MSK 3 Flashcards

Question

Hoffas fat pad inpingement

Answer 1

* Hoffas fat pad inpingement * cause of anterior knee pain

Answer 2

There is a well-circumscribed anterior paraarticular oval mass within the infrapatellar (Hoffa's) fat pad. It appears isointense to the muscles on T1WI with a central area of high signal (isointense to the articular cartilage), heterogeneous high signal on PD fat sat sequences with a central area also isointense to the articular cartilage and peripheral hypointense rim (calcification). No enhancement is seen following IV contrast administration. Note mild oedema of high signal within of the infrapatellar fat pad with no lesion of the adjacent bone. An intraarticular effusion is noted. Grade 3 vertical oblique tear of the posterior horn of the medial meniscus. Case Discussion Intracapsular (osteo-)chondroma of the knee is a rare benign tumour of cartilaginous origin due to an extrasynovial metaplasia, usually located within the infrapatellar fat pad. The main differential diagnoses include localised pigmented villonodular synovitis (also known as intraarticular giant cell tumour of the tendon sheath), calcified synovial sarcomas, calcifying bursitis, primary synovial chondromatosis, periosteal chondromas, and soft tissue chondrosarcoma. Localised pigmented villonodular synovitis typically appears as a soft tissue mass of midline location within the infrapatellar fat pad in contact with the patellar tendon. Its signal intensity is variable; however, the presence of low signal intensity on all sequences is a typical feature, indicating haemosiderin deposition.

Answer 3

calvarlia haemangioma

Answer 4

valgus stress to flexed and externally rotated knee contusion pattern: posterolateral tibial plateau and mid part of lateral femoral condyle associated with anterior cruciate ligament (ACL) tears see also: contrecoup injury of the knee, O'Donoghue unhappy triad

Answer 5

Haemophilic arthropathy refers to permanent joint disease occurring in haemophilia sufferers as a long-term consequence of repeated haemarthrosis. EpidemiologyCut Around 50% of patients with haemophilia will develop a severe arthropathy. Clinical presentation Presents similarly to osteoarthritis, with chronic joint pain, reduced range of motion and function, and reduced quality of life. Pathology Haemophilia is an X-linked recessive disease affecting mainly males. Haemarthroses may be spontaneous or result from minor trauma and typically first occurs before the age of two and continues to occur into adolescence. It is usual for the same joint to be repeatedly involved. In adulthood, haemarthroses are uncommon. However, proliferative chronically-inflamed synovium results in the development of haemophilic arthropathy. The haemarthroses results in the deposit of iron in the intraarticular region, which then leads to the proliferation of the synovium, neoangiogenesis, and ultimately damage to both the articular cartilage and subchondral bone 8. Haemophilic arthropathy is characterised by synovial hyperplasia, chronic inflammation, fibrosis, and haemosiderosis. The synovium mass erodes cartilage and subchondral bone leading to subarticular cyst formation 3. Location Haemophilic arthropathy is often monoarticular or oligoarticular. Large joints are most commonly involved in the following order of frequency 2: knee elbow ankle hip shoulder Radiographic features Plain radiograph joint effusion is seen in the setting of haemarthrosis periarticular osteoporosis: from hyperaemia epiphyseal enlargement with associated gracile diaphysis: from hyperaemia (appearances can be similar to juvenile rheumatoid arthritis and paralysis) secondary degenerative disease: symmetrical loss of joint cartilage involving all compartments equally with periarticular erosions and subchondral cysts, osteophytes and sclerosis knee 3 widened intercondylar notch squared inferior margin of the patella bulbous femoral condyles flattened condylar surfaces changes can be classified through the Arnold-Hilgartner classification 4 elbow 2 enlarged radial head widened trochlear notch ankle 1 talar tilt: relative undergrowth of the lateral side of the tibial epiphysis leads to a pronated foot

Answer 6

ant post - ITB, LCL, biceps fem ITB inserts on gerdys tubercle

Answer 7

**Associations** **positive ulnar variance is associated with ulnar impaction syndrome.** **negative ulnar variance is associated with Kienbock disease and ulnar impingement syndrome** Ulnar variance (also known as Hulten variance) refers to the relative lengths of the distal articular surfaces of the radius and ulna. Ulnar variance may be: neutral (both the ulnar and radial articular surfaces at the same level) positive (ulna projects more distally) negative (ulna projects more proximally) Variance is independent of the length of the ulnar styloid process. Pathology Aetiology trauma or mechanical distal radius/ulnar fractures with shortening (e.g. impaction) and angulation DRUJ ligamentous injuries (e.g. Galeazzi and Essex-Lopresti-fracture dislocations) surgical shortening of ulna or radius growth arrest (e.g. previous Salter-Harris fracture) congenital Madelung deformity/reverse Madelung deformity Radiographic assessment Ulnar variance changes with wrist position (more positive with maximum forearm pronation and negative with maximum forearm supination) and increases significantly during a firm grip 1. To determine ulnar variance on radiographs, the generally accepted standard view is a posteroanterior view obtained with the wrist in neutral forearm rotation, the elbow flexed 90° and the shoulder abducted 90°. Positive variance occurs when the level of the ulna is \>2.5 mm beyond the radius margin at the distal radio-ulnar joint. Negative variance is when the ulna is ≤2.5 mm than the radius at the DRUJ 1.

