor
  • maintain meticulous hemostasis
  • release tourniquet prior to wound closure
• Biopsy
  
  • perform thru the involved compartment of the tumor, if possible threw one muscle
  • for bone lesions with a soft tissue mass, it is ok to perform the biopsy using the soft tissue mass
  • Make a circular or longitudinal hole, <10% bone diameter
  • Confirm with your pathologist that you have adequate specimen
• Closure
  
  • if using a drain, bring drain out of the skin in line with surgical incision
  • layered tension-free closure

Question 12

Prognosis and characteristics of common metastatic cancer?

Answer 12

Thyroid (lytic) - 48 months
Prostate (blastic) - 40
Breast (mixed) - 24
Kidney (lytic) - variable
Lung (lytic) - 6 months

myeloma (lytic) - 2-5 years

Question 13

Work-up of this patient

Answer 13

• History
  
  • Pain, qualify the pain, other sites of pain
    
    • This is the most common presenting symptoms
  • Constitutional symptoms or specific symptoms to any carcinoma
  • Chest pain, abdominal bloating, intolerance to hot and cold
  • Neurological symptoms
    
    • Myelopathy, weankness, walking aids, bowel/bladder
  • Risk factors - smoking, family history
  • Last pap smear, mammogram, colonoscope
• Physical
  
  • Look for evidence of primary
    
    • Breast exam, thyroid mass, prostate (rectal)
    • Costovertebral tenderness = renal call
  • Look for evidence of mets
    
    • Ascultate the lungs, palpate the abdomen
    • Abdomenal exam
  • Full neurological exam including gait, ASIA
• Workup for older patient with unknown primary
  
  • Plain radiographs
    
    • Full length films of lesion, chest
  • CT chest/abdo/pelvis
  • Can consider head
  • Technetium bone scan - rule out other lesions
  • Skeletal survery - Myeloma and thyroid cancer - cold bone scan
• Blood
  
  • CBC and differential, ESR/CRP, INR, PTT
  • LFT, Cr/Urea
  • Ca, Phos, Alk Pho, LDH
    
    • ***Hypercalcemia can be fatal to patient
    • Helps to rule out metabolic bone disease (hyperparathyroid)
  • Immunoelectrophoresis - SPEP, UPEP
  • PSA, TSH
• Imaging
  
  • Radiographs - full length films of affected area
  • Blastic - Prostate > breast > lung
  • Lytic - renal, lung, thyroid, uterine, adrenal, melanoma, GI
    
    • Not responsive to rads/chemo
    • Usually need to treat operatively
  • Elbow or knee = lung or renal
  • Cortical = lung
• Biopsy
  
  • Indications to rule out primary
    
    • No history of cancer
    • History of cancer with no evidence of mets
    • When there is history of cancer and evidence of mets, ok to send reamings for path
  • See the principles of biopsy section
    
    • Use the easiest site to biopsy
    • Can do a frozen section intra-op and if the pathologist confirms carcinoma you can proceed with fixation
• Histology
  
  • Mets - epithelial cells in clumps or glands in a fibrous stroma
  • Immunohistochemical stains positive
    
    • Keratin
    • CK7 - breast, lung
    • TTF1 - lung
• Once you have the primary
  
  • Med Onc - chemo
  • Rad Onc - post-op radiation
  • Radiology - if you want them to be embolized pre-op

Question 14

Treatment prinicples of metastatic lesion

Answer 14

• Non-op
  
  • Indications
    
    • Small lesions with little disability
    • Upper extremity
    • Sensitive tumors
    • Blastic lesions
    • Short expected survival or short condition
  • Bisphosphanate - have been shown to decrease secondary skeletal events (SSE) - funded fr breast, myeloma and prostate
  • Radiation
    
    • All require post-op unless death is imminent - otherwise you risk reoperation
    • Begin radiation after surgery - 3 weeks
    • Make sure you close your wounds well and can leave in the sutures
    • Radiation needs to include the entire fixation device
  • Chemo
    
    • Lymphoma/leukemia are very sensitive to rads/chemo so you usually don’t need to do sx
• Operative
  
  • Get imaging of the full bone including joint above and below
    
    • CT may be necessary
  • Embolization - renal cell, thyroid
  • Post-op RADS - helps to minimize recurrence and for pain control
  • Indications
    
    • Femur fractures
    • >2.5cm
    • >50% cortical lesion
    • Pain refractory to rads
    • Mirel’s criteria
  • Hemiarthroplasy or tumor prosthesis
    
    • Required when there in an intra-articular, uncontained lesion
    • Can also be done for a proximal femoral neck fracture
    • Cemented
    • Considerations
      
      • Soft tissue deficient and instability
        
        • Adequate closure of capsule, abductors and ER’s
      • High risk of infection
  • Prophylactic nailing
    
    • Statically locked
    • Recon nail has a higher failure rate for both intertroch and subtroch
    • Can augment with PMMA
    • Don’t forget to vent the femur if there is no fracture when reaming
    • *Doing more than one intramedullary device for multiple lesions can put a lot of stress on the pulmonary system - might be better to stage multiple lesions and allow the patient to recover from each nail
  • ORIF with PMMA
    
    • Indications
      
      • Humerus diaphyseal or metaphyseal with uncontained defect
      • Tibia - metaphyseal defect that is extra-articular
      • Impending and complete fractures
    • Curettage, cement, screw into cement
• Spinal neurologic decompression, surgical stabilization, post-op radiation therapy
  
  • Met lesions to spine with compression of neuro elements

Question 15

Treatment of humeral lesions

Answer 15

Question 16

Treatment of tibial lesions

Answer 16

Question 17

Tumors that require chemo

Answer 17

• Indications
  
  • osteosarcoma (intramedullary and periosteal)
  • Ewing’s sarcoma/primative neuroectodermal tumor
  • malignant fibrous histiocytoma
  • mesenchymal chondrosarcoma
  • Rhabdomyosarcoma
  • Synovical cell
• Timing
  
  • ​pre-op 8-12 weeks
  • post-op 6-12 months
• ​Common Drug​
  
  • Doxorubicin
    
    • anthracycline antibiotic
    • functions as a cytostatic agent
    • side effects
      
      • cardiac toxicity

Question 18

Describe the lesion. Differential? Diagnosis? Associated conditions?

Answer 18

Non-ossifying fibroma

• Differential for larger NOF
  
  • ABC
  • Chondromyxoid fibroma
  • Fibrous dysplasia
  • Desmoplastic fibroma
• Associated conditions
  
  • Jaffe-Campanacci syndrome
    
    • congenital syndrome of multiple non-ossifying fibromas and
    • cafe au lait pigmentation
    • mental retardation
    • heart, eyes, gonads involved
  • neurofibromatosis
  • familial multifocal NOF
  • ABC

​

Question 19

Describe this XR. Differential? Diagnosis?

Answer 19

Differential for metaphyseal fibrous defect

Osteoid osteoma
Intracortical abcess
Stress fracture
Intracortical osteosarcoma

Question 20

Describe this XR? Differential? Diagnosis? Treatment?

Answer 20

Non-ossifying Fibroma

• Radiographs
  
  • diagnostic
  • metaphyseal, eccentric, “bubbly” lytic lesion surrounded by sclerotic rim
  • cortex expansion and thinning
  • as bone grows
    
    • migrates to diaphysis
    • lesions enlarge (1-7cm)
    • lesions become sclerotic as patient approaches skeletal maturity
    • avulsion of adductor magnus insertion in the posteromedial aspect of the distal femur may produce a similar looking lesion.
• CT
  
  • quantitative CT shown to be useful in predicting fracture risk
• observation
  
  • first line of treatment
  • most lesions resolve spontaneously and observation alone is the treatment for most cases
• casting
  
  • pathologic fracture
  • can be treated as per the fracture alone (long leg casting for distal femur pathologic fx)
  • Once fracture heals treat with curettage and bone grafting
• intralesional curettage and bone grafting
  
  • symptomatic and large lesion
  • increased risk of fracture shown on quantitative CT

Question 21

Describe the XR. Differential? Managment?

Answer 21

Malignant Fibrous Histiocytoma

• 20-30% arise from infection or implant
• usually >50yo
• Presentation
  
  • pain, swelling, pathological fracture
• Imaging
  
  • ​lytic
    
    • ​no evidence of cortical reaction; too fast for bone to respond
  • destructive
  • metaphyseal
• ​Mangement
  
  • ​requires a complete WU of solitary bone lesion
  • ensure no hypercalcemia
  • MRI to look at soft tissue invovlement
  • biopsy to confirm
• ​Treatment​
  
  • multi-agent chemotherapy and limb salvage resection
    
    • chemotherapy
      
      • preoperative 8-12 weeks
      • maintenance 6-12 months
    • surgical resection
      
      • trend towards limb salvage whenever possible

Question 22

Differential for multiple lesions in a young adult

Answer 22

EG

Fibrous dysplasia

Leukemia

Lymphoma

Hemangioendothelioma

Enchondroma / Olliers / Marfucci’s

Osteochondroma / MHE

NOF / Jaffe-Campanacci syndrome

Question 23

Differential for multiple lesions in an older adult

Answer 23

Paget’s

Metastatic bone disease

Multiple myeloma

Lymphoma

Hyperparathyroidism

Bone infarcts

Question 24

Lesions that have a cold bone scan

Answer 24

multiple myeloma

melanoma

Question 25

Sacral lesions < 40

Answer 25

Giant cell tumor

ABC

Ewing’s

Osteosarcoma

Question 26

Sacral lesions 40-80

Answer 26

Chordoma

Metastasis

Myeloma

Lymphoma

Chondrosarcoma

MFH

Question 27

How to assess an XR for a tumour

Answer 27

• Age
• Location
  
  • Epiphyseal vs metaphyseal vs disphyseal
  • Medullary vs cortical
• Geographic vs Permative - geographic will stay with-in the lesion​
• What is the tumor doing to the bone?
  
  • Lytic vs blastic
  • infiltrative - moth eatten, permeative
• What is the bone doing to the tumour?
  
  • Cortical reaction - expansile, sclerotic rimming, lysis
  • Periosteal reaction
  • Onion skinning, sunburst, spiculated
• Mineralization/Matrix
  
  • Ground glass
  • calcification
• Size and number
• Associated soft tissue mass

Question 28

Differential diagnosis by location

Answer 28

• Surface lesions
  
  • Osteochondroma
  • Periosteal chondroma
  • Surface ABC
  • Parosteal osteosarcoma
  • Surface chondrosarcoma
• Epiphyseal
  
  • chondroblastoma
  • Chondrosarcoma
  • OM
• Epiphyseal-Metaphyseal
  
  • GCT
  • ABC
• Metaphyseal
  
  • Unicameral bone cyst
  • Osteosarcoma
  • Enchondroma
  • Chondrosarcoma
  • Chondromyxoid fibroma
  • Non-ossifying fibroma
• Diaphyseal
  
  • Osteoid osteoma
  • Osteoblastoma
  • Stress fracture
  • OM
  • Fibrous dysplasia
  • Adamatinoma
  • Ewings
• Periarticular
  
  • Synovial chonromatosis
  • PVNS
  • NOT synovial sarcoma

Question 29

Most common tumour of the sacrum?

Answer 29

chordoma

Question 30

What is the most common malignant spinal tumour in adults?

Answer 30

chordoma

Question 31

Differential? How can you confirm you diagnosis?

Answer 31

Chordoma

• Differential
  
  • Plasmacytoma
    
    • Cold on bone scan
  • OM, Lymphoma
    
    • More acute onset with systemic features
  • Chondrosarcoma, mets
    
    • Will have associated soft tissue mass​
• Histology
  
  • characterized by foamy, vacuolated, physaliforous cells
    
    • grows in distinct nodules
  • histochemical staining
    
    • keratin positive
      
      • important to distinguish from chondrosarcoma which is not keratin positive
    • weakly S100 positive
      
      • ​can distinguish from adenocarcinoma

​

Question 32

Differential? Diagnosis? Typical Presentation? Treatment/Managment?

Answer 32

Chordoma

• Differential
  
  • Chordoma
  • Plasmacytoma
    
    • Cold on bone scan
  • OM, Lymphoma
    
    • More acute onset with systemic features
  • Chondrosarcoma, mets
    
    • Will have associated soft tissue mass
• Presentation
  
  • insidious onset of pain
  • often complain of bowel or bladder changes
  • sensory deficits rare due to distal nature of tumor
  • gastrointestinal - constipation, fecal incontinence
• Physical exam
  
  • neurologic
  • motor deficits rare because most lesions at S1 or distal
  • bowel and bladder changes are common
  • rectal exam
    
    • more than 50% of sacral chordomas are palpable on rectal exam
• Work up
  
  • CBC and diff, lytes, Cr, Urea, INR, PTT, SPEP, UPEP
  • Radiographs
    
    • often difficult to see lesion due to overlying bowel gas
    • CXR for staging
  • CT - chest/abdo/pelvis
    
    • local staging
    • will show midline bone destruction and soft tissue mass
    • calcifications often present within the soft tissue lesion
  • MRI
    
    • bright on T2
    • useful to evaluate soft tissue extension
  • Bone scan
    
    • other bony sites of metastasis
    • Hot on bone scan, which is different from plasmacytoma
• Biospsy
  
  • physoliferous cells
  • postivie keratin staining
  • S100 positive
• Consult orthopedic oncology team, radiation oncology
• radiation treatment
  
  • inoperable tumors
• wide margin surgical resection +/- radiation
  
  • standard of care in most patients
  • technique
    
    • must be willing to sacrifice sacral nerve roots to obtain adequate surgical margins
    • add radiation if margin not achieved
  • outcomes
    
    • long-term survival 25-50%

Question 33

Epidemiology of chordoma?

