MSK Flashcards

Question

Ankylosing Spondylitis

Answer 1

- HLA-B27, young men, back pain, stiffness - Associated with upper lobe pulmonary fibrosis, cardiac conduction defects, and aortitis - Symmetric erosions, widening and sclerosis of SI joint - Spine involved --> progression from lumbar to cervical - Romanus lesions - erosions of anterior superior/inferior edges caused by enthesitis (inflammation of tendon) at annulus fibrosis insertion site - Shiny corners - sclerosis of prior Romanus Lesions - Squaring of the vertebral body disc margins - Delicate syndesmophytes - bony bridging connective cerebral margins creating bamboo spine - Fully ankylosed spine - high risk of fracture with even minor trauma Andersson lesion - pseudoarthrosis of ankylosed spine

Answer 2

- Arthropathy with skin psoriasis - Affects the hands - Mineralization is perserved - Asymmetric sacroilitis - Diffuse soft tissue swelling of the digit - SAUSAGE DIGIT - Pencil in cup erosions - characteristic affecting DIPs - starts as marginal erosions and progresses centrally - Bone proliferation may occur adjacent to the erosions - Severe arthritis form causes telescoping digits - FOOT- IP and MTP digits are involved. Ivory phalanx represents osteoscleorsis . Plantar calcaneus spur with periosteal reaction Spine - lateral bony outgrowths

Answer 3

- Inflammatory Arthritis associated with sequela of infectious diarrhea, urethritis, or cervicitis - Predominantly in the feet - similar to psoriatic - Diffuse soft tissue swelling - joint space loss - marginal erosions - juxta-articular osteopenia - Bony mineralization is perserved in later stages - Calcaneus most common site - erosions, enthesophytes, fluffy periosteal reactions - Posterior - superior aspect of the calcaneus - achilles tendinitis - HANDS - ITP and MTP erosions, diaphysial periostitis - SPINE - Lateral coarse bony bridging - Sacroilliac joints - Asymmetric joints. - Association with Chlamydia, Shigella, Salmonella, Yersinia, and Campylobacter

Answer 4

- 90% of patient have joint abnormalities - Reducible subluxation when hands are viewed on PA and hands are compressed against plate - Ballcatchers/Norgaard view and oblique view don't put constraint on hands and how subluxations

Answer 5

- Secondary vs Rheumatic fever vs SLE - Type III hypersensitivity - Reducible subluxations

Answer 6

- Systemic collagen vascular disease - collagen deposition in skin and soft tissues - Soft tissue wasting - Osteoperosis - Acroosteolysis - Distal fingers affected first with atrophy of distal soft tissues - Dystrophic soft tissues and periarticular calcifications common in scleroderma tightening and fibrosis of the skin leading to joint contractures - After the skin the GI tract is most frequently involved. - Esophogeal dysmotility/dilation, patulous GE junction, dilated small bowel with closely spaced thin folds, wide mouthed sacculations. - Some develop pulmonary fibrosis

Answer 7

- resorption of the distal portion of the distal phalanges - can have associated calcifications - DDX - Collagen vascular disease (including scleroderma) - Neuropathy - Polyvinyl chloride exposure - Thermal (frost bite or burn) - thumb spared in frostbite - Hyperparathyroidism - Hajdu - Cheney - autosomal dom - short stature, craniofacial changes, progressive acroosteolysis

Answer 8

- Polymyositis - muscle inflammation - Dermatomyositis - muscle and skin inflammation - Soft tissue calcifications seen on imaging - predominantly intramuscular, can be seen subs - Periarticular Osteopenia

Answer 9

- AKA calcific tendinitis - crystal deposited in the periarticular tissues - do not deposit in the joints but instead amorphous calcification within tendons - Shoulder - supraspinatus tendon - Longus Colli - causes neck pain, odynophagia, fever, precertebral effusions - mimics prevertebral abscess - Milwaukee Shoulder - INTRA-ARTICULAR rapid destruction of rotator cuff and glenohumeral joint

Answer 10

- Inflammatory arthropathy caused by INTRA-ARTICULAR deposition of CPPD crystals - 2/2 idiopathic, hemochromatosis, hyperparathyroidism, hypophosphatasia - Rhomboid positively birefringent - Imaging - chondrocalcinosis - calc of hyaline(articular) and Fibrosis(meniscal) cartilage - Radiographs of knees, hips, wrist are diangositc - Wrist - affects the triangular fibrocartilage complex. Advanced disease can cause SLAC wrist - Knee - Patelofemoral space first involved with all 3 compartments eventually involved. Prominent subchondral cysts - Hand - 2nd and 3rd MTP - hook like or drooping osteophytes - Spine - calcification of the ligaments of the dens

Answer 11

- Proximal Migration of capitate between dissociated scaphoid and lunate - Capitate slips in between widened scaphoid and lunate

Answer 12

- Needle negatively birefringent - Sodium urate deposition in joints - inflammatory arthropathy - Great toe commonly involved - - Imaging - sharply marinated erosions with overhanging margins, soft-tissue gouty top - joint spaces preserved until late into the disease.

Answer 13

- Impaired iron metabolism - Deposition of Iron and CPPD - MCP joints involved with hook like osteophytes - Mimic CPPD arthropathy but instead of just 2nd and 3rd MCP all MCPs are involved

Answer 14

- Arthropathy secondary to enlargement of the articular cartilage with subsequent degeneration - Initial disease - widening of the joint spaces - Later disease - narrowing of cartilage space - Beak like osteophytes of Metacarpal heads - Spade like enlargement of the terminal tufts

Answer 15

- High vascularity associated with high metabolic activity as well as slow flow in the venous sinusoids accounts for the trapping of hematogenous organisms and development of osteomyelitis. - Sagittal T2 fat-saturated MR image confirms bone marrow edema and soft tissue inflammatory changes centered within the metaphysis - AP radiograph of the ankle shows ill-defined bone resorption at the metaphysis with delicate periosteal reaction

Answer 16

- Periosteal reaction may be the sole radiographic finding in cases of nonaccidental trauma, but it is nonspecific.

Answer 17

- The rapid destruction of the talonavicular joint with large effusion and debris is typical of a neuropathic joint. - The calcaneal insufficiency fracture is also typical of diabetic patients.

