ABOS Orthopaedic Surgery Part II cheat sheet

Periprosthetic joint infection: modified MSIS/ICM criteria require two positive cultures with identical organism or a sinus tract communicating with the joint for definite diagnosis.

Total hip arthroplasty wear: osteolysis is driven by particulate debris and macrophage-mediated cytokine release; polyethylene wear rate rises with smaller head size and steep cup inclination.

Aseptic loosening of a cemented femoral stem is suggested by a complete radiolucent line greater than 2 mm or stem migration on serial radiographs.

Cementless femoral fixation relies on proximal metaphyseal fit; diaphyseal-engaging stems are indicated for Dorr type C bone.

Knee arthroplasty: coronal plane alignment targets a mechanical axis within roughly 3 degrees of neutral; varus/valgus constraint is needed when collateral ligaments are incompetent.

Hip dislocation risk after THA increases with posterior approach, small femoral head, and combined anteversion outside the safe zone (approximately 25-50 degrees combined).

Aseptic loosening versus infection: ESR and CRP are the first-line serum tests; CRP normalizes within about 3 weeks after uncomplicated arthroplasty.

Osteonecrosis of the femoral head: Ficat stage III shows subchondral collapse (crescent sign); stage IV shows secondary acetabular arthritis, where arthroplasty is indicated.

Bone healing: primary (direct) healing occurs with rigid compression and no callus; secondary healing involves endochondral ossification and callus formation.

Wolff law: bone remodels along lines of mechanical stress; stress shielding follows stiff implants that reduce load transfer to bone.

Nerve conduction: demyelinating injury slows conduction velocity with preserved amplitude; axonal injury reduces amplitude.

Suture material: absorbable sutures lose tensile strength by hydrolysis; polydioxanone retains strength longer than polyglactin.

Cartilage: superficial zone has highest collagen and lowest proteoglycan content; deep zone has the highest proteoglycan content.

Antibiotic prophylaxis timing: preoperative dose within 60 minutes of incision (120 minutes for vancomycin) maximizes tissue levels.

Tendon healing proceeds through inflammatory, proliferative, and remodeling phases; immobilization delays but does not prevent the process.

Tourniquet ischemia causes anaerobic metabolism and acidosis; reperfusion injury is mediated by oxygen free radicals.

Ankle fracture: the talar shift of 1 mm reduces tibiotalar contact area substantially; anatomic mortise reduction is the goal.

Weber classification: type A is below the syndesmosis, type B is at the level, type C is above the level of the syndesmosis.

Lisfranc injury: a widened interval between the base of the second metatarsal and the medial cuneiform on weight-bearing radiographs is diagnostic.

Achilles tendon rupture: Thompson test (squeeze calf, absent plantarflexion) is the key clinical sign.

Hallux valgus: the first intermetatarsal angle greater than 15 degrees and hallux valgus angle greater than 15 degrees define deformity.

Ankle arthrodesis versus arthroplasty: arthroplasty is generally reserved for lower-demand patients with preserved alignment and bone stock.

Plantar fasciitis: pain is maximal at the medial calcaneal tuberosity with the first steps in the morning.

Jones fracture: a transverse fracture at the metaphyseal-diaphyseal junction of the fifth metatarsal has a high nonunion risk due to poor blood supply.

Kienbock disease: avascular necrosis of the lunate; negative ulnar variance is a risk factor.

Scaphoid fracture: proximal pole fractures have the highest risk of nonunion because blood supply enters distally and flows retrograde.

Dupuytren contracture: palmar fascia nodules and cords; the tabletop test indicates surgical indication when the hand cannot lie flat.

Nerve repair: epineurial repair aligns fascicles; group fascicular repair is preferred for mixed nerves.

Trigger finger: A1 pulley release; the nodule is at the level of the A1 pulley at the metacarpal head.

Free flap monitoring: the most reliable early sign of arterial thrombosis is a change in color and capillary refill; venous congestion produces a dark, swollen flap.

Carpal tunnel syndrome: median nerve compression; thenar atrophy indicates advanced disease and poorer recovery.

Bennett fracture: intra-articular fracture of the base of the first metacarpal with subluxation, treated with pinning or screw fixation.

Enneking staging: stage I is low grade, stage II high grade, stage III any grade with metastasis; A is intracompartmental, B extracompartmental.

Osteosarcoma: peak incidence in the second decade; metaphyseal location around the knee; sunburst periosteal reaction and Codman triangle.

Ewing sarcoma: diaphyseal location, small round blue cells, t(11;22) translocation; treated with neoadjuvant chemotherapy plus surgery or radiation.