Answer 33

• A malignant tumor of primitive notochordal origin
  
  • slow growing and frequently misdiagnosed as low back pain
• Epidemiology
  
  • most common primary malignant spinal tumor in adults
• demographics
  
  • 3:1 male to female ratio
  • usually in patients > 50 years
• location
  
  • 50% occur in the sacrum and coccyx
  • 35% in spheno-occiptal region
  • 15% in mobile spine
  • Note most present as 1B (with extension into the paravertebral space, but 1a is just in the vertebrae)
• Pathoanatomy
  
  • forms from malignant transformation in residual notochordal cells
  • resulting in midline location
• Prognosis
  
  • metastatic disease in 30-50%
  • occurs late in the course of the disease so long term follow up required
  • may spread to lung and rarely to bone
• survival
  
  • 60% 5-years survival
  • 25% long term survival
  • local extension may be fatal
• 50% recurrence following resection

Question 34

What is diagnosis? What are the principle of treament

Answer 34

​Cervical Chordoma

• wide margin surgical resection +/- radiation
  
  • standard of care in most patients
• Bring in other members of team - vascular/gen sx/urology/orthopedic oncology
• technique
  
  • Wide, enbloq resection
    
    • If there are mets can do intralesion excision to debulk the tumor
    • OR if there are structures that cannot be sacrificed to manintain a wide resection
    • must be willing to sacrifice sacral nerve roots to obtain adequate surgical margins
  • add radiation if margin not achieved
• outcomes
  
  • long-term survival 25-50%
• Complications
  
  • Commonly have reduced perianal sensation and sexual dysfunction
  • Low sacral resections preserve bowel/bladder
  • Middle resections will have reduced sphinceter tone, but usually preserve motor function
  • High will result in motor dysfunction
  • Cervical - dyphonia, dysphagia, horners, hypoglosseal nerve injury

Question 35

What is the most important factor in the prognosis of chordoma

Answer 35

local recurrence

reduced by en bloq excision

Question 36

Diagnosis? Differential? Treatment?

Answer 36

UBC with path#

• Differential
  
  • UBC, ABC
    
    • ABC is usually wider then the epiphysis
  • Fibrous dysplasia
  • Enchondroma
  • telanectaticosteosarcoma
  • Intraosseous ganglia
• Classification is important as it impacts treatment
  
  • active - if cyst is adjacent to the physis
  • latent - if normal bone separates cyst from physis
• 50% present with pathological fracture, otherwise painless
• Observation
  
  • If the patient is assymptomatic and the fracture is not in a weight bearing bone you may be able to observe the cyst every 2-3 months. As the patient approaches skeletal maturity it may resolve
• Immobilization alone
  
  • proximal humerus lesions with pathologic fracture (15% of lesions fill in with native bone after acute fracture)
    
    • Healing is defined as >95% opacification of the cyst with cortical thickening
    • Incomplete is <80% with no cortical thickening
• Aspiration and methylprednisolone acetate injection
  
  • active cysts (communicates with physis) in the proximal humerus
  • technique
    
    • usually requires several injections, especially in very young children
  • bone marrow injections have recently been reported to be effective, but have not yet been proven to be superior to steroid injections
  • Recurrence rate is 15-88%
• curettage and bone grafting +/- internal fixation based on tumor location
  
  • contraindications
    
    • active lesion next to physis as will cause growth arrest
  • indications
    
    • symptomatic latent cysts that have not responded to steroid injections
    • latent cysts in the proximal femur that are a structural concern and at risk for fracture and osteonecrosis
    • proximal femoral lesions with a pathologic fracture have a high rate of refracture and malunion when treated nonoperatively
  • Technique
    
    • Approach the bone, drain the cyst and currette out the fibrous lesion
    • Pack with graft
    • Allograft versus autograft versus simulated is dealers choice
    • Structural support often necessary, this is usually done with plates
    • Consider open physes
• Recent innovations
  
  • There is some recent literature to support decompression with a flexible nail that has had good results
    
    • A second procedure is needed to remove the nail
  • Some have combined this with calcium sulphate graft with good outcomes
    
    • Helps with follow-up because it is radio-opaque, so easier to assess for recurrence ​
• Recurrence rate
  
  • reported to be as high as 45%
    
    • >90% in patients >10 heal, only 60% patients <10
    • Lesions <2cm from physis have a higher risk of injury
• Complications
  
  • Local reaction to material used to fill the cavity
  • Pathological fracture
  • Growth disturbance

​

Question 37

Recurrence rate of UBC

Answer 37

• <10% fill in with fracture (15% in orthobullets)
• Recurrence rate
  
  • reported to be as high as 45%
  • >90% in patients >10 heal, only 60% patients <10
  • Lesions <2cm from physis have a higher risk of injury

Question 38

Complications associated with UBC

Answer 38

• Complications with femur fractures
  
  • Varus malunion
  • Growth arrest
  • Femoral head osteonecrosis
• Complications
  
  • Local reaction to material used to fill the cavity
  • Pathological fracture
  • Growth disturbance
  • recurrence

Question 39

Diagnosis? Differential? Common presentation?

Answer 39

• A non-neoplastic, serous fluid-filled bone lesion thought to result from temporary failure of medullary bone formation near the physis
• usually found in patients <20 years of age
• usually found in the proximal humerus
  
  • can be found in other locations including proximal femur, distal tibia, ilium, calcaneus, and occasionally metacarpals, phalanges, or distal radius
  • arises in the metaphysis adjacent to physis and progresses toward the diaphysis with bone growth
• Prognosis
  
  • as a patient approaches skeletal maturity, a UBC will often decrease in size and may heal after growth is complete
  • fracture healing usually does not lead to cyst resolution (<10%)
• Pathoanatomy
  
  • Unknown etiology
  • Due to fluid build up with-in the bone that causes resorption
  • May be due to vascular occlusion secondary to high pressure
  • Some research to suggest that lowering interstitial pressure will cause involution
• Differential
  
  • UBC, ABC
    
    • ABC is usually wider then the epiphysis
  • Fibrous dysplasia
  • Enchondroma
    
    • Occurs more in the tubular bones of the hands and feet
  • Intraosseous ganglia
  • telangectatic osteosarcoma
• Typical XR findings
  
  • central, lytic, well-demarcated metaphyseal lesion (2-3% cross physis)
  • cystic expansion with mild symmetric thinning of cortices
  • “fallen leaf” sign (pathologic fracture with fallen cortical fragment in base of empty cyst is pathognomonic)
  • trabeculated appearance after multiple fractures
  • MRI shows rim enhancement of the sclerotic rim

Question 40

Treatment?

Answer 40

UBC of proximal femur

• Cutettage, bone grafting and fixation for proximal femur fractures
  
  • Classified and treated based on the amount of bone deficit
  • Should be immbolized with a hip spica for younger patients
  • In type IA, a cyst of moderate size present in the middle of the femoral neck. The lateral buttress is intact, and sufficient bone is available in the femoral neck and lateral proximal femur to allow fixation with cannulated screws.
  • In type 1B, a large cyst is present at the base of the femoral neck. The lateral buttress is compromised; therefore, the use of a pediatric hip screw and side plate should be considered
  • Types IIA (C) and 11B (D) are characterized by a krge bsion in the femoral neck.
  • In type IllA, the lateral buttress is present, and cannulated screws can be used to stabilize the fracture.
  • In type 111B, the loss of the lateral buttress requires the use of a pediatric hip screw and a side plate for fixation following curettage and bone grafting.
• Complications with femur fractures
  
  • Varus malunion
  • Growth arrest
  • Femoral head osteonecrosis

Question 41

Differntial. Diagnosis? Common presentation and findings on imgaing

Answer 41

ABC

• Differential
  
  • Radiographic differential includes
    
    • UBC
    • telangiectatic osteosarcoma
      
      • Will usually have thicker, nodular rimming on MRI
  • Histologic differential includes
    
    • telangiectatic osteosarcoma
      
      • Will have evidence of peiomorphism
    • giant cell tumor
• A benign and non-neoplastic reactive bone lesion filled with multiple blood-filled cavities
  
  • can be locally destructive to normal bone and may extend to soft tissue
• 75% of patients are < 20 yrs.
• Radiographs
  
  • expansive, eccentric and lytic lesion with bony septae (“soap-bubble appearance”)
  • usually in metaphyseal
  • Proximal tibia and distal femur
    
    • most common tumor of the posterior elements of the spine
  • classic cases have thin rim of periosteal new bone surrounding lesion
  • no matrix mineralization
• MRI or CT scan
  
  • will show multiple fluid lines
  • Characteristic but not pathognomonic
    
    • Also see with GCT, Telangectatic osteosarcoma
  • lesion can expand into soft tissue
• Histology
  
  • Incisional biopsy is the standard
    
    • FNAB does not provide adequate specimen, especially considering the high incidence with other neoplasms
  • Characteristic findings
    
    • cavernous space
    • blood-filled spaces without endothelial lining
    • cavity lining
    • numerous benign giant cells
    • spindle cells
  • thin strands of woven (new) bone present
  • ***Important do diff from telangectatic osteosarc - which will see peliomorphism

Question 42

Differential ABC from TSO

Answer 42

• Aneurysmal Bone Cyst
  
  • 10–20
  • Femur, tibia, fibula, humerus
  • Blood-filled spaces separated by thin fibrous septa with benign-appearing spindle cells Osteoid with or without osteoblastic rimming
  • Inflammatory cells and giant cells may be present
  • Curettage with adjuvant sclerotherapy, emobo- lization, or en bloc resection
• Telangectatic osteosarcoma
  
  • 10–20
  • Distal femur, proximal tibia, proximal humerus
  • Blood-filled spaces separated by thicker fibrous septa, with malignant-appearing cells more easily noted at higher magnification
  • Pleomorphism, atypical mitotic figures, and possible osteoid formation
  • Neoadjuvant chemotherapy, wide surgical resection and reconstruction, postoperative chemotherapy

Question 43

Diagnosis? Treatment?

Answer 43

ABC

• Discuss with an experienced MSK radiologist and pathologist to ensure this is not TOS before proceeding
• nonoperative fracture management
  
  • ABC with acute fracture
  • indicated until fracture has healed. Once healed, treat as an ABC without fracture unless the fracture has led to spontaneous healing of the ABC
• aggressive curettage and bone grafting
  
  • symptomatic ABC without acute fracture
  • technique
    
    • some use adjuvant treatment (phenol)
    • Better result if you are more aggressive - ie; high speed burr
  • outcomes
    
    • local recurrence in up to 25% and more common in children with open physes
      
      • >12
      • Open physes
      • High component of cellular content
      • Mitotic index >7 per 50 feilds
• Sclerotherapy
  
  • Some reports of reduced recurrence compared to curettage
  • Others not reduced recurrence, but better functional outcomes and reduced complications
  • Ethibloc is associated with a fatal cerebellar infarct and should not be used as first line treatment
• Embolization with experimental results
• En bloc resection
  
  • Recommended to reduce recurrence rates in bones that are expendable (fibula/clavicle)

Question 44

Risk factors of recurrence with ABC

Answer 44

>12
Open physes
High component of cellular content
Mitotic index >7 per 50 feilds

Question 45

Classification of ABC

Answer 45

• Type I lesions are centrally located and well contained, with either no outline or a slightly expanded outline
• Type II lesions have marked expansion and cortical thinning with involvement of the entire bony segment.
• Type III lesions are eccentric and metaphyseal and typically involve only one cortex.
• Type IV lesions are the least common subgroup and develop subperiosteally, expand- ing away from the bone
• Type V lesions occur periosteally and expand peripherally, ultimately penetrating cortical bone.

Question 46

Describe this XR. Differential? Epidemiology of top diagnosis.

Answer 46

Giant cell tumor

• Differential for epiphyseal lesions
  
  • GCT, ABC, TOS
  • Chondroblastoma
  • Interosseous ganglia
  • Clear cell chondrosarcoma
• A benign aggressive tumor typically found in the epiphysis of long bones
• F>M (unlike most bone tumors which show male predominance)
• ages 30-50 years
• Knee>sacrum>distal radius
  
  • 50% occur around knee (distal femur or proximal tibia)
  • 10% in sacrum and vertebrae
  • while GCT can rarely occur in the spine, it usually usually occurs in the vertebral body
  • phalanges of the hand is also a very common location
  • may arise in the apophysis (like chondroblastoma)
• Malignant potential
  
  • primary malignant giant cell tumor
    
    • metastatic to lung in 2-5%
    • hand lesions have greater chance of metastasis
  • secondary malignant giant cell tumor (15%)
    
    • occurs following radiation or multiple resections of giant cell tumor - thought to be due to older techniques
    • No evidence that fracture will increase rate of transformation of mets

Question 47

Diagnosis? Common Presentation? Work-up?

Answer 47

Giant Cell Tumour

• Presentation
  
  • pain referable to involved joint
  • palpable mass
  • decreased range of motion around affected joint
  • May present as pathological fracture
• Radiographs
  
  • eccentric, lytic
  • epiphyseal/metaphyseal lesion that often extends into the distal epiphysis and borders subchondral bone
  • expansile, formation of neocortex
  • may have associated soft tissue mass
  • knee, distal radius, sacrum, vertebral body, hand, can also see in proximal femur
• Bone scan is very hot
  
  • GCT are very vascular tumour
• MRI
  
  • shows clear demarcation on T1 image between fatty marrow and tumor
  • In some cases they can be quite aggressive with associated cortical destruction and soft tissue mass
  • In very advanced tumors they can expand into the cartilage of the joint
• Histology
  
  • neoplastic cell is the mononucleur stromal cell
  • hallmark - giant cells are numerous
  • secondary aneurysmal bone cyst degeneration is not uncommon
  • Often have more nuclei than other tumors that contain giant cells (>50)
  • Mesenchymal tumour - produces Type 1 and type 2 collagen
  • VEGF (vascular endothelial growth factor) and MMP (matrix metaloprotein) are associate with metastasis

Question 48

Diagnosis? Treatment/Management?

