Orthopedic Review | Dr Hutaif General Orthopedics Revie -...

According to Perren's strain theory, what is the maximum strain tolerated by lamellar bone formation during secondary fracture healing?

In the context of Damage Control Orthopedics (DCO), which of the following criteria best classifies a polytrauma patient as 'borderline' according to the Pape/Hannover classification?

A 14-year-old boy presents with a painful, swollen thigh. Radiographs show a permeative diaphyseal lesion with an 'onion skin' periosteal reaction. Biopsy reveals sheets of small blue round cells. Which chromosomal translocation is most commonly associated with this pathology?

A 4-month-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the infant exhibits decreased spontaneous extension of the knee on the treated side. What is the most likely cause?

In total hip arthroplasty, highly cross-linked polyethylene (HXLPE) is used to decrease wear rates. Irradiation used to create these cross-links also generates free radicals. Which manufacturing process is primarily used to eliminate these free radicals and prevent in vivo oxidation?

A 65-year-old man presents with deteriorating handwriting, difficulty manipulating small objects, and frequent tripping. Examination reveals a positive Hoffmann's sign and sustained ankle clonus. An MRI confirms severe cervical spondylotic myelopathy. Which of the following physical examination findings is also most likely to be present?

The anterior cruciate ligament (ACL) consists of two distinct functional bundles. Which of the following statements correctly describes the primary tension patterns of these bundles during knee range of motion?

A 32-year-old man sustains a closed high-energy tibial shaft fracture. Two hours post-injury, he complains of severe leg pain out of proportion. Intracompartmental pressure monitoring is performed. According to current literature, which parameter is the most reliable threshold for diagnosing acute compartment syndrome and indicating fasciotomy?

In normal articular cartilage, which zone contains the highest concentration of proteoglycans and chondrocytes arranged in vertical columns?

The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is used to distinguish necrotizing fasciitis from severe cellulitis or abscess. Which of the following laboratory values is a specific component of the LRINEC score?

A 25-year-old carpenter sustains a volar laceration to his right index finger exactly at the level of the proximal interphalangeal (PIP) joint. Both the FDS and FDP tendons are transected. According to the Verdan classification, which flexor tendon zone is injured?

A 55-year-old woman with a history of gastric bypass surgery presents with bilateral groin pain. Radiographs reveal bilateral Looser zones in the femoral necks. Laboratory evaluation for her underlying metabolic bone disease will most likely show which of the following profiles?

A 40-year-old pedestrian is struck by a vehicle. Pelvic radiographs demonstrate a symphysis pubis diastasis of 3.5 cm and a widened anterior sacroiliac joint, but intact posterior sacroiliac ligaments. According to the Young-Burgess classification, what type of pelvic ring injury is this?

When a stainless steel screw is placed through a titanium alloy plate to stabilize a fracture, which mode of corrosion is most likely to occur at the interface due to the dissimilar metals being immersed in tissue fluid?

A 70-year-old woman undergoes a posterior-approach total hip arthroplasty. Six weeks postoperatively, she dislocates her hip posteriorly while bending forward to tie her shoes in a low chair. On reduction, the components are well-fixed. Which technical error during cup placement most likely predisposed her to this specific dislocation?

A 22-year-old man complains of a dull, aching pain in his right tibia that worsens at night and is dramatically relieved by ibuprofen. Radiographs show thickened cortical bone with a small 8mm radiolucent nidus. Which of the following is the most appropriate first-line definitive treatment if conservative management fails?

A 60-year-old diabetic patient presents with a swollen, warm foot. Radiographs show marked periarticular fragmentation, subluxation of the tarsometatarsal joints, and considerable bony debris, without signs of consolidation. According to the Eichenholtz classification of Charcot arthropathy, which stage does this represent?

A 12-year-old boy is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is an accepted indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

A 45-year-old woman with severe carpal tunnel syndrome undergoes electromyography (EMG). The physician notes a faster than expected conduction velocity in the median nerve in the forearm, and preservation of some intrinsic hand muscle function despite complete distal median nerve block. This finding is most likely explained by which anomalous neural connection?

