A 30-year-old woman injures her knee while skiing. Based on the MRI scan shown in Figure 5, treatment should consist of

functional rehabilitation and early motion.

A 52-year-old woman with a 2-year history of a flexible (stage II) adult-acquired flatfoot deformity has failed to respond to nonsurgical management consisting of immobilization, custom orthotics, nonsteroidal anti-inflammatory drugs, and physical th

Tendon transfer, lateral column lengthening, medial column arthrodesis, and heel cord lengthening

A previously asymptomatic 12-year-old girl sustained a direct blow to the right lateral knee from a baseball bat. Examination reveals an area of ecchymosis and tenderness over the lateral thigh. The patient can walk without pain, but range of motion

a repeat examination in 6 weeks.

A 65-year-old man with ankylosing spondylitis has neck pain after falling back over his lawnmower, striking his thoracic spine, and forcing his neck into extension. Examination reveals subtle weakness of the intrinsics and finger flexors at approxima

posterior laminectomy and spinal fusion.

03 An 18 month old child has bilateral “corner fractures” of the distal femoral metaphyses of unknown origin. Following a skeletal survey, the first step in management should consist of

notification of child protection services

A 23-year-old professional baseball pitcher reports shoulder pain and decreased velocity while pitching. Physical examination reveals a side-to-side internal rotation deficit of 25 degrees. The O’Brien sign is negative; Neer and Hawkins signs are neg

Posterior capsular stretching program

Orthopedic Review MCQs with Answers | Dr Hutaif

Question 1

A 12-year-old boy presents with an acute-on-chronic left slipped capital femoral epiphysis (SCFE). Which of the following is considered a definitive indication for prophylactic in situ pinning of the contralateral, currently asymptomatic right hip?

Explanation

Endocrine disorders, such as hypothyroidism or renal osteodystrophy, are established indications for prophylactic pinning of the contralateral hip in patients presenting with a unilateral SCFE due to the significantly higher risk of bilateral involvement. The other options are risk factors for SCFE but do not serve as absolute indications for prophylactic contralateral pinning.

Question 2

A 25-year-old male sustains a high-energy vertical shear femoral neck fracture (Pauwels type III). Which of the following internal fixation constructs provides the greatest biomechanical stability against the high shear forces inherent to this fracture pattern?

Explanation

Pauwels type III femoral neck fractures have a vertical fracture line (angle >50 degrees), which subjects the fracture to high shear forces and a high risk of varus collapse. A fixed-angle device, such as a sliding hip screw (with an additional anti-rotation screw) or a cephalomedullary nail, provides superior biomechanical stability against these shear forces compared to multiple cancellous screws.

Question 3

A 22-year-old female athlete suffers a twisting injury to her knee. Radiographs reveal a small elliptical bone fragment adjacent to the lateral tibial plateau (Segond fracture). This radiographic finding indicates an avulsion of which of the following structures?

Explanation

A Segond fracture is a cortical avulsion fracture off the lateral tibial plateau and is pathognomonic for an anterior cruciate ligament (ACL) tear. The avulsed bony fragment itself specifically represents the tibial attachment of the anterolateral ligament (ALL) and the lateral capsular ligament.

Question 4

A 55-year-old active male underwent a total hip arthroplasty (THA) 2 years ago and now complains of a high-pitched squeaking noise coming from his hip when he bends forward. He denies pain. Which of the following bearing surface combinations was most likely used?

Explanation

Audible 'squeaking' is a known complication specific to Ceramic-on-Ceramic (CoC) bearing surfaces in total hip arthroplasty. It is reported in up to 10% of CoC hips and is thought to be related to stripe wear, edge loading, micro-separation, or resonance of the ceramic components.

Question 5

A 65-year-old female presents with progressive clumsiness in her hands, difficulty buttoning her shirts, and an unsteady gait. Physical exam reveals hyperreflexia in the upper and lower extremities. Which of the following clinical tests is most specific for diagnosing an upper motor neuron lesion in this context?

Explanation

The clinical scenario is highly suggestive of cervical spondylotic myelopathy. The Hoffmann sign is elicited by flicking the nail of the middle finger; a positive response is flexion of the index finger and thumb. It is a reliable indicator of an upper motor neuron lesion affecting the upper extremities. The Babinski sign also indicates upper motor neuron pathology but is assessed in the lower extremities.

Question 6

A 15-year-old male presents with deep knee pain and a mass in the distal femur. Biopsy reveals highly pleomorphic cells producing a malignant osteoid matrix. This condition is classically associated with a germline mutation in which of the following tumor suppressor genes?

