Iraqi Board Orthopedic Surgery cheat sheet

Bone composition: 60-70% mineral (hydroxyapatite), 20-25% organic matrix (90% type I collagen), 10% water; cortical bone is 80-90% of skeletal mass but only ~20% of surface area.

Wolff law: bone remodels along lines of applied stress; Hueter-Volkmann law: compression slows physeal growth, tension accelerates it.

Nerve roots: C5 deltoid/biceps, C6 wrist extensors/brachioradialis, C7 triceps/wrist flexors/finger extensors, C8 finger flexors, T1 intrinsic hand muscles.

Radial nerve spirals in the radial groove of the humerus; axillary nerve runs 6-8 mm below the acromion at the surgical neck - both at risk in proximal humerus fractures.

Common peroneal nerve winds around the fibular neck; deep peroneal supplies tibialis anterior (L4), so foot drop localizes to L4-L5 or the fibular neck.

Open fracture microbiology: Staphylococcus aureus dominates, then gram-negative bacilli; pasture/soil-contaminated wounds add Clostridium and Pseudomonas; give tetanus prophylaxis.

Antibiotic prophylaxis for arthroplasty: cefazolin 2 g IV (3 g if >120 kg) within 60 min of incision; vancomycin only for MRSA colonization or beta-lactam allergy.

NSAIDs inhibit COX and impair prostaglandin-mediated bone healing; corticosteroids suppress osteoblasts and cause osteoporosis; heparin binds osteoblasts and increases fracture nonunion risk.

ATLS sequence: primary survey A-B-C-D-E with hemorrhage control first; pelvic binder at the greater trochanters for suspected pelvic ring injury; massive transfusion protocol 1:1:1.

Damage control orthopedics: temporary external fixation for femur/pelvis in hemodynamically unstable or physiologically borderline patients (lactate >2.5, base deficit <-6, hypothermia, coagulopathy), then definitive fixation after resuscitation.

Open fracture: urgent irrigation and debridement, tetanus status, IV antibiotics within 1 hour; Gustilo-Anderson IIIB needs soft-tissue coverage (flap), IIIC needs vascular repair.

Compartment syndrome: pain out of proportion, pain on passive stretch is the earliest reliable sign; pulselessness and paralysis are late; pressure >30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Fat embolism syndrome: 24-72 h after long bone fracture, triad of hypoxemia, petechiae, and confusion; treatment is supportive with oxygen and early fracture stabilization.

Neck of femur: intracapsular fractures risk avascular necrosis of the femoral head; displaced fractures in the elderly are treated with arthroplasty, undisplaced with cannulated screws.

Tibial shaft: the anterior compartment is most commonly affected by compartment syndrome; the tibia has poor soft-tissue cover, so open fractures need early coverage.

Fracture healing: hematoma and inflammation (days), soft callus (weeks), hard callus (months), remodeling (years); nonunion defined as no healing by 9 months without progression for 3 months.

Total hip arthroplasty bearing options: metal-on-highly crosslinked polyethylene, ceramic-on-polyethylene, ceramic-on-ceramic; metal-on-metal has been abandoned due to adverse local tissue reaction (ALTR) and pseudotumor.

Cemented femoral stem fixation is preferred in elderly osteoporotic patients; cementless porous-coated stems rely on biologic ingrowth and suit younger patients with good bone stock.

Aseptic loosening is the most common late cause of revision; periprosthetic joint infection is the most common cause of early revision within 2 years.

Periprosthetic joint infection diagnosis: MSIS/ICM criteria use serum CRP and ESR, synovial WBC count and neutrophil percentage, alpha-defensin, and two positive cultures.

Knee kinematics: the medial femoral condyle is larger and the lateral condyle translates more; the posterior cruciate ligament is retained in cruciate-retaining designs, sacrificed in posterior-stabilized designs.

Total knee arthroplasty alignment targets a mechanical axis within 3 degrees of neutral; excessive varus/valgus malalignment increases polyethylene wear and aseptic loosening.

Venous thromboembolism prophylaxis after arthroplasty: aspirin, enoxaparin, or rivaroxaban for 14-35 days; mechanical prophylaxis plus early mobilization.