A 28-year-old farmer sustains a tibial shaft fracture after his leg is trapped in a soil-tilling machine. The wound is 8 cm long with significant soft tissue stripping, but adequate periosteal coverage of the bone remains. According to the Gustilo-Anderson classification and standard antibiotic guidelines, what is the grade and appropriate initial empiric antibiotic regimen?

During the incorporation of a massive structural cortical bone allograft, what is the primary mechanism of remodeling and its resulting effect on the graft's biomechanical strength over the first year?

A 13-year-old obese male presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) and is unable to bear weight. He is scheduled for in-situ pinning. What is the primary proposed advantage of performing an incidental hip capsulotomy during the surgical fixation of this unstable SCFE?

A 15-year-old female is diagnosed with conventional high-grade osteosarcoma of the distal femur. Her family history is significant for a mother with early-onset breast cancer and a sibling with childhood leukemia. A germline mutation in which of the following tumor suppressor genes is most likely responsible for this presentation?

Which of the following statements most accurately describes the vascular supply to the scaphoid and its clinical implication in the setting of trauma?

A 45-year-old male presents with right arm pain and numbness. Examination reveals a diminished brachioradialis reflex, weakness in wrist extension, and decreased sensation over the dorsal aspect of the thumb and index finger. Which cervical nerve root is most likely compressed?

According to the Eichenholtz classification of Charcot arthropathy, which of the following radiographic findings characterizes the coalescence stage (Stage II)?

During the physical examination of a patient with a suspected anterior cruciate ligament (ACL) tear, a pivot shift test is performed. Which specific biomechanical function of the ACL is this test primarily designed to assess?

A 65-year-old male presents with deep bone pain, increasing hat size, and bowing of the tibiae. Laboratory evaluation shows a markedly elevated alkaline phosphatase with normal serum calcium and phosphorus. Which cellular defect drives the primary initial phase of this disease process?

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, she demonstrates an inability to actively extend the knee on the treated side. Which of the following harness positioning errors is the most likely cause?

In the mechanism of aseptic loosening following total joint arthroplasty, the biologic cascade triggered by polyethylene wear debris is primarily initiated by which of the following cell types phagocytosing the particles?

In a Young-Burgess Anteroposterior Compression II (APC II) pelvic ring injury, which of the following posterior ligamentous structures typically remains intact, distinguishing it from an APC III injury?

A 10-year-old boy presents with pain and swelling in the mid-thigh. Radiographs show a permeative diaphyseal lesion with an 'onion skin' periosteal reaction. Biopsy confirms Ewing sarcoma. Which of the following cytogenetic abnormalities is the diagnostic hallmark of this tumor?

A 70-year-old male with severe lumbar spinal stenosis complains of bilateral neurogenic claudication. He notes significant symptom relief when leaning forward over a shopping cart. What is the primary anatomic explanation for this positional relief?

A 25-year-old rugby player sustained a closed avulsion of the flexor digitorum profundus (FDP) from the distal phalanx of the ring finger (Jersey finger). The tendon has retracted entirely into the palm (Leddy-Packer Type I). What is the maximum recommended timeframe for surgical repair to prevent permanent loss of tendon excursion due to complete loss of vascular supply?

In evaluating a suspected Lisfranc injury, the presence of a 'fleck sign' on an anteroposterior (AP) radiograph of the foot is highly suggestive of a major ligamentous avulsion. The primary Lisfranc ligament connects which two osseous structures?

The Herring lateral pillar classification is used to predict the prognosis in Legg-Calvé-Perthes disease. This classification relies on assessing the height of the lateral pillar on an AP pelvic radiograph. During which stage of the disease must this assessment be made for it to be prognostically valid?

According to Sunderland's classification of peripheral nerve injuries, a third-degree nerve injury represents disruption of which of the following microanatomical structures?

A 55-year-old patient who underwent total hip arthroplasty with a ceramic-on-ceramic bearing surface two years ago now complains of a loud, audible squeaking sound from the hip during normal walking. Which of the following biomechanical factors is most strongly associated with the initiation of this phenomenon?