Answer 18

- Most frequently this injury results in Salter-Harris fracture of the distal radius in a child - Scaphoid fracture in a young adult - Colles fracture in an older adult.

Answer 19

- Rare non-inflammatory arthropathy - Infiltration of the soft tissues and bones by pleated B sheets of amino acids - Primary systemic - monoclonal plasma cell dyscrasia - Secondary - underlying inflammation or infection - B2 microgloblin secondary to chronic hemodyalysis - Bulky soft-tissue nodules in shoulder super-imposed on atrophic shoulder - Imaging - resembles RA - intra-articular deposition cause articular cartilage deposition - soft tissue nodules and erosions may be present

Answer 20

- Manifestations of the alkaptonuria within connective tissue - Alkaptonuria - defect in homogentisic acid oxidase- urine black on air exposure - Intervertebral calcification with disc height loss at every level - negative for significant osteophytosis along the cervical and thoracic spine. - Disease may involve the knees and glenohumeral joints, and hips. may also include the DIP and thumb CMC.

Answer 21

- Lipid laden macrophages are deposited in soft tissues and periarticular tendons, forming skin nodules and erosions with sclerotic margins - well defined erosions tend to affect the DIP joints symmetrically - soft tissues nodules and preserved bone density

Answer 22

- X linked inherited disorder - Recurrent hemarthrosis results in synovial hypertrophy and hyperemia. - Epiphyseal enlargement and early fusion. - Elbow - enlarged radial head and widening of the trochlear notch - Knee - Squaring of the patella and widened intercondylar notch. - Secondary arthritis may lead to marked joint space narrowing - Iron in synovium causes increased soft-tissue density around joints - Pseudotumor of Hemophilia - benign lesion caused b recurrent intraosseous or subperisoteal bleeding. Chronic cyclical bleeding leads to bony scalloping and pressure erosion, often with soft tissue mass.

Answer 23

- related chronic inflammatory arthropathies affecting children under age 16 - Monoarticular - affects single joint usually in knees, ankles, elbows, wrist - Polyarticular - hands feet and cervical spine as well as monoarticular joints - Still Disease - variant of JIA, systemic disease in children younger than 5. acute febrile illness, rash, adenopathy, pericarditis, and mild arthralgias - Abnormal bone length air morphology 2/2 hyperemia. - Earlier onset of disease can cause growth disturbances - Epiphyseal overgrowth and enlargement of ends of bone. Premature skeletal maturation aphyseal fusions - Knee - widening intracondylar notch, metaphysical flaring, uniform joint space narrowing - Elbow- Radial head enlargement and widening of trochlear notch - Hip Symmetrical cartilage space narrowing, profusion deformities, and gracile of femoral shaft (thinning/narrowing). - Wrist - Ankylosis - Cervical Spine ankylosis of sygapophyseal joint.(DDX Kulippel Feil Syndrome

Answer 24

- Immature osteoid is seen in the first 4-6 weeks following injury, with the lesion developing more mature bone peripherally in the weeks following that.

Answer 25

- Resorption of the great toe | - Hallmark in psoriatic arthritis

Answer 26

- Acetabular fractures can be identified on frontal views of the pelvis but are not optimally profiled for additional characterization and classification. - Bilateral 45° oblique images of the pelvis (Judet views) are considered standard for additional radiographic assessment, such as profiling of the posterior column component of an acetabular fracture.

Answer 27

- Bowing fractures (also known as plastic bowing deformity) are the most subtle form of greenstick injury. Careful attention to the morphology of the developing skeleton is needed in order to detect the injury.

Answer 28

- The combination of effusion, shown by the positive fat pad sign, and the posterior displacement of the distal humerus, indicated by the abnormal anterior humeral line, indicates a supracondylar fracture.

Answer 29

- The anterior humeral line (line extended down the anterior humeral cortex) should intersect the middle 1/3 of the capitellum.

Answer 30

- A Hill-Sachs fracture (impaction fracture of the superior, posterolateral humeral head) related to prior anterior shoulder dislocation. - These fractures are reliably and directly seen only on AP internal rotation views; they are often completely masked on the other views unless they are large

Answer 31

- Avulsion fractures of the fingers are most frequently seen on lateral views. If there is a "boutonniere" deformity (flexed proximal interphalangeal (PIP) and extended distal interphalangeal (DIP)) without fracture, it represents a disruption of the middle slip of the extensor tendon.

Answer 32

- Distal interphalangeal (DIP) joint flexion, while the proximal interphalangeal (PIP) joint is in extension, is typical of mallet (or baseball injury). Without avulsion, a tendon rupture must be diagnosed.

Answer 33

- Many patients have started using bisphosphonates in an effort to maintain bone density. It is believed that in reducing the amount of bone turnover (suppressing the activity of osteoclasts), the therapy can lead to an accumulation of skeletal microfractures, increasing the risk of insufficiency fractures. Accordingly, there has been recent note of an increase in a very unusual fracture pattern in these patients: subtrochanteric and transverse, without significant trauma, as in this case.

Answer 34

- The Monteggia fracture is used to describe any dislocation of the radius with an associated fracture of the ulnar shaft. The majority of injuries involve anterior displacement of the radius and a fracture of the proximal 1/3 of the ulnar diaphysis with apex anterior angulation. This fracture-dislocation pattern is more frequently seen in children than in adults.

Answer 35

- A Galeazzi fracture-dislocation consists of a radial shaft fracture plus distal radioulnar joint dislocation, both of which are not present in this case.

Answer 36

- These prostheses are placed when osteoarthritis is confined to a single compartment. These are contraindicated in patients with an inflammatory arthropathy. The other options are terms used for hardware in and around the knee but are not appropriate for this case. A semiconstrained component has a peg extending from the femur to the tibia that allows rotation of a total knee prosthesis. A modular prosthesis typically includes replacement of a portion of the distal femur or proximal tibia. Compress fit refers to a prosthesis fixation device, usually placed in the distal diaphysis of the femur that involves an intramedullary post with traversing pins.