Answer 8

Rheumatoid arthritis (RA) is a chronic multi-system disease with predominant musculoskeletal manifestations. Being a disease that primarily attacks synovial tissues, RA affects synovial joints, tendons, and bursae. Refer to the related articles for a general discussion of rheumatoid arthritis and for the particular discussion of its respiratory and/or cardiac manifestations. Radiographic features Regarding disease detection, as the early RA manifestations are non-osseous in nature, ultrasound and MRI have shown to be superior to radiographs and CT. Plain radiography, however, remains the mainstay of imaging in the diagnosis and follow-up of RA 2. Plain radiograph One large cohort study showed that radiographically demonstrable erosions were present in 30% of patients at diagnosis, and in 70% three years later 4. The radiographic hallmarks of rheumatoid arthritis are: erosions; important early finding, in the “bare areas”, frequently in the radial side of the metacarpophalangeal (MCP) joints 7 soft tissue swelling fusiform and periarticular; it represents a combination of joint effusion, oedema and tenosynovitis 5 this can be an early/only radiographic finding osteoporosis: initially juxta-articular, and later generalised; compounded by corticosteroid therapy and disuse joint space narrowing: symmetrical or concentric Hands and wrists Diagnosis and follow-up of patients with RA commonly involve imaging of the hands and wrists. The disease tends to affect the proximal joints in a bilaterally symmetrical distribution. RA is a synovial based process, with a predilection for: PIP and MCP joints (especially 2nd and 3rd MCP) ulnar styloid triquetrum As a rule, the DIP joints are spared. Late changes include: subchondral cyst formation: the destruction of cartilage presses synovial fluid into the bone subluxation causing: ulnar deviation of the MCP joints boutonniere and swan neck deformities hitchhiker’s thumb deformity carpal instability: scapholunate dissociation, ulnar translocation ankylosis scallop sign: erosion of the ulnar aspect of the distal radius which may be predictive of extensor tendon rupture (Vaughan-Jackson syndrome) pencil-in-cup deformity: classically psoriatic arthropathy but well-recognised in rheumatoid arthritis Elbow joint effusion (elevated fat pads) joint space narrowing periarticular erosions cystic changes Feet similar to the hands, there is a predilection for the PIP and MTP joints (especially 4th and 5th MTP) involvement of subtalar joint posterior calcaneal tubercle erosion hammertoe deformity hallux valgus Shoulder erosion of the distal clavicle marginal erosions of the humeral head: the superolateral aspect is a typical location 2 reduction in the acromiohumeral distance: "high-riding shoulder" due to subacromial-subdeltoid bursitis and high incidence of rotator cuff tear Hip concentric loss of joint space, compared with osteoarthritis (OA) where there is a tendency for superior loss of joint space acetabular protrusion Knee joint effusion typically involves the lateral or non-weight bearing portion of the joint loss of joint space involving all three compartments lack of subchondral sclerosis and osteophytes, compared with OA prepatellar bursitis Spine The cervical spine is frequently involved in RA (in approximately 50% of patients), whereas thoracic and lumbar involvement is rare. Findings include: erosion of the dens atlantoaxial subluxation atlantoaxial distance is more than 3 mm on a flexion radiograph atlantoaxial impaction (cranial settling): cephalad migration of C2 erosion and fusion of uncovertebral (apophyseal joints ) and facet joints osteoporosis and osteoporotic fractures erosion of spinous processes

Answer 9

Tuberculosis (musculoskeletal manifestations) Dr Daniel J Bell◉ and Dr Prashant Mudgal et al. Musculoskeletal tuberculosis is always secondary to a primary lesion in the lung. Epidemiology The prevalence of the disease is around 30 million globally and 1-3% of the 30 million have involvement of their bones and/or joints. Mycobacterium tuberculosis is responsible for almost all of the cases of osteoarticular tuberculosis; although atypical mycobacteria have been reported in lesions of the synovial sheath. The predisposing factors are protein-energy malnutrition, environmental conditions and living standards such as poor sanitation, overcrowded housing and slum dwelling. Trauma as a causative factor is debatable, but has been reported. Acquired immunodeficiency syndrome and other causes of immunocompromised status and repeated pregnancies and lactation in women are also a factor. Pathology Osteoarticular tuberculosis can occur in the spine, hip, knee, foot, elbow, wrist, hand, shoulder and as diaphysial foci. It has not been reported to affect the mandible or the temporomandibular joint. The major method of spread is haematogenous. The most common method of spread to the vertebral body is through the Batson prevertebral venous plexus. Osteoarticular tuberculosis is reported in various sites including: tuberculosis of the spine tuberculous arthropathy tuberculosis of the tendon sheath and bursae tuberculous osteomyelitis tuberculous dactylitis case: Patient Data AGE: 11 years old GENDER: Male 4 case questions available X-RAY Oblique Lateral X-ray Oblique Oblique view of both hand radiograph and lateral view of left elbow show soft tissue swelling and multiple cystic bony destructions involving all long tubular bones and carpal bones. Benign solid periosteal reaction along left humerus is partly visualised. Case Discussion The patient was known case of paediatric AIDS and diagnosed disseminated tuberculosis. He re-visited hospital with both wrist and left elbow swelling, multiple skin abscesses at left and, right axilla, and left elbow. The AFB staining from the abscesses were positive1+ at right hand, 3+ at right axilla and 1+ at left elbow. The left epitrochlear nodes are enlarged and positive AFB staining 1+. The plain radiograph of both hands and left elbow show multiple cystic osteolytic lesions involving all long tubular bones and carpal bones. This case demonstrates "osteitis tuberculosa multiplex cystoides" or "Jungling disease" which is the multifocal musculoskeletal TB and often found in disseminated disease and conjoined with pulmonary infection. The differential diagnoses are categorised in infection (e.g. disseminated pyogenic osteomyelitis) and neoplasms (e.g. eosinophilic granuloma or small round cell tumours). Oblique view of both hand radiograph and lateral view of left elbow show soft tissue swelling and multiple cystic bony destructions involving all long tubular bones and carpal bones. Benign solid periosteal reaction along left humerus is partly visualised. Case Discussion The patient was known case of paediatric AIDS and diagnosed disseminated tuberculosis. He re-visited hospital with both wrist and left elbow swelling, multiple skin abscesses at left and, right axilla, and left elbow. The AFB staining from the abscesses were positive1+ at right hand, 3+ at right axilla and 1+ at left elbow. The left epitrochlear nodes are enlarged and positive AFB staining 1+. The plain radiograph of both hands and left elbow show multiple cystic osteolytic lesions involving all long tubular bones and carpal bones. This case demonstrates "osteitis tuberculosa multiplex cystoides" or "Jungling disease" which is the multifocal musculoskeletal TB and often found in disseminated disease and conjoined with pulmonary infection. The differential diagnoses are categorised in infection (e.g. disseminated pyogenic osteomyelitis) and neoplasms (e.g. eosinophilic granuloma or small round cell tumours). Tuberculous spondylitis Dr Bahman Rasuli◉ and Dr Hani Makky Al Salam et al. Tuberculous spondylitis, also known as Pott disease, refers to vertebral body osteomyelitis and intervertebral discitis from tuberculosis (TB). The spine is the most frequent location of musculoskeletal tuberculosis, and commonly related symptoms are back pain and lower limb weakness/paraplegia. Epidemiology Tuberculous spondylitis is one of the more common infections of spine in countries where TB is prevalent. Unfortunately, the incidence of tuberculous spondylitis, as with other forms of TB, is on the rise, due to new multiple drug resistant strains. Discitis and/or osteomyelitis comprise approximately 50% of all musculoskeletal tuberculosis, and usually affects the lower thoracic and upper lumbar levels of the spine 2. Clinical presentation Patients usually present with back pain, lower limb weakness/paraplegia, and kyphotic deformity. Constitutional symptoms (fever and weight loss) are also common but not as pronounced as with bacterial discitis/osteomyelitis. Pathology The spine is involved due to hematogenous spread via the venous plexus of Batson 2. There is usually a slow collapse of one or usually more vertebral bodies, which spreads underneath the longitudinal ligaments. This results in an acute kyphotic or "gibbus" deformity. This angulation, coupled with epidural granulation tissue and bony fragments, can lead to cord compression. Unlike pyogenic infections, the discs can be preserved and it more commonly involves the thoracic spine. In late-stage spinal TB, large paraspinal abscesses without severe pain or frank pus are common, leading to the expression "cold abscess". Radiographic features Plain radiograph The spread of infection is typically described as 'sub-ligamentous': beneath the anterior longitudinal ligament, usually sparing the posterior elements and often involving multiple levels. Tuberculous spondylitis can be difficult to detect in early stages because of relative preservation of the disc space. A reduction in vertebral height is often seen with the irregularity of the anterosuperior endplate being relatively early and subtle sign. Due to the subligamentous extension, there may be some irregularity of the anterior vertebral margin. This is a classical appearance with TB spondylitis. Later, paraspinal collections can develop which can be remarkably large. Ivory vertebrae can result in re-ossification. Other associated features may include: gibbus deformity vertebra plana As with other extrapulmonary TB, the chest film may be unrevealing (no pulmonary lesions seen in up to 50% of cases), with the source being a primary lung lesion that is clinically silent. CT and MRI Cross-sectional imaging is required to assess better the extent of involvement and particularly for the presence of an epidural component and cord compression. MRI is the modality of choice for this, with CT with contrast being a distant second. Features include irregularity of both the endplate and anterior aspect of the vertebral bodies, with bone marrow oedema and enhancement seen on MRI: T1: hypointense marrow in adjacent vertebrae T2: hyperintense marrow, disc, soft tissue infection T1 C+ (Gd): marrow, subligamentous, discal, dural enhancement The paraspinal collections are typically well circumscribed, with fluid centres and well-defined enhancing margins 7. Differential diagnosis In many parts of the developing world, TB is the most common cause of vertebral body infection, with the majority of cases seen in patients under the age of 20. TB can also affect the meninges of the spine, causing an intense pachymeningitis that enhances dramatically. brucellosis: can present as granulomatous osteomyelitis of the spine that can be difficult to distinguish from TB. Both are acid-fast bacilli, which may cause caseating granuloma(s) fungal infection sarcoidosis pyogenic infection compared to pyogenic infection tuberculous spondylitis has relatively preserved disk-space height, forms large paraspinal abscesses with a smooth enhancing wall and there is usually systemic involvement of multiple organs see: tuberculous spondylitis versus pyogenic spondylitis metastasis Robins Mycobacterial Osteomyelitis (p. 1196) Tuberculous osteomyelitis occurs in 1% to 3% of patients with tuberculosis; organisms are typically bloodborne, although direct extension or lymphatic seeding can occur. The spine is involved in 40% of cases (Pott disease) with frequent invasion into soft tissues and abscess formation. Lesions exhibit typical granulomatous reaction with caseous necrosis.