A 30-year-old male sustains a closed, high-energy tibial shaft fracture and complains of unremitting pain out of proportion to his injury. His blood pressure is 130/80 mmHg. Compartment pressures are measured. Which of the following values provides the most reliable threshold for diagnosing acute compartment syndrome and indicating urgent fasciotomy?

In the evaluation of anterior shoulder instability, the concept of the 'glenoid track' is used to determine surgical management. A Hill-Sachs lesion is designated as 'off-track' when which of the following conditions is met?

In applying a locking compression plate (LCP) for a diaphyseal fracture, what is the primary biomechanical advantage compared to a conventional non-locking plate?

Demineralized bone matrix (DBM) is commonly used as a bone graft substitute in orthopedic surgery. Which of the following best describes its biological properties?

A 2-year-old child presents with progressive bowing of the lower extremities. Laboratory findings show normal serum calcium, markedly decreased serum phosphate, and elevated alkaline phosphatase. Genetic testing reveals a mutation in the PHEX gene. What is the most appropriate medical treatment?

In normal adult articular cartilage, which zone contains the highest concentration of proteoglycans and is primarily responsible for resisting compressive forces?

Staphylococcus epidermidis is a frequent cause of prosthetic joint infections. Which of the following molecules primarily mediates the accumulation phase and the structural integrity of its biofilm?

A 62-year-old female with a history of breast cancer presents with severe thigh pain. Radiographs reveal a purely lytic lesion in the subtrochanteric femur that occupies greater than 2/3 of the bone's cortical diameter. She describes the pain as worsening with weight-bearing. According to Mirels' criteria, what score does this lesion receive based solely on its size and radiographic appearance?

A 6-year-old boy with normal intelligence presents with short trunk dwarfism, knock knees, and a barrel chest. Urine analysis shows elevated levels of keratan sulfate. Radiographs of the cervical spine are most likely to demonstrate which of the following abnormalities?

According to Perren's strain theory of bone healing, what is the maximum strain environment that allows for the formation of lamellar bone across a fracture gap?

A new diagnostic test for a rare orthopedic condition has a sensitivity of 90% and a specificity of 90%. If the prevalence of the condition in the tested population is 1%, what is the approximate positive predictive value (PPV) of the test?

In total joint arthroplasty, the phenomenon where microscopic asperities on the surface of an implant cold-weld together and are subsequently torn away during continuous motion is classified as which type of wear?

A 25-year-old male is involved in a severe motor vehicle accident and sustains a burst fracture of T10 with paraplegia. He has flaccid lower extremities, areflexia, and a heart rate of 55 bpm with a blood pressure of 85/50 mmHg. The bulbocavernosus reflex is absent. The resolution of spinal shock in this patient is best indicated clinically by the return of which of the following?

The kinetic energy transferred to tissues by a ballistic projectile is mathematically related to the mass of the bullet and its velocity. If the velocity of a bullet is doubled while the mass remains constant, the kinetic energy transferred increases by a factor of:

A 15-year-old male presents with a mass in his distal femur. Radiographs show a sclerotic, destructive lesion with a Codman triangle. Biopsy confirms conventional osteosarcoma. Which of the following genetic alterations is most frequently associated with the pathogenesis of this tumor?

During the post-operative rehabilitation of a flexor tendon repair in the hand, which phase of tendon healing is characterized by the highest risk of iatrogenic rupture due to a marked decrease in tensile strength?

During normal human gait, the center of gravity undergoes sinusoidal vertical displacements. Which of the following mechanisms (a primary determinant of gait) acts during midstance to minimize the maximum vertical height of the center of gravity, thereby reducing energy expenditure?

A 4-month-old female is evaluated for asymmetric thigh folds. Ultrasound of the hip reveals an alpha angle of 40 degrees and a beta angle of 80 degrees. According to the Graf classification for Developmental Dysplasia of the Hip (DDH), what is the appropriate interpretation and recommended next step?

Rivaroxaban is an oral anticoagulant commonly prescribed for deep vein thrombosis prophylaxis following total joint arthroplasty. What is its specific mechanism of action within the coagulation cascade?

A 24-year-old male sustains bilateral closed femoral shaft fractures. Thirty-six hours after admission, he develops confusion, a petechial rash over his axillae, and dyspnea. Which of the following is considered a 'major criterion' for the diagnosis of Fat Embolism Syndrome according to Gurd and Wilson's criteria?

