Hand and Upper Extremity Surgery
Concepts
Hand questions are anatomy dense. Know flexor tendon zones: zone I distal to the FDS insertion (jersey finger, FDP avulsion), zone II the fibro-osseous canal, zone III the palm, zone IV the carpal tunnel, zone V proximal to the carpal tunnel. Extensor zones I–VIII place mallet finger at zone I and boutonnière deformity at zone III. Nerve exam: median (thumb opposition, thumb–index pinch, thenar wasting), ulnar (Froment sign, intrinsic wasting, clawing), radial (wrist extension; first dorsal interosseous is ulnar).
Common traps: missing a scaphoid fracture because initial radiographs are normal - immobilize and repeat imaging, since proximal pole fractures carry the highest nonunion and avascular necrosis risk. Distal radius fractures require checking DRUJ stability, median nerve symptoms and associated carpal injuries. A fight bite over the metacarpophalangeal joint is a human bite with Eikenella risk: irrigate, give antibiotics, and never close primarily.
Rule of thumb: any penetrating injury over the MCP joint is a fight bite until proven otherwise, and any hand infection with fluctuance needs surgical drainage.
Worked example: a patient cannot flex the distal interphalangeal joint after grabbing a jersey - FDP avulsion (jersey finger), a zone I injury; splint in extension and refer.
Also know carpal tunnel syndrome (nocturnal symptoms, thenar wasting), Dupuytren contracture (palmar fascia, not tendon) and Kienböck disease (lunate avascular necrosis).