Answer 10

Avascular necrosis of the hip Dr Yuranga Weerakkody◉ and Assoc Prof Frank Gaillard◉◈ et al. Avascular necrosis of the hip is more common than other sites, presumably due to a combination of precarious blood supply and high loading when standing. Clinical presentation The most common presenting symptom is a pain in the region of affected hip, thigh, groin, and buttock. Although few patients may remain asymptomatic until late stages. Pathology Typically it affects the superior articular surface (between 10-2 o'clock) and begins in the most anterior part of the hip. Aetiology It can be thought of as traumatic (secondary to the neck of femur fractures) or non-traumatic. In non-traumatic cases, it is bilateral in 40%. traumatic chronic corticosteroid therapy alcoholism smoking systemic lupus erythematosus (SLE) hyperlipidaemias HIV haemoglobinopathies chronic renal failure diabetes mellitus pregnancy-related Radiographic features Specific staging system (Ficat staging) exists for the hip which includes x-ray, MRI and bone scan appearances, and covers much of the imaging appearances, thus please refer to that article. Other than describing the general appearance of the affected region, the following are necessary to include in the report as they have a bearing on prognosis and treatment: position estimating percentage volume of the head involved (axial) and percentage weight-bearing surface involved (coronal) coexisting osteoarthritis or secondary degenerative change joint effusion presence of a potentially unstable osteochondral fragment: rim sign subchondral fractures CT Often more sensitive than plain film in showing subchondral fractures. MRI MRI is the most sensitive modality, with a sensitivity of 71-100% and specificity of 94-100%1. As there is a high rate of bilateral involvement, both hips should be included in the field of view of at least some sequences. T1: usually the initial specific findings are areas of low signal representing oedema, which can be bordered by a hyperintense line which represents blood products T2: may show a second hyperintense inner line between normal marrow and ischaemic marrow. This appearance is highly specific for AVN hip and known as "double line sign". The Mitchell classification is commonly used to classify AVN based on MR-images. Differential diagnosis In some situations consider subchondral insufficiency fracture of the femoral head - considered by some as a different entity 9 General imaging differential considerations include: haematopoietic marrow (see bone marrow) Pitt's pit fovea centralis idiopathic transient osteoporosis of the hip (ITOH) hyperaemia with diffuse increased uptake of radiotracer by the femoral head, neck, and intertrochanteric region chondroblastoma fracture infection pain and fever usually involves both sides of the joint metastases

Answer 11

(most commonly benign)

Answer 12

mnemonic: GIVE INFARCTS Gaucher disease Idiopathic (Legg-Calve-Perthes, Kohler, Chandler) Vasculitis (SLE, polyarteritis nodosa, rheumatoid arthritis) Environmental (frostbite, thermal injury) Irradiation Neoplasia (-associated coagulopathy) Fat (prolonged corticosteroid use increases marrow) Alcoholism Renal failure + dialysis Caisson disease Trauma (femoral neck fracture, hip dislocation) Sickle cell disease Location: femoral head (most common), humeral head, femoral condyles

Answer 13

Bennet #: * Dorsal tradial dislocation * force from abductor pollicis langus * a small fragment maintains articulations w trapezium Rolando #: * Comminuted BENNETT # * Fracture line may have "Y", "V" or "T" configuration