According to the Sunderland classification of peripheral nerve injuries, which of the following best characterizes a third-degree nerve injury?

When evaluating the orthopedic literature regarding a novel surgical technique, which of the following study designs provides the highest level of evidence (Level I)?

Bone morphogenetic proteins (BMPs) are extensively used in orthopedics for their osteoinductive properties. Which of the following best describes the intracellular signaling pathway activated directly upon BMP binding to its cell surface receptor?

A 28-year-old male polytrauma patient is intubated in the ICU after a motor vehicle accident. He has a comminuted tibia fracture. The nursing staff notes a tense calf. Which of the following criteria is the most reliable threshold for diagnosing acute compartment syndrome and proceeding with fasciotomy in this obtunded patient?

A 16-year-old female undergoes neoadjuvant chemotherapy followed by wide surgical resection of a high-grade intramedullary osteosarcoma of the distal femur. Which of the following findings from the surgical pathology report is the most significant prognostic factor for her overall survival?

Highly cross-linked polyethylene (HXLPE) was introduced in total hip arthroplasty to reduce osteolysis secondary to wear debris. Which of the following is a known adverse biomechanical consequence of increasing the radiation dose to maximize polyethylene cross-linking?

A 12-year-old obese boy undergoes in-situ percutaneous single screw fixation for a stable slipped capital femoral epiphysis (SCFE). Which of the following screw positions on fluoroscopy places the hip at the highest risk for unrecognized joint penetration and subsequent chondrolysis?

During a posterior approach to the hip for total hip arthroplasty, the preservation or meticulous repair of which of the following structures has been shown in the literature to be most critical in minimizing the risk of postoperative posterior dislocation?

Articular cartilage relies on a specific structural organization to resist load and shear forces. Which collagen type provides the primary tensile strength of articular cartilage, and in which histologic zone is it found in the highest concentration?

According to the Young-Burgess classification system for pelvic ring fractures, an Anteroposterior Compression Type III (APC-III) injury is characterized by complete pelvic instability. This requires the disruption of the anterior ring as well as which of the following ligamentous structures?

A 65-year-old female with long-standing rheumatoid arthritis presents with progressive hand clumsiness and hyperreflexia. Cervical radiographs reveal atlantoaxial subluxation. Which of the following radiographic parameters is the most critical indicator of impending neurologic deterioration and the need for surgical stabilization?

A 3-year-old unimmunized child presents with a swollen, erythematous knee and a fever of 39°C. Arthrocentesis yields cloudy fluid with a WBC count of 85,000 cells/µL. Gram stain reveals Gram-negative coccobacilli. Which of the following is the most likely causative organism, and what is the optimal empiric antibiotic therapy?

A 45-year-old male undergoes tendon lengthening. Which viscoelastic property describes the continuous increase in length of the tendon over time under a constant load?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is approved for use in anterior lumbar interbody fusion (ALIF). What is the FDA-approved carrier for rhBMP-2 in this procedure?

A 30-year-old male sustains a closed tibial shaft fracture. He complains of severe pain out of proportion to the injury. Which measurement best confirms the diagnosis of acute compartment syndrome?

A 25-year-old male is involved in a high-speed motor vehicle collision and sustains an APC-II pelvic ring injury. What is the primary anatomic structure disrupted that defines this specific injury pattern?

A 35-year-old female presents with a lytic epiphyseal lesion of the distal femur. Biopsy confirms a Giant Cell Tumor (GCT) of bone. If medical therapy is initiated, which molecular pathway is targeted by the drug of choice?

A 12-year-old obese male presents with an acute-on-chronic Slipped Capital Femoral Epiphysis (SCFE). Which of the following is considered an absolute indication for prophylactic pinning of the contralateral asymptomatic hip?

A 50-year-old active male undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing. Which of the following is the most notable disadvantage or complication specific to this bearing surface?

In evaluating a patient with suspected cervical spondylotic myelopathy, the examiner flicks the distal phalanx of the middle finger, resulting in reflex flexion of the thumb and index finger. What is the name of this clinical sign?

