Orthopedic With Answer Sh Review | Dr Hutaif General Or -...

Question 1

A 40-year-old female presents to the trauma bay following a high-speed motor vehicle collision. Pelvic radiographs and CT scans demonstrate a transverse sacral fracture with fracture lines extending transversely across the central sacral canal. According to the Denis classification of sacral fractures, which of the following neurologic deficits is most specifically associated with this injury zone compared to lateral zones?

Explanation

The patient has a Denis Zone III sacral fracture, which involves the central sacral canal. Zone I (alar) fractures are associated with L5 nerve root injuries (foot drop, great toe extension weakness). Zone II (foraminal) fractures commonly present with sciatica-type symptoms (L5, S1, S2). Zone III (central) fractures carry the highest risk of neurologic injury (up to 57%), specifically involving the sacral nerve roots S2-S4, which present as saddle anesthesia and loss of bowel, bladder, or sexual function (loss of voluntary anal sphincter control).

Question 2

During a total hip arthroplasty utilizing the direct anterior approach (DAA), the surgeon develops an internervous plane to access the hip joint capsule. This true internervous plane exists between muscles innervated by which of the following pairs of nerves?

Explanation

The direct anterior approach (Smith-Petersen) to the hip exploits a true internervous plane between the tensor fasciae latae (TFL), innervated by the superior gluteal nerve, and the sartorius, innervated by the femoral nerve. Distally, the plane continues between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve).

Question 3

A 12-year-old obese male presents with left groin and knee pain, and is diagnosed with a slipped capital femoral epiphysis (SCFE). The right hip is completely asymptomatic with normal radiographs. Which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy) are absolute indications for prophylactic contralateral pinning in SCFE due to the extraordinarily high risk (often >50-100%) of developing a bilateral slip. Other relative indications include young age at presentation (<10 years for girls, <12 years for boys) and poor reliability for follow-up, but endocrine etiology remains the classic absolute indication.

Question 4

A 22-year-old collegiate soccer player undergoes anterior cruciate ligament (ACL) reconstruction using a doubled semitendinosus and gracilis (hamstring) autograft. Compared to bone-patellar tendon-bone (BPTB) autografts, hamstring autografts are associated with a higher incidence of which of the following long-term post-operative outcomes?

Explanation

Hamstring autograft harvesting inevitably leads to a selective deficit in deep knee flexion strength and internal tibial rotation strength, particularly past 90 degrees of flexion. BPTB autografts are more commonly associated with anterior knee pain, patellar fractures, and pain while kneeling.

Question 5

A 25-year-old male is evaluated for worsening leg pain following a closed tibial shaft fracture sustained in a fall. He requires increasing doses of opioids. Examination reveals tense compartments and pain with passive toe extension. Which of the following pressure measurements is the most widely accepted and accurate threshold for diagnosing acute compartment syndrome and indicating a four-compartment fasciotomy?

Explanation

The most widely accepted threshold for fasciotomy in acute compartment syndrome is a delta pressure (Diastolic Blood Pressure minus Intracompartmental Pressure) of less than 30 mmHg. Relying on an absolute pressure threshold (e.g., > 30 mmHg) can lead to unnecessary fasciotomies, especially in hypertensive patients, whereas delta pressure accounts for the perfusion gradient necessary to maintain tissue viability.

Question 6

During the repair of a complete flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) laceration in Zone II of the hand, preserving or reconstructing specific pulleys is vital to prevent bowstringing. Which pulley is biomechanically the most critical to preserve over the proximal phalanx?

Explanation

The A2 and A4 pulleys are the most critical biomechanically to prevent bowstringing of the flexor tendons and ensure appropriate tendon excursion. The A2 pulley is located over the proximal half of the proximal phalanx, while the A4 pulley is located over the middle phalanx.

Question 7

A 45-year-old female undergoes open reduction and internal fixation of a transverse midshaft radius fracture. The surgeon utilizes absolute stability by applying a dynamic compression plate (DCP). Under these highly stable biomechanical conditions, bone healing occurs primarily via which of the following biological processes?

Explanation

Absolute stability (rigid fixation with compression) abolishes interfragmentary strain and completely suppresses callus formation. Bone healing under absolute stability occurs via primary bone healing, which relies on intramembranous ossification and direct remodeling by osteoclastic cutting cones followed by osteoblastic bone deposition. Endochondral ossification (callus formation) is seen with relative stability constructs (e.g., IM nails, external fixators, bridge plating).