Explanation

The pathology describes an osteosarcoma. Germline mutations in TP53 (Li-Fraumeni syndrome) and RB1 (hereditary retinoblastoma) are highly associated with the development of osteosarcoma. The other genes listed are associated with different familial cancer syndromes (e.g., APC for FAP, NF1 for neurofibromatosis).

Question 7

According to Perren's strain theory, what is the maximum interfragmentary strain threshold required for primary (direct) bone healing to occur without the formation of a visible fracture callus?

Explanation

Primary bone healing occurs via cutting cones and Haversian remodeling without the formation of an intermediate cartilaginous callus. According to Perren's strain theory, this requires absolute stability, defined as an interfragmentary strain of less than 2%. Strains between 2% and 10% result in secondary bone healing (callus formation), while strains above 10% lead to nonunion.

Question 8

A 24-year-old male falls onto an outstretched hand and sustains a displaced fracture of the proximal pole of the scaphoid. He is at high risk for avascular necrosis (AVN). The scaphoid is predominantly supplied by retrograde blood flow from which of the following vessels?

Explanation

The blood supply to the scaphoid predominantly comes from the dorsal carpal branch of the radial artery, which enters the scaphoid at the dorsal ridge near the waist and supplies the proximal pole via retrograde intraosseous flow. Because of this tenuous retrograde supply, proximal pole fractures have a high rate of AVN and nonunion.

Question 9

A 30-year-old male suffers an axial load injury to a plantarflexed foot. Radiographs demonstrate widening between the 1st and 2nd metatarsal bases with a 'fleck sign' in the intermetatarsal space. This bony fragment represents an avulsion of the Lisfranc ligament from which specific osseous structure?

Explanation

The Lisfranc ligament is a stout intra-articular ligament that connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the 2nd metatarsal. The classic 'fleck sign' pathognomonic for a Lisfranc injury represents a bony avulsion of this ligament, most commonly from the base of the 2nd metatarsal.

Question 10

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her follow-up appointment, she is noted to have decreased active extension of the left knee. The harness is removed. Which nerve is most likely compressed, and what is the primary cause?

Explanation

Femoral nerve palsy is the most common nerve palsy associated with Pavlik harness treatment and is caused by hyperflexion of the hip, causing the nerve to be compressed against the inguinal ligament. It clinically presents as a loss of active knee extension. Treatment involves immediate adjustment or temporary removal of the harness.

Question 11

A 40-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. He is admitted for observation while awaiting soft tissue swelling to decrease. Which of the following clinical findings is the most reliable early indicator of an impending acute compartment syndrome?

Explanation

Pain out of proportion to the injury, particularly pain elicited by passive stretch of the muscles in the involved compartment, is the earliest and most sensitive clinical sign of acute compartment syndrome. The '5 Ps' (pallor, pulselessness, paresthesias, paralysis) are typically late and unreliable signs.

Question 12

A 20-year-old male presents with recurrent anterior shoulder dislocations. Advanced imaging reveals an anterior glenoid bone defect comprising 25% of the glenoid width. Which of the following surgical interventions is most appropriate to restore stability?

Explanation

In the setting of recurrent anterior shoulder instability with critical glenoid bone loss (typically defined as >20-25% of the glenoid width), an isolated soft tissue repair (e.g., arthroscopic Bankart) has unacceptably high failure rates. A bony augmentation procedure, such as a Latarjet (coracoid transfer), is required to restore the articular arc and provide a sling effect via the conjoined tendon.

Question 13

In posterior cruciate substituting (PS) total knee arthroplasty (TKA), the implant design utilizes a cam on the femoral component and a post on the tibial polyethylene. The primary mechanical purpose of this cam-post engagement is to induce which of the following kinematic motions?

Explanation

In a PS TKA, the posterior cruciate ligament is resected. To substitute for its function, the cam-post mechanism engages during deeper flexion, mechanically forcing the femur to translate posteriorly on the tibia. This 'femoral rollback' improves clearance, prevents posterior impingement, and increases the maximum flexion angle.

Question 14

A 70-year-old male complains of bilateral lower extremity pain and cramping that worsens with walking. To differentiate between neurogenic claudication (lumbar spinal stenosis) and vascular claudication, which of the following historical features strongly supports a neurogenic etiology?

Explanation

Neurogenic claudication is classically relieved by flexion of the lumbar spine, which increases the cross-sectional area of the spinal canal and neural foramina. Thus, patients find relief when walking uphill, sitting, or leaning over a shopping cart. Conversely, vascular claudication is worsened by any exertion (uphill walking requires more metabolic demand) and is relieved simply by standing still.

Question 15

A 35-year-old female presents with an expansile, eccentric, lytic lesion in the epiphysis of the distal femur. A biopsy confirms the diagnosis of giant cell tumor (GCT) of bone. If she requires systemic medical therapy for unresectable disease, she may be treated with Denosumab. What is the mechanism of action of this drug?