Periprosthetic fracture around a total hip: Vancouver classification (A trochanteric, B around stem, C distal to stem); B1 stable stem, B2 loose stem, B3 poor bone stock.

Cervical spine clearance: NEXUS criteria (no midline tenderness, no neuro deficit, normal alertness, no intoxication, no distracting injury) or Canadian C-Spine Rule; otherwise CT.

Spinal cord injury: ASIA impairment scale A (complete) to E (normal); methylprednisolone is not routinely recommended per current guidelines.

Neurogenic shock: hypotension with bradycardia after cord injury above T6; treat with fluids, vasopressors, and atropine for bradycardia.

Spinal shock: transient loss of all reflexes and flaccid paralysis below the lesion, resolving over days to weeks; distinguish from neurogenic shock.

Thoracolumbar trauma: TLICS score (morphology, posterior ligamentous complex integrity, neurologic status); score >4 generally favors surgery.

Cauda equina syndrome: saddle anesthesia, urinary retention, bilateral leg weakness; a surgical emergency requiring urgent decompression, ideally within 24-48 hours.

Lumbar disc herniation: the L4-L5 and L5-S1 levels are most common; a paracentral herniation compresses the traversing nerve root (L5 at L4-L5), a far-lateral herniation compresses the exiting root.

Scoliosis: adolescent idiopathic curves >25 degrees may need bracing, >45-50 degrees surgical fusion; the Cobb angle is measured on the standing PA radiograph.

Developmental dysplasia of the hip: Ortolani (reduces a dislocated hip) and Barlow (dislocates a reduced hip) tests in neonates; Pavlik harness for infants under 6 months; ultrasound screening is preferred before ossification of the femoral head.

Legg-Calve-Perthes disease: avascular necrosis of the femoral head in children 4-8 years; containment treatment with abduction bracing or osteotomy; poor prognosis with lateral pillar involvement.

Slipped capital femoral epiphysis: obese adolescent with groin or knee pain and external rotation deformity; in situ pinning; risk of avascular necrosis and chondrolysis.

Clubfoot (talipes equinovarus): Ponseti method with serial manipulation and casting, percutaneous Achilles tenotomy, then foot abduction orthosis; avoid extensive surgery.

Osteogenesis imperfecta: type I collagen defect, blue sclerae, recurrent fractures; bisphosphonates reduce fracture rate; avoid intramedullary rodding in mild cases.

Physeal fractures: Salter-Harris I through V (SALTER: Slipped, Above, Lower, Through, Crush); types III-V risk growth arrest; type I often needs only cast immobilization.

Pediatric supracondylar humerus fracture: Gartland classification; type III is displaced and needs closed reduction and percutaneous pinning; watch for cubitus varus and compartment syndrome.

Achondroplasia: fibroblast growth factor receptor 3 (FGFR3) mutation; rhizomelic short stature, frontal bossing, foramen magnum stenosis, and spinal stenosis; growth hormone and limb lengthening are options.

Anterior cruciate ligament: the ACL prevents anterior tibial translation and rotational instability; the Lachman test is most sensitive; reconstruction uses bone-patellar tendon-bone or hamstring autograft.

Meniscus: the medial meniscus is more commonly torn; a red-red zone tear has blood supply and may heal; a bucket-handle tear causes a locked knee and needs arthroscopic repair.

Rotator cuff: supraspinatus is the most commonly torn tendon; the Neer and Hawkins tests are used; acute full-thickness tears in young patients are repaired, degenerative tears may be managed with physiotherapy.

Shoulder instability: anterior dislocation is most common; the Bankart lesion is detachment of the labrum, the Hill-Sachs lesion is a posterolateral humeral head defect; recurrent instability may need a Latarjet procedure.

Achilles tendon rupture: positive Thompson test, palpable gap, plantar flexion weakness; treat with functional bracing or surgical repair; the watershed area is 2-6 cm above the calcaneus.

Ankle sprain: the anterior talofibular ligament is the most commonly injured; the anterior drawer test assesses it; lateral ligament complex includes ATFL, CFL, and PTFL.