A 45-year-old female sustains a posterior medial meniscus root tear. Biomechanically, this injury is most equivalent to which of the following?

A 22-year-old male sustains a displaced proximal pole scaphoid fracture. The risk of avascular necrosis is extremely high due to the scaphoid's retrograde blood supply. Which artery provides the primary blood supply to the proximal pole?

In a suspected Lisfranc injury, which radiographic finding is considered pathognomonic (the "Fleck sign") for avulsion of the Lisfranc ligament?

Articular cartilage is highly specialized to resist compressive forces. In which zone of articular cartilage are the type II collagen fibers oriented perpendicular to the joint surface?

A 24-year-old male with bilateral femur fractures develops hypoxemia, altered mental status, and a petechial rash 48 hours after admission. Which of the following is considered a major criterion for Fat Embolism Syndrome according to Gurd and Wilson?

During a posterior-stabilized total knee arthroplasty (PS-TKA), the cam-post mechanism is designed to substitute for which resected structure?

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). Hyperflexion of the hips in the harness puts the patient at highest risk for which complication?

A 60-year-old male presents with a large, painful, destructive lesion in his proximal humerus. Biopsy shows atypical chondrocytes with endosteal scalloping and cortical destruction. What is the primary treatment modality for conventional high-grade chondrosarcoma?

A 68-year-old male presents with bilateral leg pain that worsens with walking and improves when leaning forward on a shopping cart. He is diagnosed with lumbar spinal stenosis. What pathomechanism primarily explains the relief of symptoms when flexing the spine?

In bone-patellar tendon-bone (BTB) ACL reconstruction, which phase of graft healing is characterized by peak fibroblast proliferation and the beginning of collagen remodeling, but marks the weakest point of the graft?

A 30-year-old carpenter lacerates his flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons in "Zone II" of his index finger. Why is this region classically referred to as "no man's land"?

Which type of bone healing occurs under conditions of absolute stability, such as following rigid compression plating of a simple transverse radius fracture?

A hamstring graft used for anterior cruciate ligament reconstruction is subjected to a constant physiological load over time, resulting in a gradual, time-dependent increase in deformation. Which of the following viscoelastic properties does this describe?

A 28-year-old male presents with a slow-growing, painful mass near his knee joint. MRI shows a soft tissue mass with heterogeneous signal intensity. Biopsy confirms a biphasic spindle cell neoplasm. Which chromosomal translocation is most characteristic of this tumor?

A 4-year-old boy presents with profound bowing of the lower extremities and a waddling gait. Laboratory studies reveal normal serum calcium, significantly decreased serum phosphate, elevated alkaline phosphatase, and normal parathyroid hormone levels. What is the most likely genetic mutation responsible for this condition?

When utilizing an uncemented total hip arthroplasty, the surgeon aims to achieve initial mechanical stability to promote osseointegration. What is the commonly accepted maximum threshold of micromotion at the bone-implant interface beyond which fibrous tissue formation predictably occurs instead of bone ingrowth?

Tranexamic acid (TXA) is frequently utilized in orthopedic trauma and arthroplasty to minimize perioperative blood loss. What is the precise mechanism of action of this medication?

Staphylococcus aureus is a predominant pathogen in periprosthetic joint infections. Which bacterial surface protein plays a critical role in evading the host immune system by binding to the Fc portion of IgG?

A 24-year-old male sustains a closed femoral shaft fracture. Forty-eight hours post-admission, he develops sudden onset tachypnea, confusion, and a petechial rash over his axillae. Which of the following is the most definitive primary prevention strategy for this clinical syndrome?

Which of the following pharmacological agents acts by primarily binding and inhibiting sclerostin, thereby upregulating the Wnt/beta-catenin signaling pathway to dramatically increase osteoblastic bone formation?

During fracture fixation, a surgeon considers combining stainless steel screws with a titanium plate. Why is this combination strictly avoided in orthopedic surgery?

A patient sustains a severe compressive radial nerve injury. According to Sunderland's classification, which grade of nerve injury is characterized by complete disruption of the axon and myelin sheath but complete preservation of the endoneurium, perineurium, and epineurium?