Answer 48

Giant cell tumor

• Differential for epiphyseal lesions
  
  • GCT, ABC, TOS
  • Chondroblastoma
  • Interosseous ganglia
  • Clear cell chondrosarcoma
• If the diagnosis is clear from the XR, you can go ahead with treatment - confirm with MSK radiologist and ortho oncologist first
• Staging (if you need to stage)
  
  • ​Full imaging of bone
  • Bone scan to rule out other lesions
  • MRI to assess local staging
  • CXR - 2% mets to lungs
• Biopsy after staging if concerns
• Radiation alone
  
  • only indicated for inoperable or multiply recurrent lesions
  • leads to 15% malignant transformation
• Medical management
  
  • medical therapy can be used to augment or replace surgical management depending on the specific clinical senario
  • bisphosphonates
    
    • osteclast inhibitors which may decrease the size of the defect in giant cell tumors
  • denosumab
    
    • monoclonal antibody against RANK-ligand
    • recent clinical trials suggest denosumab can decrease the size of the bone defect in giant cell tumor
  • Interferon
    
    • often used with mets
• extensive curettage and reconstruction (with adjuvant treatment)
  
  • challenge of treatment is to remove lesion while preserving joint and providing support to subchondral joint
  • Aggressive curettage
    
    • extensive exterioration (removal of a large cortical window over the lesion) is required
    • Need to be aggressive with burrs a
  • Adjuvant Treatment
    
    • 10-30% recurrence with curettage alone verses 3% with adjuvant treatment
    • hydrogen peroxide, argon beam, phenol
    • Liquid nitrogen not used because it causes fracture
  • Augment
    
    • can fill lesion with bone cement or autograft/allograft bone
    • bone cement - cheap, structural, easy to see recurrence
  • Stabilization
    
    • _​_locking plate
• En bloc resection with structural allograft and endoprosthesis
  
  • Recurrence
  • Grade 3
  • Expendable bone
    
    • Clavicle, distal ulna, proximal and middle fibula
• ​Surgical excision of mets with treatment of interferon

Question 49

Special considerations in GCT you should be aware of

Answer 49

• hand lesion treatment is controversial
  
  • if no cortical breakthrough treat with curettage and cementing
  • if significant cortical breakthrough consider intercalary resection (with free fibular graft) vs. amputation
• Sacrum
  
  • Often hard to get access to, commonly abuts the SI joint
  • Radiation can be considered
  • Pre-op embolization can be beneficial in the spine to help control bleeding of these vascular tumors
• Mets to lungs
  
  • Elevation of c-myc oncogene
  • Treat with surgical resection and interferon with good results

Question 50

Enneking and capancci classificaiton of GCT

Answer 50

Enneking

1. Benign, indolent, or biologically static
2. Progressive growth, limited by natural barriers
3. Locally aggressive with corre- sponding soft-tissue mass

Campanacci

1. Radiographically well-circumscribed lucent lesion with no aggressive features (eg, periosteal reaction, soft-tissue mass, cortical breach). Rare.
2. Relatively well-defined radiographic borders without a radiopaque rim
3. Indistinct or ill-defined borders with radiographic demonstration of cortical bone destruction, and a soft-tissue mass

Question 51

Differnetial? Diagnosis?

Answer 51

osteofibrous dysplasia

• Differential
  
  • ​OFD and AD
  • fibrous dysplasia
  • nonossifying fibroma
  • unicameral bone cyst
  • aneurysmal bone cyst
  • chondromyxoid fibroma
  • Langerhans cell histiocytosis (ie, eosinophilic granu- loma)
  • osteomyelitis
  • osteosarcoma
  • chondrosarcoma
  • hemangioendothelioma
  • angiosarcoma
  • metastatic carcinoma

Question 52

Risk of mets in adamatinoma

Answer 52

25% overall

Classic AD (lower with OFD-like AD)
Symptoms \< 1 yr
Initial management of intralesional or marginal resection

Question 53

Differential? Diagnosis? Management Plan?

Answer 53

Adamantinoma

• 20-40 yo
• tibial lesion, similar in appearce to osteofibrous dysplasia
• Presentation
  
  • pain of months to years duration
• Physical exam
  
  • bowing deformity or a palpable mass of tibia is common
• Radiographic characteristics
  
  • multiple sharply circumscribed lucent lesions (“soap bubble” appearance) with interspersed sclerotic bone in mid tibia
  • some lesions may destroy cortex
  • may see bowing of the tibia
  • unlike other primary bone tumors, adamantinoma typically shows no periosteal reaction
• CT extremity and chest
  
  • Can help determine the extent of cortical destruction
  • rule out mets
• MRI
  
  • Important to determine the margins of the tumour and the soft tissue expansion to get tumour free margin
  • Can help assess for multi-focal disease
• Biopsy
  
  • Important even for benign looking lesions
  • Open biospy with adequate sample
  • Can be very hetergeneous and is important to differentiate from osteofibrous dysplasia
• wide-margin surgical resection
  
  • often requires intercallary resection with allograft or intercallary megaprosthesis reconstruction
  • as adamantinoma is a low-grade malignancy, radiotherapy and/or chemotherapy is not typically used for local control of disease
• Surgical resection of mets

​

Question 54

Diagnosis? Management?

Answer 54

Adamantinoma

• full history and physical
• XR
• CT chest and lesion, MRI
• alway biopsy in 20-40 becasue AD can look like OFD
• This lesion was treated with wide resection and bone graft

Question 55

Diangosis? Management

Answer 55

Osteofibrous Dysplasia

• < 10 yo
• M>F
• tibia, confined to cortices
• usually regresses into childhood
• Presentation​
  
  • may be asymptomatic
  • painless swelling
  • anterior or anterolateral bowing of the tibia
  • pseudoarthrosis develops in 10-30% of patients
• Radiographs
  
  • anterior eccentric lytic tibial lesion in child that often leads to tibial bowing
  • usually diaphyseal
  • no periosteal reaction
  • confined to anterior cortex
  • looks very similar to adamantinoma
• observation
  
  • first line of treatment
  • alone is the treatment for most patients
  • bracing
    
    • if deformity significant and interfering with walking
    • can help to minimize fracture
  • Casting pathological fracture
    
    • _​_usually sufficient to heal fracture but will take longer
• deformity correction with osteotomy
  
  • indication
    
    • rarely needed
    • significant deformity
  • perform after skeletal maturity

​

Question 56

Diagnosis? Associated conditions and manifestations?

Answer 56

Fibrous Dysplasia

• A developmental abnormality caused by failure of the production of normal lamellar bone
  
  • Fill in with a fibrous tissues, thought to be due to differntiation of cells
• females > males
• found in any and all ages
• onset for 75% of patients at <30 years of age
• location
  
  • the _proximal femu_r is most common site, followed by rib, maxilla, and tibia
• Genetics
  
  • GS alpha protein (chromosome 20q13) activating mutation (affects cAMP signaling pathway leading to increased production of cAMP)
  • not inherited
  • high production of FGF-23 which may lead to hypophosphatemia
• Associated conditions
  
  • McCune Albright syndrome (30-50%)
    
    • condition defined by the presence of (triad)
    • skin abnormalities (cafe au lait spots in coast of Maine pattern - irregular borders)
    • endocrine abnormalities (precocious puberty)
    • renal phosphate wasing due to FGF-23 (oncogenic osteomalacia)
    • Vaginal bleeding, faster growth, advanced tanner staging
    • unilateral polyostotic fibrous dysplasia
    • Risk of malignancy = 4%
  • Mazabraud syndrome
    
    • polyostotic fibrous dysplasia
    • soft-tissue intramuscular myxomas
      
      • Slowly growing mass, usually present later
    • No malignant transformation
  • Cherubism
    
    • Symmetric invovlement of mandible and maxilla
    • Can distort the orbits
    • Becomes quiet when reaches skeletal maturtiy
  • Osteofibrous dysplasia
    
    • rare form that primarily affects the tibia and is confined to the cortices
• nonorthopedic manifestations (more common with polyostotic)
  
  • Hyperthyroidism
  • Hypophosphatemia
  • Acromegaly
  • hyperprolactinemia
  • Abnormalities of brain, heart, liver and spleen
  • severe cranial deformities with blindness can occur
• Prognosis
  
  • 1% risk of malignant transformation to osteosarcoma, fibrosarcoma, or malignant fibrous histiocytoma
  • Most common site is craniofacial bones
  • poor prognosis
  • 4% in Mcune albright

Question 57

Syndromes associated with fibrous dysplasia

Answer 57

• McCune Albright syndrome (30-50%)
  
  • condition defined by the presence of (triad)
    
    • skin abnormalities (cafe au lait spots in coast of Maine pattern - irregular borders)
    • endocrine abnormalities (precocious puberty)
      
      • renal phosphate wasing due to FGF-23 (oncogenic osteomalacia)
      • Vaginal bleeding, faster growth, advanced tanner staging
    • unilateral polyostotic fibrous dysplasia
      
      • Risk of malignancy = 4%
• Mazabraud syndrome
  
  • polyostotic fibrous dysplasia
  • soft-tissue intramuscular myxomas
    
    • Slowly growing mass, usually present later
  • No malignant transformation
• Cherubism
  
  • Symmetric invovlement of mandible and maxilla
    
    • Can distort the orbits
  • Becomes quiet when reaches skeletal maturtiy
• Osteofibrous dysplasia
  
  • rare form that primarily affects the tibia and is confined to the cortices

Question 58

Extraskeletal manifestations of fibrous dysplasia?

Answer 58

• Skin (with mcune albright)
  
  • irregular cafe au lait spots
• Hyperthyroidism
• Hypophosphatemia
• Acromegaly
• hyperprolactinemia
  
  • precocious puberty
• Abnormalities of brain, heart, liver and spleen
• severe cranial deformities with blindness can occur

Question 59

25yo female comes in with pain in her leg and progressive deformity. Diagnosis? Work-up?

Answer 59

Fibrous Dysplasia

• Symptoms
  
  • usually asymptomatic and discovered as an incidental finding
  • may have swelling or deformity
  • bone lesions may be monostotic (80%) or polystotic (20%)
  • pain from stress fractures
  • Complete medical history to rule out associated endocrine anomalies
• Physical exam
  
  • inspection
    
    • cafe au lait spots, skin hyperpigmentation
      
      • larger and more irregular borders than neurofibromatosis
    • swelling around lesion (prominent jaw, rib mass, bossing of the skull)
  • Can get bowing of affected bones due to microfracture and remodelling
  • Look for signs of precocious puberty
• Screening blood work with referal to pediatrician for full endocrine work-up​
  
  • ALP, urine hydroxyproline
    
    • Usually elevated with active disease
    • Can be used to follow response to treatment
  • TSH, Ca, Phos
  • Testosterone, estrogen, estradiol
• Radiographs
  
  • central lytic lesions in medullary canal (diaphysis or metaphysis)
  • may have cortical thinning with expansile lesion
  • highly lytic lesions or a ground glass appearance
  • “punched-out” lesion with well defined margin of sclerotic bone is common
  • modest expansion of bone
  • Shepherd’s crook deformity
  • vertebral collapse and kyphoscoliosis
  • Evidence of malignant transformation
    
    • Lytic lesion where previously sclerotic
    • Periosteal reaction
    • Cortical disruption
    • Soft tissue mass
• Bone scan
  
  • usually warm, cold does not rule lesion out
  • Helpful to identify polyostotic lesions
• CT
  
  • Can help assess bone quality and extent of lesion
• MRI
  
  • Can help assess full lesion with cystic degeneration
  • Help stage the soft tissue lesion following malignant degen
• Histology
  
  • ​alphabet soup
  • Trabeculae not lined with osteoblasts

Question 60

15yo male. Fall from height and unable to WB on right side. Diagnosis? Treatment?