Answer 37

- the most common ossicles and seasmoid bones in the posterior knee - The meniscal ossicle is along the posteriomedial aspect of the knee. Can be intrameniscal appearance when looking at CT or MRI.

Answer 38

- Plantaris tendon can make a full thickness tear of the ACL only seem partly ripped. - The tendon is present in 90% of people.

Answer 39

- AKA - avulsive cortical irregularity, distal metaphyseal femoral defect, cortical desmoid, medial supracondylar defect of the femur - seen along the posteromedial defect along the distal end of the femur - located near the adductor magnus aponeurosis or the origin of the medial head of the gastrocnemius tendon. - Ages 15-20, a reaction to trauma. - Imaging XR - lucent saucer-like defect T1 hypointense t2 hyperintense

Answer 40

- Thickened enhancing rim of synovium with the tendon sheath. - Debris within the fluid - Increased T2 signal in the tendon - Tendon tear - Adjacent soft tissue infection

Answer 41

- Necrotic bone surrounded by purulent material or granulation tissue.

Answer 42

- Bone shell surrounding the sequestrum and the infected tissue

Answer 43

- Cortical and periosteal defect that allows pus to drain from the infected medullary cavity into the adjacent surrounding tissues.

Answer 44

- intramuscular abscess with an enhancing peripheral rim. - Inflammation in the adjacent soft tissues - No changes in the bone marrow signal to suggest osteomyelitis - No enhancement of the deep fascia to suggest necrotizing fasciitis

Answer 45

- T1 low signal in a geographic medullary distribution - T2 high signal in the same region with same distribution T1 signal associated with reactive edema but not osteomyleltis - Low, hazy reticulated, low subcortical low subchondral

Answer 46

- Thick enhancing rim | - Central T1 low and T2 high signal

Answer 47

- Autoimmune disorder - Bone biopsy show inflammation with histiocytes, lymphocytes, and plasma cells. - Blood cultures typically negative. - Children aged 9-14

Answer 48

- First 1 -2 weeks - no osseous changes - Earliest sign is indistinctness of the cortex - Permeative osseous destruction, endosteal scalloping, and periosteal reaction follow after - Later - Formation of sequestrum, involucrum or abscess

Answer 49

- Areas of non-enhancement - Indicates devitalized tissue. - Gas in itself is not enough to diagnose gangrene as there can be communications with the skin

Answer 50

- Contrast enhancement of the involved area is more indicative of cellulitis than soft tissue edema - T1 hypointense to fat and T2 hyperintense to the muscle can be seen with both. - Skin ulceration not required to make diagnosis of cellulitis

Answer 51

- Sinus tracts - replacement of the soft tissue fat - Fluid collections - Disappearance of subchondral cysts on sequential imaging - Extensive marrow abnormalities - NO OSTEO Signs - thin rim enhancement of the joint effusions - presence of subchondral cysts - intrareticular loose bodies

Answer 52

- Posterior SC dislocation is less common than anterior and results from substantial force, either direct or indirect. - It is more common in males than females and may result in injury to the adjacent arch vessels or trachea. - Though the serendipity view, an angled AP view, historically was used to make this diagnosis and may be effective, CT is definitive; because of the clinical impact of this diagnosis, CT is the imaging method that should be used.

Answer 53

- Appears as a sclerotic line in the posterior calcaneus - Scenario of a older person who started taking up walking. - Do not expect to see a lucent fracture line in a calcaneal fatigue fracture.

Answer 54

- The fracture within the mid calcaneus is presumed to be intraarticular because Boehler angle is reduced (normal value is 20-40 degrees) .

Answer 55

- A type of Salter-Harris I injury seen in children who participate in excessive activities. Wrists in gymnasts, ankles in runners, and proximal humeri in baseball pitchers are at risk.

Answer 56

- Low-velocity knee dislocation, such as a misstep on stairs in the setting of morbid obesity, is less likely (about 5%) to be associated with an injury to the popliteal artery compared with high-velocity injuries (as high as 50% in some studies).

Answer 57

- The first finding is associated with the lateral aspect if the fifth metatarsal head. Progression then occurs medially (first toe ) to laterally.

Answer 58

- Vertically oriented, thin ossification spanning adjacent vertebral bodies resulting from inflammation and subsequent ossification of Sharpey fibers which are the outer fibers of the annulus fibrosus portion.

Answer 59

- Benign neoplasm fo the synovium. - Causes hemosiderin deposition secondary to multiple interarticular hemorrhages. - EARLY - joint effusion, juxta-articular erosions, sparing of the joint space - LATE - secondary osteoarthritis can develop to receptive bleeding and altered joint mechanics. - Blood causes low T1 and T2 signal. - can look like amyloidosis but is monoarticular - NO Calcifications - not synovial osteochondromatosis.

Answer 60

- Can lead to distention of the of the iliopsoas bursa. - Bursa can be laden with debris-laden macrophages associated with particle disease. - Aspirated material from the bursa out the joint is thick and gelatinous.

Answer 61

- Numerable calcified and ossified nodules in the joint and synovium with shallow well marinated erosions. Intracapsular nodules in swelling joint effusion and secondary degenerative arthritis. - usually monoarticular. - consider PVNS because of erosions but PVNS has no calcs

Answer 62

- Scapular notching - Bone resorption at the inferior scapular border secondary to receptive contact between the medial aspect of the humeral cup and the inferior border for -the scapular during adduction. - anterior superior dislocation of the humerus - glenospohere dissociation - periprosthetic fracture - infection - hardware loosening - nerve injury

Answer 63

- Change in position is most sensitive and specific for the detection of loosening - Cement loosening must be greater than 2mm to be considered for loosening

Answer 64

- Seen in RA, CPPD, Ankylosing spondylitis. | - Acromegaly and ochronosis

Answer 65

- Osteoarthritis

Answer 66

Osteoarthritis or post-traumatic osteoarthritis

Answer 67

- Soft tissue injury along the first metatarsophalangeal joint

Answer 68

- Second digit longer than the first toe, secondary to likely shortening of the first digit.