Explanation

Giant cell tumor of bone consists of neoplastic stromal cells that express high levels of RANKL, which recruits and activates the reactive multinucleated giant cells (osteoclasts) responsible for the bone destruction. Denosumab is a human monoclonal antibody that binds to RANKL, preventing it from activating the RANK receptor on osteoclasts, thereby halting tumor-associated osteolysis.

Question 16

Articular cartilage is a highly specialized tissue divided into distinct structural zones. Which zone contains the highest concentration of proteoglycans, the lowest water content, and collagen fibrils oriented strictly perpendicular to the articular surface?

Explanation

The deep (radial) zone of articular cartilage is characterized by thick type II collagen fibrils oriented perpendicularly to the joint surface to resist compressive loads. It has the highest concentration of proteoglycans and the lowest water content compared to the more superficial zones.

Question 17

A 28-year-old carpenter sustains a laceration over the volar aspect of his proximal phalanx (Zone II), completely severing the flexor digitorum profundus (FDP) tendon. To allow for a safe early active motion rehabilitation protocol, what is the optimal core suture configuration for the tendon repair?

Explanation

To withstand the forces of an early active motion rehabilitation protocol (which helps prevent tendon adhesions in Zone II), an FDP repair requires sufficient tensile strength. Biomechanical studies have shown that 4- to 6-strand core suture repairs provide the optimal balance of strength without adding excessive bulk that would impede gliding. A 2-strand repair is too weak for early active motion.

Question 18

A 55-year-old diabetic male presents with a painless, red, hot, and swollen right foot. He is afebrile with normal inflammatory markers. Radiographs demonstrate periarticular fragmentation, subluxation, and bony debris at the midfoot. According to the Eichenholtz classification, what is the most appropriate initial management?

Explanation

The patient is presenting with acute Charcot arthropathy (Eichenholtz Stage 1: Development/Fragmentation), characterized by a red, hot, swollen foot with radiographic evidence of osteopenia, fragmentation, and joint subluxation. The mainstay of treatment in the acute phase is strict offloading and immobilization, most effectively achieved with a total contact cast, until the joint transitions to the coalescence phase.

Question 19

The Ponseti method is the gold standard for the treatment of idiopathic clubfoot (talipes equinovarus). According to this technique, the serial casting process follows a specific order of deformity correction (CAVE). What is the first component of the deformity that must be corrected?

Explanation

In the Ponseti method, the deformities are corrected in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, Equinus. The cavus is corrected first by elevating the first ray (supinating the forefoot) to align it with the hindfoot. Only then is the entire foot abducted around the head of the talus to correct adductus and varus.

Question 20

A 35-year-old male is brought to the trauma bay after a motorcycle collision. He is hypotensive and tachycardic. Pelvic radiographs show an Anteroposterior Compression Type III (APC III) injury with a widely displaced symphysis pubis and disrupted sacroiliac joints. When applying a non-invasive pelvic binder to reduce the pelvic volume, over which anatomic landmarks should the binder be centered?

Explanation

For effective reduction of pelvic ring volume and hemorrhage control in an 'open book' (APC) pelvic fracture, a pelvic binder or sheet must be centered directly over the greater trochanters. Placing it over the iliac crests is a common error and can paradoxically open the pelvis further or fail to provide adequate mechanical compression of the posterior venous plexus.

Question 21

A 40-year-old male presents with a hemodynamically unstable APC-III pelvic ring injury following a motorcycle collision. Despite a properly applied pelvic binder and massive transfusion protocol, he remains profoundly hypotensive. What is the most common anatomical source of massive hemorrhage in this fracture pattern?

Explanation

Up to 80% of massive hemorrhage in pelvic ring injuries is venous in origin, most frequently arising from the presacral venous plexus. While arterial bleeding (such as from the superior gluteal artery) can be catastrophic, it is more commonly associated with posterior ring disruptions and represents a smaller percentage of overall pelvic bleeding.

Question 22

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the parents report that the infant is no longer actively extending the knee on the treated side. What is the most likely iatrogenic cause of this physical finding?

Explanation

Excessive hip flexion in a Pavlik harness can cause a transient femoral nerve palsy, resulting in decreased active knee extension. The anterior straps should be adjusted to decrease hip flexion, which usually allows the palsy to resolve spontaneously.

Question 23

A 25-year-old male sustains an axial load injury to his cervical spine. Open-mouth odontoid radiographs reveal a combined lateral overhang of the C1 lateral masses on C2 of 8.1 mm. According to the Rule of Spence, this specific measurement indicates the disruption of which of the following structures?