Answer 60

Fibrous Dysplasia

• Work-up
  
  • ALP, hydroxyproline urine
  • TSH, Ca, Phos
  • Testosterone, estrogen, estrodiol if concerned
  • Full length XR
  • Bone Scan - assess for other lesions
  • CT/MRI
• observation
  
  • asymptomatic patients
• Diphosphonate therapy
  
  • symptomatic polyostotic fibrous dysplasia
  • effective in decreasing pain and reducing bone turnover
  • Evidence of:
    
    • Cortical thickening
    • Decreased pain
    • Progressive ossification
    • Prevent pathological fracture
    • Decrease N-telopeptide
    • Decrease size of the lesion
• Ca and Vitamin D
  
  • Can help prevent secondary hyperparathyroidsim
• internal fixation and bone grafting
  
  • indications
    
    • symptomatic lesions
    • impending/actual fractures through lesions in areas of high stress (femoral neck)
    • severe deformity
    • neurologic compromise in the spine
    • Nonunion
    • malignancy
  • technique
    
    • never use autogenous cancellous bone, as the transplanted bone will quickly turn into fibrous dysplastic woven bone
      
      • use cortical allografts
    • intramedullary device more effective than a plate in the lower extremity
    • Then can currette the lesion if accessible
• Pathological fracture
  
  • Casting
    
    • Microfracture/pathological fracture needs to be treated first with cast immobilizaition in the upper extremity
  • Proximal femur fractures
    
    • Treat with IM Nail
    • IV bisphosphanates
• osteotomies
  
  • Valgus osteotomy - coxa valga
    
    • Helps to reduce risk of pathological fracture
  • Medializing osteotomy - shepard’s crook
• Outcomes
  
  • Upper extremity does well with operative or non-operative treatment
  • Lower extremity more often requires internal fixation
  • <18 have worse outcomes due to recurrent pathological fractures

Question 61

Indications to operate on fibrous dysplasia

Answer 61

• symptomatic lesions
• impending/actual fractures through lesions in areas of high stress (femoral neck)
• severe deformity
• neurologic compromise in the spine
• Nonunion
• malignancy

Question 62

Manifestations of Pagets

Answer 62

• Orthopedic
  
  • long bone bowing and bone pain
  • fractures
  • large joint osteoarthritis (medial OA with protrusio)
  • Spinal cord compression
  • high output cardiac failure
• Other
  
  • Hearing loss
  • Warmth over affected area
  • Vertigo
  • Cranial nerve palsies
  • • Paget’s sarcoma
  • less than 1% will develop malignant Paget’s sarcoma (secondary sarcoma)
  • osteosarcoma is the most common, followed by fibrosarcoma and chondrosarcoma
  • most common in pelvis, femur, and humerus
  • Paget’s sarcoma has a poor prognosis
  • 5-year survival for non-metastatic Paget’s sarcoma is less than 5%
  • appropriate treatment for Paget’s sarcoma includes chemotherapy and wide surgical resection

Question 63

Stages of Pagets

Answer 63

• (1) an initial, short-lived burst of multinucleate osteoclastic activity, causing bone resorption
  
  • Get increased ALP
• (2) a mixed phase of both osteoclastic and osteoblastic activity, with increased levels of bone turnover leading to deposition of structurally abnormal bone
• (3) a final chronic sclerotic phase, during which bone formation outweighs bone resorption

Question 64

Work-up for Pagets

Answer 64

• Labs
  
  • ESR, CRP
    
    • If elevated may be due to malignant transformation
  • elevated serum alkaline phosphatase, urinary hydroxyproline (collagen breakdown marker)
    
    • Can be used to monitor response to therapy
  • increased urinary N-telopeptide, alpha-C-telopeptide, and deoxypyridinoline
  • normal calcium levels and Vit D
    
    • Should be used to screen for other metabolic disease
• Radiographs
• coarsened trabeculae which give the bone a blastic appearance
• both increased and decreased osteodensity may exist depending on phase of disease
• lytic phase
  
  • lucent areas with expansion and thinned, intact cortices
  • ‘blade of grass’ or ‘flame-shaped’ lucent advancing edge
• mixed phase
  
  • combination of lysis and sclerosis with coarsened trabeculae
• sclerotic phase
  
  • bone enlargement with cortical thickening, sclerotic and lucent areas
  • remodeled cortices
  • loss of distinction between cortices and medullary cavity
• long bone bowing
• bowing of femur or tibia
• fractures
  
  • commonly femoral neck
• hip and knee osteoarthritis
• osteitis circumscripta
  
  • (cotton wool exudates) in skull
• Arthritis associated with pagets
  
  • Medial OA (as opposed to superior)
  • Coxa vara
  • protrusio
• Paget’s secondary sarcoma
  
  • shows cortical bone destruction
  • soft tissue mass
• MRI
  
  • may show lumbar spinal stenosis
  • Would show a mix of fat and tumour in the marrow in the lytic phase
  • Will enhance with gadollinium
• Bone scan
  
  • accurately marks site of disease
  • intensely hot in lytic and mixed phase
  • less hot in sclerotic phase
• CT Scan
  
  • cortical thickening and coarsened trabeculae

Question 65

Medical Treatment of Pagets

Answer 65

• bisphosphonates
  
  • oral agents
    
    • alendronate and risedronate
    • etidronate disodium (Didronel)
    • older generation medication
    • inhibits osteoclasts and osteoblasts
    • cannot be used for more than 6 months at a time
  • intravenous agents
    
    • pamidronate, zoledronic acid (Zometa)
    • newer generation medications that only inhibit osteoclasts
    • disadvantageous in that they only come in IV form
• calcitonin
  
  • causes osteoclasts to shrink in size and decreases their bone resorptive activity within minutes
  • administered subcutaneously or intramuscularly
• teriparatide
  
  • is contraindicated in Paget’s disease due to risk of secondary osteosarcoma

Question 66

Approach to THA in this patient?

Answer 66

Pagets

• Indications
  
  • affected patients with degenerative joint disease
• technique
  
  • treat Paget’s with pharmacologic agents prior to arthroplasty to reduce excessive bleeding
  • Ok to do cementless
  • Malignment leads to early loosening
    
    • May need osteotomy
    • May need to burr out the canal (better than a rasp or reamer)
  • Component positioning
    
    • Protrusio, sclerosis
    • May need TM cup or antiprotrusio cage
    • Lateralizing liner
• outcomes
  
  • greater incidence of suboptimal alignment secondary to pagetoid bone
• Complications
  
  • HO - consider radiation
  • Blood loss
  • Non-union of osteotomy
  • Periprosthetic fracture
  • Loosening

Question 67

contraindications to limb salvage surgery

Answer 67

• Major neurovascular structures encased by tumor when vascular bypass is not feasible
• Pathologic fracture with hematoma violating compartment boundary
• Inappropriately performed biopsy or biopsy-site complications
• Severe infection in the surgical field
• Immature skeletal age with predicted leg-length discrepancy >8 cm
• Extensive muscle or soft-tissue involvement
• Poor response to preoperative chemotherapy

Question 68

Enneking staging system

Answer 68

• IA
  
  • Low Grade
  • T1 - intracompartmental
• IB
  
  • Low Grade
  • T2 - extracompartmental
• IIA
  
  • High Grade
  • T1 - intracompartmental
• IIB
  
  • High Grade
  • T2 - extracompartmental
• III
  
  • Metastatic
  • T1 - intracompartmental
  • M1 (regional or distant)
• III
  
  • Metastatic
  • T2 - extracompartmental
  • M1 (regional or distant)

Question 69

Diagnosis? Genetics? Characteristics?

Answer 69

Osteosarcoma

• Bimodal
  
  • ​second decade
  • later - pagets, radiation
• ​knee > proximal femur, humerus, pelvis
• Usually presents as IIB
  
  • ​20% have pulmonary mets
• ​Associated with retinoblastoma gene (Rb) and p53​
  
  • Le-Fremeni Syndrome
  • risk increased in Rothmund Thomson syndrome

Question 70

Prognostic factors of osteosarcoma

Answer 70

• advanced stage of disease (most predictive of survival)
• < 90% necrosis after chemo
• tumor site and size
• expression of P-glycoprotein
• high serum alkaline phosphatase
• high lactic dehydrogenase
• vascular involvement
• surgical margins
• type of chemotherapy regimen
• Skip mets
• Lymph node invovlement

Question 71

Comes in with pain, fever, chills, night sweats. Diagnosis? Work-up?

Answer 71

• Blood work
  
  • ESR, CRP, ALP, LDH
• Full length XR
  
  • blastic destructive lesion
  • sunburst, hair on end, codmans triangle
  • calcification/osteoid
  • large soft tissue mass
• MRI lesion
• Bone Scan - skip lesions, distant bony mets
• CT chest - more sensitive than CXR for pulmonary mets
• Biosy
  
  • lacey osteoid, high grade mitotic figures and malgnant features

Question 72

Treatment of osteosarcoma

Answer 72

• Preoperative chemotherapy 8-12 weeks; restage tumor and assess response, surgery; 6-12 months after surgical resection
• Multi-modal Chemotherapy
  
  • Goals
    
    • Treat metastases
    • Reduce tumour bulk
  • Common drugs - mutli-agent to reduce incidence of resistanace
    
    • Doxyrubici, cisplatnin, metotrexate, isofosamide
  • 98% necrosis after neo-adjuvant chemotherapy is good prognostic sign
  • Can assess this on the post-chemo CT, will show increased mineralization
  • expression of multi-drug resistance (MDR) gene portends poor prognosis
    
    • present in 25% of primary lesions and 50% of metastatic lesions
  • Can try other chemo if not good response, but expect that it won’t work
• Surgical technique
  
  • trend towards limb salvage whenever possible
  • overall survival in osteosarcoma is equal after limb salvage vs. amputation to deal with local extent of disease
  • Rotationplasty is a great surgical option which optimizes the patient’s function, and most commonly done in a pediatric population
  • Endoprosthesis
    
    • Pros
      
      • No need for ingrowth, no need to protect WB, no disease transmission
    • Cons
      
      • Infection, neuropraxia, necrosis, DVT, instability
    • Late
      
      • Aseptic loosening, infection, instability, fatigue fracture, wear, dissocation of components

Question 73

What are the outcomes of a patient with osteosarcoma

Answer 73

• Decreases with grade and mets
  
  • 83% in parosteal
  • 61% in high grade with good response to chemo
  • 37% in high grade with low response to chemo
• Surgical site recurrence is 4-6% and is equal for limb salvage and amputation
• Recurrence is 30-40%
  
  • Most common site is micromets to lungs
  • <20% survival rate, but should be offered repeat decompression

Question 74

Biopsy approach to C1-2

Answer 74

Anterior Retropharyngeal approach

• Supine / right transverse submandibular incision (extend vertically PRN)
• Incise platysma & fascia in line with skin incision
• ID Marginal Mandibular branch of VII and ligate retromandibular vein @ IJV
• Dissect deep to veins, stay ANTERIOR to SCM, keeping Carotid lateral
• Resect submandibular gland and ligate duct (CN XII close as well)
• Divide digastric, retract CN XII superiorly
• Dissection between Carotid Sheath & Larynx
• Ligate branches of ICA and IJV
• ID Superior laryngeal nerve
• Divide alar and prevertebral fascia to expose longus colli
• Biopsy through longus colli
• Expose anterior arch of C1 and body of C2

Question 75

Biopsy approach to C3-T1

Answer 75

Smith-Robinson Approach with following modifiers

• Vertical incision along anterior border of SCM (extensile)
• Platysma split longitudinally
• Longus colli split (as opposed to midline split and subperiosteal dissection)

Question 76

Biposy Approach T2-T12

Answer 76

Posterior Approach (Transpedicular Biopsy)

• Radiologically guided TPB better but if have to do open
• Prone, on bolsters
• Expose to facet joints and pedicle as with standard approach
• Landmark: middle of TP (top to bottom) at junction of pars (landmark is Mammilary Process)

Question 77

L1-Sacrum biopsy

Answer 77

Anterior Retroperitoneal Approach (L1 to Sacrum)

Question 78

Biopsy appraoch to scapula

Answer 78

• Acromion: Deltoid split
• Spine: Transverse incision directly over spine containing hematoma in deltoid
• Body: Judet posterior approach
• Glenoid: Posterior approach (usually IS/TM but go through fibers of TM)
• Coracoid: Deltopectoral approach extended proximally to coracoid

Question 79

Biopsy appraoch to humerus

Answer 79

• Head:
  
  • Anterior lesion through anterior raphe of deltoid to contain hematoma
  • Posterior lesion either make window anteriorly or posterior approach
  • For GT / LT / Neck do it through a deltoid split lateral to deltopectoral interval
• Shaft:
  
  • Modified Henry (find Radial Nerve between BR / Brach distally, retract laterally)
• Capitellu: Kocher (ECU / Anconeus) - anconeus is expendable; pronate to protect the PIN
• Trochlea: Medial approach to elbow (find Ulnar nerve)

Question 80

Biopsy appraoches to radius

Answer 80

• Distal radius
  
  • dorsally threw 2nd extensor compartment
  • ECRB and ECRL are expandable for wrist fusion
• ​Shaft - Henry Approach​
  
  • Proximal 1/3 - Supinate (taking off supinator)
  • Middle 1/3 - Pronate (taking off pronator teres)
  • Distal 1/3 - Supinate (taking off pronator quadratus)
  • Head - Kocher (ECU / Anconeus) – biopsy through anconeus (expendable) Must pronate arm to protect PIN

Question 81

Biopsy appraoches in hand

Answer 81

• Stay dorsally for MC and phalanges to avoid NV bundle
• Distal row carpals - stay dorsal and in line with adjacent metacarpal
• Scaphoid Russe approach
  *

Question 82

Biopsy approach to pelvis

Answer 82

• Iliac Crest:
  
  • If superficial, then may be able to Needle Bx; O/W approach as bone graft If lateral to crest, then go lateral (sacrifice small amount of abductors)
  • If medial to crest, then go medial (definitive resection is ilioinguinal)
• Anterior column
  
  • Problem is the femoral vessels; Watson-Jones through Medius
• Posterior column
  
  • Problem is sciatic nerve; Modified Kocher-Langenbeck
  • Go through posterior edge of gluteus maximus
• Pubis: Pfannenstiel approach
• Ischium
  
  • Lithotomy position, incision medial to Poupart’s Ligament, curve around ischium Detach adductor & Obt Externus from pubis and ischium (beware S. Cord) GMax on inferior ischium – retract; Free hamstrings off ischium
• Sacrum
  
  • CT Guided Bx or open midline posterior approach, needle through ala / body Combined anterior / posterior approach with diverting loop colostomy

Question 83

Approach to femoral biospy

Answer 83

• Femoral Head
  
  • If looks benign, Watson-Jones, curet through cortical window, bone graft, ORIF
  • If primary bone tumor or malignancy Bx through trochanter and do 2-stage
  • If primary bone then resection arthroplasty; If malignant

Question 84

Approach to tumors around the knee for biopsy

Answer 84

• Popliteal fossa
  
  • Classic indication is for parosteal OSA
  • MRI to rule out pop. artery aneurysm / location of vessels / within tumor?
  • Go through one of the 4 muscles of the popliteal fossa (Hams / Gastrox)
  • Biceps
• Medial tibial plateau
  
  • Medial approach to knee (infrapatellar br. of saphenous n) 3cm medial to patella with curved incision, pes posteriorly
  • Separate medial head of gastrox from posterior capsule
• Lateral tibial plateau
  
  • Lateral approach to knee (common peroneal nerve @ Biceps, Lat Inf Geniculate) 3cm lateral to patella with curved incision @ Gerdy’s tubercle
  • Interval ITB / Biceps (Go through Biceps for Bx)

Question 85

Biopsy appraoch to talus and calcaneus

Answer 85

• Talus - most require BKA/Symes
  
  • Head
    
    • Medial approach (Tib Ant / Tib Post)
    • May require medial malleolar osteotomy to visualize talus
  • Neck
    
    • Medial approach via medial malleolar osteotomy
  • body/dome
    
    • Ollier Type Incision
    • 2cm anterior to anterior border of fibula, cross ankle 2cm medial to tip of LM End incision at base of 5th MT
    • Dangers: Superficial peroneal nerve
• Calcaneus
  
  • Essentially same as ORIF incision (L-shaped lateral above heel pad) (beware Sural)
  • Retract peronei anteriorly after incising sheath
• Navicular: Medial longitudinal over tib post
• Cuboid: Distal extension of calcaneous ORIF (Glaborous / Nonglaborous skin jct)
• Medial Cuneiform: Medial distal to navicular, reflect abductor hallucis plantar / medial
• Middle CF: Dorsomedial approach EHL / EDC (beware artery!)
• Lateral CF: Lateral to EDC (beware DP / Deep peroneal nerve)
• MT: Dorsal longitudinal incision over bone with elevation of extensor tendons Dorsal longitudinal incision over bone with elevation of extensor tendons

Question 86

Diagnosis? Treatment?