Patellofemoral pain: assess the Q angle and J sign; treatment is quadriceps and gluteal strengthening; lateral release is reserved for lateral patellar compression syndrome.

Hamstring strain: the biceps femoris is most commonly affected; return to sport after pain-free full strength and eccentric loading; recurrence risk is high if returned early.

Carpal tunnel syndrome: median nerve compression under the transverse carpal ligament; night pain, thenar atrophy, positive Phalen and Tinel tests; release the flexor retinaculum.

Guyon canal: ulnar nerve compression at the wrist; causes intrinsic wasting and clawing; the canal is between the pisiform and the hook of hamate.

Scaphoid fracture: the proximal pole has retrograde blood supply and the highest risk of avascular necrosis; tenderness in the anatomic snuffbox; immobilize with a thumb spica cast.

Kienbock disease: avascular necrosis of the lunate; risk factor is ulna minus variance; treatment options include radial shortening or lunate decompression.

Dupuytren contracture: palmar fascia fibrosis, common in northern European ancestry and diabetes; nodules and cords, most often the ring and little fingers; treat with fasciectomy or collagenase injection.

De Quervain tenosynovitis: first dorsal compartment (abductor pollicis longus and extensor pollicis brevis); positive Finkelstein test; treat with splint, steroid injection, or release.

Flexor tendon zones: zone II (no man's land) has the worst prognosis due to the flexor sheath; use the modified Kessler core suture with epitendinous repair and early protected motion.

Nerve repair: primary repair within 72 hours for clean lacerations; nerve gap >2-3 cm may need a graft; the sural nerve is a common donor; Tinel sign advances with regeneration at ~1 mm/day.

Ankle fracture: the Lauge-Hansen classification describes injury mechanism; the Danis-Weber classification is by fibular fracture level relative to the syndesmosis (A below, B at, C above).

Syndesmotic injury: the external rotation stress test and the squeeze test; a widened tibiofibular clear space >5 mm on mortise view; treat with a syndesmotic screw or tightrope.

Achilles tendon: the most commonly ruptured tendon; the Thompson test; avoid steroid injections near the tendon due to rupture risk.

Plantar fasciitis: medial heel pain worse with first steps; the windlass test; treat with stretching, orthotics, and night splints; surgery is rare.

Hallux valgus: first metatarsal varus and hallux pronation; the intermetatarsal angle and hallux valgus angle measured on weight-bearing radiographs; bunionectomy with osteotomy for symptomatic cases.

Tarsal coalition: a calcaneonavicular or talocalcaneal fibrous/cartilaginous bar causing rigid flatfoot in adolescents; a CT or MRI confirms; resection or fusion.

Charcot arthropathy: neuropathic (diabetes) midfoot collapse; the 6 Ds (destruction, density, debris, dislocation, distension, disorganization); treat with a total contact cast and offloading.

Lisfranc injury: tarsometatarsal fracture-dislocation; the fleck sign on radiographs; weight-bearing radiographs may be needed; treatment is anatomic reduction and fixation.

Osteosarcoma: bimodal age, metaphysis of the distal femur or proximal tibia, sunburst periosteal reaction and Codman triangle; treat with neoadjuvant chemotherapy and limb-salvage resection.

Ewing sarcoma: a small round blue cell tumor in children and adolescents, diaphysis of long bones, onion-skin periosteal reaction; t(11;22) EWS-FLI1 translocation; chemotherapy plus surgery.

Giant cell tumor: epiphysis of long bones after skeletal maturity, soap-bubble lytic lesion; treat with curettage and bone cement; denosumab is an option for recurrent or unresectable cases.

Osteochondroma: the most common benign bone tumor; a cartilage-capped bony outgrowth at the metaphysis, continuous with the cortex; multiple lesions suggest multiple hereditary exostoses.

Bone metastases: the prostate, breast, and lung are the most common primary sites; lytic lesions (lung, kidney, thyroid) vs blastic (prostate, breast); bisphosphonates or denosumab reduce skeletal-related events.

Osteoporosis: T-score <= -2.5 on DXA; the FRAX tool estimates 10-year fracture risk; treat with bisphosphonates, denosumab, or anabolic agents (teriparatide, romosozumab).