Explanation

The Rule of Spence dictates that a combined lateral mass displacement of C1 on C2 greater than 6.9 mm on an AP open-mouth radiograph signifies transverse ligament rupture. This indicates a highly unstable Jefferson fracture that typically requires rigid immobilization (halo) or upper cervical fusion.

Question 24

A 32-year-old male presents with a locked posterior shoulder dislocation after an epileptic seizure. A CT scan confirms a reverse Hill-Sachs lesion involving 35% of the anterior humeral head articular surface. Which of the following surgical interventions is most appropriate to prevent recurrent instability?

Explanation

A reverse Hill-Sachs lesion involving 20-40% of the humeral head articular surface is best treated with a McLaughlin procedure or its modification (lesser tuberosity transfer). This fills the defect and prevents it from engaging on the posterior glenoid rim during internal rotation.

Question 25

A 65-year-old female presents with a painful popping sensation over the anterior knee when extending from a flexed position, 18 months after a primary total knee arthroplasty. What implant design and specific complication are most likely associated with her clinical presentation?

Explanation

Patellar clunk syndrome is characterized by a fibrous nodule forming at the superior pole of the patella, which catches in the intercondylar box of a posterior-stabilized femoral component during knee extension. Arthroscopic resection of the fibrous nodule is curative.

Question 26

A 13-year-old boy presents to the emergency department with acute severe hip pain and inability to bear weight after a minor fall. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant prognostic implication of his inability to bear weight?

Explanation

The Loder classification defines a SCFE as unstable if the patient is unable to bear weight with or without crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 50%) compared to stable SCFE.

Question 27

A 32-year-old male sustains a closed talar neck fracture following a motor vehicle collision. Six weeks after open reduction and internal fixation, an AP radiograph of the ankle reveals a subchondral radiolucent band in the dome of the talus (Hawkins sign). What does this radiographic finding indicate?

Explanation

The Hawkins sign is a subchondral radiolucent band representing subchondral osteopenia. It indicates that the blood supply to the talar body is intact and actively resorbing bone, making avascular necrosis highly unlikely.

Question 28

A 24-year-old manual laborer presents with acute swelling, severe pain, and a flexed posture of his dominant index finger after a puncture wound. Which of the following is NOT one of Kanavel's cardinal signs of flexor tendon sheath infection?

Explanation

Kanavel's four cardinal signs of purulent flexor tenosynovitis are: fusiform swelling, flexed posture, pain with passive extension, and tenderness along the flexor sheath. Pain with active flexion is not considered one of the specific cardinal signs.

Question 29

A 45-year-old male is admitted with a highly comminuted tibia fracture. He develops escalating leg pain requiring increasing doses of narcotics. Which pressure measurement confirms an absolute indication for emergency four-compartment fasciotomy?

Explanation

Compartment syndrome is a clinical diagnosis, but when pressures are measured, a delta pressure (Diastolic BP minus compartment pressure) of less than 30 mmHg is considered a definitive indication for fasciotomy.

Question 30

A 21-year-old collegiate rugby player undergoes a Latarjet procedure for recurrent anterior shoulder instability with 25% glenoid bone loss. Which nerve is at greatest risk of iatrogenic injury during the coracoid transfer and fixation?

Explanation

The musculocutaneous nerve typically enters the coracobrachialis 5-8 cm distal to the coracoid process, placing it at high risk during retraction, mobilization, and fixation of the coracoid graft in the Latarjet procedure.

Question 31

A 65-year-old male is involved in a high-speed MVC and sustains a burst fracture of the C1 ring (Jefferson fracture). Open-mouth odontoid radiographs demonstrate lateral displacement of the C1 lateral masses. A total combined overhang of the C1 lateral masses on C2 greater than what threshold implies an incompetent transverse ligament (Rule of Spence)?

Explanation

According to the Rule of Spence, a combined lateral mass displacement of C1 over C2 of greater than 6.9 mm on an AP open-mouth radiograph implies rupture of the transverse ligament.

Question 32

A 14-year-old boy presents with a painful mass in his diaphyseal femur. Biopsy reveals small round blue cells. Cytogenetic analysis demonstrates a t(11;22) chromosomal translocation. Which fusion gene product is most likely responsible for this malignancy?

Explanation

The clinical presentation and histology describe Ewing sarcoma. The t(11;22) translocation results in the EWS-FLI1 fusion protein, which is diagnostic for this tumor.

Question 33

Manufacturers have introduced Vitamin E-blended highly cross-linked polyethylene for total joint arthroplasty components. The primary biomechanical purpose of incorporating Vitamin E is to prevent which of the following processes?