Question 8

A 65-year-old male presents with deteriorating handwriting, dropping objects, and an unsteady, broad-based gait. Physical examination reveals a positive Hoffmann sign and an inverted brachioradialis reflex. MRI of the cervical spine shows severe central canal stenosis at the C5-C6 level. On motor examination, which of the following deficits is most likely to be observed due to specific nerve root compression at this level?

Explanation

The patient has cervical spondylotic myelopathy. The C5-C6 intervertebral disc level corresponds to the exiting C6 nerve root. The C6 nerve root innervates the wrist extensors (extensor carpi radialis longus and brevis) and contributes to elbow flexion (biceps, brachialis). Weakness in elbow extension would be C7 (C6-C7 level). Shoulder abduction is C5. Finger abduction is T1. Thumb IP joint flexion is C8.

Question 9

A 28-year-old male sustains a severe hyperplantarflexion injury to his foot. Radiographs demonstrate widening between the base of the first and second metatarsals. An MRI confirms a complete rupture of the Lisfranc ligament. Anatomically, the Lisfranc ligament originates from which structure and inserts onto which structure?

Explanation

The Lisfranc ligament is a strong interosseous ligament that runs obliquely from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the primary stabilizer of the tarsometatarsal joint complex, as there is no transverse ligament connecting the bases of the first and second metatarsals.

Question 10

A 14-year-old boy presents with progressive knee pain. Plain radiographs reveal an aggressive, ill-defined metaphyseal radiolucent lesion in the distal femur with a 'sunburst' periosteal reaction and a Codman's triangle. A core needle biopsy is obtained. Which of the following histological descriptions is the hallmark finding for the most likely diagnosis?

Explanation

The clinical and radiographic presentation (metaphyseal lesion, sunburst periosteal reaction, Codman's triangle in a teenager) is classic for osteosarcoma. The defining histological hallmark of osteosarcoma is the production of malignant osteoid by atypical, malignant spindle-shaped mesenchymal cells. Option A describes Ewing sarcoma. Option C describes Giant Cell Tumor. Option D describes an Osteochondroma. Option E describes a Chondroblastoma.

Question 11

A 72-year-old female presents with a painful right total knee arthroplasty, 3 years post-operatively. According to the 2018 International Consensus Meeting (ICM) criteria for Periprosthetic Joint Infection (PJI), which of the following is considered a 'Major Criterion' definitively diagnostic of a PJI?

Explanation

According to the 2018 ICM criteria, the Major Criteria for diagnosing PJI (either one is definitively diagnostic) are: 1) Two positive periprosthetic cultures with phenotypically identical organisms, or 2) A sinus tract communicating with the joint. All other options (leukocyte esterase, synovial WBC count, alpha-defensin, serum CRP/D-dimer) are minor criteria used in the scoring system.

Question 12

In the evolution of bearing surfaces for total hip arthroplasty, ultra-high-molecular-weight polyethylene (UHMWPE) is often subjected to gamma irradiation to induce high degrees of cross-linking, followed by a thermal treatment (remelting or annealing). Highly cross-linking the polyethylene results in which of the following mechanical trade-offs?

Explanation

Highly cross-linked polyethylene (HXLPE) was developed to significantly decrease the volumetric wear rate, thereby reducing osteolysis and aseptic loosening. However, the cross-linking process alters the mechanical properties of the material, leading to a decrease in ultimate tensile strength, fatigue resistance, and fracture toughness. This makes HXLPE more susceptible to fatigue-related mechanical failure, such as rim fracture, though its wear properties are vastly superior to conventional UHMWPE.

Question 13

A 24-year-old male falls onto an outstretched hand and sustains a minimally displaced fracture through the proximal third of the scaphoid. The proximal pole is highly susceptible to avascular necrosis due to its tenuous blood supply. The primary blood supply to the proximal pole of the scaphoid originates from branches of the radial artery that enter the bone at which specific anatomical location?

Explanation

The blood supply to the scaphoid is retrograde. Branches of the radial artery enter the scaphoid predominantly at the dorsal ridge, which is located on the non-articular dorsal surface at the level of the scaphoid waist/distal pole. From there, the intraosseous vessels travel proximally to supply the proximal pole. Thus, proximal pole fractures interrupt this retrograde supply, leading to a high risk of avascular necrosis.