Answer 14

* Decompression sickness * Dr Daniel J Bell◉ and Dr M Venkatesh et al. * Decompression sickness (DCS), also known as diver's disease, aerobullosis, the bends or caisson disease, is an uncommon diving-related decompression illness that is an acute neurological emergency typically occurring in deep sea divers. * Clinical Presentation * Decompression sickness can be further clinically subdivided into: * mild symptoms: arthralgia, skin marbling, small patchy haemorrhages, and lymphatic obstruction * serious and life-threatening symptoms: affecting the brain, spinal cord, inner ear, and/or lung * Pathology * Nitrogen gas bubbles can cause neurovascular infarction of the brain and spinal cord leading to neurological deficit. There are various theories to explain this, which hypothesise between arterial occlusion, venous infarction and cellular nitrogen toxicity. * Location * The white matter tracts of the spinal cord and brain are predominantly affected due to their high myelin content 3. Cord lesions are more common than brain lesions. In the spinal cord, there is a predilection for the thoracic cord segments to be affected, thought to be secondary to more nitrogen accumulating in the lateral and posterior columns where there is higher fat content and also the relatively low blood flow compared to the cervical and lumbar segments. * Complications * bone infarction * spinal cord infarct * Radiographic features * MRI * Radiological changes are seen in early stages in MRI, but have very low specificity. The affected white matter may show ischaemic lesions or the bubbles themselves. There may also be an accumulation of nitrogen bubbles in marrow fat. * Normal MRI of the cord does not rule out the diagnosis 3. If there are MRI findings, these tend to normalise after a few weeks. * Treatment and prognosis * hyperbaric oxygen on site and during transportation followed by treatment in a recompression chamber * The quicker treatment begins, the higher the chance of successful recovery. * History and etymology * A caisson is a watertight container used in underwater construction work. * The bends refers to the joint pain associated with the disease https://www.semanticscholar.org/paper/A-study-of-old-lesions-of-caisson-disease-of-bone-Gregg-Walder/06dd820f98223d54ee36dcdf4c42bc4182fdc9b6

Answer 15

Post-traumatic digital ischemia from thrombosis of ulnar artery at Guyon's canal. Epidemiologyincidence rare demographics male: female ratio is 9:1 age bracket is 40s-50s location unilateral, dominant ring finger +/- small finger less commonly, index and middle fingers thumb is spared risk factors occupations using vibrating tools such as carpenters, machinists, mechanics sports such as baseball catchers, mountain biking, golf, volleyball, karate Pathophysiologymechanism single or repetitive blunt impact on hypothenar eminence leads to ulnar artery thrombosis or aneurysm hook of hamate functions as an anvil, causing thrombosis distal embolisation leads to ulceration, gangrene

Answer 16

Medial knee pain Say Grace before T Sartorius, Gracillus, Bicepts tendon

Answer 17

1. Lytic or Sclerotic 2. Age \<30 or \>30 3. Location in the body 4. Location in the bone 5. Periosteal Reaction 6. Tumour Matrix 7. Bone Destruction 8. Margins 9. Soft tissue component

Answer 18

* Pedunculated osteochondroma * sessile osteochondroma * enchondromas * usually just lucent lesions * but in other bones have a chondroid matrix * Chondroblastoma * epiphysis/growth plate tumour * UBC * fallen fragment * ABC * diaphyseal * NOF * cortically based lesion * expansile * healing NOF as it heals becomes sclerotic

Answer 19

Achilles tendinopathy Dr Mohamed Saber and Dr Yuranga Weerakkody◉ et al. Achilles tendinopathy refers to a combination of pathological changes affecting the Achilles tendon usually due to overuse and excessive chronic stress upon the tendon. It can be seen both in athletes and non-athletes. It is hard to differentiate clinically from a paratendinopathy (which is most common). It may or may not be associated with an Achilles tendon tear. Epidemiology It can affect a range of people from athletes to recreational exercisers and even inactive people. It affects non-athletes in around one-third of cases. Pathology Macroscopically, tendinopathy results in enlargement, disruption of fibrillar pattern and an increase in tendon vascularity. Histopathologically, there is evidence of disorganised proliferation of tenocytes, disrupted organisation of collagen fibres, and an increase in the non-collagenous matrix, and neovascularisation. Usually, there is no evidence of inflammation, but the cause is thought of as a failed healing response 1. Repetitive microtrauma from unusual or excessive mechanical loading is deemed to be a causative factor. Location **It particularly affects the mid and distal portions of the tendon 2.** Radiographic features Ultrasound Often shows thickening and rounding of the affected portion of the tendon. **The cutoff value of 1 cm in anteroposterior diameter is usually used for diagnosis. T**here is also evidence of neovascularisation, which, if present, is usually indicative of a poorer outcome and more severe clinical symptoms. Additional signs include increased Kager fat pad echogenicity and thickening of a hypoechoic paratenon. **MRI** **Can show increased intratendinous signal and tendon enlargement, with oedema in Kager fat pad in cases of tendinosis.**

Answer 20

Juxtacortical (periosteal) Chondroma Non-contrast MR of the knee shows a 2.5 x 1.8 cm T2 hyperintense, T1 intermediate multilobulated mass at the anterolateral proximal right tibial shaft, which appears to arise from the cortex or periosteum. There is T2 hyperintensity within the tibialis anterior muscle surrounding the mass, consistent with intramuscular oedema. There is no evidence of significant bone marrow oedema of the tibia. Case Discussion The small lytic mass associated with the anterolateral cortex of the tibia metaphysis shows evidence of chondroid-type mineralisation by radiography ("rings and arcs" pattern of calcification). The MR images nicely demonstrate the lesion originating from the superficial cortex, without intramedullary invasion. The absence of associated reactive marrow oedema is suggestive of a benign aetiology. The MR signal characteristics (T1 intermediate, T2 hyperintense) are typical of chondral tissue. The differential diagnosis includes: periosteal (juxta-cortical) chondroma chondromyxoid fibroma (intramedullary \>\> juxta-cortical location, sclerotic rim, and radiographically apparent chondroid matrix is uncommon) non-epiphyseal chondroblastoma (classically T2 hypointense due to immature chondroid matrix, usually associated with reactive marrow oedema) The presentation and imaging appearance, including the lobulated and exophytic morphology, are most consistent a benign juxtacortical chondroma. Histology Soft, gray mass associated with a piece of bone. The mass measures approximately 2.0 x 2.0 x 1.7 cm. Sections show a cartilaginous neoplasm that has some degree of nuclear atypia and areas of myxoid changes. However, it is known that benign periosteal or juxtacortical chondromas can have atypia. Furthermore, the mass is relatively small, measuring 2.5 cm by imaging, and is well-circumscribed. Immunostains (Ki-67, p53) were indeterminate. DIAGNOSIS: juxtacortical (periosteal) chondroma. Juxtacortical chondroma Dr Sarah Robertson and Dr Yuranga Weerakkody◉ et al. Juxtacortical chondromas, also known as periosteal chondromas, are rare benign chondral tumours that arise from the periosteum of tubular bones. They are thought to account for ~2% of benign bone tumours. Epidemiology They tend to present around the 2nd to 4th decades. There is a recognised male predilection 1. Location Typical sites include 3: proximal humerus and distal femur (70%) phalanges (25%) tibia radius ulna Radiographic features Plain radiograph may be seen as a saucerisation of the adjacent bony cortex with a sclerotic periosteal reaction distinct soft tissue mass may be difficult to identify matrix calcification may be seen in ~50% of cases; as with all chondroid lesions, this tends to be ring and arc most lesions are \<3 cm in size 1 MRI Typically seen as a soft tissue lesion abutting the cortex and may better demonstrate evidence of pressure erosion of neighbouring bone. Often has a lobulated configuration. Tends to lack associated medullary bone or soft tissue oedema. Signal characteristics include 8: T1: typically iso to low signal relative to muscle T2/T2\*: high signal but with low signal areas representing calcification T1 C+ (Gd): heterogeneous and tends to show peripheral predominant contrast enhancement Treatment and prognosis They are benign lesions, however, may be similar in imaging and histopathologic appearance to juxtacortical chondrosarcomas. Local excision is often the treatment of choice. Once resected lesions usually do not recur. Differential diagnosis Imaging differential considerations include: periosteal osteosarcoma: lobulated margins and high T2 chondral nodules of periosteal chondroma are absent non-epiphyseal chondroblastoma: typically associated with reactive marrow oedema on MR juxtacortical chondrosarcoma: often larger than 3 cm (mean size 5.5 cm) bizarre parosteal osteochondromatous proliferation (Nora lesion): for phalangeal lesions cortical desmoid: for the posteromedial distal femoral lesions tenosynovial giant cell tumour: for phalangeal lesions

