APMLE Part III cheat sheet

Diabetic foot ulcer classification: Wagner grades 0-5 (0 = intact skin with deformity, 1 = superficial ulcer, 2 = deep to tendon/bone, 3 = deep with abscess/osteomyelitis, 4 = localized gangrene, 5 = whole-foot gangrene).

Total contact casting is the gold-standard offloading for neuropathic plantar forefoot/midfoot ulcers; contraindicated with active deep infection, osteomyelitis, or severe ischemia.

Osteomyelitis of the foot: probe-to-bone test has high positive predictive value; combine with plain radiographs (changes lag 10-14 days) and MRI for confirmation.

Charcot neuroarthropathy Eichenholtz stages: I (development, fragmentation), II (coalescence), III (reconstruction/consolidation); offloading is the mainstay in stages I-II.

Ankle-brachial index <=0.90 suggests peripheral arterial disease; values >1.3 suggest non-compressible calcified vessels common in diabetes.

Compartment syndrome of the foot: earliest sign is pain out of proportion, especially with passive stretch; compartment pressure >30 mmHg (or within 30 mmHg of diastolic) supports fasciotomy.

Jones fracture (metaphyseal-diaphyseal junction of the 5th metatarsal) has a high nonunion risk due to a watershed blood supply; non-weightbearing or surgical fixation is typical.

Lisfranc injury: weightbearing AP radiograph showing >2 mm widening between 1st and 2nd metatarsal bases is diagnostic; missed injuries lead to chronic midfoot instability.

Achilles tendon rupture: positive Thompson (Simmonds) test and palpable gap; risk increased by fluoroquinolone use and pre-existing tendinopathy.

Perioperative hyperglycemia: target glucose roughly 140-180 mg/dL in hospitalized/surgical patients; avoid tight control below 110 mg/dL due to hypoglycemia risk.

Preoperative cardiovascular risk: active cardiac conditions (unstable angina, decompensated heart failure, severe valvular disease, recent MI) warrant delay and cardiology evaluation before elective surgery.

Venous thromboembolism prophylaxis: Caprini score guides risk; mechanical prophylaxis preferred when bleeding risk is high, pharmacologic (e.g., LMWH) when risk outweighs bleeding.

Antibiotic prophylaxis timing: administer within 60 minutes before incision (within 120 minutes for vancomycin or fluoroquinolones) to achieve peak tissue levels.

Warfarin perioperative management: for most procedures, stop ~5 days pre-op and bridge with LMWH only in high thrombotic-risk patients (e.g., mechanical mitral valve).

Metformin: hold on the day of surgery and restart after 48 hours when renal function is stable and contrast/hemodynamic insults have resolved.

Hypertension urgency vs emergency: emergency requires end-organ damage (encephalopathy, aortic dissection, pulmonary edema) and IV therapy; asymptomatic elevation does not.

Smoking cessation at least 4 weeks before elective surgery reduces wound and pulmonary complications; nicotine replacement is acceptable.

Anesthesia risk: ASA physical status classification I-VI stratifies perioperative risk and guides preoperative testing intensity.