Question 14

A 4-month-old female is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up examination, the orthopedist notes that the harness straps are excessively tightened in the anterior aspect, placing the hips in extreme hyperflexion. This specific positioning error puts the child at highest risk for which of the following complications?

Explanation

In Pavlik harness treatment for DDH, hyperflexion of the hips (>120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy (manifesting as loss of active knee extension). Conversely, excessive forced abduction places the patient at highest risk for avascular necrosis (AVN) of the femoral head due to compression of the medial circumflex femoral artery.

Question 15

In the evaluation of recurrent anterior shoulder instability, the 'glenoid track' concept is utilized to determine if a Hill-Sachs lesion is engaging. By definition, a Hill-Sachs lesion is considered 'off-track' (engaging) if its medial margin extends medial to the glenoid track. In a patient with an intact anterior glenoid rim (no bony Bankart), the width of the glenoid track is calculated as approximately what percentage of the native anterior-posterior glenoid width?

Explanation

The glenoid track is defined as the contact zone between the glenoid and the humeral head when the arm is in abduction and external rotation. In a normal shoulder without anterior bone loss, the width of the glenoid track is approximately 83% of the anterior-posterior width of the native glenoid. If there is an anterior glenoid bone defect, the track width is reduced by the width of that defect (83% of native width minus the defect width).

Question 16

A 15-year-old female gymnast presents with insidious onset of mechanical low back pain. Standing lateral radiographs reveal a Grade 2 L5-S1 spondylolisthesis. According to the Wiltse classification of spondylolisthesis, this patient most likely has a Type II slip. What is the primary underlying anatomic pathomechanism for a Wiltse Type II spondylolisthesis?

Explanation

The Wiltse classification categorizes spondylolisthesis by etiology. Type I is Dysplastic (congenital abnormalities of the upper sacrum or L5 arch). Type II is Isthmic, caused by a defect (often a stress fracture from repetitive hyperextension, classic in gymnasts) in the pars interarticularis. Type III is Degenerative (older adults, intact pars). Type IV is Traumatic (acute fracture of the bony hook other than the pars). Type V is Pathologic (tumor/infection).

Question 17

During a posterior-stabilized (PS) total knee arthroplasty, trial components are inserted. The surgeon evaluates the gap kinematics and notes that the knee is perfectly balanced in full extension, but the joint is exceptionally tight in 90 degrees of flexion, restricting rollback. Assuming the tibial cut is correct, which of the following is the most appropriate surgical step to achieve a balanced flexion-extension gap?

Explanation

A knee that is tight in flexion but balanced in extension requires an isolated increase in the flexion gap. Downsizing the femoral component (when referencing anteriorly) decreases the anterior-posterior dimension of the femoral component by resecting more posterior condylar bone, thus selectively opening and loosening the flexion gap without affecting the extension gap. Resecting more distal femur would open the extension gap. Releasing the posterior capsule affects the extension gap.

Question 18

The Canadian Orthopaedic Trauma Society (COTS) conducted a landmark multicenter randomized clinical trial comparing nonoperative management to open reduction and internal fixation (ORIF) for completely displaced midshaft clavicle fractures. According to the results of this trial, which of the following outcomes was significantly associated with ORIF compared to nonoperative management?

Explanation

The COTS trial for completely displaced midshaft clavicle fractures demonstrated that ORIF significantly decreased the rate of nonunion and symptomatic malunion compared to nonoperative treatment. ORIF also led to faster times to clinical and radiographic union, and improved early functional outcomes, although complication profiles (like hardware prominence requiring removal in ORIF) differed.

Question 19

A 6-year-old boy falls off monkey bars and presents to the emergency department with a Gartland Type III extension-type supracondylar humerus fracture. Radiographs indicate that the distal fracture fragment is severely posterolaterally displaced. Based on this specific displacement pattern, which neurologic structure is at the greatest risk of injury from the proximal fragment?

Explanation

In extension-type supracondylar humerus fractures, the displacement of the distal fragment dictates the location of the sharp proximal fragment. If the distal fragment goes posterolaterally, the proximal fragment is driven anteromedially. This anteromedial spike puts the median nerve (and its anterior interosseous branch) and the brachial artery at highest risk. Conversely, if the distal fragment displaces posteromedially, the proximal fragment goes anterolaterally, risking the radial nerve.