Answer 21

hyperextension injury ## Footnote direct force to anterior tibia with foot planted contusion pattern: "kissing contusions" of anterior tibial plateau and anterior femoral condyle associated with ACL, PCL, meniscal injuries, and in severe cases knee dislocation

Answer 22

* chondrocalcinosis * subchonral cysts with little osteophyes * can mimic OA, RA , Gout or chots * any joint * calc in and around joints: hyaline cartilage, fibor cartilage, syndoivum, capsile, tendons ligaments * Can resemble OA, but WORSE in the patellofemoral joint * DDx * Gout * Charcot Earth (CPPD is AKA psuedocharcot) * OA * RA * Septic arthritis

Answer 23

7.3. Partial-Thickness Tears Partial-thickness tears are defined as a disruption of tendon fibers that does not allow communication between the glenohumeral joint cavity and the subacromial-subdeltoid bursa. Partial tears may be intrasubstance, or extend to either the bursal or articular surfaces of the tendon (figure 1-39). Articular surface partial-thickness tears most commonly affect the anterior aspect of the critical zone of the supraspinatus and are more prevalent than intrasubstance and bursal surface tears. Theoretical basis for the increased frequency of articular surface tears include peculiar histological and biomechanical properties. The bursal side layers are primarily composed of tendon bundles, which are resistant to rupture and may elongate under tensile load, whereas articular side layers are composed of a complex of tendon fibers, ligaments, and joint capsule, which is more susceptible to tear.176

Answer 24

* asymmetric * oligo or poly arthropathy * DIP (primarily) and PIP * can mimic OA * proliferative bone chagnes * periostitis (radio styloid) * osteolysis Pencil in cup * enthesitis dactylitis * RF neg *

Answer 25

* Matches the prox zone of the hands * Has the same ddx (RA and CPPD) as well as a few more * Neuropathic charcot arthropay * Disorgansies joints, fragmented and sclerotic bone. Starts with systic change * CPPD * Cystic change, can mimic charcot Earth. Aka pseudocharcot * Gout * OAL usually secondary (coalition, truam, tibiaasias posterior dysfunction (pes planus)

Answer 26

boutonniere's Syndrome ## Footnote Boutonnière deformity is the eponymous name of a musculoskeletal manifestation of rheumatoid arthritis presenting in a digit, with the combination of: flexion contracture of a proximal interphalangeal (PIP) joint extension of a distal interphalangeal (DIP) joint Pathology Boutonnière deformities occur when the central slip of the extensor digitorum tendon is torn or stretched resulting in PIP joint flexion. Increasing PIP joint flexion causes further extensor retinaculum damage resulting in "buttonholing" of the proximal phalanx between the lateral bands of the extensor tendon. Secondary DIP joint extension then occurs 4. Etiology inflammatory arthritis 4 central slip of extensor digitorum tendinopathy or rupture 4 History and etymology "Boutonnière" is French for buttonhole. The appearance apparently reminded (presumably French-speaking) surgeons of a buttonhole.

Answer 27

Segond fracture Dr Subhan Iqbal◉ and Assoc Prof Frank Gaillard◉◈ et al. Segond fracture is an avulsion fracture of the knee that involves the lateral aspect of the tibial plateau and is very frequently (~75% of cases) associated with disruption of the anterior cruciate ligament (ACL). On the frontal knee radiograph, it may be referred to as the lateral capsular sign. Clinical presentation Contrary to the more common causes of an ACL tear, which typically involve a valgus stress 3, a Segond fracture usually occurs as a result of internal rotation and varus stress 1,4. Typically these injuries are seen in two settings: falls sports: especially soccer, skiing, basketball and baseball 4,10 Pathology Somewhat surprisingly, the exact cause of a Segond fracture continues to be contentious. The conventional teaching has been that it is the result of avulsion of the middle third of the lateral capsular ligaments 7. Other candidate structures include the iliotibial band and anterior oblique band of the fibular collateral ligament 3. In 2017, the ALL expert group released a consensus paper 8 recognising the presence of the anterolateral ligament 9, and noted a constant attachment to the lateral meniscus. However, the ALL is inconsistently identified on MRI 7. Radiographic features Plain radiograph The classical appearance of a Segond fracture is that of a curvilinear or elliptic bone fragment projected parallel to the lateral aspect of the tibial plateau. This has been referred to as the lateral capsular sign 1, which is best seen on the anteroposterior view of the knee. MRI MRI is essential in all cases of Segond fractures to identify internal derangement. Disruption of the ACL is the most common, however, there are additional frequently encountered injuries. Associated injuries include 1,3: ACL tear most common associated injury 75-100% of cases 6 medial or lateral meniscal tear 66-75% of cases 6 posterior horn most common avulsion of ACL from the tibial attachment: rare avulsion of fibular attachment of the long head of biceps femoris avulsion of the fibular collateral ligament Treatment and prognosis Although the fracture itself is small, the extensive ligamentous injury associated with it usually requires surgical intervention, to correct anterior rotational instability 4. Healing of the Segond fracture is associated with a particular bone excrescence arising below the lateral tibial plateau. History and etymology First described by Paul Ferdinand Segond, French surgeon (1851-1912) based on cadaveric experiments 1,2,4. Differential diagnosis Imaging differential considerations include: arcuate sign: avulsion fracture of the head of the fibula 5 fragment orientated more horizontally

Answer 28

Olecranon bursitis refers to inflammation of the olecranon bursa. The olecranon bursa is a subcutaneous sac that overlies the olecranon process and contains a small amount of fluid to prevent against injury of subcutaneous tissue and skin from the uncovered bony olecranon. Pathology Aetiology Bursitis can develop secondary to many causes: excessive use - e.g. student's elbow trauma acute trauma repetitive trauma infection - septic inflammation - rheumatoid arthritis, gouty arthropathy and CPPD Radiographic features Plain film Lateral radiograph of the elbow reveals soft tissue swelling superficial to the olecranon. Traumatic fracture or calcification in gout or CPPD may be evident. Ultrasound May show a fluid collection in the olecranon bursa, features of synovial proliferation and/or hyperaemia. A small proportion of patients may also show presence of an associated loose body or features of associated triceps tendonitis (+/- calcifications) 2.