Answer 86

Parosteal osteosarcoma

• low grade
• usually found in popliteal fossa
• No need for chemo unless there is a high grade component
• Wide surgical excision

Question 87

Compare osteoid osetoma to osteoblastoma

Answer 87

• Osteoid Osteoma
  
  • ​<1.5cm
  • pain releived with NSAIDS
  • self limited
  • diaphysis long bones
    
    • ​femur>tiba>spine
  • ​Nonsurgical managment
• ​Osteoblastoma
  
  • ​>1.5cm
  • pain not releived with NSAIDS
  • progressive
  • spine>proximal humerus>hip
    
    • ​50% have neuro symptoms
  • ​Intralesions curettage and adjunt (phenol)

Question 88

Characteristics of an osetoid osteoma? Associated manisfestations?

Answer 88

• 5-30 years (mostly in the second decade of life)
• 2:1 male to female ratio
• 50% in diaphysis or metaphysis of long bones of lower extremity (tibia, femur)
  
  • proximal femur > tibia diaphysis > posterior elements of the spine > fingers and carpus > feet
  • the most common location is the proximal femur
  • the most common intra-articular location is the hip joint
  • the most common locations in the hand are the scaphoid and proximal phalanx
• Pathophysiology
  
  • thought to be from nerve fibers associated with blood vessels within the nidus
  • pain is secondary to prostaglandin secretion
• Associated conditions
  
  • growth disturbance
  • painful scoliosis
  • flexion contractures
• Prognosis
  
  • pain from lesoins usually resolves after an average of 3 years
  • the lesion spontaneously resolves in 5-7 years
  • in the spine, early resection (within 18 months) leads to resolution of scoliosis in young children (<11years)

Question 89

Diagnosis? Treatment?

Answer 89

• clinical observation and NSAID administration
  
  • indications
    
    • NSAIDS are 1st line and will lead to a dramatic decrease in symptoms
      
      • ~50% can be treated with NSAIDS alone
    • also indicated for painful spine lesions without scoliosis
  • fingertip lesions (distal phalanx) may not respond to NSAIDS
• percutaneous CT guided radiofrequency ablation (or curettage)
  
  • relative indications
    
    • failure of medical management
    • periarticular lesions, which increase the risk of cartilage injury and premature degenerative disease.
    • spinal lesions (controversial) - depends on the location of the lesion and proximity to neural elements
    • Contraindication to taking NSAIDS
  • contraindications
    
    • lesions close to spinal cord or nerve roots
  • technique
    
    • done under CT guidance
    • probe at 80-90 deg C for 6 minutes to produce a 1cm zone of necrosis
    • curettage has been described as well with some success
  • outcomes
    
    • 90% of patients are successfully treated with 1-2 sessions of RFA
    • 10-15% recurrence rate
• Intralesion curettage with nidus resection
  
  • indications
    
    • location of lesion is not amenable to CT guided percutaneous radiofrequency ablation
    • spine lesion associated with painful scoliosis
  • technique
    
    • successful treatment depends on complete marginal resection of nidus (sclerotic bone is normal and can be left behind)
    • percutaneous approach
    • open approach
  • outcomes
    
    • depending on the child’s age and duration of symptoms, removal of the osteoid osteoma will allow resolution of scoliosis without further treatment

Question 90

Differential? Managment? Treatment?

Answer 90

Osteoblastoma

• Present with local swelling, tenderness
• Not relevied with NSAIDS
• XR
  
  • can be difficult to discern from osteosarcoma
  • >2cm
• Bone Scan
  
  • ​Hot​
• CT is the scan of choice to help deliniate size of lesion
  
  • Cortical destruction, soft tissue expansion
  • Expansive bone remodelling with reactive scleosis and central mineralization​
• MRI is not useful
• Extended intralesional curettage with adjuvant agent (phenol or liquid nitrogen)
  
  • no role for non-op therapy
  • recurrence reprted in 10-20%
  • Need to be aggressive with the use of burrs to get back to normal bone
• En Bloc resection
  
  • Recurrent lesions
  • Aggressive, large lesion in expendable bone
  • Ouctome - lower recurrence than intralesional excision

Question 91

Enneking classification of pelvic tumors

Answer 91

• Type III require no reconstruction and do well
• The more bone resected the more limited the options
• Often requires multi-disciplinary approach
  
  • general surgery - visceral resection, requires mesh to prevent herniation
  • plastic surgery for soft tissue coverage

Question 92

Option for Type 1 pelvic deficiet

Answer 92

Iliac Wing

No support - good results, with less need for pain meds and assistive devices

Sciatic Buttress

Question 93

Options for treatment of Type 2 pelvic deficiet

Answer 93

acetabulum

• Resection arthroplasty
  
  • ​50% mobilization
  • shorter surgical time, fewer complication rate and less need for sebsequent revision
  • Complications
    
    • ​infection, nonunion
    • neruopraxia (pudendal)
• ​​Reconstruction options require a significant amout of ilium to allow for stability of the prothesis
  
  • Saddle prosthesis
    
    • ​benefit of retaining limb length, ease of insertion and modular device
    • less used because of high complication rate
      
      • ​infection, dislocation, nerve plasy, fracture, device migration
  • ​​Allograft-prosethetic composite
    
    • ​young patients who benefit from limb length and have the ability to remodel the graft
    • 50% complication rate
      
      • ​infection, nerve palsy, nonunion, instability

Question 94

What is the enneking grading system for benign tumors?

Answer 94

1. Latent
   
   • ​will not progress, may heal spontaneously
2. Active
   
   • ​progresses but respects natural barriers
3. Aggressive
   
   • ​can destroy natural barriers

Question 95

Characteristics of endcondroma

Answer 95

• A benign chondrogenic lesion caused by an abnormality of chondroblast function in the physis
  
  • chondroblasts escape the physis and proliferate in metaphysis
• 2nd most common benign cartilage lesion (osteochondroma is most common)
• Age & location
  
  • age range is 10-60 years
  • occurs in medullary cavity in diaphysis or metaphysis
  • hand is most common location (60%)
    
    • presentation as pathological fractures common
  • other locations include the femur (20%) and proximal humerus (10%)
• solitary enchondroma
  
  • 1% chance of malignant transformation (chondrosarcoma)
• Ollier’s disease (multipe enchondromatosis)
  
  • no genetic predisposition has been identified
  • multiple enchondromas in long bone diaphysis
  • 10-30% chance of malignant transformation into chondrosarcoma
  • however associated with high rate of both skeletal and non-skeletal malignancies
  • involved bones are dysplastic
• Maffucci’s syndrome
  
  • no genetic predisposition has been identified
  • multiple enchondromas and soft-tissue angiomas
  • 100% chance of malignant transformation into chondrosarcoma
  • increased risk of visceral malignancies (astrocytoma, GI malignancy)

Question 96

Diagnosis?

Answer 96

Ollier’s Disease

• no genetic predisposition has been identified
• multiple enchondromas in long bone diaphysis
• 10-30% chance of malignant transformation into chondrosarcoma
• however associated with high rate of both skeletal and non-skeletal malignancies
• involved bones are dysplastic

Question 97

Diagnosis?

Answer 97

Maffucci Syndrome

• no genetic predisposition has been identified
• multiple enchondromas and soft-tissue angiomas
• 100% chance of malignant transformation into chondrosarcoma
• increased risk of visceral malignancies (astrocytoma, GI malignancy)

Question 98

Diagnosis? Treatment?

Answer 98

Pathological #, Enchondroma

• Painless tumor, pain=chondrosarcoma
• Most common in hand
• 10-60 yo
• Physical Exam
  
  • enchondroma may disrupt the growth plate and lead to shortening and angular deformities
• Radiograph
  
  • “pop-corn” mineralization (calcification), stippled rings in diaphyseal or metaphyseal medullary cavity
  • occasionally may have purely lytic appearance (especially in hand)
    
    • The hand will always apprear more aggressive and can be expansile
• Treatment
  
  • ​Most will be treated with observation
    
    • XR 3 month, 1 year
    • if evidence of progression can further work-up
  • Pathological fracture
    
    • immobilize and wait to heal
    • then curettage and grafting +/- hardware
    • no adjunct needed for enchondroma alone

Question 99

What are indications radiographically of low grade chondrosarcoma versus enchondroma

Answer 99

• Low grade features
  
  • Dense calcifications with rings and spiclues
  • Uniform calcification
  • Eccentric, lobular growth of soft tissue
• High grade features
  
  • Faint, amorphous calcification
  • Large noncalcified areas
  • Lysis within a previously calcified area
  • Concentric growth of soft tissue mass

Clinically the most important thing is pain

Question 100

Describe the lesion. Differential? Appraoch.

Answer 100

Enchondroma vs Chondrosarcoma in situ

• Take a complete history and physical
  
  • pain is indication for chondrosarcoma
• Radiograph
  
  • Low grade features
    
    • Dense calcifications with rings and spiclues
    • Uniform calcification
    • Eccentric, lobular growth of soft tissue
  • High grade features
    
    • Faint, amorphous calcification
    • Large noncalcified areas
    • Lysis within a previously calcified area
    • Concentric growth of soft tissue mass
• Bone scan
  
  • If lights up more than an internal reference (pelvis); then you should be more concerned of condrosarcoma
• CT
  
  • Can be usuful to determine osseous architecture
  • Degree of endosteal scalloping
• MRI
  
  • ​​​may show steak of cartilage or “sled runner tracks”
  • Can help to look at proximity to joint and NV structures
  • >90% medullary fill = chondrosarcoma
  • Non-contiguous cartilage can indicate chondrosarcoma if <90% medullary fill
• CT chest - staging
• Biopsy indications
  
  • Pain, night pain and pain at rest
  • FNA - if there is a big enough soft tissue component
  • Core - better if with-in bone, but may have sampling error
  • Open - always need to talk to patient about heterogeneous nature of tumor
    
    • Best for sampling error
    • If you think it is low grade chondrosarcoma/chondrosarcoma in situ, you can send a frozen section
      
      • If comes back low grade can proceed with intrealesional curretage
      • If there are concerns, close with meticulous hemostasis and wait for biopsy results
    • The other option is to wait for results for definative treatment
      
      • But sometimes the lesion you send from curettage will have a better sample than open biopsy alone
• curettage and bone grafting
  
  • indications - enchondroma
    
    • lesion that shows any change on serial xrays
    • hand lesions after fracture has first been allowed to heal with immobilization
    • Impending fracture
  • Often there is concern of chondrosarcoma in situ - frozen section
    
    • Send biopsy from the most aggressive looking area
  • Adjuvant therapy for enchondroma alone is not routinely utilized
• Intralesion curette with adjuvant and bone graft/PMMA
  
  • For low grade chondrosarcoma as per frozen section
  • Approach away from NV structures
  • Aggressive intralesion curettage
    
    • Send most aggressive area for biopsy
    • Use curettes and high speed burr
  • Adjuvant
    
    • Decreases recurrence
    • Phenol, liquid nitrogen
  • PMMA vs allograft
    
    • PMMA gives structural support right away
  • May need hardware for additional stabilization for large or precarious defect
• Post-op
  
  • Protect WB initially after surgery with immediate ROM
  • 2 years before full return to sports due to increased risk of fracture

Question 101

Pathoanatomy of osteochondroma

Answer 101

• A benign chondrogenic lesion derived from aberrant cartilage from the perichondral ring
• Epidemiology
  
  • the most common benign bone tumor
  • true incidence is unknown as many are asymptomatic
  • common in adolescents and young adults (tested ages: 9, 10, 12, 20, 24)
• location
  
  • occur on the surface of the bone and often at sites of tendon insertion
  • common location
    
    • knee (proximal tibia, distal femur)
    • proximal femur
    • proximal humerus
    • subungal exostosis (occurs most often at hallux)
• Pathoanatomy
  
  • hamartomatous proliferation of bone and cartilage
  • possibly arise from growth plate cartilage that grows through the cortex by endochondral ossification under the periosteum
  • perichondral node of Ranvier defect may allow growth from the physis to extend from the surface
  • the stalk of the lesion is cortical and cancellous bone formed from ossified cartilage
• Genetics
  
  • mutation in EXT gene affects prehypertrophic chondrocytes of growth plate
  • loss of regulation of Indian hedgehog protein is currently being investigated in the pathogenesis of this disease
• Prognosis
  
  • <1% with solitary osteochondroma
  • ~5-10% with MHE develop secondary chondrosarcoma

Question 102

What is the most common benign tumor of bone?

Answer 102

osteochondroma

Question 103

Diagnosis?