Answer 69

- non-hereditary dysplasia with presence of multiple enchondromas - commonly involve the metaphyseal regions of the long bones - Lesions are usually asymmetric. - Skull and spine are spared - Lesions regress with skeletal maturity - Can cause growth deformities, bowing, or sarcomatous degeneration - MR Imaging - lobulated with T2 internal hyperintensity

Answer 70

- Located in the metaphysis with epiphyseal extension to the subarticular margin. - Occurs in ages 20-50 - Well- defined lytic without a defined sclerotic margin, eccentric in location and extends to a subarticular margin. - Imaging - Aggressive appearance - expansile, remodeling, cortical thinning/breakthrough, soft tissue masses, wide zone of transition.

Answer 71

- AKA fibroxanthoma, benign fibrous cortical defect. - Fibrous tumor, > 3cm is usually called fibrous cortical defect. - Multiloculated with sclerotic rim. - 'DO NOT TOUCH' - IF Fractured - treat with curettage and bone grafting

Answer 72

- Ill defined lesion with permeative infiltrative pattern, wide zone of margin transition and lack of sclerotic margin, aggressive periosteal reaction, cortical destruction and soft tissue mass.

Answer 73

- Thick separations measuring >2mm - Lesions larger than 10cm - Presence of globular/nodular non-adipose areas

Answer 74

- Autosomal Dominant - Symmetric widening of the metaphases with multiple metaphyseal or metaphyseal equivalent osteochondromas. - Spinal involvement at 27% of patient - Increased risk of transformation to osteochondroma 1-3% due to increased number and increased risk of transformation per lesion.

Answer 75

- Synovial based lesion, joint effusions, and osseous erosions. - Usually seen in less capacious joints such as hip, shoulder, elbow, and ankle. - Tendency to bleed with hemosiderin deposition - Imaging - Low signal on T1 and T2 secondary to hemosiderin deposition - Blooming artifact on GRE/SWI imaging because of the hemosiderin deposition.

Answer 76

- Fibroblastic and myofibroplastic tumor - Medial non-weight bearing surface of the fascia - 2.3% of all benign tumors in the foot. - More common in men - Bilateral in 20-50% of cases - Imaging - US - hypoechoic or heterogenous - T1 - low to isointense - T2 - heterogenous signal intensity

Answer 77

Diffuse Idiopathic Skeletal Hyperostosis

Answer 78

- Heel pain - Thickening of the plantar fascia, usually at the calcanea margin - Variable degree of soft tissue and osseous inflammation

Answer 79

- Mass-like fibrosis of the plantar digital nerve, at the level of the metatarsal heads, most commonly between the 3rd -4th and 2nd-3rd inter-metatarsal spaces.

Answer 80

- Most common primary bone malignancy in childhood and adolescence - Metaphyseal in location - Permeative with a wide zone of transition - Cortical destruction - soft tissue mass - Aggressive metaphyseal lesion with densely mineralized osteoid matrix

Answer 81

- Osseous excrescence with corticomedullary continuity

Answer 82

- Benign Cartilage tumor most commonly a lytic epiphyseal lesion with sclerotic margin

Answer 83

- Malignant tumor of cartilage composed of chondroid matrix with a peak incidence ranging from 50-70 years

Answer 84

- Benign Tumors with vascular channels. - High T2 weighted MR signal (slow flow-- no flow voids) - Enhance on post-contrast T1 imaging - Phleboliths may be seen on radiographs.

Answer 85

- Developmental tumor-like, fibrosis-osseous condition with a tendency toward spontaneous regression. - No residual skeletal deformity. - Almost exclusively in the tibial diaphysis. Involves anterior cortex. - Imaging - Radiographs - Osseous bowing, osseous enlargement, intracortical osteolysis without adjacent sclerotic band - DDX - Adamantinoma, fibrous dysplasia

Answer 86

- Rare, exophytic, growths from osseous cortical surfaces consisting of bone, cartilage, and fibrous tissue. - Secondary to repair from trauma or benign proliferative process.

Answer 87

- Dense lesions involving the skull paranasal sinuses and mandible. - Associated with Gardner syndrome(intestinal polyposis) - No treatment is usually needed unless they become symptomatic.

Answer 88

- Eccentrically positioned lesion in relation to the nerve. - Split fat sign - thin rim of fat surrounding the lesion - Fascicular Sign - Multiple small ring-like structures

Answer 89

- Target Sign | - Shows increased signal peripherally, with more intermediate signal centrally on T2

Answer 90

- Split fat sign - thin rim of fat surrounding the lesion | - Fascicular Sign - Multiple small ring-like structures

Answer 91

- Benign disorder characterize by formation of multiple contra-articular nodules composed of hyaline cartilage. - Imaging - T1 low to intermediate - T2 hyperintense - T1C+ enhancement of the nodules

Answer 92

- Resemble synovial tissue but don't arise from the synovial tissues - Occur near a tissue or within a tendon sheath - Most commonly occurs in the popliteal fossa about the knee - More common in young adults but in all age groups - Imaging - Has internal mineralization - T1 - intensity similar or slightly lower than muscle - T2 - hyperintense to skeletal muscle - T1 C+ - intense enhancement

Answer 93

- Centrally located, intramedullary, geographic lucent lesions - Associated with endosteal scalloping and expansile remodeling. - Metaphyseal location but can be metadiaphyseal - Pathologic fracture through the lesions is seen >50% patients who present with pathologic fracture - 'Fallen Fragment' Sign- small fragment migrating through the fluid-filled cyst to the dependent portion of the lesion.

Answer 94

- Benign cystic lesion - Majority are located around the wrist - Can occur around other major joints - Imaging - T1 hypointense - T2 Hyperintense - US - Cystic

Answer 95

- hereditary disease - multiple enchondromas and soft tissue vascular malformations - Usually involves short bone and surrounding soft tissue - High rate of conversion of enchondromas to malignant lesions

Answer 96

- Chondroid matrix (ring and arcs, popcorn, focal stippled and flocculent) - Endosteal scalloping - Pathologic fracture - Features that are more malignant - Cortical destruction - Soft tissue masses

Answer 97

- Chondroid matrix (ring and arcs, popcorn, focal stippled, and flocculent) - Endosteal scalloping - Pathologic Fracture - No malignant features such as cortical destruction or soft tissue masses.

