Musculoskeletal Imaging
Core concepts
Understand bone structure and the radiographic appearance of fracture healing, plus the classic fracture patterns (transverse, spiral, comminuted, avulsion). Learn the principles of bone tumor evaluation: age, location (epiphysis, metaphysis, diaphysis), margin, matrix, and periosteal reaction (benign versus aggressive). Know the features of osteosarcoma, Ewing sarcoma, chondrosarcoma, and giant cell tumor. Understand arthritis patterns: osteoarthritis (joint space narrowing, osteophytes, subchondral sclerosis), rheumatoid arthritis (erosions, symmetric involvement), and seronegative spondyloarthropathies. Learn the imaging of the spine: disc herniation, spinal stenosis, and the signs of infection versus malignancy. Understand MRI of the knee and shoulder (meniscal tears, ACL, rotator cuff). Know the principles of bone density and osteoporosis.
Traps
Age is the strongest discriminator for bone tumors: metaphyseal lesions in children versus epiphyseal in young adults (GCT) versus diaphyseal (Ewing). A wide zone of transition and aggressive periosteal reaction suggest malignancy. Do not confuse osteophytes with fractures. In the spine, Modic changes reflect degenerative disease, not infection. Remember that a normal radiograph does not exclude a stress fracture - use MRI.
Rule of thumb
Use the mnemonic "age, location, margin, matrix, periosteal reaction" for any bone lesion. A narrow zone of transition with sclerotic margin favors a benign process.