Answer 103

multiple hereditary exostosis (MHE)

• mutations affect the prehypertrophic chondrocytes of the physis
• genetics
  
  • autosomal dominant
  • mutations in EXT1, EXT2, and EXT3 genes (tumor suppressor genes)
• EXT1 mutation have a more severe presentation compared to patients with the EXT2 mutation including
  
  • higher rate of chondrosarcoma
  • more exostoses
  • more limb malalignment with less forearm and knee range of motion
  • more pelvic and flatbone involvement
• prognosis
  
  • 5%-10% malignant transformation to chondrosarcoma in patients with MHE
  • proximal lesions more likely to undergo malignant transformation than distal lesions
  • most common location of secondary chondrosarcoma is the pelvis (usually occur as low-grade chondrosarcomas)

Question 104

Work-up for MHE/osteochondroma

Answer 104

• History
  
  • most lesions are asymptomatic
  • usually present with painless mass
    
    • pain = chondrosarcom
  • may have mechanical symptoms or symptoms of neurovascular compression
  • they continue to grow until skeletal maturity
    
    • continued growth = chondrosarc
  • MHE
    
    • short, deformed limbs
    • joint pain, loss of function
    • UE lead to little loss of function
    • may have sx of OA
• Physical exam
  
  • palpable mass
  • may have mechanical symptoms secondary to mass
  • Multiple hereditary exostosis (MHE)
    
    • most common deformities include
      
      • forearm bowing and shortening
      • radial head subluxation/dislocation
      • ulnar deviation of the hand
    • Assess for LLD and do rotational profile
      
      • Proximal femur - valgus, anteversion
      • Acetabulum/femoral neck - lateralize femur
      • Distal femur - valgus knees, patellar dislocation
      • Ankle - short fibula, valgus ankle
    • Full NV exam
      
      • Can get vascular occlusion or neuropraxia secondary to lesion
      • Pseudoaneurysm, occulsion, thrombosis
      • Claudication, ischemia
• Secondary chondrosarcoma
  
  • acute onset of pain
  • Adults with growing osteosarcoma
  • Average age is 31
  • Cartilage cap > 2cm
• Radiograph
  
  • sessile (broad base) or pedunculated (narrow stalk) lesions found on the surface of bones -
  • higher risk of malignant degeneration in sessile lesions
  • pedunculated lesions grow away from the involved joint
    
    • cortex of the lesion is continuous with the cortex of the bone
    • cavity of the lesion is continuous with the medullary cavity of the bone
  • cartilage cap is usually radiolucent and involutes at skeletal maturity
  • nodules of metaplastic cartilage can occur within the bursa over cartilage caps
• Malignant Conversion
  
  • cartilage cap > 2cm
  • You may also get lytic destruction of the cortices
• CT, MRI or US
  
  • used to better characterize lesions
  • Absolute size of the lesion is not an indicator of conversion to osteosarcoma
  • thickness of the cartilage can be helpful (> 2cm)
  • Be aware that bursal formation from mechanical irritation can mimic this

Question 105

Treatment of MHE/osteochondroma

Answer 105

• Osteochondromas
  
  • observation alone
    
    • asymptomatic or minimally symptomatic cases
  • operative
    
    • marginal resection at base of stalk, including cartilage cap
    • symptomatic lesions
    • lesion may cause inflammation to surrounding tissue
    • lesion may be cosmetically displeasing
    • try to delay surgery until skeletal maturity
• Multiple hereditary exostosis (MHE)
  
  • Highly debatable as to when to operate and if to operate for functional deformity
  • Some will say that forearm changes are well tolerated and do not need reconstruction
• nonoperative - observe
  
  • most patients do not require intervention prior to reaching skeletal maturity
• surgical excision of the osteochondroma
  
  • indications
    
    • dislocated radial heads
      
      • Attempts to reconstruct radial head often lead to a painful, stiff, arm
    • loss of forearm rotation
  • outcomes
    
    • simple excision of the osteochondroma optimizes chance of improved motion
• Forearm reconstruction - ulnar lengthening with distal radius osteotomy
  
  • Will improve cosmesis
  • Debate as to whether you get improved function
• Lower limb epiphyseodesis +/- corrective osteotomy or TSF for older child
  
  • Proximal femur - varus derotational osteotomy
  • Acebulum/femur - excision to prevent lateralization of femur
  • Knee
    
    • Epiphyseodesis with excision of osetochondroma
      
      • In younger children with valgus knees or ankles
    • HTO or distal femoral osteotomy
      
      • For severe deformity around the knee
  • Ankle
    
    • Hemiepiphyseodesis with excision of osetochondroma
      
      • Valgus > 15 deg
    • Distal fibular lengthening
      
      • when distal fibular physis is above tibial physis
    • Supramalleolar osteotomy with excision of osteochondroma

Question 106

Differential? Diagnosis? Treatment?

Answer 106

Chondromyxoid Fibroma

• in the same family as chondroblastoma
• Differential
  
  • GCT
  • ABC
  • Enchondroma
  • EG
  • Fibrous dysplasia
  • Osteoblastoma
  • Osteofibrous dysplasia
  • NOF
• Age & Location
  
  • usually located in long bones,
    
    • especially the tibia in metaphyseal areas
  • sometimes located in the foot
  • More common in males
• Genetics
  
  • may contain genetic rearrangement of chromosome 6 at postion q13
  • Sox-9 at higher levels than in chondroblastoma
• Prognosis
  
  • worse in children
  • more lobulated tumor
  • abundant myxoid material
  • recurrence in CMF is not uncommon and has been described in up to 20%-30% cases
• Presents with long standing pain
• Radiographs
  
  • lytic eccentric metaphyseal lesion that is sharply demarcated from adjacent bone
  • mineralization usually not present
  • Sclerotic rim with pseudotrabeculae
  • Scalloped borders
• ​CT and MRI are necessary to help characterize the lesion
• Intralesional curretage and PMMA
  
  • recurrence in 25%
  • Advocated to use PMMA because of the aggressive nature and high risk of recurrence
  • More aggressive with recurrence and rare sarcoma progression, but no reports of mets

Question 107

Epidemiology of chondroblastoma

Answer 107

• A benign chondrogenic lesion (differs from giant cell tumor by its chondroid matrix)
• 2:1 male:female
• most patients under 25 years of age
• location
  
  • epiphyseal lesion in young patients (usually around 12 years of age)
  • distal femur, proximal tibia, proximal humerus, proximal femur, and apophysis or triradiate cartilage of the pelvis
  • Keep in mind that the sesamoid bones are an epiphyseal equivalent
• Pathophysiology
  
  • thought to arise from cartilaginous epiphyseal plate
  • these lesions are almost always apophyseal
• Genetics
  
  • may have genetic abnormalities on chromosome 5 and 8
  • Sox-9 gene
    
    • Found in lower quantities in chondroblastoma than chondromyxoid fibroma
  • Indian Hedgehog/parathyroid hormone–related protein (IHh/PTHrP) and fibroblast growth factor
  • Mesenchymal lineage
• Prognosis
  
  • 1-2% of benign chondroblasts metastasize to the lungs (similar to giant cell tumor in this respect)
  • recurrence is 10%-15% after surgical resection

Question 108

Work-up of the following. Differntial? Likely diagnosis?

Answer 108

Chondroblastoma

• differential with radiographs
  
  • giant cell tumor
  • Enchondroma
  • ABC
  • EG
  • Fibrous dysplasia
  • osteomyelitis
  • clear cell chondrosarcoma
• Symptoms
  
  • progressive pain referred to involved joint
• Physical examination
  
  • exam may show mechanical symptoms with limitations of motion
• AP, lateral, and oblique of involved area
  
  • well-circumscribed
  • epiphyseal lytic lesion
  • thin rim of sclerotic bone
  • sharply demarcated from normal medullary cavity
  • lesions often cross physis into metaphysis
  • stippled calcifications within the lesion may or may not be present (25%-45%)
  • cortical expansion may be present
  • soft tissue expansion rare
• CT Chest - rule out mets
• CT
  
  • not required
  • defines bony extent of lesion
  • Proximity to subchondral bone
  • May help identify pathological fracture
• MRI
  
  • edema around lesion
• Histology
  
  • chondroblasts arranged in “cobblestone” or “chickenwire” pattern may be present
  • scattered multinucleated giant cells with focal areas of chondroid matrix
  • occasional multinucleated giant cells may be present
  • S100+ cells with large central nuclei
  • 1/3 of chonroblastomas have a secondary ABC

Question 109

Differential? Treatment?

Answer 109

Chondroblastoma

• Differential
  
  • enchondroma
  • EG
  • osteomyelitis
  • GCT
  • ABC
  • fibrous dysplasia
  • clear cell chondrosarcoma
• Rule out mets to lungs
• Can consider observing these
  
  • Pain, erosion and change over time is more suggestive of a chondrosarcoma
• extended intralesional curettage and bone grafting
  
  • standard of treatment in symptomatic individuals
  • technique
    
    • may do local adjuvant treatment with phenol or cryotherapy, although not usually used
    • Need to do adequate curettage with high speed burr
      
      • Be cautions around the physis and subchondral bone
    • Bone grafting is better than PMMA
    • Approach to the femur
      
      • Window the trochanter
      • Be careful not contaminate the physis, joint
      • Risk of osteonecrosis
  • Outcomes
    
    • High rates of recurrence
• En Bloc Resection
  
  • Expendable bones
• Wide resection with amputation and limb salvage
  
  • For aggressive recurrence
• Resection of rare benign pulmonary metastasis
  
  • if pulmonary metastasis
  • No benefit of chemo

Question 110

Complications associated with treatment of chondroblastoma

Answer 110

• Recurrence
  
  • Incomplete resection (especially around the joint and physis)
  • Aggressivity (more aggressive in the pelvis)
• Pulmonary mets - rare
• Degenerative joint disease with function impariment
• Pathological fractures

Question 111

Diagnosis?

Answer 111

Abbcess

Question 112

Characteristic findings of Hands-Schuller-Christian disease

Answer 112

• dibetes incipidus
• exopthalamos
• EG

Question 113

Differential for soft tissue sarcoma

Answer 113

synovial sarcoma (can calcify)
liposarcoma
rhabdomyosarcoma
fibrosarcoma
leiomyosarcoma
angiosarcoma

Question 114

Soft Tissue Sarcoma that metastasize to nodes

Answer 114

SCARE

• synovial cell sarcoma
• clear cell sarcoma
• angiosarcoma
• rhabdomyosarcoma
• epitheliosarcoma

Question 115

Staging studies for ST sarcoma

Answer 115

• Local imaging
  
  • Orthogonal radiographs MRI with gadolinium
• Systemic
  
  • Chest radiographs
  • Chest CT scans Examination of locoregional
  • lymph nodes; image/biopsy when enlarged
• Myxoid liposarcoma
  
  • add CT ABD, pelvis; bone scan Role of PET for evaluation of mets to retroperitoneum/bone

Question 116

What characteristics of ST sarcoma make it ammenable to excision alone with no pre-op radiation

Answer 116

• supericial
• small <5cm

can be high grade or low grade

Question 117

What is the treatment for a positive tumor bed

Answer 117

reexcsion with radiation

Question 118

Comprare pre-op to post-op rads for ST radiation

Answer 118

• Pre-op
  
  • 50 grey
  • smaller bed, well oxygenated tissue
  • pathological tissue
  • higher wound complications
• Post-op
  
  • 60 grey
  • larger bed, poorly oxygenated tissue
  • radiating normal tissue
  • fewer wound complications

Question 119

Options for radiation therapy

Answer 119

• external beam radiation
• brachytherapy
• Cyberknife - Frameless Single-Fraction Stereotactic Radiosurgery

Question 120

MRI is diagnostic for what ST sarcomas

Answer 120

lipoma
neurilemoma (schwanoma)
intramuscular myxoma

Question 121

What is the prognosis for ST Sarcoma

Answer 121

No mets - 90% at 5 years
Mets - 15% at 5 years
Worse with deeper, larger lesions
Worst - multiple, unresectable pulmonary mets

Question 122

What are 6 biological capabilities for a tumor to metastasize

Answer 122

1. Evading apoptosis
2. Self-sufficiency in growth signals
3. Insensitivity to anti-growth signals
4. Tissue invasion and metastasis inactivation
5. Limitless replicative potential
6. Sustained angiogenesis

Question 123

What is the only ST sarcoma you might consider chemo for

Answer 123

synovial cell

Question 124

What are common chemotherapy medications

Answer 124

• Anthracyclines (end in –rubicin)
  
  • Doxorubicin
  • Works through inhibition of DNA and Topoisomerase II
  • Main side effects = Leukopenia + Cardiac Toxicity (manifests as CHF)
• Alkylating Agents
  
  • seem to cause cystitis and hematuria
  • Cyclophosphamide
  • Requires cyctochrome P450 to work
  • Stop giving it if patient has dysura or hematuria
• Ifosfamide
  
  • Causes platelet suppression
• Cisplatin
  
  • Contains platinum
  • Is nephrotoxic
  • Causes ototoxicity
• Antimetabolites
  
  • Methotrexate
• Anti-folate
  
  • Hepatotoxic, can be Teratogenic
• Vinca Alkaloids
  
  • Vincristine & Vinblastine
  • Work by inhibiting tubulin
  • Can be neurotoxic, patient presents with neuro symptoms

Question 125

What are the common side effects of chemo

Answer 125

• Immunosuppression
• fatigue
• infection
• Hair loss, comes back after a few weeks, can be curly (called the ‘chemo perm’)
• Certain agents have certain toxicities
  
  • doxyrubicin = cardiac
  • isofosamide = platelet suppression
  • cisplatin = ototoxicity
  • methotrexate = hepatotoxic
  • vincristine = neurotoxic

Question 126

What are risk factors for secondary chondrosarcoma

Answer 126

• Clinical
  
  • Pain
  • Increasing size of a palpable lesion
  • Male predominance (2:1)
  • Location in the pelvis or hip
  • Peak age in mid 30s
• Radiographic
  