Answer 98

- Fat containing lesions - Mainly metaphyseal - rarely diaphysial or epiphyseal - Most prevalent in the proximal femur, but can occur in other long bones, calcaneus, ilium, and ribs - Central or ring like calcifications/ossification is pathognomonic - Benign - treatment is not indicated.

Answer 99

- Most commonly in vertebral bodies. - Can involve posterior elements without body involvement - Imaging - Coarsened trabeculation - T1 and T2 - hyperintense - T1 C+ enhance avidly.

Answer 100

- The MR images demonstrate a break in the cartilage and subchondral bone plate, high T2 signal surrounding the lesion, and cysts at the border of the lesion, all of which indicate an unstable osteochondral lesion (osteochondritis dissecans). Osteochondritis dissecans involves the articular surface, commonly affecting the lateral aspect of the medial femoral condyle.

Answer 101

- Distal lateral aspect of medial cuneiform and 2nd metatarsal base

Answer 102

-The findings are classic for transient lateral patellar dislocation with contusion (edema) to the lateral femoral condyle, medial patella, medial patellofemoral ligament injury and lateral patella tilt.

Answer 103

- Older men with deposition of calcium dense material | - One of the few causes of shoulder arthritis in adults (esp males)

Answer 104

- There is an avulsion fracture fragment lateral to the right anterior superior iliac spine (ASIS). This is where the sartorius attaches. The rectus femoris attaches to the anterior inferior iliac spine (AIIS), the iliopsoas attaches to the lesser tuberosity (and avulsion fractures here warrant a workup for a pathologic fracture), and the hamstrings attach to the ischial tuberosity.

Answer 105

- The femoral head ossification center is markedly hypoplastic. The acetabulum is shallow with cranial subluxation of the femur.

Answer 106

- Radial tears are also vertically oriented but occur perpendicular to the longitudinal circumferential fibers of the meniscus; they resemble a spoke on a wheel when viewed on axial images.

Answer 107

- Vertical-longitudinal tears are oriented straight up-and-down and usually lie near the peripheral edge of the meniscus, following the meniscal circumferential fibers.

Answer 108

- Vertical flap tears start in a radial orientation at the free edge of the meniscus and then turn longitudinal. They usually displace, hence the "flap" designation

Answer 109

- Premature focal fusion of the ulnar aspect of the distal radial epiphysis, in turn promoted by the abnormal extrinsic ligaments that tether the carpus to the radius.

Answer 110

- Most common location is the 3rd inter metatarsal space. 2nd most common location is the 2nd intermetatarsal space. - Non-neoplastic, painful, fibrosing process of the plantar digital nerve.

Answer 111

- An isolated fracture of the sustentaculum, along with a bone bruise of the lateral process of the talus . These imply "kissing" injuries, which in turn imply transient dislocation at the subtalar joint. This diagnosis is supported by disruption of the talocalcaneal interosseous and cervical ligaments within the tarsal sinus

Answer 112

- Differentiate using zoning patterns - Parosteal osteosarcoma is more mature centrally and myositis ossificans is more mature peripherally. - Both can have uptake on PET SCAN - Both can have enhancement on MR - Periosteal Reaction.

Answer 113

- Undifferentiated pleomorphic sarcoma (formerly known as malignant fibrous histiocytoma) is a very common lesion in the adult population. With no specificity to its appearance, it should be considered in most cases of an aggressive soft tissue mass, though the most common site is in the deep soft tissues of the thigh.

Answer 114

- SLAP tears involve the superior glenoid labrum, where the long head of biceps tendon inserts. They can extend into the tendon, involve the glenohumeral ligaments or extend into other quadrants of the labrum. - type I: fraying of the superior labrum free margin commonly asymptomatic often due to degeneration type II: detachment of the superior labrum and biceps anchor from the underlying superior glenoid at the chondrolabral junction (undercuts the anchor) in younger patients (<40 years of age) these are associated with Bankart lesions in older patients (>40 years of age) they are associated with rotator cuff tears 2 seen in overhead athletes type III: bucket handle tear of the superior labrum without extension into the long head of biceps tendon type IV: bucket handle tear of the superior labrum with extension into the long head of biceps tendon

Answer 115

- Posterior tubercle fracture of calcaneus in patients with diabetes. - LOOK FOR: The vascular calcifications suggest the diagnosis of diabetes. These patients are at risk for insufficiency fractures; posterior tubercle is a favorite location. This has been termed the calcaneal insufficiency avulsion (CIA) fracture.

Answer 116

- Abnormal femoral head or neck morphology to suggest a cam-type of impingement.

Answer 117

- Overgrowth of the acetabulum, or retroversion suggests pincer type of impingement.

Answer 118

- Uncovering of the femoral head laterally and anteriorly. | - Arthrogram shows hypertrophy and degeneration of the labrum with severe cartilage thinning

Answer 119

- AP and lateral radiographs of the knees reveal linear bands of increased density that extend from the tibial and femoral metaphyses into the diaphyses, consistent with osteopathia striata. Osteopathia striata represents an uncommon sclerosing dysplasia and is usually bilateral in distribution.

Answer 120

- The absence of an anterosuperior labrum with a thick, cord-like middle glenohumeral ligament (MGHL), simulating an anterior labral tear is diagnostic of the Buford labral variant. Though at first glance one might assume a Buford complex is an extensive tear of the anterosuperior labrum, one can use images in all 3 planes to confirm that the structure is the MGHL and joins the joint capsule; moreover, the anteroinferior labrum will reconstitute normally, The thickened MGHL is also demonstrated by on the coronal image. One should not mistakenly call this a torn labrum. The Buford complex seems to be adaptive for those patients who have them and past experience shows that if surgeons attach these to the glenoid rim the patients generally have poor outcomes.

Answer 121

- Example --> The exam shows joint space loss, large subchondral cysts, and most importantly, overgrowth of the radial head . - Overgrowth should be seen only in arthropathy acquired during childhood, most commonly hemophilic arthropathy and juvenile idiopathic arthritis (JIA). It is not uncommon for hemophilic arthropathy to affect a single joint, whereas JIA usually affects several joints in a symmetric fashion. The ankle, elbow, and knee are the most frequently affected joints in hemophilic arthropathy.