Answer 29

ACL MCL Meniscus

Answer 30

* PLC * LCL * BF * Pop t * arcuate lig * popliteofibular lig * Common peroneal nerve may be injured

Answer 31

Flap tear Dr Balint Botz ◉ and Dr Yuranga Weerakkody◉ et al. A flap tear is a type of meniscal tear which usually comprises of a displaced flap fragment. horizontal tears can give rise to flap tears, which can be classified as superior or inferior when displaced. Superior flaps arise from the superior surface of the meniscus and inferior flaps from the inferior surface. oblique tears could also give rise to flaps which are mechanical unstable and associated with mechanical symptoms 2 Location Flap tears occur six to seven times more frequently in the medial meniscus 3.

Answer 32

* MUGR * "Mugger" * Monteggia = Ulna fracture and radial dislocation * Galleazzi = Radial fracture with Ulnar dilocation * A in Monteggia = proximal in the alphabet = proximal findings * Z is distal in the alphabet = distal findings.

Answer 33

Periosteal Chondromas A rare type of chondroma (benign chondrogenic lesion) which occur on surface of long bones Epidemiologydemographics occur in 10-20 year-olds locationsurface of long bones (under periosteum) in distal femur, proximal humerus, and proximal femur 59% of lesions in proximal humerus other locations in the hand (metacarpal or phalanges) Presentation Symptoms many are painful secondary to irritation of tendons Imaging Radiographs well-demarcated, shallow cortical defect punctate mineralization (calcification) in 1/3. saucerization of underlying bone radiographs important to differentiate from chondrosarcoma (histology may be similar) Studies Histologysimilar to enchondroma except for increased cellularity and more malignant looking cells (can look like chondrosarcoma) bland hyaline cartilage small chondroid cells in lacunar spaces Treatment Operativemarginal excision including underlying cortexindications severe symptoms interferring with function technique lesion will recur if cartilage is left behind bone graft any large defects

Answer 34

Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 62021 Picture frame vertebral body Dr Yuranga Weerakkody◉ and Dr Mohammad Taghi Niknejad et al. Picture frame vertebral body is a radiologic appearance in which the cortex of the vertebral body is thickened. This sign can be seen in patients with Paget disease. It is a result of disorganised new cortical bone formation after excessive osteoclastic activity causes the resorption of normal bone. Radiographic features At radiography, this results in increased opacity of the cortex on all sides of the vertebral body. Differential diagnosis rugger jersey spine the characteristic sclerosis is seen only at the superior and inferior vertebral endplates

Answer 35

Phocomelia Dr Karwan T. Khoshnaw and Dr Yuranga Weerakkody◉ et al. Phocomelia is an extremely rare congenital skeletal disorder that characteristically affects the limbs. It can affect either the upper limbs or lower limbs or both. Phocomelia is also a descriptive term to describe the characteristic limb anomalies occurring with its associated conditions. Pathology It characteristically manifests as a deficiency or shortening of the proximal to mid portions of the limbs. Associations Phocomelia can occur sporadically. However, recognised associations include: thalidomide embryopathy: most common cause of historically Roberts syndrome TAR syndrome 4 Grebe syndrome Holt-Oram syndrome DK phocomelia syndrome/von Voss-Cherstvoy syndrome Schinzel-phocomelia syndrome 5 Radiographic features Antenatal ultrasound Classically with upper limb involvement, the hands are present, but with variable deficiency and or foreshortening of the arm and/or forearm. The hands may be of normal or abnormal morphology. History and etymology Derived from the Greek phoco meaning "seal" and melia meaning "limb". Differential diagnosis congenital limb amputation amelia

Answer 36

Findings: A bony overgrowth extending outwards from the surface of the right radial head away from the joint. The appearance is typical for an osteochondroma (exostosis). Cross-sectional imaging, preferably MRI, is advised to measure the cartilage cap, especially if there is a history of pain. Epidemiology Osteochondromas develop during childhood (period of most rapid skeletal growth), but once formed remain for the rest of the individual's life. They can present at any age and are most frequently found incidentally. They are usually sporadic, but can be part of: hereditary multiple exostoses (HME): also known as diaphyseal aclasis Trevor disease: also known as dysplasia epiphysealis hemimelica Malignant transformation occurs in the cartilage cap, and is uncommon in sporadic solitary osteochondromas (~1%), whereas in the setting of hereditary multiple exostoses the rate is much higher (5-25%) 5. Clinical presentation Symptomatic presentation is either due to mechanical effects of the lesion, fracture, or malignant transformation. Mechanical symptoms include: impingement upon nearby structures: nerve compression vascular compression reactive myositis palpable lump bursal formation and bursitis Fractures occur typically through the neck of pedunculated lesions. Ongoing growth and or pain after skeletal maturity has been reached is suspicious for malignant degeneration. Pathology Osteochondromas are considered a chondroid neoplasm and are primarily a part of the growth plate which separates and continues growing independently, without an associated epiphysis, usually away from the nearby joint. The medullary cavity is continuous with the parent bone, and hyaline cartilage caps them. Osteochondromas can be congenital or occur as a result of previous trauma to the growth plate, including previous irradiation 3,4. Location They most commonly arise from the appendicular skeleton, especially around the knee 3: lower limb: 50% of all cases 3 femur (especially distal): most common: 30% tibia (especially proximal): 15-20% less common locations: feet, pelvis upper limb humerus: 10-20% less common locations: hands, scapula spine: the posterior elements of the spine are an uncommon but not rare site for these tumours Radiographic features Plain radiograph An osteochondroma can be either sessile or pedunculated and is seen in the metaphyseal region typically projecting away from the epiphysis. There is often associated broadening of the metaphysis from which it arises. The cartilage cap is variable in appearance. It may be thin and difficult to identify, or thick with rings and arcs calcification and irregular subchondral bone. New cortical irregularity or continued growth after skeletal maturity has been reached, as well as frankly aggressive features (e.g. bony destruction, large soft tissue component, metastases) are all worrying for malignant transformation.