Question 20

Denosumab is an increasingly utilized pharmacological agent in orthopedics, particularly in the management of osteoporosis and as a neoadjuvant therapy for Giant Cell Tumor of Bone (GCTB). At a molecular level, Denosumab exerts its primary effect by acting as a monoclonal antibody that binds directly to which of the following targets?

Explanation

Denosumab is a fully human monoclonal antibody that specifically binds to the Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL). By binding to RANKL, it prevents RANKL from interacting with the RANK receptor on the surface of osteoclasts and osteoclast precursors. This inhibits osteoclast formation, function, and survival, thereby potently decreasing bone resorption.

Question 21

A 30-year-old male undergoes intramedullary nailing of a closed tibial shaft fracture. Six hours postoperatively, he complains of escalating leg pain requiring increasing doses of IV opioids. Which of the following physical examination findings is the most sensitive early clinical indicator of acute compartment syndrome?

Explanation

Pain with passive stretch of the muscles in the affected compartment is the most sensitive and earliest clinical sign of acute compartment syndrome. Loss of pulses and paralysis are late and ominous findings indicating established ischemia.

Question 22

A 25-year-old male presents with a Pauwels type III femoral neck fracture after a fall from a height. Which of the following fixation constructs provides the most biomechanical stability against vertical shear forces for this specific fracture pattern?

Explanation

Pauwels type III fractures have a high shear angle (>50 degrees). Biomechanical studies demonstrate that a sliding hip screw (fixed-angle device) with a derotation screw provides superior resistance to vertical shear compared to cannulated screws.

Question 23

A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture. Following closed reduction and percutaneous pinning in the operating room, the child's hand is warm and pink, but the radial pulse remains absent. What is the most appropriate next step in management?

Explanation

A 'pink, pulseless' hand following stable reduction and pinning of a supracondylar fracture indicates adequate collateral perfusion. Close clinical observation is the standard of care, as the pulse often returns within a few days as vasospasm resolves.

Question 24

A 22-year-old collegiate soccer player undergoes anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BTB) autograft. Which of the following is the most commonly reported long-term complication specific to this graft choice?

Explanation

Anterior knee pain (donor site morbidity) is the most common complication following BTB autograft ACL reconstruction. Patellar fracture and tendon rupture are severe but rare complications.

Question 25

A 28-year-old male with a closed tibial shaft fracture develops severe leg pain. His resting diastolic blood pressure is 70 mmHg. Intracompartmental pressure is measured. Which of the following pressure criteria is most reliable for diagnosing acute compartment syndrome?

Explanation

The Delta P (diastolic blood pressure minus intracompartmental pressure) is the most reliable indicator for acute compartment syndrome. A Delta P of less than 30 mmHg is the standard threshold indicating the need for emergent fasciotomy.

Question 26

During arthroscopy, articular cartilage is evaluated. The superficial zone of articular cartilage is primarily designed to resist shear forces. Which of the following best describes the collagen fiber orientation and chondrocyte morphology in this superficial zone?

Explanation

In the superficial zone of articular cartilage, collagen fibers are oriented parallel to the joint surface to resist shear forces. The chondrocytes in this layer are flattened and elongated.

Question 27

A 6-week-old female infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notes the infant has stopped kicking her left leg. Examination reveals decreased active knee extension on the left. What is the most appropriate next step in management?

Explanation

The infant has developed a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The most appropriate management is to temporarily discontinue the harness until neurologic function returns.

Question 28

During a primary total knee arthroplasty, the surgeon assesses the gaps with trial components. The knee is balanced in extension but is too tight in flexion. Which of the following is the most appropriate surgical step to correct this mismatch?

Explanation

A tight flexion gap with a balanced extension gap can be addressed by increasing the posterior tibial slope, which opens the flexion gap without affecting the extension gap. Recessing the PCL or downsizing the femoral component are alternative options.

Question 29

A 22-year-old male presents with a scaphoid waist fracture. He is counseled on the risk of avascular necrosis (AVN). The major blood supply to the proximal pole of the scaphoid is derived from vessels entering at which of the following locations?

Explanation

The primary blood supply to the scaphoid comes from the dorsal carpal branch of the radial artery. It enters the scaphoid at the dorsal ridge (distal to the waist) and flows retrogradely to the proximal pole.