  • Surface irregularity
  • Blurriness of the border
  • Osteochondroma >5 cm
  • Increase in size of osteochondroma
  • Cartilage cap >2 cm
  • Inhomogeneous mineralization of large cartilage cap
• Genetic
  
  • Hereditary multiple exostosis (EXT1, EXT2, EXT3 mutations)
  • Ollier disease
  • Maffucci syndrome

Question 127

Risk of secondary chondrosarcoma

Answer 127

• <1% solitary
• 2-4% MHE
• 20-40% Olliers/maffuccis

Question 128

What are two chondrosarcoma subtypes you are aware of

Answer 128

• Clear cell chondrosarcoma
  
  • malignant immature cartilaginous tumor accounting for <2% of all chondrosarcomas
  • most common in 3rd and 4th decades of life
  • commonly presents with insidious onset of pain
  • presents as an epiphyseal lesion and can be mistaken for low-grade chondroblastoma
  • locally destructive with potential to metastasize
• Mesenchymal chondrosarcoma
  
  • chondrosarcoma variant which presents with a biphasic pattern of neoplastic cartilage with associated neoplastic small round blue cell component
  • occurs in younger patients than typical chondrosarcomas
  • may occur at several discontinuous sites at presentation and can occur in the soft tissues
  • treatment includes neo-adjuvant chemotherapy followed by wide surgical resection

Question 129

When would you consider chemo in chondrosarcoma

Answer 129

mesenchymal chondrosarc

de-differential chondrosarc

Question 130

What is the treatment of chondrosarcoma

Answer 130

• Low grade
  
  • intralesional curettage
  • except in the pelvis
• High grade
  
  • wide resection
• No role for chemo
• No role for rads

Question 131

What are 3 anatomic structures when considering hemipelvectomy

Answer 131

• Sciatic nerve
• Femoral NV bundle
• Hip joint
• • Consider hemipelvectomy if two or more structures compromised.*

Question 132

Most common complications associated with hemipelvectomy

Answer 132

• wound infection
• flap necrosis
• loss of bowel/bladder function

Question 133

Options for endoprosthesis reconstruction

Answer 133

• Pre-op considerations
  
  • tumor must not invade structures
    
    • talk to MSK radiologist
    • venogram (UE)
  • stable, painless limb
    
    • abductor claw plate - femur
    • preserve the rotator cuff if possble (may have to do an extra-articular resection and won’t be able to)
  • surrounding soft tissues support
    
    • consider that you might need flaps
• Pelvis
  
  • Saddle prosthesis
  • stabilize with the psoas and the abductors
• Hip
  
  • Proximal femoral replacement
  • Ensure reconstruction of the Abductors with a claw plate
• Distal femur
  
  • distal femoral megaprosthesis with rotating hinge
  • patella can usually be salvaged do rarely need to do an extensor reconstruction
  • can also do a full femoral replacement
• Proximal tibia
  
  • Endoprosthesis with rotating hinge platform for joint stability
  • Soft tissue coverage is one of the biggest problems in this area
  • reconstruction of patellar tendon with medial gastroc rotational flap
• Scapula
  
  • provides better support and function, but requires soft tissue transfers for function and coverage
• Shoulder
  
  • may have to do extra-articular because of biceps
  • involves resection of deltoid, cuff and glenoid
  • include a pectoralis transfer to improve fuction and stability
• Skeletally immature
  
  • ​>10-12yo can use an adult prosthesis with contralateral epiphyseodesis
  • <6 should do amputation
    *

Question 134

Considerations for limb amputation or salvage in upper extremity sarcoma

Answer 134

• talk to your MSK radiologist regarding proximity to the NV structures
• Indications of brachial plexus invovlement
  
  • irretractable pain
  • motor weakness
  • venogram - obliteration of axillary vein
• Usually decided intraoperatively endoprosthesis vs four corner amputation
• Shoulder is unique in that the biceps allows more contamination of the joint and may have to perform an extra-articular amputation
• Try to also preserve rotator cuff
  
  • if you take the cuff perform and arthrodesis or a ‘spacer hemiarthroplasty’
• Endoprosthesis vs APC

Question 135

What is the utilitarian incision for the shoulder girdle

Answer 135

• Anteriorly along deltopec, include the previous biopsy tract, then posterior along the joint
• Release pec major
• Release conjoint tendon then can see the brachial plexus
  
  • can also do a clavicular osteotomy to see more
  • then can assess whether to do an amputation or an endoprosthesis

Question 136

Describe a four corner amputation

Answer 136

• Indications
  
  • fungating axillary sarcoma
  • large sarcoma invovling the shoulder girdle
  • recurrence following limb salvage
  • recurrent breast invovling brachial plexus
  • pathological sarcoma fracture with poor response to chemotherapy
• Helpful adjunct studies
  
  • angiography to determine where the vessels are
  • venography to determine vessel patency and indirect invovlement of tumor in the plexus
• Consider plastics consult pre-op for help with closure if there is significant invovlement precluding closure with either an anterior or posteriorly based flap
• Involves resection of the arm, scapula and lateral clavicle
• Lateral ducubitus with a roll under the axilla, free drape the arm
• Incision circumferential around the arm with either an anterior or posterior flap
• Elevate posterior flap, ensure to take biposy site with associated hematoma with the amputation
• Remove the posterior muscle attachements, make a small hole in the fascia; elevate rhomboids, trapezius and levator scapula
• serratus anterior is elevated of the chest wall with the scapula; the vessels of the scapular triangle are ligated
• the subclavian artery and viens are identified and ligated; as is the brachial plexus
• osteotomize the clavicle and release the pec
• Closure
  
  • copious irrigation
  • two layered closure with the anterior or posterior flap
  • two subfascial drains

Question 137

Describe hemipelvectomy

Answer 137

• Indications
  
  • unresectable tumor in a young patient
  • recurrence from previous limb slavage
  • infection and necrosis of AKA for vascular disease
  • necrotizing fascitis
• Preop must talk to MSK radiologist to make sure you are doing appropriate surgery
  
  • >2 of the following
    
    • hip
    • femoral nerve
    • sciatic nerve
  • General surgery, plastic surgery
  • Bowel prep
  • Prep the vaginal vault
• Pre-op imaing
  
  • CT, MRI
  • angiography
  • venography
• Posterior flap
  
  • biopsy should be performed anteriorly to preserve the gluteus maximus
  • semilateral position
  • Ilioinguinal approach
    
    • ​elevate retroperitoneum off the tumor
    • iliac and hypogastric arteries are disected
    • release abdominal wall from symphysis to PSIS
  • extend the perineal incision
    
    • expose the ischirectal space
    • release the pubis protecting the bladder and urethra
  • elevate the posterior flap
    
    • deteach the pelvic floor by abducting and flexing the leg
    • beginning at ramus and extending to SI joint
  • complete by amputating the SI articulation
  • copious irrigation
  • sew over abductors and glut max and close the fasciocutaneous flap with two drains
• Anterior flap
  
  • used for tumors invovling the buttock or chronic OM in patient with parapalegia
  • Lateral position, anus is sutured shut
  • start posteriorly at the ischiorectal space
  • abdominal and posterior musculature is released off the iliac crest, the sacrotuberus and sacrospinous ligaments are released
  • the anterior incision is made, the IT band will be taken with the ampuation
  • vastus lateralis and quads are stripped off the femur to use as flaps
  • the femoral vessels in the adductor canal are identified and ligated, the saphenous nerve is sharply transected
  • as the quads are elevated off the femur the profundus is identified and ligated
  • pubis is divided and released protecting the bladder and urethra
  • iliac vessels are identified and ligated, nerve roots are sharply transected and psoas is divided
  • pelvic diaphragm and sacrum are divided
  • Anterior flap is flipped up, multilayer closure with drains

Question 138

Describe a hip disarticulation

Answer 138

• Inicision 1 cm anterior to ASIS, 1 cm anterior to GT, 2cm distal to pubic bone
• Divide the femoral vessels and nerve
• Divide anterior musculature, release psoas from its insertion
• Transection of the pectineus and adductor compartment from the ischial tuberosity
• Incise the hip capsule and complete the posterior skin incision
• Divide gluteus maximus, IT and rectus, release the ER from their insertion
• Sciatic nerve is disected and transected, the posterior capsule is released
• The obturator internus and glueus medius are used to close over the acetabulum
• Gluteal fascia is secured to the inguinal fascia
• Skin is closed with insertion of drains

Question 139

Describe a knee disarticulation

Answer 139

• Skin incision at the level of the tibial tubercle with a long posterior flap
• complete the incsion threw the skin
• identify and clamp the saphenous vessels
• the patellar tendon is peeled off the tubercle and retained
• Disect the joint working from anterior to posterior, leave a cuff of ACL
• Dissect off the posterior tissues, disect the tissue off the fibula
• Identify tibial nerve and popliteal vessels, identify and release the peroneal nerve
• complete the posterior flap incision
• oversew the patellar tendon to the ACL
• two layer closure of posterior flap

Question 140

What are the key points for an AKA

Answer 140

• Maintain as much length as possible
• however, ideal cut is 12 cm above knee joint to allow for prosthetic fitting
• Technique
  
  • fishmouth
  • 5-10 degrees of adduction is ideal for improved prosthesis function
  • adductor myodesis
    
    • improves clinical outcomes
    • creates dynamic muscle balance
    • provides soft tissue envelope that enhances prosthetic fitting

Question 141

Technical points of a symes amputation

Answer 141

• requirements
  
  • patent tibialis posterior artery is required
  • Healthy posterior heel pad
  • more energy efficient than midfoot even though it is more proximal
  • stable heel pad is most important factor
  • May require concurrent achilles lengthening
• Technique
  
  • Anterior incision in a fishmouth fashion across the ankle with 90 deg inferior along CC joint
  • Remove talus and calcaenous carefully so you don’t disrupt the posteirior soft tissues
  • Anterior and posterior NV bundles are ligated
  • Heel pad +/- achilles is sewn to the anterior tibia
  • Copious irrigation, skin is closed in mulitple layers with minimal tension
• Prosthesis
  
  • May not be able to use initially
  • End socket that fits into shoe
  • Has to compensate for loss of dorsiflexion
  • Allow adequate clearance from ground
  • Allow for pushoff
  • Foot is slightly everted

Question 142

What are important technical concerns for a chopart amputation

Answer 142

lengthening of the Achilles tendon

transfer of the tibialis anterior to the talar neck

prevents equinus contracture

Question 143

What are the important technical details for a TMT amputation

Answer 143

• preserves length with less deformity that a TMT
• tenodesis of tib ant and peroneals to prevent deformity

Question 144

What are the phases of rehab after lower limb amputation

Answer 144

• Phase 1 (week 1)
  
  • Bed-to-wheelchair mobility
  • Range-of-motion exercises
  • Edema control
  • RRD applied at 48 h
  • Transfer to acute rehabilitation facility at 48 h
• Phase 2 (week 2-5)
  
  • Wound healing
  • RRD education
  • Stump shrinkage
  • Independent gait training with walker/ crutches
  • Simulated weight bearing on stump with elastic strap
• Phase 3 (week 6-9)
  
  • New prosthesis
  • Progressive weight bearing with wheeled walker
  • Walking on uneven surfaces, home environment
• Phase 4 (week 10 and beyond)
  
  • Return to active lifestyle
  • Advanced ambulation patterns Vocational and sport-specific training

Question 145

Contraindications to bisphosphanates

Answer 145

• severe renal disease
  
  • primary mode of excretion is renal
• following lumbar fusion
  
  • decreased spinal fusion rates in lab animal models (increased fusion mass size, but decreases the actual fusion rate)

Question 146

side effects of bisphosphonates

Answer 146

Jaw osteonecrosis
Atypical subtrochanteric and femoral stress fractures
Radiographic changes consistent with osteopetrosis

Question 147

Causes of hypercalcemia

Answer 147

• malignancy - caused by parathyroid-related hormone protein (PTHrP)
  • characterized by:
    
    • hypercalcemia, hypophosphatemia, low PTH
  • examples of malignancies:
  • Paget’s Disease
  • Multiple Myeloma
  • Squamous cell cancer of the lung
  • ectopic production of PTH
  • Multiple endocrine neoplasia (type I and II)
  • Pituitary adenoma
• medical conditions
  • primary hyperparathyroidism
  • sarcoidosis
  • Familial hypocalciuric hypercalcemia
  • hyperthyroidism
  • Addison’s disease
  • Zollinger-Ellison syndrome
  • drugs
  • thiazide diuretics
  • dietary
  • calcium ingestion (milk-alkali syndrome)
  • hypervitaminosis D
  • hypervitaminosis A

Question 148

Presentation and treatment of hypercalcemia

Answer 148

• Presentation
  
  • CNS
    
    • confusion
    • stupor
    • weakness
  • gastrointestinal
    
    • constipation
    • anorexia
    • nausea
    • vomiting
  • kidney
    
    • polyuria
    • kidney stones
    • polydipsia
• Treatment
  
  • Hydration
    
    • saline diuresis
  • Drug therapies
    
    • loop diuretics
    • bisphosphonates
    • mithramycin
    • calcitonin
    • galium nitrate
  • Dialysis (severe)

Question 149

Presentation of hypocalcemia

Answer 149

• Symptom
  
  • symptoms of hypocalcemia
    
    • paresthesia
    • fingertip, toes, perioral
    • abdominal pain, biliary colic
    • muscle cramps, tetany
    • dyspnea (laryngospasm, bronchospasm)
    • convulsions
    • mental status changes
    • anxiety, fatigue, mood swings
• Physical exam
  
  • findings of tetany
    
    • Trousseau’s Sign
      
      • carpopedal spasm after blood pressure readings
      • inflate BP cuff 20mmHg above systolic BP x 3-5min
      • hand adopts a MCP flexed, DIP and PIP extended position
      • more sensitive than Chvostek’s sign
    • Chvostek’s Sign
      