Paget disease: increased osteoclast then osteoblast activity, mosaic pattern of lamellar bone, elevated alkaline phosphatase, bone deformity and pain; treat with bisphosphonates.

Osteomyelitis: acute hematogenous in children (Staphylococcus aureus), contiguous spread in adults; MRI is most sensitive; treat with prolonged antibiotics and debridement; chronic disease may need sequestrectomy.

Septic arthritis: an emergency; joint aspiration with Gram stain and culture; Staphylococcus aureus is the most common organism; treat with IV antibiotics and urgent drainage.

Periprosthetic joint infection: acute (<3 weeks) may be treated with debridement, antibiotics, and implant retention (DAIR); chronic infection needs a two-stage exchange.

Biofilm: bacteria adhere to implants and secrete an extracellular matrix; biofilm bacteria are up to 1000 times more resistant to antibiotics; rifampicin is added for staphylococcal biofilm infections.

Osteomyelitis classification: Cierny-Mader (medullary, superficial, localized, diffuse) combined with host status (A, B, C); treatment depends on both.

Necrotizing fasciitis: a surgical emergency; pain out of proportion, rapidly spreading erythema, crepitus, and systemic toxicity; treat with urgent debridement and broad-spectrum antibiotics.

Gas gangrene: Clostridium perfringens; crepitus, myonecrosis, and gas on radiographs; treat with high-dose penicillin and debridement; hyperbaric oxygen is adjunctive.

Post-traumatic osteomyelitis: the most common organism is Staphylococcus aureus; obtain deep tissue cultures, not superficial swabs; remove infected hardware when possible.

Surgical site infection prevention: preoperative chlorhexidine skin preparation, normothermia, glycemic control, and avoidance of shaving; antibiotic prophylaxis within 60 minutes of incision.

Amputation levels: transtibial preserves the knee and saves energy; transfemoral needs more energy; the energy cost of walking rises with proximal amputation.

Prosthetic knee components: single-axis, polycentric, and microprocessor knees; microprocessor knees improve stability and reduce falls but need regular charging.

Transtibial socket designs: patellar tendon-bearing (PTB) and total surface-bearing (TSB); the patellar tendon is a pressure-tolerant area, while the fibular head and tibial crest are pressure-sensitive.

Orthotic principles: three-point pressure systems correct deformity; a Milwaukee brace treats thoracic scoliosis, a Boston brace treats thoracolumbar curves.

Above-knee prosthesis: ischial containment socket; the ischial tuberosity bears weight; the knee joint axis should align with the anatomical knee.

Rehabilitation after total knee arthroplasty: early mobilization, quadriceps strengthening, and range-of-motion exercises; aim for full extension and 90-120 degrees of flexion.

Spinal cord injury rehabilitation: functional goals depend on the level; C6 patients can feed with adaptive equipment; T10 patients can ambulate with orthoses.

Cardiopulmonary rehabilitation: exercise prescription uses the FITT principle (frequency, intensity, time, type); monitor heart rate and rate of perceived exertion.

Informed consent: must include diagnosis, nature of the procedure, risks, benefits, alternatives, and consequences of refusal; the patient must have capacity and be free of coercion.

Confidentiality: patient information is shared only with consent or when required by law; exceptions include communicable disease reporting and imminent harm.

Medical error disclosure: disclose harmful errors to the patient, apologize, explain, and document; this is an ethical and professional obligation.

Research ethics: the Declaration of Helsinki governs human subjects research; institutional review board (IRB) approval is required before data collection; informed consent is mandatory.

Levels of evidence: level I is a systematic review of randomized controlled trials; level V is expert opinion or case report; the hierarchy guides clinical decisions.

Study designs: randomized controlled trials minimize confounding; cohort studies measure incidence and relative risk; case-control studies estimate odds ratios for rare outcomes.

Sensitivity and specificity: sensitivity is the proportion of true positives detected; specificity is the proportion of true negatives; positive predictive value depends on prevalence.

Patient safety: the WHO surgical safety checklist includes sign-in, time-out, and sign-out; wrong-site surgery prevention uses marking and verification protocols.