Question 30

A 68-year-old male presents with bilateral lower extremity radicular pain that worsens with walking. He notes relief when leaning forward on a shopping cart. Which of the following anatomical changes dynamically increases the cross-sectional area of the spinal canal and neural foramina in this position?

Explanation

Flexion of the lumbar spine causes the ligamentum flavum to stretch and "unbuckle." This increases the cross-sectional area of the spinal canal and neural foramina, relieving symptoms of neurogenic claudication.

Question 31

A 25-year-old athlete undergoes an anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BTB) autograft. Compared to a hamstring autograft, which of the following is an established complication more frequently associated with BTB autografts?

Explanation

Bone-patellar tendon-bone (BTB) autografts are associated with a higher incidence of anterior knee pain and kneeling pain compared to hamstring autografts. Both grafts offer excellent long-term stability and comparable rupture rates.

Question 32

A 30-year-old male sustains a high-energy midfoot injury. Radiographs reveal a fleck sign at the base of the second metatarsal. The Lisfranc ligament originates from the medial cuneiform and inserts onto which of the following structures?

Explanation

The Lisfranc ligament is a strong interosseous ligament running from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is critical for the stabilization of the tarsometatarsal joint complex.

Question 33

A 14-year-old boy presents with progressive knee pain and a palpable distal femoral mass. Biopsy confirms high-grade conventional osteosarcoma. Which of the following underlying genetic mutations is most strongly associated with the pathogenesis of this tumor?

Explanation

High-grade conventional osteosarcoma is strongly associated with mutations in the Rb1 and p53 tumor suppressor genes, as seen in hereditary retinoblastoma and Li-Fraumeni syndrome. The t(11;22) translocation is characteristic of Ewing sarcoma.

Question 34

A 13-year-old boy presents with a limp and obligate external rotation of his right hip when flexed. He is diagnosed with a severe, stable slipped capital femoral epiphysis (SCFE). Which of the following is the most common serious complication of in situ single-screw fixation for this condition?

Explanation

Chondrolysis is a major complication of SCFE treatment, often associated with unrecognized joint penetration by the hardware during in situ pinning. Avascular necrosis is more commonly associated with unstable SCFE.

Question 35

During secondary bone healing following a closed diaphyseal fracture treated with a cast, a cartilaginous soft callus forms. Which of the following growth factors is most critical in promoting the differentiation of mesenchymal stem cells into chondrocytes during this phase?

Explanation

Bone morphogenetic proteins, particularly BMP-2, are potent osteoinductive growth factors. They play a critical role in inducing mesenchymal stem cells to differentiate into both chondroblasts and osteoblasts during fracture healing.

Question 36

A 65-year-old male is undergoing total hip arthroplasty. The surgeon opts for a highly cross-linked polyethylene (XLPE) liner. Which of the following best describes the mechanical trade-off associated with the increased radiation dose used to cross-link the polyethylene?

Explanation

While highly cross-linking polyethylene significantly improves wear resistance, it concurrently decreases its mechanical properties, including ultimate tensile strength, fatigue resistance, and fracture toughness. This makes the liner more susceptible to fracture under high loads.

Question 37

A 35-year-old male sustains a vertical, displaced femoral neck fracture (Pauwels Type III). He undergoes closed reduction and internal fixation with three parallel cancellous screws. Which of the following biomechanical forces is most responsible for the high rate of nonunion in this specific fracture pattern?

Explanation

Pauwels Type III femoral neck fractures have a vertically oriented fracture line (angle > 50 degrees). This vertical orientation subjects the fracture site to high shear forces during weight-bearing, which is the primary cause of fixation failure and nonunion.

Question 38

A 40-year-old carpenter suffers a laceration over the volar aspect of his proximal phalanx in zone II. Both the FDS and FDP tendons are severed. To optimize tendon gliding and minimize rupture risk, what is the ideal number of core suture strands crossing the repair site?

Explanation

A 4-strand or 6-strand core suture repair significantly increases the tensile strength of the tendon while minimizing bulk. This strength is necessary to allow for early active motion protocols, which prevent adhesions in zone II.

Question 39

A 22-year-old rugby player undergoes an anterior stabilization procedure for recurrent shoulder dislocations. Preoperative CT reveals a 25% loss of the anterior glenoid rim. Which of the following procedures is most appropriate to restore glenohumeral stability?