      • facial muscle contractions after tapping on the facial nerve
  • dermatologic
    
    • fungal nail infections
    • hair loss
    • blotchy skin
    • pigment loss, vitiligo
• ECG - prolonged QT potential

Question 150

What is the presentation of Hyperparathyroidism

Answer 150

• Symptoms
  
  • often asymptomatic
  • weakness
  • kidney stones (“stones”)
  • bone pain (“bones”)
  • constipations (“groans”)
  • uncommon cause of secondary hypertension
• Imaging
  
  • ​Brown’s tumor
    
    • demineralization of bone
  • will see demineralization in skull and very often the phalanges
• Serology
  
  • primary
    
    • hypercalcemia
    • ↑ PTH
  • secondary
    
    • hypocalcemia/normocalcemia
    • ↑ PTH
  • malignancy
    
    • ↓ PTH
    • ↑ alkaline phosphatase
  • normal anion gap metabolic acidosis
    
    • ↓ renal reclamation of bicarbonate
• Urinalysis
  
  • primary
    
    • hypercalciuria (renal stones)
    • ↑ cAMP
• Radiograph
  
  • cystic bone spaces (“salt and pepper”)
    
    • often in the skull
  • loss of phalange bone mass
    
    • ↑ concavity (see key image of this topic)
• EKG
  
  • shortened QT

Question 151

Complications of hyperparathyroidism

Answer 151

• Peptic ulcer disease
  
  • ↑ gastrin production stimulated by ↑ Ca2+
• Acute pancreatitis
  
  • ↑ lipase activity stimulated by ↑ Ca2+
• CNS dysfunction
  
  • anxiety, confusion, coma
  • result of metastatic calcification of the brain
• Osteoporsis
  
  • Bone loss occurs as result of bone resorption due to excess PTH

Question 152

Compare primary, secondary and tertiary hyperparathyroidism

Answer 152

• Primary
  
  • typically the result of hypersecretion of PTH by a parathyroid adenoma/hyperplasia
  • may result in osteitis fibrosa cystica
    
    • breakdown of bone, predominently subperiosteal bone
    • commonly involves the jaw
• Secondary
  
  • secondary parathyroid hyperplasia as compensation from hypocalcemia or hyperphosphatemia
    
    • ↓ gut Ca2+ absorption
    • ↑ phosphorous
  • associated conditions
    
    • chronic renal disease
      
      • renal disease causes hypovitaminosis D
      • leads to ↓ Ca2+ absorption
    • renal osteodystrophy
• Tertiary
  
  • parathyroid glands become dysregulated after secondary hyperparathyroidism
  • secrete PTH regardless of Ca2+ level

Question 153

Treatment of hyperparathyroidism

Answer 153

• Acute hypercalcemia
  
  • IV fluids
  • Loop diuretics
• Symptomatic hypercalcemia is treated surgically
  
  • treat with parathyroidectoy
    
    • complications include post-op hypocalcemia
    • manifests as numbness, tingling, and muscle cramps
    • should be treated with IV calcium gluconate

Question 154

Treatment of hypocalcemia

Answer 154

• calcium gluconate infusion
  
  • with cardiac monitoring to prevent hypercalcemia
• activated vitamin D (calcitriol)

Question 155

What is the presentation and treatment of hypoparathyroidism

Answer 155

• Usually iatrogenic
• presents with hypocalcemia
• treatment
  
  • Ca and Vit D supplements
  • follow closely

Question 156

What is the pathophysiology of hypophosphatasia

Answer 156

• Pathophysiology
  
  • low levels of alkaline phosphate result in decreased synthesis of inorganic phosphate necessary for bone matrix formation
  • osteoid that forms in the hypertrophic zone of the growth plate fails to mineralize
  • the zone of provisional calcification never forms and growth is inhibited
• Genetics
  
  • inheritance pattern
  • autosomal recessive
  • caused by a mutation in the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP)

Question 157

What is are the orthopedic associations and presentation of hypophosphatasia

Answer 157

• Associated conditions
  
  • orthopaedic manifestations
    
    • similar to rickets
    • bow legs
    • short stature
  • non-orthopaedic manifestations
    
    • abnormal tooth formation
    • loss of teeth
• Clinical findings
  
  • presentation similar to rickets
  • genu varum
  • short stature
  • abnormal dentition
• Radiographs
  
  • abnormal bone formation
  • “deossification of bone” adjacent to growth plate
  • physeal widening

Question 158

What it the treatment of hypophosphatasia

Answer 158

none known

Question 159

Differential diagnosis for hypocalcemia

Answer 159

• decreased PTH that can be caused by
  
  • hypoparathyrodism
  • renal osteodystrophy
  • pseudohypoparathyroidism (this topic)
  • pseudopseuodohypoparathyroidism
• decreased vitamin D3

Question 160

What is the most common cause of hypoparathyroidism

Answer 160

thyroidectomy most common cause

Question 161

What is the pathophysiology and conditions associated with renal osteodystrophy

Answer 161

• Pathophysiology
  
  • hypocalcemia
    
    • due to the inability of the damaged kidney to convert vitamin D3 to calcitrol (the active form)
    • because of phosphate retention (hyperphosphatemia)
  • hyperparathyroidism and secondary hyperphosphatemia
    
    • caused by hypocalcemia and lack of phosphate excretion by damaged kidney
  • uremia related phosphate retention
    
    • is a key pathological step
• Associated conditions
  
  • carpal tunnel syndrome
  • tendinitis and tendon rupture
  • AVN
  • osteomalacia (adults) and growth retardation (children)
  • deposition of amyloid (β2 microglobulin)
  • pathologic fracture
    
    • from brown tumors (hyperparathyroidism) or amyloid deposits
  • osteomyelitis and septic arthritis

Question 162

What are the radiographic findings associated with renal osteodytrophy

Answer 162

• Looser’s zones
• brown tumor
• osteosclerosis
  
  • from mineralization of osteomalacic bone
  • rugger jersey spine
• widened growth plate and zone of provisional calcification (children)
• varus deformity of the femurs (children)
• fracture
• soft-tissue calcification
• osteopenia

Question 163

What is the pathology and conditions associated with rickets

Answer 163

• A defect in mineralization of osteoid matrix caused by inadequate calcium and phosphate
  
  • prior to closure of physis known as rickets
  • after physeal closure called osteomalacia
• Pathophysiology
  
  • disruption of calcium/phosphate homeostasis
  • poor calcification of cartilage matrix of growing long bones
  • occurs at zone of provisional calcification
    
    • leads to increased physeal width and cortical thinning and bowing
    • Vitamin D and PTH play an important role in calcium homeostasis
• Associated conditions
  
  • brittle bones with physeal cupping/widening
  • bowing of long bones
  • ligamentous laxity
  • flattening of skull
  • enlargement of costal cartilage (rachitic rosary)
  • kyphosis (cat back)

Question 164

What is the differential for looser zones

Answer 164

• Insufficient nutritional quantities or faulty metabolism of vitamin D or phosphorus
• Renal tubular acidosis
• Malnutrition during pregnancy
• Malabsorption syndrome
• Hypophosphatemia
• Chronic renal failure
• Tumor-induced osteomalacia

Question 165

Differential for rickets

Answer 165

familial hypophosphatemic (vitamin D-resistant) (see below)
vitamin D-deficient (Nutritional)
vitamin D-dependent (type I & type II)
renal osteodystrophy
hypophosphatasia

Question 166

What is the pathophysiology of familial hypophosphatemic rickets

Answer 166

• Also known as
  
  • Vitamin D resistant Rickets
  • X-linked hypophosphatemic
• Most common form of heritable rickets
  
  • caused by inability of renal tubules to absorb phosphate
  • GFR is normal
    
    • impaired vitamin D3 response
• Genetics
• X-linked dominant
• Presentation
  
  • tibial bowing as result of widened proximal tibia physis
• Labs
  
  • low serum phosphorous
  • elevated alkaline phosphatase
  • serum calcium is usually normal or low normal
• Treatment with Pi has shown poor results; at this point in time treatment is supportive

Question 167

Risk factors for rickets

Answer 167

rare now that Vitamin D is added to milk
still seen in

premature infants
patients with malabsorption syndromes (celiac sprue) or chronic parenteral nutrition
Asian immigrants
Patients with out of the ordinary dietary choices

Question 168

What are the clinical findings and treatment of rickets

Answer 168

• Clinical findings
  
  • rachitic rosary (enlargement of costochondral junction)
  • bowing of knees
  • codfish vertebrae
  • retarded bone growth (widened osteoid seams, physeal cupping)
  • muscle hypotonia
  • dental disease
  • pathologic fractures
  • waddling gate
• Laboratory values
  
  • low to normal serum calcium
  • low serum phosphate
  • elevated alkaline phosphatase
  • elevated parathyroid hormone
  • low vitamin D
• Treatment
  
  • Vitamin D (5000 IU daily)

Question 169

What is the cause of hereditary vitamen D dependant rickets

Answer 169

• Rare disorder
  
  • Clinical features similar to Vitamin D-Deficient Rickets but more severe
  • May have alopecia
• Type I
  
  • caused by defect in renal 25-(OH)-vitamin D1 alpha-hydroxylase
  • defect prevents conversion of inactive form of vitamin D to active form
  • responsible gene on chromosome 12q14
• Type II
  
  • caused by a defect in intracellular receptor for 1,25-(OH)2-vitamin D
• Genetics
  
  • type I
    
    • autosomal recessive
    • Laboratory values
      
      • type II is distinguished from type I by markedly elevated levels of 1,25-(OH)2-Vitamin D
• Treatment
  
  • physiologic doses (1-2 micrograms/day) of 1,25-(OH)2-Vit D
    
    • type I
  • daily high dose Vitamin D + elemental calcium
    
    • type II

Question 170

What are the major and minor criteria for myeloma

Answer 170

• major criteria
  
  • biopsy confirmation of plasmacytoma
  • >30% plasma cells on bone marrow biopsy
  • serum IgG > 3.5g/dL, IgA > 2g/dL
  • urine IgA > 1g/24hr or presence of Bence Jones proteins
• minor criteria
  
  • 10-30% plasma cells on bone marrow biopsy
  • serum or urine protein levels below those listed for major criteria
  • presence of multiple lytic bone lesions (“punched out” lesions without evidence of surrounding sclerosis)
  • decreased serum IgG levels

Question 171

Presentation and imaging associated with lymphoma

Answer 171

• Males, 35-55
• Pelvis, spine ribs
• Symptoms
  
  • pain unrelieved by rest
  • 25% present with a pathologic fracture
  • neurologic symptoms from spinal compression
  • fever, nightsweats, weight loss (B-cell symptoms)
• Symptoms
  
  • swollen large soft tissue masses are common
• Radiology
  
  • large ill-defined diffuse lytic lesions with a subtle mottled appearance
  • more common in the diaphysis of long bones
  • 25% show cortical thickening
  • “ivory” vertebrae
  • multiple sites of disease is common
• differential diagnosis
  
  • metastatic disease
  • multiple myeloma
  • osteomyelitis
• CT chest, abdo, pelvis for staging
• Bone scan
• Blood Smear
• Histology
  
  • CD20 positive
  • CD45 positive
  • lymphocyte common antigen positive

Question 172

Posterior appraoch to the knee

Answer 172

• S shaped incision from posteromedial to posterolateral
• identify the medial sural cutaneous nerve and follow it to the neurovascular bundle
  
  • nerve
  • vein
  • artery
• ligate the superior and middle geniculate arteries PRN and retract the NV bundle laterally
• identify the semiM under the gastroc, release the medial head of the gastroc as needed; do not deinnervate it
• open the capsule

Question 173

Approach to PVNS

Answer 173

• Differential for intra-articular
  
  • PVNS
  • synovial chondromatosis
• Usually presents in young adults
  
  • in the knee, but also hip, shoulder, elbow
  • presents as pain with mechanical symptoms and limited ROM
  • recurrent atraumatic hemarthorsis
  • 40% of patients with a popliteal cyst will have PVNS with-in the cyst
• XR may show nothing, or an intra-articular swelling
  
  • periarticular lytic lesions
• MRI
  
  • hypointense on both T1 and T2 due to hemociderin deposits
  • can be a single nodule or multiple nodules
• Treatment
  
  • arthroscopic to get most
  • possible open
    
    • multiple approaches
    • posterior approach to knee, possible medial and lateral
    • use this to get common extra-articular posterior nodules
  • Savlage is TJA or ankle fusion
  • GCT of tendon sheath is the same pathology and should be treated with margial excision
• Complications
  
  • Recurrence is common (30-50%)
    
    • treat with repeat resection

Question 174

What is typical of myositis ossificans? What is your differential for a calcified soft tissue lesion?

Answer 174

• Differential
  
  • myositis ossificans
  • HO
  • hemangioma
  • tumoral calcinosis
  • synovial cell sarcoma
• Young males, post-traumatic calcification of hematoma
  
  • increases in size over 6 months than will start to resolve after one year
• can be with-in the muscle or on diaphysis of long bones
• MRI - rim enhancement in the first 3 weeks
• CT - eggshell lesion
• Make sure you rule out a malignancy, then you can monitor

Question 175

What is the benefit of gadolinium

Answer 175

• Improves the clarity of the scan
• Can highlight the vascularity of a lesion
  
  • bengin lesion will be less vascular
• Rim enhancement
  
  • abcess
  • myositis ossificans
• Spine
  
  • scar/infection vs disc

Question 176

Options for resections in strange places

Answer 176

• Proximal fibula
  
  • resect it and secure the bicpes and LCL to the femur and tibia
• Distal fibula
  
  • Reconstruct with ipsilateral proximal fibular or contralateral vascularized fibular graft