Answer 37

Findings: A displaced and overlapped fracture of the ulnar shaft is present. Additionally, the radial head is dislocated anteriorly. Case credit: Frank Gaillard, rID: 8012 Key Points these are typically seen in children and warrant close investigation of both the elbow and the wrist there is a chance the patient could have an associated distal radius injury as is the case in some studies (24%) monteggia fracture-dislocations are not easy to image and require highly modified techniques such as horizontal beam lateral

Answer 38

Osteochondral injury staging Dr Mostafa El-Feky◉ and Assoc Prof Frank Gaillard◉◈ et al. Osteochondral injury staging system for MRI attempts to grade the stability and severity of osteochondral injury and is used to plan management. stage I injury limited to articular cartilage MRI findings: subchondral oedema x-ray findings: none stage II cartilage injury with associated subchondral fracture but without detachment thin sclerotic margin x-ray findings: usually none; may see fracture as sclerotic or osteopenic area two subtypes 2,3 type A: cystic on CT and/or oedema on MRI type B: non-displaced and incompletely undercut by fluid (MR) or lucency (CT), with an open connection to the articular cartilage (essentially 2a without oedema on MRI) stage III detached, non-displaced fragment MRI findings: high signal around osteochondral fracture (rim sign) but not displaced x-ray findings: slight lucency between osteochondral fragment and remainder of the bone stage IV osteochondral fragment displaced usually joint effusion present, surrounding fragment and filling donor site x-ray findings: increased lucency between osteochondral fragment and remainder of the bone, or loose body with donor site irregularity stage V subchondral cyst formation secondary degenerative change x-ray findings: secondary osteoarthritis

Answer 39

* can be normal in kids and young adults. normal gascularity flow of suynovial lfludi * Signs of OA * myxoid degn * Evidence of trauma * contusion * Meniscal cyst * meniscal tear * Contacts an articular surface on more than 1 slice * meniscal tear * if see in only 1 slice * around 50% chance of a tear *

Answer 40

* Hydroxyapatite deposition disease (HADD) * globular foci of calcification in the expected location of the supraspinatus (white) infraspinatus (black arrow) and pect major (arrowheads tendon). * HADD * no know cause. * 2/3 assymptomatic * can be the cause of acute pain and a/w fever, increased ESR and CRP. * AKA calcific tendonitis, hydroxyapatite rheumatism, calcific periarthritits and pertendinitis calcarea. * calc appears clowud like and amorphous and can involve the tendon, ligament, bursa or. joint capusle. * intraarticuilar deposition can destroy the point space, resulting in a condition referred to as Milwaukee shoulder. * The shoulder is most commonly involved. * On CT accompanying erosion of the underlying bone canbe seen. * Electron microscopy needed to dx. * Can appear aggressive erosive esp when involveing the pect major origin which can be mis interpreted as malignancy. * Pope Jr, T., 2015. Aunt Minnie's Atlas And Imaging-Specific Diagnosis. Philadelphia: Wolters Kluwer.

Answer 41

* Gout mono sodium * Pseudogeout: CPPD intra articular * HADD

Answer 42

Complex regional pain syndrome Dr Balint Botz ◉ and Assoc Prof Frank Gaillard◉◈ et al. Complex regional pain syndrome (CRPS), also known as Sudeck atrophy, is a condition which can affect the extremities in a wide clinical spectrum. CRPS is principally a clinical diagnosis seen more commonly in females than males with a mean age of presentation of 50 to 70 years 12. No one imaging study is sensitive or specific to rule in or rule out the syndrome. Terminology Two types of CRPS have been described 8: type 1: no underlying single nerve lesion (formerly known as reflex sympathetic dystrophy) type 2: underlying nerve lesion identified (formerly known as causalgia) Clinical presentation Patients present after an initiating event (see causes below) with symptoms of more than 6 months duration such as oedema, changes in skin blood flow, abnormal motor activity, allodynia or hyperalgesia 11. Symptoms are often out of proportion to the initiating event and not limited to a single peripheral nerve 8. Pathology Aetiology trauma: often minor surgery 11 idiopathic: immobilisation unknown in many cases CNS disorders myocardial infarction Location Occurs in hands and feet distal to the injury. Radiographic features Plain radiograph severe patchy osteopenia, particularly in the periarticular region soft tissue swelling, with eventual soft tissue atrophy subperiosteal bone resorption preservation of joint space It is important to differentiate this from disuse osteopenia since the clinician could initiate aggressive physical therapy for the latter. MRI patchy bone marrow oedema signal (particularly subcortical), although bone marrow signal may be normal in some cases soft tissue oedema and enhancement skin thickening joint effusion synovial hypertrophy muscle atrophy in later stages Nuclear medicine increased uptake on all three phases diffusely increased juxta-articular activity around all joints of a hand or foot on delayed images is the most sensitive indicator Treatment and prognosis In most cases, a multidisciplinary approach is required whereby a combination of various treatments may be employed, such as physical therapy, systemic or regional medications, sympathectomy or spinal cord stimulation, and psychotherapy. Interventional radiology can offer pain relief by peripheral nerve block procedures. References

Answer 43

Case courtesy of Dr Angela Byrne, Radiopaedia.org, rID: 8112 Chondroblastoma https://radiopaedia.org/cases/chondroblastoma-distal-femur-2?lang=us

Answer 44

5. Gouty arthritis • monosodium urate crystals in synovial fluid • asymptomatic periods from months to years Target areas: commonly CCMC +all hand joints './ development of chronic tophaceous gout =lobulated soft-tissue masses './ well-defined eccentric erosions with overhanging edge (often periarticular) + sclerotic margins './ preservation of joint spaces './ absence of osteoporosis './ most extensive changes in common carpometacarpal compartment: './ scalloped erosions of bases of ulnar metacarpals

Answer 45

* Patella dislocation relocation (PDR) * kissing contusions to the medial patella facet and the lateral femoral condyle * large lipohaemarthrosis * sprain/tear of the medial patella retinaculum. * hoffas fat pad injury * redislocation occurs in up to 63% of patients * A/W ACL tears Pope Jr, T., 2015. Aunt Minnie's Atlas And Imaging-Specific Diagnosis. Philadelphia: Wolters Kluwer.

Answer 46

Parrot beak meniscal tear Dr Magdalena Chmiel-Nowak◉ and Dr Yuranga Weerakkody◉ et al. Parrot beak meniscal tear is a type of radial meniscal tear with a more oblique course, which on axial images gives the characteristic appearance of a curved V, similar to a parrot's beak. As it is obliquely orientated in relation to the coronal and sagittal plane, it results in a marching cleft sign on sagittal images. This type of tear is usually symptomatic, as the partially torn meniscal flap in unstable. Practical points Some authors advise that the term should be reserved for arthroscopy reports, and not used in MRI reports as a meniscal tear pattern descriptor 1.