Giant cell tumor: epiphyseal location in skeletally mature patients; soap-bubble lytic lesion; treated with curettage and cementing.

Chondrosarcoma: peak in older adults; axial skeleton; resistant to chemotherapy and radiation, so wide surgical resection is the mainstay.

Soft tissue sarcoma: biopsy tract must be excised en bloc with the tumor at definitive resection.

Metastatic bone disease: breast, prostate, lung, kidney, and thyroid are the most common primary sites; Mirels score guides prophylactic fixation.

Osteoid osteoma: painful at night, relieved by NSAIDs; nidus less than 2 cm surrounded by sclerosis.

Developmental dysplasia of the hip: Ortolani reduces a dislocated hip, Barlow dislocates a reducible hip; ultrasound is used before ossification of the femoral head.

Legg-Calve-Perthes: avascular necrosis of the proximal femoral head in children; lateral pillar classification guides prognosis.

Slipped capital femoral epiphysis: medial knee pain may be the presenting complaint; frog-leg lateral radiograph shows the slip; in situ pinning is standard.

Clubfoot (talipes equinovarus): Ponseti method of serial casting with Achilles tenotomy for residual equinus.

Scoliosis: adolescent idiopathic curves of 10-25 degrees are observed; 25-45 degrees are braced; greater than 45-50 degrees may need surgery.

Supracondylar humerus fracture: Gartland type III is completely displaced; the anterior humeral line should pass through the middle third of the capitellum.

Osteogenesis imperfecta: type I collagen defect; blue sclerae, hearing loss, and recurrent fractures; bisphosphonates reduce fracture rate.

Physeal injury: Salter-Harris types I through V; type III and IV cross the physis into the epiphysis and risk growth arrest.

Rotator cuff: supraspinatus initiates abduction; the drop arm test suggests a full-thickness tear.

Shoulder dislocation: anterior dislocations are most common; axillary nerve injury is assessed by deltoid sensation and contraction.

Bankart lesion is a labral tear at the anteroinferior glenoid; Hill-Sachs is a posterolateral humeral head impaction.

Elbow: terrible triad is dislocation with radial head and coronoid fractures; repair of the lateral collateral ligament complex is key to stability.

Radial head fracture: Mason type I is nondisplaced, type II displaced with a single fragment, type III comminuted.

Total shoulder arthroplasty: glenoid component loosening is the most common long-term complication.

Frozen shoulder: capsular contracture with loss of external rotation; associated with diabetes mellitus.

Lateral epicondylitis: pain at the extensor carpi radialis brevis origin; resisted wrist extension reproduces symptoms.

Cauda equina syndrome: saddle anesthesia, bowel/bladder dysfunction, and bilateral leg symptoms require emergent MRI and decompression.

Cervical myelopathy: Hoffman sign and Babinski sign suggest upper motor neuron involvement; MRI is the definitive study.

Lumbar stenosis: neurogenic claudication relieved by flexion and worsened by extension.

Spondylolisthesis: Meyerding grades I through V; grade V is spondyloptosis.

Disc herniation: the posterolateral herniation compresses the traversing nerve root at that level in the lumbar spine.

Thoracolumbar fracture: the Denis three-column model; two or more column involvement suggests instability.

Cervical radiculopathy: C6 root is affected by C5-C6 disc herniation.

Ankylosing spondylitis: bamboo spine; the cervical spine is at high risk for fracture with minimal trauma.

ACL injury: pivot shift and Lachman tests are most sensitive; the Lachman test is best performed at 20-30 degrees of flexion.

Meniscal tear: a displaced bucket-handle tear causes a locked knee; the McMurray test reproduces pain and clicking.

Patellar dislocation: the apprehension test and J sign; medial patellofemoral ligament reconstruction is indicated for recurrent instability.

Hip labral tear: anterior hip pain with positive FABER or anterior impingement test; femoroacetabular impingement is a common cause.

Shoulder instability: apprehension and relocation tests; anterior instability is most common in throwing athletes.

Concussion: return-to-play requires stepwise progression; symptoms must resolve before advancing stages.

Ankle sprain: the anterior talofibular ligament is injured first in inversion injuries.

Tendinopathy: eccentric loading is the mainstay of nonoperative treatment for Achilles and patellar tendinopathy.

Open fracture: urgent irrigation and debridement with antibiotics; Gustilo-Anderson classification guides treatment.

Compartment syndrome: pain with passive stretch is the earliest reliable sign; pressure greater than 30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Pelvic ring injury: hemodynamic instability with a pelvic binder; the Young-Burgess classification describes injury patterns.

Femoral shaft fracture: antegrade intramedullary nailing is standard; the piriformis entry point is used for antegrade nailing.