Bone composition: 60-70% mineral (hydroxyapatite), 20-25% organic matrix (90% type I collagen), 10% water; cortical bone is 80-90% of skeletal mass but only ~20% of surface area.

Wolff law: bone remodels along lines of applied stress; Hueter-Volkmann law: compression slows physeal growth, tension accelerates it.

Nerve roots: C5 deltoid/biceps, C6 wrist extensors/brachioradialis, C7 triceps/wrist flexors/finger extensors, C8 finger flexors, T1 intrinsic hand muscles.

Radial nerve spirals in the radial groove of the humerus; axillary nerve runs 6-8 mm below the acromion at the surgical neck - both at risk in proximal humerus fractures.

Common peroneal nerve winds around the fibular neck; deep peroneal supplies tibialis anterior (L4), so foot drop localizes to L4-L5 or the fibular neck.

Open fracture microbiology: Staphylococcus aureus dominates, then gram-negative bacilli; pasture/soil-contaminated wounds add Clostridium and Pseudomonas; give tetanus prophylaxis.

Antibiotic prophylaxis for arthroplasty: cefazolin 2 g IV (3 g if >120 kg) within 60 min of incision; vancomycin only for MRSA colonization or beta-lactam allergy.

NSAIDs inhibit COX and impair prostaglandin-mediated bone healing; corticosteroids suppress osteoblasts and cause osteoporosis; heparin binds osteoblasts and increases fracture nonunion risk.

ATLS sequence: primary survey A-B-C-D-E with hemorrhage control first; pelvic binder at the greater trochanters for suspected pelvic ring injury; massive transfusion protocol 1:1:1.

Damage control orthopedics: temporary external fixation for femur/pelvis in hemodynamically unstable or physiologically borderline patients (lactate >2.5, base deficit <-6, hypothermia, coagulopathy), then definitive fixation after resuscitation.

Open fracture: urgent irrigation and debridement, tetanus status, IV antibiotics within 1 hour; Gustilo-Anderson IIIB needs soft-tissue coverage (flap), IIIC needs vascular repair.

Compartment syndrome: pain out of proportion, pain on passive stretch is the earliest reliable sign; pulselessness and paralysis are late; pressure >30 mmHg or within 30 mmHg of diastolic pressure warrants fasciotomy.

Fat embolism syndrome: 24-72 h after long bone fracture, triad of hypoxemia, petechiae, and confusion; treatment is supportive with oxygen and early fracture stabilization.

Neck of femur: intracapsular fractures risk avascular necrosis of the femoral head; displaced fractures in the elderly are treated with arthroplasty, undisplaced with cannulated screws.

Tibial shaft: the anterior compartment is most commonly affected by compartment syndrome; the tibia has poor soft-tissue cover, so open fractures need early coverage.

Fracture healing: hematoma and inflammation (days), soft callus (weeks), hard callus (months), remodeling (years); nonunion defined as no healing by 9 months without progression for 3 months.

Total hip arthroplasty bearing options: metal-on-highly crosslinked polyethylene, ceramic-on-polyethylene, ceramic-on-ceramic; metal-on-metal has been abandoned due to adverse local tissue reaction (ALTR) and pseudotumor.

Cemented femoral stem fixation is preferred in elderly osteoporotic patients; cementless porous-coated stems rely on biologic ingrowth and suit younger patients with good bone stock.

Aseptic loosening is the most common late cause of revision; periprosthetic joint infection is the most common cause of early revision within 2 years.

Periprosthetic joint infection diagnosis: MSIS/ICM criteria use serum CRP and ESR, synovial WBC count and neutrophil percentage, alpha-defensin, and two positive cultures.

Knee kinematics: the medial femoral condyle is larger and the lateral condyle translates more; the posterior cruciate ligament is retained in cruciate-retaining designs, sacrificed in posterior-stabilized designs.

Total knee arthroplasty alignment targets a mechanical axis within 3 degrees of neutral; excessive varus/valgus malalignment increases polyethylene wear and aseptic loosening.

Venous thromboembolism prophylaxis after arthroplasty: aspirin, enoxaparin, or rivaroxaban for 14-35 days; mechanical prophylaxis plus early mobilization.

