AOBOS Orthopedics cheat sheet

Somatic dysfunction is documented by TART: Tissue texture change, Asymmetry, Restriction of motion, and Tenderness.

Fryette type I (neutral) mechanics: sidebending and rotation occur to opposite sides and the curve is group; type II (non-neutral) has same-side sidebending and rotation at a single segment.

Bone remodeling is coupled: osteoclast-mediated resorption precedes osteoblast-mediated formation; the RANKL/OPG ratio controls osteoclast differentiation and activity.

Compartment syndrome is suggested when compartment pressure is within 30 mmHg of diastolic blood pressure (delta pressure <30 mmHg); fasciotomy is indicated for confirmed compartment syndrome.

Salter-Harris types: I through physis, II above physis (metaphysis), III below physis (epiphysis), IV through both, V crush injury.

Femoral head blood supply arises mainly from the medial femoral circumflex artery via lateral epiphyseal vessels; femoral neck fractures risk avascular necrosis.

Heterotopic ossification risk is reduced by NSAIDs or low-dose radiation after high-risk hip surgery; established HO may require excision after maturation.

ATLS primary survey order: catastrophic hemorrhage control, airway with cervical protection, breathing/ventilation, circulation with hemorrhage control, disability, exposure/environment.

Gustilo-Anderson open fracture: I <1 cm clean; II >1 cm without extensive soft-tissue damage; IIIA adequate coverage; IIIB requires flap; IIIC arterial injury requiring repair.

Pelvic ring injury with hemodynamic instability: apply a pelvic binder at the greater trochanters; exclude retroperitoneal bleed and consider angioembolization for arterial hemorrhage.

Garden femoral neck classification: I incomplete/valgus impacted; II complete nondisplaced; III complete partially displaced; IV complete displaced; higher grade increases AVN risk.

Weber ankle classification: A fracture below syndesmosis; B at syndesmosis; C above syndesmosis; C injuries have higher syndesmotic instability.

Colles fracture has dorsal angulation of distal radius; Smith fracture has volar angulation; both are distal radius fractures.

Gartland supracondylar humerus: I nondisplaced; II displaced with intact posterior hinge; III completely displaced; type III often needs pinning.

Damage-control orthopedics prioritizes temporary external fixation and physiologic stabilization in polytrauma before definitive fixation.

THA acetabular cup target inclination is about 40° (range 30-50°); anteversion about 15-20°; malposition increases dislocation and wear.

Highly crosslinked polyethylene reduces wear and osteolysis versus conventional polyethylene; ceramic-on-ceramic bearings risk squeaking and liner fracture.

Periprosthetic joint infection diagnosis uses major criteria (sinus tract, positive cultures) and minor criteria including ESR/CRP, synovial WBC, alpha-defensin, and purulence.

Aseptic loosening is driven by particulate wear debris and macrophage-mediated osteolysis; radiographs show progressive radiolucent lines and component migration.

Displaced femoral neck fracture in an elderly low-demand patient is commonly treated with hemiarthroplasty; a younger or active patient may receive THA.

Paprosky classification grades acetabular bone loss in revision THA; grade III defects require augments, cages, or trabecular metal constructs.

Unicompartmental knee arthroplasty is considered for isolated medial compartment arthritis with correctable deformity and intact cruciate ligaments.

Mechanical axis after total knee arthroplasty should be neutral; varus/valgus malalignment accelerates polyethylene wear and loosening.

ACL injury: Lachman test is most sensitive; pivot-shift test is most specific; MRI shows discontinuity and bone contusion.

Meniscal red-red zone is peripheral and vascularized; red-white zone is partially vascular; white-white zone is avascular and has poor healing.

Bankart lesion is anteroinferior labral tear; Hill-Sachs lesion is posterolateral humeral head impaction from anterior shoulder dislocation.

Rotator cuff: supraspinatus initiates abduction; Jobe test isolates supraspinatus; drop-arm sign suggests massive tear.

Outerbridge cartilage grading: 0 normal; I softening; II superficial fibrillation; III deep fissures; IV exposed subchondral bone.

Femoroacetabular impingement: cam deformity raises alpha angle; pincer deformity is acetabular overcoverage; labral tear common.

Concussion management uses graded return-to-sport protocol after symptom resolution; no same-day return if any concussion signs.