Explanation

Vitamin E acts as a potent antioxidant. It neutralizes free radicals introduced during the irradiation cross-linking process, thereby preventing long-term oxidative degradation of the polyethylene component.

Question 34

A 55-year-old female undergoes arthroscopy for a symptomatic medial meniscal posterior root tear. Biomechanically, an unrepaired complete medial meniscus root tear alters knee joint contact pressures most similarly to which of the following states?

Explanation

A meniscal root tear eliminates the ability of the meniscus to convert axial loads into circumferential hoop stresses. This functionally unloads the meniscus, rendering it biomechanically equivalent to a total meniscectomy.

Question 35

Following reamed intramedullary nailing of an isolated closed tibial shaft fracture, what is the most frequently reported long-term complication?

Explanation

Anterior knee pain is the most common complication following intramedullary nailing of the tibia, occurring in up to 40-50% of patients regardless of whether a parapatellar or transtendinous approach is used.

Question 36

An 18-year-old football player sustains a high-energy midfoot injury. Imaging confirms a Lisfranc fracture-dislocation. The primary Lisfranc ligament connects which two osseous structures?

Explanation

The Lisfranc ligament is a strong intra-articular ligament that originates from the plantar-lateral aspect of the medial cuneiform and attaches to the plantar-medial base of the second metatarsal.

Question 37

A 60-year-old woman undergoes volar plate fixation for a displaced distal radius fracture. Four months postoperatively, she suddenly loses the ability to actively flex her thumb interphalangeal joint. This complication is most directly related to plate placement distal to which anatomic landmark?

Explanation

Placement of a volar plate distal to the watershed line of the distal radius causes hardware prominence. This can lead to attritional rupture of the flexor pollicis longus (FPL) tendon.

Question 38

A 6-year-old child sustains a displaced extension-type supracondylar humerus fracture. Upon clinical examination, the child is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (unable to make an 'OK' sign). Which nerve branch is most likely injured?

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus and the flexor digitorum profundus to the index finger.

Question 39

A 32-year-old male undergoes reamed intramedullary nailing for a closed tibial shaft fracture. In the postoperative period and after union is achieved, what is the most frequently reported long-term complication associated with this specific surgical intervention?

Explanation

Anterior knee pain is the most common complication following intramedullary nailing of tibial shaft fractures, occurring in up to 40-50% of patients. It occurs regardless of whether a parapatellar or transtendinous approach is used.

Question 40

During a primary total knee arthroplasty in a patient with a fixed 20-degree valgus deformity, the surgeon notes a tight lateral extension gap. If a sequential lateral release is utilized to balance the knee in extension, which of the following structures is typically released first?

Explanation

In a valgus knee with a tight extension gap, the iliotibial band (ITB) is typically the first structure released. The popliteus tendon is preferentially released if the knee is tight in flexion.

Question 41

A 45-year-old male is involved in a motor vehicle collision and sustains a traumatic spondylolisthesis of C2 (Hangman's fracture). What is the classic primary mechanism of injury for this fracture pattern?

Explanation

A Hangman's fracture (traumatic spondylolisthesis of the axis) classically occurs secondary to hyperextension and axial loading forces. This leads to bilateral fractures through the pars interarticularis of C2.

Question 42

A 40-year-old female undergoes open reduction and internal fixation of a displaced radial shaft fracture using a lag screw and neutralization plate, providing absolute stability. By which biological mechanism will this fracture primarily heal?

Explanation

Absolute stability (e.g., lag screw and plate) minimizes interfragmentary strain and suppresses callus formation. Healing occurs via primary bone healing, characterized by osteoclastic cutting cones followed by osteoblastic bone deposition directly across the fracture line.

Question 43

A 14-year-old boy presents with a painful, swollen thigh. Radiographs reveal a permeative diaphyseal lesion with an 'onion-skin' periosteal reaction. Biopsy confirms Ewing sarcoma. Which chromosomal translocation is most characteristic of this tumor?

Explanation

Ewing sarcoma is classically associated with the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein. This is highly tested on board examinations for diagnostic confirmation.

Question 44

A 28-year-old football player sustains a midfoot injury. Radiographs reveal a widening between the first and second metatarsals with a 'Fleck sign'. The critical torn ligament in this injury anatomically connects which two skeletal structures?

Explanation

The Lisfranc ligament is an interosseous ligament that connects the medial cuneiform to the base of the second metatarsal. A 'Fleck sign' represents an avulsion of this ligament and indicates a Lisfranc injury.

Question 45

A 25-year-old male is admitted with a highly comminuted closed tibial plateau fracture. Which of the following clinical findings is the earliest and most sensitive indicator of developing acute compartment syndrome in the affected leg?

