ABOS Orthopaedic Surgery cheat sheet

Salter-Harris classification runs I through V by increasing physeal involvement: I through the physis alone, II physis plus metaphysis, III physis plus epiphysis, IV through metaphysis, physis, and epiphysis, V crush injury; types III and IV cross the joint and risk articular incongruity.

Gartland classification of supracondylar humerus fractures: I nondisplaced, II displaced with intact posterior cortex, III completely displaced; a flexion-type III variant exists. Type III with absent pulse and a pale hand warrants urgent reduction and vascular reassessment.

Open fracture antibiotic timing: Gram-positive coverage (cefazolin) for type I/II; add an aminoglycoside for type III; add penicillin for farm or soil contamination to cover anaerobes and Clostridium.

Compartment syndrome pressure threshold: a delta pressure (diastolic blood pressure minus compartment pressure) of 30 mmHg or less is an indication for urgent fasciotomy; absolute pressure alone is unreliable.

Developmental dysplasia of the hip: Ortolani reduces a dislocated hip, Barlow dislocates a reducible hip; both lose sensitivity after 3 months, when limited abduction and Galeazzi sign dominate.

Osteosarcoma and Ewing sarcoma peak in the first two decades; osteosarcoma favors the distal femur metaphysis, Ewing favors the diaphysis and is associated with an 11;22 translocation.

Bone healing timeline: soft callus at 2-3 weeks, hard callus at 3-6 weeks, remodeling over months to years; smoking, NSAIDs, and diabetes delay union.

Carpal tunnel syndrome electrodiagnostic grading: sensory latency prolongation precedes motor latency; thenar atrophy and constant numbness indicate advanced disease requiring surgical release.

Case presentation structure: patient demographics and mechanism, then key physical findings, then imaging interpretation, then differential, then definitive plan with alternatives and complications - examiners score the reasoning chain, not just the answer.

When shown a radiograph, state the view, then alignment, then bone quality, then joint spaces, then soft tissues; commit to a diagnosis before offering treatment.

Total hip arthroplasty indications: end-stage arthritis with failed nonoperative management; document the nonoperative trial (activity modification, NSAIDs, injections, physical therapy) to justify surgery.

Periprosthetic joint infection workup: serum ESR and CRP, synovial fluid cell count and differential, and cultures; chronic infection typically requires two-stage exchange, acute infection may allow debridement and retention.

Compartment syndrome and cauda equina syndrome are the two emergencies that must be named early in any limb or spine case; delay beyond 24-48 hours in cauda equina worsens prognosis.

Pediatric supracondylar fracture with a pink pulseless hand: most regain pulse after closed reduction; a white pulseless hand or persistent ischemia after reduction requires exploration.

Informed consent discussion must include alternatives (including nonoperative), expected recovery, and the specific major risks of that procedure - examiners frequently probe for the risks you omitted.

For any tumor case, state the staging (Enneking for bone, TNM for soft tissue), whether a biopsy will be done at a referral center, and that biopsy tract must be excised at definitive surgery.