Answer 47

* In the absence of a fracture, a painful encondrona is considered malignant until proven otherwise. * Malignant transformation occurs but is rare. * Malignant transformation is more common in central lesions

Answer 48

haemochromatosis. Overhanging (hooked) osteophytes of the metacarpal heads of the right index. Case Discussion The overhanging osteophytes (a.k.a. hooked or beak-like osteophytes) at the heads of the metacarpals of index and long fingers are typical for haemochromatosis. Chondrocalcinosis is not prominent in this case. The main differential diagnosis of haemochromatosis is CPPD. References

Answer 49

Generalised increased bone density (mnemonic) Dr Sachintha Hapugoda◉ and Dr Maunil Ajay Bhuta et al. A handy mnemonic for causes of generalised increased bone density / osteosclerosis: Regular Sex Makes Occasional Perversions Much More Fun, Happening and Lovely Mnemonic R: renal osteodystrophy (case 1 and 2) S: sickle cell disease, salt and pepper skull (case 2) M: metastasis (osteoblastic/sclerotic) O: osteopetrosis P: pyknodysostosis; Paget disease M: myelofibrosis M: mastocytosis F: fluorosis H: hyperparathyroidism; hypervitaminosis A and D L: lymphoma Case 1: Plain X-ray hands of a young patient with CRF shows signs of secondary hyperparathyroidism: irregular, frayed and ill-defined cortical outline, pronounced at radial aspect of middle phalanges –\> subperiosteal bone resorption multiple lytic expansile lesions –\> brown tumours (arrows) osteosclerosis accentuated trabecular pattern non-essential trabeculae are resorbed; those that remain appear prominent) Case Discussion Renal osteodystrophy is a constellation of musculoskeletal abnormalities that occur in patients with chronic renal failure. Manifestations include: osteomalacia (adults) / rickets (children) secondary hyperparathyroidism: bone resorption, osteosclerosis, soft tissue & vascular calcifications and brown tumours aluminium intoxication if the patient is on dialysis Comment: Subperiosteal bone resorption is the hallmark of HPTH and is first identified in hands.

Answer 50

Ivory vertebra (ewing sarcoma 1st case, BrCa second case) Dr Mostafa El-Feky and Radswiki◉ et al. The ivory vertebra (also known as ivory vertebra sign) sign refers to the diffuse and homogeneous increase in opacity of a vertebral body that otherwise retains its size and contours, and with no change in the opacity and size of adjacent intervertebral discs. Pathology Etiology The cause for an ivory vertebra depends on the age of the patient 1. Pediatric lymphoma: commonest cause, usually Hodgkin lymphoma osteosarcoma osteoblastoma blastic metastatic disease neuroblastoma medulloblastoma Ewing sarcoma (rare) Adult osteoblastic metastases prostate cancer breast cancer lymphoma (usually Hodgkin lymphoma) tuberculous spondylitis hemangioma chordoma Paget disease of bone vertebral body expansion (unlike hemangioma) coarsened trabeculae SAPHO syndrome 3 Rarely, the ivory vertebra can also be seen in 4: primary bone sarcoma sarcoidosis systemic mastocytosis Radiographic features Plain radiograph and CT Plain radiographs and CT will demonstrate diffuse sclerosis of the vertebral body with variable involvement of the posterior vertebral elements. MRI MRI demonstrates hypointense signals within the corresponding vertebra which is directly proportional to the degree of sclerosis of the vertebral body.

Answer 51

lateral patellar dislocation twisting injury to flexed knee anterolateral lateral femoral condyle and inferomedial patella associated with medial patellar retinaculum +/- medial patellofemoral ligament injury +/- medial patellotibial ligament injuries References

Answer 52

Wrist berg behind PCL Humpry Anterior One or the other present in 75% of cases

Answer 53

poly ostotic osseous expansion ground glass appearance this is Fibrous dysplasia

Answer 54

95% of OSA = Primary Osseous * Conventional OSA * Low grade OSA * telangiectatic OSA * Small Cell OSA * multicentric OSA

Answer 55

Parosteal osteosarcoma Dr Matt A. Morgan◉ and Assoc Prof Frank Gaillard◉◈ et al. Parosteal osteosarcoma is a subtype of osteosarcoma and arises from the outer layer of the periosteum. Epidemiology It is the most common type of juxtacortical or surface osteosarcoma and accounts for ~5% of all osteosarcomas. It typically presents in early adulthood and middle age with a peak incidence in the third decade. It affects females slightly more than males 9. Clinical presentation Patients usually present with a painless, slowly enlarging mass 9. Pathology They are usually located at the metaphysis (80-90%), most commonly at the posterior aspect of the distal femur (60%), followed by either end of the tibia, and then the proximal humerus. They are composed of a dense osteoid component attached to the outer cortex over a narrow zone. Parosteal osteosarcoma originates from the outer fibrous layer of periosteum. It exhibits extensive bone matrix and minimal fibroblastic cellular atypia, and as such is considered to be a low-grade tumour. Radiographic features large lobulated exophytic, 'cauliflower-like' mass with central dense ossification adjacent to the bone string sign: thin radiolucent line separating the tumour from the cortex, seen in 30% of cases tumour stalk: grows within the tumour in late stages and obliterates the radiolucent cleavage plane +/- soft tissue mass cortical thickening without aggressive periosteal reaction is often seen tumour extension into the medullary cavity is frequently seen MRI It exhibits predominantly low signal intensity both on T1 and T2 weighted imaging. High signal intensity on T2 is suggestive of a high-grade tumour. Treatment and prognosis Parosteal osteosarcomas are usually low-grade lesions are usually treated with surgical resection and no neoadjuvant chemotherapy or radiation. As they are frequently metaphyseal in location, large parosteal osteosarcomas or those with deep medullary invasion may require limb salvage, including joint replacement. Parosteal osteosarcomas have an excellent prognosis (80-95% long-term survival). Differential diagnosis On imaging consider cortical desmoid: avulsive injury of the posterior femoral cortex myositis ossificans: the ossification pattern of parosteal OS is the radiographic inverse of that seen in myositis ossificans, with the densest ossification in the centre of the lesion and the least radiopaque bone at the periphery (eggshell pattern); there is also often a history of trauma, progressive decrease in size or constant size and significant oedema in early stages on MRI. sessile osteochondroma: parosteal OS lacks corticomedullary continuity between the tumour and the underlying medullary canal. juxtacortical chondrosarcoma high-grade surface osteosarcoma parosteal lipoma: radiolucent mass adjacent to the cortical surface on plain film and on cross-sectional imaging will usually show a definite fat component 2

Answer 56

* GCT * subarticular * Geode * synovial fluid escaping into juxtartiular surface * OM * any age * aggressive * lytic * Pagets * thickened cortex * osseos expansion * coarsend trabecular * Flame sign of lytic phase pagets disease

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