OMSB Orthopedic Surgery (OEORTHO) cheat sheet

Compartment syndrome: pressure delta (diastolic BP minus compartment pressure) below 30 mmHg is the threshold for fasciotomy; clinical signs are unreliable in obtunded or sedated patients, so serial measurement is indicated.

Open fracture: Gustilo-Anderson grading - I is wound under 1 cm and clean; II is 1–10 cm without extensive soft-tissue damage; IIIA has adequate soft-tissue coverage despite extensive laceration; IIIB requires flap coverage; IIIC has arterial injury needing repair. All get tetanus prophylaxis, IV antibiotics, and urgent irrigation and debridement.

Septic arthritis of a native adult joint: arthrocentesis showing WBC above 50,000/mm3 with neutrophil predominance (often above 90%) supports the diagnosis; synovial fluid Gram stain and culture plus blood cultures are mandatory, and the joint requires urgent drainage plus IV antibiotics.

Cauda equina syndrome is a surgical emergency: bilateral sciatica, saddle anesthesia, bladder or bowel dysfunction, and progressive motor deficit demand urgent MRI and decompression, ideally within 24–48 hours of symptom onset.

Anterior shoulder dislocation: axillary nerve injury is the most common nerve lesion (deltoid weakness, regimental badge sensory loss); obtain pre- and post-reduction radiographs, and assess for Hill-Sachs (humeral head impaction) and Bankart (anteroinferior labral) lesions.

Pediatric supracondylar humerus fracture: Gartland classification - I is nondisplaced, II is displaced with intact posterior cortex, III is completely displaced, IV is unstable in all directions; a pulseless pink hand is treated with reduction and pinning rather than immediate vascular exploration.

Developmental dysplasia of the hip: Ortolani reduces a dislocated hip, Barlow dislocates a reducible hip; ultrasound is the imaging of choice before 4–6 months of age, after which plain radiographs are used.

Osteosarcoma: bimodal age peaks (adolescence and over 60); classic metaphyseal lesion of the distal femur with sunburst periosteal reaction and Codman triangle; neoadjuvant chemotherapy plus limb-salvage resection is standard, and lung metastases are the main prognostic factor.

Total hip arthroplasty dislocation: posterior approach carries higher dislocation risk; avoid hip flexion beyond 90 degrees, adduction past midline, and internal rotation in the early postoperative period. Sciatic nerve palsy is a known complication of the posterior approach.

Femoral neck fracture in the elderly: Garden I–II (incomplete or complete nondisplaced) may be treated with cannulated screws; displaced (Garden III–IV) fractures in older patients are treated with arthroplasty to reduce nonunion and avascular necrosis risk. In younger patients, urgent reduction and internal fixation is preferred.

Tibial plateau fractures: Schatzker types I–VI; types IV–VI are bicondylar or involve the tibial spines and carry higher risk of compartment syndrome and articular depression requiring CT planning and often a lateral or dual approach.

Ankle fracture: the Danis-Weber classification is based on the level of the fibular fracture relative to the syndesmosis - A is below, B is at the level, C is above. Weber C implies syndesmotic injury; a high fibular fracture with medial clear space widening requires syndesmotic fixation.

Pediatric bone healing: the physis is weaker than the surrounding ligament, so Salter-Harris injuries are common; types I–V are described, and types III–V cross the physis and risk growth arrest. The distal radius and distal tibia are the most frequent sites.

Compartment syndrome in pediatric supracondylar fractures: the volar forearm is most commonly affected; a pulseless white hand with severe pain on passive stretch requires emergent reduction and pinning, with vascular exploration if perfusion does not return.

Osteoporosis: DEXA T-score of -2.5 or lower defines osteoporosis; a fragility fracture of the hip, spine, or distal radius warrants pharmacologic treatment regardless of T-score. Bisphosphonates are first-line, and teriparatide is used for severe disease.

Paget disease of bone: elevated alkaline phosphatase with normal calcium and phosphate; the pelvis, skull, and femur are common sites; complications include pathologic fracture, secondary osteoarthritis, deafness from skull involvement, and rare sarcomatous transformation.

Rickets: low calcium and phosphate with elevated alkaline phosphatase and PTH; widening of the physes, rachitic rosary, and bowing; vitamin D deficiency is the most common cause, and treatment is vitamin D plus calcium replacement.

Osteomyelitis: Staphylococcus aureus is the most common pathogen; in sickle cell disease, Salmonella is a classic cause; in neonates, group B Streptococcus and gram-negative organisms are common. MRI is the most sensitive imaging modality, and bone biopsy guides antibiotic therapy.

Rotator cuff tears: the supraspinatus is the most commonly torn tendon; the drop-arm test and external rotation lag sign suggest full-thickness tears; MRI is the imaging of choice, and acute full-thickness tears in young active patients are treated with repair.

Anterior cruciate ligament injury: a positive Lachman test is the most sensitive examination; the pivot-shift test is highly specific; MRI confirms the diagnosis, and reconstruction is indicated for instability in active patients.

Meniscal tear: a positive McMurray test suggests a tear; a locked knee with a displaced bucket-handle tear requires urgent arthroscopy. Degenerative tears in older patients are often managed with physical therapy.

Carpal tunnel syndrome: median nerve compression; nocturnal paresthesias in the thumb, index, and middle fingers; Tinel and Phalen tests are supportive; nerve conduction studies confirm; splinting and corticosteroid injection are first-line, and release is indicated for persistent or severe disease.

Lumbar disc herniation: the L4–L5 and L5–S1 levels are most common; L5 root compression causes weakness of great toe dorsiflexion (extensor hallucis longus), and S1 root compression causes loss of the ankle reflex and plantar flexion weakness. Cauda equina syndrome requires urgent decompression.

Spinal stenosis: neurogenic claudication relieved by sitting or leaning forward (shopping-cart sign), unlike vascular claudication; MRI is diagnostic, and decompression is indicated for progressive or refractory symptoms.

Total knee arthroplasty: the most common indications are end-stage osteoarthritis with pain and functional limitation; complications include periprosthetic joint infection (diagnosed with synovial fluid analysis and cultures), aseptic loosening, and stiffness. Prophylaxis for venous thromboembolism is standard.

Osteoarthritis: weight-bearing radiographs show joint space narrowing, subchondral sclerosis, osteophytes, and cysts; management begins with exercise and weight loss, then NSAIDs, intra-articular corticosteroid injections, and arthroplasty for end-stage disease.

Slipped capital femoral epiphysis: adolescent with groin or knee pain and an externally rotated limb; frog-leg lateral radiograph is diagnostic; in situ screw fixation is standard, and bilateral prophylaxis is considered in young or endocrinopathy-associated cases.