Periprosthetic fracture around a total hip: Vancouver classification (A trochanteric, B around stem, C distal to stem); B1 stable stem, B2 loose stem, B3 poor bone stock.

Cervical spine clearance: NEXUS criteria (no midline tenderness, no neuro deficit, normal alertness, no intoxication, no distracting injury) or Canadian C-Spine Rule; otherwise CT.

Spinal cord injury: ASIA impairment scale A (complete) to E (normal); methylprednisolone is not routinely recommended per current guidelines.

Neurogenic shock: hypotension with bradycardia after cord injury above T6; treat with fluids, vasopressors, and atropine for bradycardia.

Spinal shock: transient loss of all reflexes and flaccid paralysis below the lesion, resolving over days to weeks; distinguish from neurogenic shock.

Thoracolumbar trauma: TLICS score (morphology, posterior ligamentous complex integrity, neurologic status); score >4 generally favors surgery.

Cauda equina syndrome: saddle anesthesia, urinary retention, bilateral leg weakness; a surgical emergency requiring urgent decompression, ideally within 24-48 hours.

Lumbar disc herniation: the L4-L5 and L5-S1 levels are most common; a paracentral herniation compresses the traversing nerve root (L5 at L4-L5), a far-lateral herniation compresses the exiting root.

Scoliosis: adolescent idiopathic curves >25 degrees may need bracing, >45-50 degrees surgical fusion; the Cobb angle is measured on the standing PA radiograph.

Developmental dysplasia of the hip: Ortolani (reduces a dislocated hip) and Barlow (dislocates a reduced hip) tests in neonates; Pavlik harness for infants under 6 months; ultrasound screening is preferred before ossification of the femoral head.

Legg-Calve-Perthes disease: avascular necrosis of the femoral head in children 4-8 years; containment treatment with abduction bracing or osteotomy; poor prognosis with lateral pillar involvement.

Slipped capital femoral epiphysis: obese adolescent with groin or knee pain and external rotation deformity; in situ pinning; risk of avascular necrosis and chondrolysis.

Clubfoot (talipes equinovarus): Ponseti method with serial manipulation and casting, percutaneous Achilles tenotomy, then foot abduction orthosis; avoid extensive surgery.

Osteogenesis imperfecta: type I collagen defect, blue sclerae, recurrent fractures; bisphosphonates reduce fracture rate; avoid intramedullary rodding in mild cases.

Physeal fractures: Salter-Harris I through V (SALTER: Slipped, Above, Lower, Through, Crush); types III-V risk growth arrest; type I often needs only cast immobilization.

Pediatric supracondylar humerus fracture: Gartland classification; type III is displaced and needs closed reduction and percutaneous pinning; watch for cubitus varus and compartment syndrome.

Achondroplasia: fibroblast growth factor receptor 3 (FGFR3) mutation; rhizomelic short stature, frontal bossing, foramen magnum stenosis, and spinal stenosis; growth hormone and limb lengthening are options.

Anterior cruciate ligament: the ACL prevents anterior tibial translation and rotational instability; the Lachman test is most sensitive; reconstruction uses bone-patellar tendon-bone or hamstring autograft.

Meniscus: the medial meniscus is more commonly torn; a red-red zone tear has blood supply and may heal; a bucket-handle tear causes a locked knee and needs arthroscopic repair.

Rotator cuff: supraspinatus is the most commonly torn tendon; the Neer and Hawkins tests are used; acute full-thickness tears in young patients are repaired, degenerative tears may be managed with physiotherapy.

Shoulder instability: anterior dislocation is most common; the Bankart lesion is detachment of the labrum, the Hill-Sachs lesion is a posterolateral humeral head defect; recurrent instability may need a Latarjet procedure.

Achilles tendon rupture: positive Thompson test, palpable gap, plantar flexion weakness; treat with functional bracing or surgical repair; the watershed area is 2-6 cm above the calcaneus.

Ankle sprain: the anterior talofibular ligament is the most commonly injured; the anterior drawer test assesses it; lateral ligament complex includes ATFL, CFL, and PTFL.