Explanation

Pain out of proportion to the injury, especially pain exacerbated by passive stretch of the involved compartment's muscles, is the earliest and most reliable clinical sign of acute compartment syndrome. Pulselessness and paralysis are very late and ominous signs.

Question 46

An infant is diagnosed with idiopathic clubfoot (talipes equinovarus) and treatment with the Ponseti method is initiated. According to this standardized casting technique, what is the correct sequence of deformity correction?

Explanation

The Ponseti method systematically corrects clubfoot deformities in the specific order of the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. Equinus is typically corrected last, often requiring a percutaneous Achilles tenotomy.

Question 47

A 22-year-old athlete sustains a twisting knee injury. On examination, a Dial test reveals 15 degrees of increased external tibial rotation at 30 degrees of knee flexion compared to the contralateral knee, but symmetric rotation at 90 degrees of flexion. This isolated finding indicates an injury to which structure(s)?

Explanation

A positive Dial test (increased external rotation) at 30 degrees of flexion but not at 90 degrees is specific for an isolated injury to the posterolateral corner (PLC). If rotation is increased at both 30 and 90 degrees, it indicates a combined PLC and posterior cruciate ligament (PCL) injury.

Question 48

A surgeon utilizes the volar (Henry) approach to the forearm for fixation of a proximal radius fracture. The proximal internervous plane of this surgical approach lies between the brachioradialis and which other muscle?

Explanation

The proximal internervous plane for the volar (Henry) approach to the radius lies between the brachioradialis (radial nerve) and the pronator teres (median nerve). Distally, the plane is between the brachioradialis and the flexor carpi radialis.

Question 49

A 65-year-old undergoes a total hip arthroplasty utilizing an ultra-high molecular weight polyethylene (UHMWPE) liner. Which sterilization method has historically been associated with in vivo oxidation and accelerated premature wear of the polyethylene component?

Explanation

Gamma irradiation in air produces free radicals within the polyethylene that react with oxygen, leading to oxidation, chain scission, and subsequent embrittlement and accelerated wear. Modern components are cross-linked and sterilized in inert environments to prevent this.

Question 50

A 35-year-old carpenter presents with a painful, swollen index finger following a minor puncture wound. Which of the following is NOT one of Kanavel's four cardinal signs of acute pyogenic flexor tenosynovitis?

Explanation

Kanavel's four cardinal signs include fusiform swelling, flexed resting posture (NOT rigidly extended), tenderness along the flexor sheath, and pain on passive extension. A resting extended posture contradicts these criteria.

Question 51

A 70-year-old male complains of bilateral lower extremity heaviness and cramping that worsens with walking upright and improves dramatically when he leans forward on a shopping cart. This neurogenic claudication is most commonly driven by the hypertrophic infolding of which spinal structure?

Explanation

Neurogenic claudication is a hallmark of lumbar spinal stenosis. The stenosis is often exacerbated by hypertrophy and infolding of the ligamentum flavum, which narrows the spinal canal, particularly during spinal extension.

Question 52

According to the Seddon classification of peripheral nerve injuries, which of the following accurately describes the histopathology of an axonotmesis?

Explanation

Axonotmesis involves loss of axonal continuity and subsequent Wallerian degeneration, but the connective tissue framework (endoneurium, perineurium, and epineurium) remains completely or partially intact. This intact framework allows for potential spontaneous axonal regeneration.

Question 53

A 45-year-old is brought to the trauma bay following a crush injury. Radiographs show an anteroposterior compression type III (APC III) open book pelvic ring injury. If this patient becomes rapidly hemodynamically unstable, what is the most common anatomical source of major pelvic hemorrhage?

Explanation

While arterial bleeding (such as from the superior gluteal or internal pudendal arteries) can be life-threatening and require embolization, the vast majority (approximately 80-90%) of pelvic hemorrhage in severe pelvic ring fractures originates from the presacral venous plexus and bleeding cancellous bone.

Question 54

During an open carpal tunnel release, the surgeon must carefully identify and protect the recurrent motor branch of the median nerve. This specific nerve branch innervates all of the following muscles EXCEPT the:

Explanation

The recurrent motor branch of the median nerve innervates the thenar musculature (opponens pollicis, abductor pollicis brevis, and superficial head of the flexor pollicis brevis). The adductor pollicis is innervated by the deep branch of the ulnar nerve.

Question 55

In the management of Legg-Calve-Perthes disease, the Herring lateral pillar classification is widely used to determine prognosis. A hip where the lateral pillar of the femoral head maintains greater than 50% but less than 100% of its original height is classified as:

Explanation

In the Herring classification, Group B indicates >50% lateral pillar height maintained. Group A has no loss of height, and Group C has <50% of the original lateral pillar height maintained.