Answer 122

- The predominant sclerotic pattern mixed with non-aggressive lucency, in conjunction with evidence of slow enlargement of the bone and dense periosteal reaction secures the diagnosis of chronic osteomyelitis in this case. - The question then becomes whether the infection is active. Comparison to prior radiographs, evaluating for any changes, may provide critical information and should always be the 1st step. - MR is always going to appear abnormal and it may be difficult to evaluate for active inflammation superimposed on chronic disease. However, MR will demonstrate a sinus tract or abscess; if the clinical setting suggests ongoing infection, MR would be a useful 2nd step. - Biopsy may be considered if necessary for identification of a specific organism which would be useful for treatment management.

Answer 123

- Malignant soft tissue tumor of uncertain differentiation - Imaging - Calcification in 1/3 but variable in extent - Changes involving adjacent bone in 11-25% - CT attenuation is similar or ↓ relative to muscle - Heterogeneous signal intensity on MR - Split fat sign, triple sign, bowl of grapes sign on MR - May have deceptively bland, well-defined, homogeneous appearance on imaging - Malignant extremity soft tissue neoplasms are rare in young adults. The most common in ages 15-40 is synovial sarcoma. Despite the name, which came from pathology descriptions many years ago, these lesions are almost never intraarticular but usually occur near joints. - Dystrophic calcification, not present here, is reported to occur in 30%. The lack of calcification argues against myositis ossificans (MO). Even in the early, noncalcified stages, there should be extensive edema surrounding MO due to its traumatic origin. Neurofibroma and myxoma are slow-growing benign lesions that should not have no-enhancing necrotic areas, which is visible on the postcontrast image.

Answer 124

- An oval lesion within the rectus abdominus. In a young woman, lesions at this site are usually desmoid tumors. The rapid enlargement of the lesion, might be concerning. - Signal characteristics are typical of desmoid tumor, which often contains homogeneous low-signal material on T2, but virtually always enhances avidly, as in this case. Pregnancy often results in rapid enlargement of this otherwise slowly growing benign lesion; the history assures the diagnosis in this case.

Answer 125

- The dense, globular calcification is somewhat linear and extends along the fascial plane; this is a typical location in dermatomyositis, one of the inflammatory myopathies. - Similar calcific deposits could be seen in metastatic calcification of hyperparathyroidism (HPT); however, the term used in the incorrect answer of hyperparathyroidism is "neostosis," which is bone formation along the cortex of bone in patients newly treated for renal osteodystrophy; the imaged calcification does not follow this pattern. In addition, large calcifications associated with HPT usually cluster in a periarticular location.

Answer 126

- Heavy metal ingestion may result in formation of dense metaphyseal lines . In this case with a history of irritability and falling, a serum lead level should be obtained. An abdominal radiograph may demonstrate flecks of lead-based paint in the gastrointestinal tract. - Incidentally, a growing child may show dense metaphyseal lines normally; however, when the lines are physiologic, they generally are not seen in the fibula. This case clearly shows fibular abnormality as well, making normal physiologic bone deposition unlikely. Finally, there is no finding to suggest nonaccidental trauma, so skeletal survey is not recommended.

Answer 127

- Sequential axial T1 MR images show progressive enlargement of the ulnar nerve as it courses distally rather than gradual tapering, representing ulnar nerve neuropathy, which accounts for the atrophy of hypothenar musculature. - The history of cycling is convincing, so much so that this constellation of history and findings has been called bicyclist palsy.

Answer 128

- Coronal T1FS + gad, patient prone - MR imaging is the best imaging modality to demonstrate a Morton neuroma, but this imaging can be performed in multiple ways. Due to the location and characteristics of this mass, it is best demonstrated on coronal (short axis) sequences. Enhancement can vary but is often intense. Morton neuromas are usually difficult to perceive on T2 fat-saturated images. Placing the patient in a prone position increases the degree the mass extends into the plantar subcutaneous fat, increasing conspicuity.

Answer 129

The clavicles are diminutive bilaterally; this appearance or complete absence is characteristic of cleidocranial dysostosis, a disorder of failure of development of midline structures.

Answer 130

- AP and lateral radiographs demonstrate a geographic lucent lesion with a narrow zone of transition but no significant sclerosis at the margin. - Giant cell tumor originates within the metaphysis and extend into the epiphysis following physeal closure, often ending in a subchondral position. Chondroblastoma arises in the epiphysis and may extend into the metaphysis; it usually has a more sclerotic margin, is found in younger patients, and should not be strongly considered in the differential. Brodie abscess would elicit strong sclerotic reactive bone, not seen here. Aneurysmal bone cyst is generally more "aneurysmal" and also is extremely uncommon in patients older than 30 years of age.

Answer 131

- The morphology of the Achilles tendon is abnormal. It is thickened in a fusiform fashion ~ 5 cm proximal to its insertion on the calcaneus. This bulbous appearance is easily demonstrated with proper windowing of the image because the Achilles tendon is outlined by Kager fat pad anteriorly. The morphology and location are typical of either Achilles tendinopathy or tear. If there were an accessory soleus, it would bulge into Kager fat pad from the anterior side (the current outline of muscles and tendons is normal). - The morphology of the talus, calcaneus, and navicular is normal, helping to exclude coalition; moreover, the middle subtalar facet is visible, whereas it would not be in the setting of talocalcaneal coalition. The lateral process of the talus is discretely visible at the angle of Gissane and is intact without fracture line.

Answer 132

- The dense, regular periosteal reaction involving all of the metatarsals in a similar way with no underlying osseous or joint pathology, as well as involving the tibia is typical of hypertrophic osteoarthropathy.

Answer 133

- Iliopsoas bursa is located beneath and medial to the iliopsoas tendon and can communicate with the hip joint in approximately 15%. - Paralabral cysts, on the other hand, are typically located lateral to the iliopsoas tendon. - The 3 main causes of iliopsoas bursitis are acute trauma, overuse injuries, and rheumatoid arthritis. Those due to sport-related activity are likely the result of bursal trauma during overzealous hip flexion and extension. Athletes who participate in rowing, running uphill, competitive track and field, and strength training are particularly at risk for developing iliopsoas bursitis.