Patellofemoral pain: assess the Q angle and J sign; treatment is quadriceps and gluteal strengthening; lateral release is reserved for lateral patellar compression syndrome.

Hamstring strain: the biceps femoris is most commonly affected; return to sport after pain-free full strength and eccentric loading; recurrence risk is high if returned early.

Carpal tunnel syndrome: median nerve compression under the transverse carpal ligament; night pain, thenar atrophy, positive Phalen and Tinel tests; release the flexor retinaculum.

Guyon canal: ulnar nerve compression at the wrist; causes intrinsic wasting and clawing; the canal is between the pisiform and the hook of hamate.

Scaphoid fracture: the proximal pole has retrograde blood supply and the highest risk of avascular necrosis; tenderness in the anatomic snuffbox; immobilize with a thumb spica cast.

Kienbock disease: avascular necrosis of the lunate; risk factor is ulna minus variance; treatment options include radial shortening or lunate decompression.

Dupuytren contracture: palmar fascia fibrosis, common in northern European ancestry and diabetes; nodules and cords, most often the ring and little fingers; treat with fasciectomy or collagenase injection.

De Quervain tenosynovitis: first dorsal compartment (abductor pollicis longus and extensor pollicis brevis); positive Finkelstein test; treat with splint, steroid injection, or release.

Flexor tendon zones: zone II (no man's land) has the worst prognosis due to the flexor sheath; use the modified Kessler core suture with epitendinous repair and early protected motion.

Nerve repair: primary repair within 72 hours for clean lacerations; nerve gap >2-3 cm may need a graft; the sural nerve is a common donor; Tinel sign advances with regeneration at ~1 mm/day.

Ankle fracture: the Lauge-Hansen classification describes injury mechanism; the Danis-Weber classification is by fibular fracture level relative to the syndesmosis (A below, B at, C above).

Syndesmotic injury: the external rotation stress test and the squeeze test; a widened tibiofibular clear space >5 mm on mortise view; treat with a syndesmotic screw or tightrope.

Achilles tendon: the most commonly ruptured tendon; the Thompson test; avoid steroid injections near the tendon due to rupture risk.

Plantar fasciitis: medial heel pain worse with first steps; the windlass test; treat with stretching, orthotics, and night splints; surgery is rare.

Hallux valgus: first metatarsal varus and hallux pronation; the intermetatarsal angle and hallux valgus angle measured on weight-bearing radiographs; bunionectomy with osteotomy for symptomatic cases.

Tarsal coalition: a calcaneonavicular or talocalcaneal fibrous/cartilaginous bar causing rigid flatfoot in adolescents; a CT or MRI confirms; resection or fusion.

Charcot arthropathy: neuropathic (diabetes) midfoot collapse; the 6 Ds (destruction, density, debris, dislocation, distension, disorganization); treat with a total contact cast and offloading.

Lisfranc injury: tarsometatarsal fracture-dislocation; the fleck sign on radiographs; weight-bearing radiographs may be needed; treatment is anatomic reduction and fixation.

Osteosarcoma: bimodal age, metaphysis of the distal femur or proximal tibia, sunburst periosteal reaction and Codman triangle; treat with neoadjuvant chemotherapy and limb-salvage resection.

Ewing sarcoma: a small round blue cell tumor in children and adolescents, diaphysis of long bones, onion-skin periosteal reaction; t(11;22) EWS-FLI1 translocation; chemotherapy plus surgery.

Giant cell tumor: epiphysis of long bones after skeletal maturity, soap-bubble lytic lesion; treat with curettage and bone cement; denosumab is an option for recurrent or unresectable cases.

Osteochondroma: the most common benign bone tumor; a cartilage-capped bony outgrowth at the metaphysis, continuous with the cortex; multiple lesions suggest multiple hereditary exostoses.

Bone metastases: the prostate, breast, and lung are the most common primary sites; lytic lesions (lung, kidney, thyroid) vs blastic (prostate, breast); bisphosphonates or denosumab reduce skeletal-related events.

Osteoporosis: T-score <= -2.5 on DXA; the FRAX tool estimates 10-year fracture risk; treat with bisphosphonates, denosumab, or anabolic agents (teriparatide, romosozumab).