Question 56

A 16-year-old girl is diagnosed with a high-grade osteosarcoma of the distal femur and begins treatment. What is the most critical local prognostic factor for her long-term overall survival?

Explanation

The histologic response to neoadjuvant chemotherapy, specifically the percentage of tumor necrosis (with >90% defining a 'good responder'), is the most significant local prognostic factor for long-term survival in osteosarcoma patients.

Question 57

A 5-year-old boy presents with a displaced Gartland type III supracondylar humerus fracture. On examination, the hand is pink and well-perfused, but the radial pulse is absent. Which of the following is the most appropriate initial management?

Explanation

A pulseless, pink hand in a pediatric supracondylar fracture should first be managed with urgent closed reduction and percutaneous pinning. Vascular status typically normalizes once the fracture is reduced, relieving the kink or tether on the brachial artery.

Question 58

A 45-year-old active female sustains a medial meniscus posterior root tear. From a biomechanical perspective, how does this injury alter the knee joint kinematics and contact pressures?

Explanation

A medial meniscus posterior root tear severely compromises the meniscal hoop tension. Biomechanically, the loss of hoop stress containment results in peak contact pressures equivalent to a complete meniscectomy, predisposing the joint to rapid arthrosis.

Question 59

A 30-year-old male is brought to the trauma bay hemodynamically unstable following a motorcycle collision. Pelvic radiographs reveal an anteroposterior compression (APC III) injury with a widened symphysis pubis and disrupted sacroiliac joints. Where should a pelvic binder be applied initially?

Explanation

A pelvic binder must be placed centered over the greater trochanters to effectively close the pelvic volume and stabilize the fracture. Placement over the iliac crests is incorrect and can act as a fulcrum, exacerbating the pelvic deformity.

Question 60

In the setting of revision total hip arthroplasty for recurrent posterior instability in a patient with deficient abductors, a dual mobility cup is chosen. What is the primary biomechanical advantage of a dual mobility construct in preventing dislocation?

Explanation

Dual mobility components increase both the effective head size and the jump distance required for the head to escape the cup. This significantly reduces the risk of dislocation, making it ideal for revision settings or patients with high instability risks.

Question 61

A 15-year-old boy presents with progressive knee pain. Radiographs show a destructive, bone-forming lesion in the distal femur with a "sunburst" periosteal reaction. A biopsy confirms conventional osteosarcoma. Which of the following genetic abnormalities is most commonly associated with this tumor?

Explanation

Osteosarcoma is strongly associated with mutations in tumor suppressor genes such as RB1 and TP53. The t(11;22) translocation is characteristic of Ewing sarcoma, while t(X;18) is seen in synovial sarcoma.

Question 62

A 40-year-old manual laborer presents with wrist pain and a known scaphoid nonunion. Radiographs reveal Scaphoid Nonunion Advanced Collapse (SNAC) Stage II. Which of the following best describes the pattern of arthritic involvement in this stage?

Explanation

SNAC Stage II is characterized by osteoarthritis involving the entire radioscaphoid joint. The radiolunate joint is typically spared in all SNAC stages due to its congruent spherical articulation, distinguishing it from the elliptical radioscaphoid joint.

Question 63

According to the Musculoskeletal Infection Society (MSIS) / International Consensus Meeting (ICM) criteria, which of the following synovial fluid analysis results is a major definitive criterion for diagnosing a chronic periprosthetic joint infection?

Explanation

For chronic periprosthetic joint infection, the widely accepted threshold is a synovial fluid WBC count greater than 3,000 cells/uL with >80% polymorphonuclear neutrophils (PMNs). Acute post-operative PJI utilizes a much higher threshold, typically >10,000 to 27,000 cells/uL.

Question 64

During secondary bone healing via endochondral ossification, a soft cartilaginous callus is formed and subsequently replaced by woven bone. Which type of collagen predominates in the soft cartilaginous callus prior to its replacement?

Explanation

During endochondral ossification, the initial soft callus is composed primarily of cartilage, which is characterized by Type II collagen. As mineralization occurs and the hard callus forms, Type II collagen is replaced by Type I collagen.

Question 65

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the parents report the infant has stopped kicking the affected leg. Examination reveals weakness in knee extension. This complication is most likely due to excessive positioning in which direction?

Explanation

Femoral nerve palsy is the most common neurologic complication associated with the Pavlik harness and is caused by excessive hip flexion compressing the nerve against the inguinal ligament. It usually resolves completely after adjusting or temporarily discontinuing the harness.

Question 66

A 32-year-old male sustains a comminuted tibia fracture. Four hours post-injury, he complains of severe leg pain out of proportion to the injury. Which of the following absolute measurements or calculations provides the most reliable indication for emergent fasciotomy?