Explanation

An anterior glenoid bone loss of greater than 20-25% is an absolute indication for a bony augmentation procedure, such as the Latarjet procedure. Soft tissue repairs alone have an unacceptably high failure rate in the setting of critical bone loss.

Question 40

A 50-year-old male is involved in a motor vehicle accident. CT reveals a burst fracture of C5 with 60% canal compromise. He has 0/5 strength in bilateral extremities and absent rectal tone. The bulbocavernosus reflex is absent. Which of the following terms best describes his current neurological state?

Explanation

The absence of the bulbocavernosus reflex in the immediate post-traumatic period defines spinal shock, a state of transient physiological suppression of cord function. A complete spinal cord injury cannot be definitively diagnosed until spinal shock resolves.

Question 41

A 45-year-old male presents with acute posterior ankle pain after hearing a "pop" while playing tennis. The Thompson test is positive. The decision is made to manage the patient non-operatively. Which of the following rehabilitation protocols provides the lowest rerupture rate?

Explanation

Modern early functional rehabilitation protocols, which include early weight-bearing in an equinus brace and early range of motion, yield rerupture rates for non-operative management comparable to operative treatment.

Question 42

A 6-year-old boy presents with a Gartland type III extension-type supracondylar humerus fracture. Examination reveals a pulseless but well-perfused, pink hand. After closed reduction and percutaneous pinning, the hand remains pink but the radial pulse remains absent. What is the most appropriate next step in management?

Explanation

In a pulseless but well-perfused (pink) hand after adequate reduction and pinning of a pediatric supracondylar humerus fracture, observation is recommended. Collateral circulation is sufficient, and the pulse typically returns within 24-48 hours.

Question 43

A 14-year-old boy presents with a destructive diaphyseal lesion of the femur with an associated periosteal "onion skin" reaction. Biopsy confirms Ewing sarcoma. Which of the following genetic translocations is most characteristic of this diagnosis?

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, which creates the EWS-FLI1 fusion protein. The t(X;18) translocation is seen in synovial sarcoma, and t(12;16) in myxoid liposarcoma.

Question 44

A 68-year-old male presents with chronic knee pain 2 years after a primary total knee arthroplasty. Aspiration yields synovial fluid with a WBC count of 4,500 cells/uL and 85% polymorphonuclear leukocytes. Alpha-defensin testing is positive. What is the most appropriate definitive management for a chronic periprosthetic joint infection in a medically optimized patient?

Explanation

Two-stage revision arthroplasty is the gold standard for chronic periprosthetic joint infection in North America. Debridement, antibiotics, and implant retention (DAIR) is reserved strictly for acute infections.

Question 45

A 65-year-old male presents with progressive hand clumsiness and frequent falls. Examination demonstrates a positive Hoffmann sign bilaterally and inverted supinator reflexes. MRI reveals severe cervical stenosis at C4-C5 and C5-C6 with cord signal change. Which of the following physical exam findings is most specific for cervical myelopathy?

Explanation

The inverted supinator reflex is highly specific for cervical myelopathy. While Hoffmann and Babinski signs indicate upper motor neuron lesions, they are less specific to the cervical spine compared to the inverted supinator sign which localizes to C5-C6.

Question 46

A 45-year-old skier sustains a Schatzker type VI tibial plateau fracture. He has tense, swollen leg compartments with pain out of proportion to the injury. A pressure monitor displays a compartment pressure of 45 mmHg. His diastolic blood pressure is 60 mmHg. What is the delta pressure, and is a fasciotomy indicated?

Explanation

Delta pressure is calculated as Diastolic BP minus Compartment Pressure (60 - 45 = 15 mmHg). A delta pressure less than 30 mmHg is an absolute indication for emergency four-compartment fasciotomy.

Question 47

A 55-year-old female is undergoing a total hip arthroplasty via the posterolateral approach. To prevent sciatic nerve injury, the surgeon must carefully protect it during the exposure. Which of the following external rotators of the hip intimately protects the sciatic nerve deep to it and should be carefully isolated?

Explanation

The quadratus femoris muscle protects the sciatic nerve deep to it. During the posterior approach, aggressive dissection into the quadratus femoris must be avoided to prevent damage to the underlying sciatic nerve and medial circumflex femoral artery branches.