Paget disease: increased osteoclast then osteoblast activity, mosaic pattern of lamellar bone, elevated alkaline phosphatase, bone deformity and pain; treat with bisphosphonates.

Osteomyelitis: acute hematogenous in children (Staphylococcus aureus), contiguous spread in adults; MRI is most sensitive; treat with prolonged antibiotics and debridement; chronic disease may need sequestrectomy.

Septic arthritis: an emergency; joint aspiration with Gram stain and culture; Staphylococcus aureus is the most common organism; treat with IV antibiotics and urgent drainage.

Periprosthetic joint infection: acute (<3 weeks) may be treated with debridement, antibiotics, and implant retention (DAIR); chronic infection needs a two-stage exchange.

Biofilm: bacteria adhere to implants and secrete an extracellular matrix; biofilm bacteria are up to 1000 times more resistant to antibiotics; rifampicin is added for staphylococcal biofilm infections.

Osteomyelitis classification: Cierny-Mader (medullary, superficial, localized, diffuse) combined with host status (A, B, C); treatment depends on both.

Necrotizing fasciitis: a surgical emergency; pain out of proportion, rapidly spreading erythema, crepitus, and systemic toxicity; treat with urgent debridement and broad-spectrum antibiotics.

Gas gangrene: Clostridium perfringens; crepitus, myonecrosis, and gas on radiographs; treat with high-dose penicillin and debridement; hyperbaric oxygen is adjunctive.

Post-traumatic osteomyelitis: the most common organism is Staphylococcus aureus; obtain deep tissue cultures, not superficial swabs; remove infected hardware when possible.

Surgical site infection prevention: preoperative chlorhexidine skin preparation, normothermia, glycemic control, and avoidance of shaving; antibiotic prophylaxis within 60 minutes of incision.

Amputation levels: transtibial preserves the knee and saves energy; transfemoral needs more energy; the energy cost of walking rises with proximal amputation.

Prosthetic knee components: single-axis, polycentric, and microprocessor knees; microprocessor knees improve stability and reduce falls but need regular charging.

Transtibial socket designs: patellar tendon-bearing (PTB) and total surface-bearing (TSB); the patellar tendon is a pressure-tolerant area, while the fibular head and tibial crest are pressure-sensitive.

Orthotic principles: three-point pressure systems correct deformity; a Milwaukee brace treats thoracic scoliosis, a Boston brace treats thoracolumbar curves.

Above-knee prosthesis: ischial containment socket; the ischial tuberosity bears weight; the knee joint axis should align with the anatomical knee.

Rehabilitation after total knee arthroplasty: early mobilization, quadriceps strengthening, and range-of-motion exercises; aim for full extension and 90-120 degrees of flexion.

Spinal cord injury rehabilitation: functional goals depend on the level; C6 patients can feed with adaptive equipment; T10 patients can ambulate with orthoses.

Cardiopulmonary rehabilitation: exercise prescription uses the FITT principle (frequency, intensity, time, type); monitor heart rate and rate of perceived exertion.

Informed consent: must include diagnosis, nature of the procedure, risks, benefits, alternatives, and consequences of refusal; the patient must have capacity and be free of coercion.

Confidentiality: patient information is shared only with consent or when required by law; exceptions include communicable disease reporting and imminent harm.

Medical error disclosure: disclose harmful errors to the patient, apologize, explain, and document; this is an ethical and professional obligation.

Research ethics: the Declaration of Helsinki governs human subjects research; institutional review board (IRB) approval is required before data collection; informed consent is mandatory.

Levels of evidence: level I is a systematic review of randomized controlled trials; level V is expert opinion or case report; the hierarchy guides clinical decisions.

Study designs: randomized controlled trials minimize confounding; cohort studies measure incidence and relative risk; case-control studies estimate odds ratios for rare outcomes.

Sensitivity and specificity: sensitivity is the proportion of true positives detected; specificity is the proportion of true negatives; positive predictive value depends on prevalence.

Patient safety: the WHO surgical safety checklist includes sign-in, time-out, and sign-out; wrong-site surgery prevention uses marking and verification protocols.