Tibial plateau fracture: Schatzker types I through VI; type VI is bicondylar with metaphyseal-diaphyseal dissociation.

Distal radius fracture: Colles fracture is dorsally displaced; Smith fracture is volarly displaced.

Fat embolism: occurs 24-72 hours after long bone fractures; petechiae, hypoxemia, and confusion.

Nonunion: lack of healing at 6 months with no progression on serial radiographs; hypertrophic nonunion has abundant callus.

Informed consent requires disclosure of risks, benefits, alternatives, and the consequences of declining treatment.

Surgical time-out verifies patient identity, procedure, site, and side before incision.

Wrong-site surgery prevention includes marking the site with the patient awake and verifying laterality.

Conflict of interest: financial relationships with industry must be disclosed to patients and institutions.

Peer review and quality improvement: morbidity and mortality conferences are protected quality-assurance activities.

Documentation: the medical record is a legal document; amendments should be dated and signed, not erased.

Informed refusal: a competent patient may decline treatment after understanding the consequences.

Scope of practice: consultation and referral are appropriate when the condition exceeds the physician's expertise.

Open fracture: urgent irrigation and debridement with antibiotics; Gustilo-Anderson classification guides treatment.

Compartment syndrome: pain with passive stretch is the earliest reliable sign; pressure greater than 30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Pelvic ring injury: hemodynamic instability with a pelvic binder; the Young-Burgess classification describes injury patterns.

Femoral shaft fracture: antegrade intramedullary nailing is standard; the piriformis entry point is used for antegrade nailing.

Tibial plateau fracture: Schatzker types I through VI; type VI is bicondylar with metaphyseal-diaphyseal dissociation.

Distal radius fracture: Colles fracture is dorsally displaced; Smith fracture is volarly displaced.

Fat embolism: occurs 24-72 hours after long bone fractures; petechiae, hypoxemia, and confusion.

Nonunion: lack of healing at 6 months with no progression on serial radiographs; hypertrophic nonunion has abundant callus.

Open fracture: urgent irrigation and debridement with antibiotics; Gustilo-Anderson classification guides treatment.

Compartment syndrome: pain with passive stretch is the earliest reliable sign; pressure greater than 30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Pelvic ring injury: hemodynamic instability with a pelvic binder; the Young-Burgess classification describes injury patterns.

Femoral shaft fracture: antegrade intramedullary nailing is standard; the piriformis entry point is used for antegrade nailing.

Tibial plateau fracture: Schatzker types I through VI; type VI is bicondylar with metaphyseal-diaphyseal dissociation.

Distal radius fracture: Colles fracture is dorsally displaced; Smith fracture is volarly displaced.

Fat embolism: occurs 24-72 hours after long bone fractures; petechiae, hypoxemia, and confusion.

Nonunion: lack of healing at 6 months with no progression on serial radiographs; hypertrophic nonunion has abundant callus.

Open fracture: urgent irrigation and debridement with antibiotics; Gustilo-Anderson classification guides treatment.

Compartment syndrome: pain with passive stretch is the earliest reliable sign; pressure greater than 30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Pelvic ring injury: hemodynamic instability with a pelvic binder; the Young-Burgess classification describes injury patterns.

Femoral shaft fracture: antegrade intramedullary nailing is standard; the piriformis entry point is used for antegrade nailing.

Tibial plateau fracture: Schatzker types I through VI; type VI is bicondylar with metaphyseal-diaphyseal dissociation.

Distal radius fracture: Colles fracture is dorsally displaced; Smith fracture is volarly displaced.

Fat embolism: occurs 24-72 hours after long bone fractures; petechiae, hypoxemia, and confusion.

Nonunion: lack of healing at 6 months with no progression on serial radiographs; hypertrophic nonunion has abundant callus.

Open fracture: urgent irrigation and debridement with antibiotics; Gustilo-Anderson classification guides treatment.

Compartment syndrome: pain with passive stretch is the earliest reliable sign; pressure greater than 30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Pelvic ring injury: hemodynamic instability with a pelvic binder; the Young-Burgess classification describes injury patterns.

Femoral shaft fracture: antegrade intramedullary nailing is standard; the piriformis entry point is used for antegrade nailing.

Tibial plateau fracture: Schatzker types I through VI; type VI is bicondylar with metaphyseal-diaphyseal dissociation.

Distal radius fracture: Colles fracture is dorsally displaced; Smith fracture is volarly displaced.

Fat embolism: occurs 24-72 hours after long bone fractures; petechiae, hypoxemia, and confusion.

Nonunion: lack of healing at 6 months with no progression on serial radiographs; hypertrophic nonunion has abundant callus.