Explanation

The Delta P threshold is the most reliable parameter for diagnosing acute compartment syndrome, defined as the diastolic blood pressure minus the compartment pressure being less than 30 mmHg. This calculation accounts for systemic perfusion better than absolute pressure values.

Question 67

A 24-year-old football player sustains an axial load injury to a plantarflexed foot. Radiographs demonstrate a subtle widening between the first and second metatarsals with a small avulsion fracture (Fleck sign). The torn ligament primarily connects which two structures?

Explanation

The Lisfranc ligament is a strong interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. The "Fleck sign" represents an avulsion fracture of this ligament at the second metatarsal base.

Question 68

A 21-year-old rugby player presents with recurrent anterior shoulder dislocations. A 3D CT scan of the shoulder reveals 26% anterior glenoid bone loss. Which of the following is the most appropriate surgical intervention?

Explanation

The Latarjet procedure, which transfers the coracoid process to the anterior glenoid neck, is the gold standard for recurrent anterior shoulder instability associated with critical glenoid bone loss (typically >20-25%). Soft tissue procedures alone have an unacceptably high failure rate in this setting.

Question 69

A 55-year-old female undergoes volar locked plating for a distal radius fracture. At her 6-month follow-up, she presents with an inability to actively flex the interphalangeal joint of her thumb. This complication is most highly associated with plate placement distal to which anatomic landmark?

Explanation

Placement of a volar plate distal to the watershed line of the distal radius places the hardware in direct contact with the flexor tendons. This prominent hardware causes irritation and can lead to rupture of the flexor pollicis longus (FPL) tendon.

Question 70

A 35-year-old female is diagnosed with an aggressive giant cell tumor of the proximal tibia. She is started on denosumab therapy prior to surgery. What is the precise mechanism of action of this medication?

Explanation

Denosumab is a monoclonal antibody that binds to RANK Ligand (RANKL), preventing it from interacting with the RANK receptor on osteoclasts and giant cells. This effectively halts osteoclast-mediated bone resorption and promotes tumor consolidation.

Question 71

A 28-year-old carpenter sustains a laceration to his index finger volar surface, resulting in a Zone II flexor digitorum profundus (FDP) and superficialis (FDS) transection. Following primary repair, early active mobilization is prescribed. What is the primary biologic advantage of this protocol?

Explanation

Early active mobilization following flexor tendon repair in Zone II enhances intrinsic tendon healing. It significantly decreases peritendinous adhesion formation and improves final tendon glide and excursion without unacceptably increasing the rupture rate.

Question 72

A 62-year-old male with a metal-on-metal total hip arthroplasty presents with groin pain and a palpable anterior thigh mass. Aspiration is negative for infection. Tissue biopsy demonstrates an Adverse Local Tissue Reaction (ALVAL). Which histological finding is a hallmark of this condition?

Explanation

Adverse local tissue reaction (ALVAL) or pseudotumor formation associated with metal-on-metal bearings is characterized histologically as a delayed type IV hypersensitivity reaction. The classic hallmark is a dense, perivascular lymphocytic infiltrate.

Question 73

A 65-year-old male presents with deep bone pain in his proximal femur. Blood work reveals hypercalcemia and mild renal insufficiency. Radiographs show a large solitary lytic lesion in the subtrochanteric region without a sclerotic rim. What is the most likely primary diagnosis?

Explanation

Multiple myeloma is the most common primary bone malignancy in adults over 40. The classic presentation involves lytic bone lesions ("punched-out"), hypercalcemia, renal insufficiency, and anemia, known collectively as the CRAB criteria.

Question 74

A 45-year-old male is involved in a high-speed motor vehicle collision and presents with severe neck pain. CT scan demonstrates bilateral fractures through the pars interarticularis of the C2 vertebra (Hangman's fracture). What is the classic mechanism of injury for this fracture pattern?

Explanation

A Hangman's fracture (traumatic spondylolisthesis of the axis) typically involves bilateral fractures of the C2 pars interarticularis. The classic mechanism of injury is forceful hyperextension combined with axial loading, frequently seen in motor vehicle accidents or diving injuries.

Question 75

Bone Morphogenetic Proteins (BMP-2 and BMP-7) are potent osteoinductive agents utilized in spine fusion and fracture nonunions. Following binding to cell surface receptors, which intracellular signaling proteins do BMPs primarily phosphorylate to induce osteoblastic gene transcription?

Explanation

Bone Morphogenetic Proteins (BMPs) bind to serine/threonine kinase receptors on the mesenchymal stem cell surface. This binding phosphorylates and activates downstream receptor-regulated SMAD proteins (specifically SMAD 1, 5, and 8), which translocate to the nucleus to promote osteoblast differentiation.

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