Assessment, Diagnosis, and Diagnostic Imaging
Domain 1: Assessment, Diagnosis, and Diagnostic Imaging
This domain tests whether you can build a focused orthopaedic history, perform a reproducible physical exam, and choose the right imaging or laboratory test instead of ordering everything at once.
Core rules
- History: onset (traumatic vs insidious), mechanism, pain location and radiation, night/rest pain, stiffness duration, functional loss, systemic symptoms (fever, weight loss, chills), prior injury/surgery, medications (steroids, anticoagulants, bisphosphonates).
- Exam sequence: inspect (swelling, deformity, erythema, atrophy), palpate (point tenderness, joint effusion, crepitus), range of motion active then passive, strength, and neurovascular status (pulses, capillary refill, sensation, motor).
- Radiographs first for acute trauma, suspected arthritis, or focal bone pain; obtain at least two orthogonal views and include the joint above and below.
- CT for complex fractures, intra-articular extension, spine trauma, and bone detail. MRI for soft-tissue injury, ligament/meniscus tears, osteomyelitis, and cord pathology. Ultrasound for tendons, effusions, DVT, and guided procedures. Bone scan for occult fracture, metastasis, or infection when MRI is unavailable. DXA for osteoporosis.
- Labs: CBC, ESR/CRP for infection/inflammation; synovial fluid cell count, crystals, Gram stain and culture for a hot joint.
Worked example
An 82-year-old cannot bear weight after a low-energy fall. Hip radiographs are negative but there is groin pain and limited rotation. The next step is MRI of the hip (or CT if MRI is contraindicated) to exclude an occult femoral neck fracture; discharge without further imaging risks displacement.
Traps
Ordering MRI before plain films in acute trauma; attributing night pain in an older adult to osteoarthritis; failing to document distal neurovascular status; and treating a hot joint as gout without aspiration.