Question 48

A 22-year-old male athlete presents with recurrent anterior shoulder dislocations. An MRI reveals an engaging Hill-Sachs lesion and anterior glenoid bone loss of 25%. What is the most appropriate surgical management for this patient to prevent recurrence?

Explanation

A Latarjet procedure (coracoid transfer) is indicated for patients with recurrent anterior shoulder instability and significant glenoid bone loss (>20-25%). Soft tissue stabilization alone has unacceptably high failure rates in the setting of critical bone loss.

Question 49

A 6-week-old female infant is brought to the clinic. The Ortolani maneuver is positive on the left hip. Ultrasound demonstrates an alpha angle of 45 degrees. Which of the following is the most appropriate initial treatment?

Explanation

A positive Ortolani sign indicates a dislocated but reducible hip, confirming DDH, and an alpha angle <60 degrees is abnormal. The Pavlik harness is the gold standard initial treatment for infants under 6 months of age.

Question 50

When designing a locked plating construct for a comminuted diaphyseal fracture to promote secondary bone healing via callus formation, which of the following modifications effectively increases the working length and construct flexibility?

Explanation

Leaving screw holes empty immediately adjacent to the fracture increases the working length of the plate. This enhances the flexibility of the construct, allowing interfragmentary micro-motion which stimulates secondary bone healing.

Question 51

A 30-year-old carpenter lacerates his index finger volar surface at the level of the proximal phalanx, disrupting both the FDS and FDP tendons. This injury corresponds to which flexor tendon zone, and what is its primary anatomical characteristic?

Explanation

Lacerations at the level of the proximal phalanx involve Zone II, historically known as "no man's land". This zone contains both the FDS and FDP within the tight fibro-osseous digital sheath, making surgical repair prone to adhesions.

Question 52

A 28-year-old male arrives in hemorrhagic shock after a motorcycle accident. Radiographs reveal an AP compression type III (APC-III) pelvic ring injury. To be maximally effective in reducing pelvic volume, where should a pelvic binder be centered?

Explanation

Pelvic binders are most effective at reducing pelvic volume and controlling hemorrhage when centered precisely over the greater trochanters. Placement over the iliac crests is less effective and may exacerbate certain fracture patterns.

Question 53

A 35-year-old female presents with knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion extending into the metaphysis of the distal femur. Biopsy confirms a Giant Cell Tumor of bone. What is the mechanism of action of denosumab, a potential medical treatment?

Explanation

Denosumab is a monoclonal antibody that binds to and inhibits RANK Ligand (RANKL). This prevents the activation of the RANK receptor on osteoclasts and giant cells, thereby halting osteoclast-mediated bone destruction.

Question 54

A 72-year-old man presents with bilateral leg heaviness and pain that worsens with walking upright and improves when leaning forward on a shopping cart. Examination reveals normal distal pulses. Which of the following pathological changes is the primary driver of central canal stenosis in this condition?

Explanation

This patient has classic symptoms of neurogenic claudication due to lumbar spinal stenosis. The most common anatomical causes of central canal stenosis are facet arthropathy, disc space narrowing, and hypertrophy or buckling of the ligamentum flavum.

Question 55

A 24-year-old football player presents with midfoot pain after an axial load to a plantarflexed foot. Radiographs demonstrate a 3 mm widening between the medial and middle cuneiforms, and a "fleck sign". The primary injured ligament connects which two structures?

Explanation

The Lisfranc ligament traverses from the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. A "fleck sign" represents a bony avulsion of this ligament, indicating severe midfoot instability.

Question 56

An 11-year-old obese male complains of left knee and groin pain for 3 weeks. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). During physical examination, when the affected hip is passively flexed, which obligate motion is classically observed?

Explanation

In patients with SCFE, the femoral neck typically displaces anteriorly and superiorly relative to the epiphysis. This anatomical change causes obligate external rotation of the hip during passive hip flexion.

Question 57

A 62-year-old female sustains a dorsally displaced distal radius fracture. During conservative management in a cast, she reports escalating numbness in her thumb, index, and long fingers. Which nerve is most commonly compressed in this setting?

Explanation

Acute carpal tunnel syndrome, caused by compression of the median nerve, is the most common neurologic complication associated with distal radius fractures. Treatment involves removing constrictive casts and potentially surgical release if symptoms persist.

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