Musculoskeletal Health
Musculoskeletal Health
This domain tests tendon, ligament, muscle, and joint ultrasound: probe orientation, anisotropy, dynamic maneuvers, and Doppler for inflammation.
Core rules
- Tendons are fibrillar and echogenic when the beam is perpendicular. Anisotropy occurs when the beam is not at 90°; the tendon becomes falsely hypoechoic and mimics a tear.
- Scan in two orthogonal planes and confirm with dynamic movement or contralateral comparison.
- Use a high-frequency linear probe for superficial structures; a lower-frequency or standoff pad helps deep or curved parts.
- Rotator cuff: subscapularis in internal rotation, supraspinatus in the Crass position (hand on hip), infraspinatus and teres minor in external rotation.
- Power Doppler detects synovitis and enthesitis; optimize gain and box size, and avoid pressure that blanches flow.
- Measure tendons perpendicular to their long axis; for plantar fascia, measure at its thickest point near the calcaneal insertion.
Worked example
A patient has lateral shoulder pain, and the supraspinatus looks hypoechoic in one view. Rotate the probe to perpendicular; if the tendon becomes uniformly echogenic, the finding was anisotropy. If a focal defect persists in two planes, contains fluid, and no fibers cross it, call a full-thickness tear.
Traps
Overcalling a tear from anisotropy; failing to adjust focus to tendon depth; mistaking hyaline cartilage for fluid; not comparing sides; using excessive pressure with Doppler.