Tendinopathy histology shows collagen disorganization and failed healing, not acute inflammation; eccentric loading is a common treatment.

TLICS score: morphology (1-4), posterior ligamentous complex (0-3), neurologic status (0-3); score >4 generally operative; <4 nonoperative.

NEXUS cervical spine clearance: no posterior midline tenderness, no intoxication, normal alertness, no focal deficit, no distracting injury, and able to rotate neck 45°.

Adolescent idiopathic scoliosis: Cobb angle >10° defines scoliosis; bracing considered for 25-40° in skeletally immature patients; Risser stage estimates maturity.

Meyerding spondylolisthesis grades: I 0-25%, II 26-50%, III 51-75%, IV 76-100%, V >100% (spondyloptosis).

Cauda equina syndrome red flags include saddle anesthesia, bowel/bladder dysfunction, bilateral sciatica, and progressive motor deficit; urgent MRI is required.

Lumbar disc herniation: straight-leg raise test; most patients improve with nonoperative care; surgery for progressive deficit or cauda equina.

Osteoporotic vertebral compression fracture: kyphoplasty/vertebroplasty may reduce pain; neurologic deficit or posterior element involvement changes management.

ASIA impairment scale grades A complete to E normal; sacral sparing distinguishes incomplete injuries.

Carpal tunnel syndrome: median nerve compression at wrist; Phalen and Tinel tests; thenar atrophy in advanced cases; EMG/NCS confirms.

Scaphoid fracture: snuffbox tenderness; proximal pole fractures risk avascular necrosis; MRI is sensitive for occult fracture.

Dupuytren contracture involves palmar fascia; tabletop test positive when hand cannot lay flat; collagenase or surgery for functional impairment.

Trigger finger is stenosing tenosynovitis at A1 pulley; clicking and locking; corticosteroid injection or release.

Kienbock disease is avascular necrosis of lunate; MRI staging; risk with negative ulnar variance.

Bennett fracture is intra-articular thumb metacarpal base fracture; Rolando is comminuted; both often need pinning.

Flexor tendon zones: zone II is 'no man's land' between A1 and A2 pulleys; repair requires careful pulley management.

Seddon nerve injury: neurapraxia is conduction block; axonotmesis is axonal loss with intact sheath; neurotmesis is complete transection.

Lateral ankle sprain most commonly injures anterior talofibular ligament; Ottawa ankle rules guide radiography after trauma.

Achilles tendon rupture: positive Thompson test; palpable gap; plantarflexion weakness; surgical vs functional rehabilitation.

Lisfranc injury: malalignment of tarsometatarsal joint; weight-bearing CT improves detection; diastasis between first and second metatarsal bases is key.

Hallux valgus: increased hallux valgus angle and intermetatarsal angle; bunion at first MTP; surgery for symptomatic failure of conservative care.

Plantar fasciitis: medial heel pain; windlass mechanism; first-step pain; medial calcaneal tubercle tenderness.

Charcot neuroarthropathy: diabetes; midfoot collapse; rocker-bottom foot; warmth/redness; offloading is central.

Tarsal tunnel syndrome: tibial nerve compression behind medial malleolus; burning heel pain; Tinel sign; EMG/NCS.

Morton neuroma: interdigital nerve thickening, commonly third webspace; Mulder click; MRI/ultrasound.

SCFE: obese adolescent; hip/knee pain; frog-leg lateral shows slip; Klein line may not intersect femoral head; risk AVN.

Developmental dysplasia of hip: Ortolani reduces dislocated hip; Barlow dislocates reducible hip; Pavlik harness for infants.

Legg-Calve-Perthes: avascular necrosis of femoral head in children; containment treatment; risk of early osteoarthritis.

Osteosarcoma: metaphysis of distal femur/proximal tibia; sunburst periosteal reaction; lung metastases common.

Ewing sarcoma: diaphysis; t(11;22) EWSR1-FLI1; onion-skin periosteal reaction; systemic chemotherapy.

Giant cell tumor: epiphysis; soap-bubble lytic lesion; RANKL inhibitor denosumab; risk of recurrence.

Osteochondroma: cartilage-capped exostosis; continuous with marrow; multiple hereditary exostoses if multiple.

Salter-Harris type II is most common; metaphyseal fragment; physis injury may cause growth disturbance.