Answer 134

- Little Leaguer's shoulder is a Salter I injury. In this case there is widening of the physis that may make one consider the diagnosis. However, extension to the metaphysis is not part of Little Leaguer's shoulder injury. Although there may be periosteal reaPriogction or sclerosis associated with Little Leaguer's shoulder (which is often chronic), it is not required for the diagnosis.

Answer 135

- The radiographic flattening of the head of the 2nd metatarsal. - It is most commonly believed to occur related to chronic repetitive trauma.

Answer 136

- Pincer impingement is the result of an acetabular abnormality, either local anterior overcoverage (acetabular retroversion) or, more often, generalized overcoverage (coxa profunda) by the acetabulum. - One radiographic sign of acetabular retroversion that has been described is the crossover sign, as seen here. The image shows the anterior acetabular rim "crossing over" the posterior rim. In normal morphology, the anterior rim should always project medial to the posterior rim on the AP pelvis.

Answer 137

- Pleomorphic liposarcomas have markedly heterogeneous signal intensity on MR with little visible mature fat. - Atypical lipomatous tumors and hibernomas both have prominent mature fat. Myxoid liposarcomas have little mature fat, but have a relatively homogeneous appearance that can mimic a cyst.

Answer 138

- The oblique radiograph of the fingertips shows acroosteosclerosis and tapering of the distal soft tissues in a patient with progressive systemic sclerosis (PSS). - Pulmonary interstitial disease associated with PSS may have a significant impact on patient survival and pulmonary screening is indicated.

Answer 139

- Imaging in this case shows a change in the original benign-appearing lesion of the metatarsal (Fig. 2) with a new cortical breach with sequestrum and periosteal new bone (Fig. 1). These findings indicate reactivation of a Brodie abscess. - Osteoid osteoma does not fit the initial presentation, and neither enchondroma nor fibrous dysplasia would develop reactive characteristics without a fracture (not visualized here).

Answer 140

- The mass predominantly (, Fig. 1) occupies the knee joint posterior to the cruciate ligaments. It contains no matrix on the radiograph and is predominantly low signal on both T1 and T2 images. There is mild enhancement following contrast administration. - On closer inspection, you will notice similar imaging characteristics of the mass within the suprapatellar recess. The findings are typical of diffuse pigmented villonodular synovitis (a.k.a. tenosynovial giant cell tumor). - Intraarticular chondroma usually shows chondroid matrix on radiograph and benign cartilage nodules on MR, neither of which is present in this case. Synovial hemangioma shows tubular vascular structures, also not demonstrated here. Synovial chondromatosis should demonstrate multiple round bodies or else a conglomerate mass that has characteristics of cartilage &/or bone on MR imaging; it may be calcified on radiographs.

Answer 141

- The coarsened trabeculae are typical of rickets. - The widened and irregular zone of provisional calcification is an even more classic sign, indicating the lack of mineralization in growth centers that is seen in rickets. - Since the metaphyses about the knee contribute to bone lengthening to a larger extent than other long bone physes, an AP view of the knees is a sensitive screener to detect manifestations of rickets, including fraying of the metaphyses, widening and cupping of the physes, and bowing of the knees centered at the joint line.

Answer 142

- The medial metaphyseal fragmentation, accompanied by unossified epiphyseal cartilage is typical of Blount disease. - Imaging Findings - Anteroposterior radiograph shows a vertically oriented irregular medial tibial growth plate , as well as a beak-like appearance of the proximal tibial metaphysis. - Coronal T1WI (#1) and PD FSE FS (#2) MR images emphasize the medial beaking of the metaphysis , as well as hypertrophy of the medial tibial plateau cartilage . There is also mild overgrowth of the medial femoral condyle.

Answer 143

- The appearance of a central lytic geographic lesion in the distal radius of a child most frequently represents unicameral bone cyst. The "fallen fragment" sign secures the diagnosis. - The "fallen fragment" sign is infrequently seen in unicameral bone cyst but is fairly pathognomonic as long as it is not conflated with a sequestrum.

Answer 144

- Aneurysmal bone cyst (ABC) is usually more eccentric than central in location. Also, ABC tends to be more bubbly or aneurysmal in appearance than the mildly expanded lesion seen in this case.

Answer 145

- A hematoma appears as a hypoechoic fluid collection and may contain debris . - Active hemorrhage may be hyperechoic, and within a few hours the bleeding will appear homogeneously hypoechoic. - Several hours later, serum, cellular elements, and fibrin elements will separate out, resulting in an identifiable fluid-fluid level (not seen here).

Answer 146

- Tarsal coalition is a condition in which 2 tarsal bones are abnormally connected because of incomplete segmentation during development. In osseous coalition, the tarsals have an abnormal bony connection and in nonosseous (a.k.a. fibrocartilaginous) coalition they are connected by cartilage, fibrous tissue, or both. - The 2 common types are calcaneonavicular and talocalcaneal coalition. - Anteater sign, in which the anterior process of the calcaneus is elongated in the setting of calcaneonavicular coalition. Though there is no true osseous connection, the anterior process of the calcaneus extends abnormally close to the navicular . - Irregularity and sclerosis at that interface confirms chronic stresses at the site because of coalition. Teenagers and young adults are the most common age group in which this abnormality becomes symptomatic.

Answer 147

- The gracile, osteoporotic bones with multiple old fractures and hypertrophic callus formation are typical of osteogenesis imperfecta. - Osteogenesis imperfecta has several subtypes ranging from relatively mild to severe; lethal soon after birth. Hypertrophic callus formation may be seen throughout this range of subtypes.

Answer 148

- Continuity with the parent nerve is the most suggestive | - centrally hypoechoic, posterior acoustic enhancement, echogenic peripheral capsule

Answer 149

- The median nerve fascicles are enlarged and seen in cross section on the axial images and give the appearance of a cable on sagittal; the appearance of these fascicles surrounded by fatty stroma is classic for this diagnosis. It is not a true lipoma but has prominent fatty stroma in which the individual fascicles of the enlarged nerve sit.

