Musculoskeletal Radiology
Musculoskeletal Radiology
This domain tests fracture description, arthritis patterns, bone tumor analysis, and spine imaging. The exam favors systematic reading and aggressive-versus-benign features.
Core rules
- Describe fractures by bone, location, pattern (transverse, oblique, spiral, comminuted), displacement, angulation, and intra-articular extension. Check the joint above and below.
- Bone tumors: age, location (epiphysis, metaphysis, diaphysis), margin (narrow zone means slow-growing), matrix (osteoid, chondroid, fibrous), and periosteal reaction. Wide zone, cortical destruction, and aggressive periosteal reaction favor malignancy.
- Arthritis: osteoarthritis has joint-space narrowing, sclerosis, and osteophytes; rheumatoid arthritis has marginal erosions and periarticular osteopenia; psoriatic arthritis has enthesitis and pencil-in-cup change; gout has punched-out erosions with overhanging edges.
- MRI bone marrow edema is nonspecific: trauma, infection, tumor, and reactive stress all cause it.
Worked example
A 12-year-old has knee pain and a distal femoral metaphyseal lesion with a wide transition zone, cortical breakthrough, and sunburst periosteal reaction. These are aggressive features; osteosarcoma is the leading diagnosis. The next step is MRI of the entire bone to assess skip lesions and neurovascular involvement before biopsy.
Traps
Calling a growth-plate injury normal; missing a subtle scaphoid or femoral neck fracture; overreading bone marrow edema as tumor; ignoring tumor margins; misdiagnosing CPPD or gout without seeing chondrocalcinosis or erosions.