Answer 150

- The decreased carpal angle, without evidence of trauma but rather a modeling deformity of the distal radial physis, is typical of Madelung deformity. The extrinsic ligament thickening and tethering is a constant feature. - The presence of soft tissue (ligamentous) abnormalities can be used to differentiate congenital Madelung deformity from post-traumatic. Coronal MR imaging is best for identifying the thickened radiolunate ligament seen with this diagnosis.

Answer 151

- The presence of phleboliths within a soft tissue mass, as well as fatty stroma, allows a radiographic diagnosis of hemangioma/vascular malformation. - The multiple round calcifications have lucent centers, typical of phleboliths. These phleboliths indicate that the soft tissue mass is a hemangioma/vascular malformation. - Uncommonly, a hemangioma may cause extrinsic scalloping of the adjacent osseous structure, weakening the cortex enough to result in pathologic fracture.

Answer 152

- Low-grade osteosarcoma (OS) arising on surface of bone - Imaging Metaphyseal in 90% Fusiform along length of bone, with tendency to "wrap around" circumference as it enlarges Bone is mature at site of origin, less mature at periphery MR fluid-sensitive sequences Enhancement of soft tissue and involved marrow Marrow involvement in 40-50%, best seen on MR Any regions of differentially prominent nonnecrotic soft tissue mass should be biopsied - Tx - Wide margin resection - Better long term outcomes vs other osteosarcomas

Answer 153

- Fibroxanthoma (nonossifying fibroma) often demonstrates sclerosis around the outer margins. This is especially frequently seen in older teenagers or young adults and suggests that the lesion is starting to fill in with normal bone; this is the usual (though not invariable) natural history of these lesions.

Answer 154

- Benign cartilaginous neoplasms. - CMF is a very rare lesion. In the long bones, it is usually found within the tibia rather than the femur. It may be eccentric but is not cortically based. Finally, CMF does not spontaneously undergo regression or healing, as is seen in the proximal portion of this lesion.

Answer 155

- The signal of the bodies in synovial chondromatosis is variable, depending on their maturity and whether they have developed a vascular supply. - They may develop normal marrow signal if they are fully ossified or may appear cartilaginous. - They can remain immature and remain low signal on all sequences while being uncalcified on radiograph. - The multiple round bodies packing the bursa are diagnostic of synovial chondromatosis.

Answer 156

- Pes anserinus bursitis is highly location-specific. Fluid is seen surrounding the pes tendons (sartorius, gracilis, semitendinosus) within several centimeters of their insertion on the anteromedial tibia in this bursitis. Clinically, the mass may be fluctuant and may change in size, generally depending on the length of time spent standing. - The location of a fluid collection at the anteromedial tibia, surrounding any of the pes tendons (sartorius, gracilis, semitendinosus), is typical for pes anserine bursitis.

Answer 157

- Bursitis relating to the semimembranosus tendon occurs at the level of the knee joint. The bursal fluid also assumes a crescentic shape in semimembranosus bursitis.

Answer 158

- The ballooned epiphyses and destructive arthritis at the knee, as seen in this case, is typical of hemophilia. Hemophilic patients may develop pseudotumors due to osseous, subperiosteal, or soft tissue bleeds. These pseudotumors occur most frequently in the iliac wing and femur, as in this case. The soft tissue mass, scalloping of the bone, and bizarre horizontal periosteal reaction is typical of a hemophilic pseudotumor.

Answer 159

- New onset of painful flatfoot in an older woman should raise the question of tibialis posterior injury.

Answer 160

- The medial epicondylar apophysis has been avulsed and pulled into the joint, now entrapped. The absence of the medial epicondylar apophysis in normal position and presence of an ossification center where one might expect the trochlear epiphysis makes this diagnosis. - The 1st to ossify is the capitellum, followed by the radial head. The medial epicondyle is the 3rd center to ossify, followed by the trochlea. A medial epicondylar fragment may be pulled into the joint by the forearm flexors, where it might be mistaken for a trochlear ossification center and therefore overlooked. As a generalization, one should never see a "trochlea" if there is not a normally placed medial epicondylar apophysis.

Answer 161

- Often consists of multiple nodules, though the patient may complain of only a single dominant mass. A careful search on MR should identify the other sites of abnormality. - Multiple nodules adjacent to the plantar aponeurosis are typical of plantar fibromatosis. Although in many cases these fibrous lesions show low signal on T2 imaging, they may be hyperintense as in this case. The degree of contrast enhancement is also variable; though little enhancement is seen in this case, it may be intense.

Answer 162

- This represents avulsion of the lateral capsular ligament from the lateral tibial rim. There is close to 100% association with anterior cruciate ligament disruption.

Answer 163

- Non-ossifying fibroma/fibrous cortical defect - MR Imaging MR images of the lesion show it to have hypointense elements on all sequences . The fluid-sensitive sequences also show hyperintense regions of the lesion. In addition, there is predominant hypointensity along the posteromedial cortical portion of the lesion . The is no cortical breakthrough or indication of aggressiveness. - XR Imaging. - cortical-based metadiaphyseal lesion . The lesion has a thin sclerotic margin and is lytic with the exception of sclerosis along the posterior and medial aspects .

Answer 164

- radiographs show multiple lacy, lytic, nonaggressive lesions within the phalanges of the hand.

Answer 165

- This lesion most frequently is found in the phalanges and often results in extrinsic scalloping of the adjacent bones that may mimic erosions. With the cartilage space appearing normal, most types or arthritis should not be considered. Therefore, giant cell tumor of the tendon sheath is the most reasonable and likely diagnosis.

Answer 166

- Altered signal within the lunate in the presence of ulnar minus variance (the ulna is > 2 mm shorter than the radius) indicates edema and stage 1 Kienbock disease (osteonecrosis) of the lunate. There is a high statistical association of ulnar negative variance and lunate osteonecrosis.

Answer 167

- Radiographs show serpiginous sclerotic densities within the femoral diametaphysis. These imaging findings are typical of medullary infarct. In places, there appears to be a sclerotic margin . The serpiginous morphology is typical of bone infarct. Although one might consider the diagnosis of enchondroma because some of the density is in the form of "dots," an enchondroma does not present radiographically with a sclerotic margin. This type of matrix is not found in either fibrous dysplasia or Paget disease; neither of these diagnoses is a serious consideration.

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