Figure 19 shows the radiograph of a 12-year-old boy who sustained an injury to his hand when another child fell on him. Management should consist of

open reduction and internal fixation through a dorsal approach.

What is the most appropriate surgical treatment for a stage III symptomatic scapholunate advanced collapsed (SLAC) wrist?

Scaphoid excision and capitate-lunate-triquetrum-hamate arthrodesis

Which of the following best characterizes the antigenicity of allograft bone?

Cell surface glycoproteins are primarily responsible for the antigenicity of the graft.

A 35-year-old man who is an avid weight lifter competing in local tournaments reports new onset pain and loss of motion in his dominant right shoulder. Examination reveals joint line tenderness, active elevation to 100 degrees, and external rotation

Anti-inflammatory drugs and a range-of-motion stretching program

An 18-year-old man has had an enlarging mass in his hand for the past 3 months. Radiographs, an MRI scan, and biopsy specimens are shown in Figures 54a through 54d. What is the most likely diagnosis?

Bizarre parosteal osteochondromatous proliferation (BPOP)

A 67-year-old woman has a painful, arthritic proximal interphalangeal (PIP) joint, and nonsurgical measures have failed to improve the pain. What implant and joint replacement approach combination has been demonstrated to have the lowest rate of revi

Silicone replacement arthroplasty through a volar approach

Orthopedic Review MCQs with Answers | Dr. Hutaif

Question 1

A 28-year-old male presents with a displaced Pauwels type III femoral neck fracture after a motor vehicle collision. He undergoes open reduction and internal fixation. Which of the following factors is most strongly associated with the development of osteonecrosis of the femoral head in this patient?

Explanation

The initial degree of displacement is the most significant determinant for the development of osteonecrosis of the femoral head in young adults with femoral neck fractures. It correlates directly with the magnitude of disruption to the retinacular vessels. While quality of reduction is critical for union, and time to surgery remains heavily debated, the initial displacement is consistently shown to dictate the ischemic insult.

Question 2

A 13-year-old obese boy presents with left thigh pain and a limp for 3 weeks. Examination reveals an obligate external rotation of the left hip with passive flexion. Radiographs show a mild slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate definitive management for the affected hip?

Explanation

The standard of care for a stable, mild to moderate SCFE is in situ fixation using a single cannulated screw placed in the center of the epiphysis. Open reduction increases the risk of avascular necrosis and is generally reserved for severe, unstable slips in specialized centers using specific surgical exposures (e.g., modified Dunn approach).

Question 3

Which of the following fracture fixation constructs relies primarily on endochondral ossification for bone healing?

Explanation

Intramedullary nailing provides relative stability, which permits micromotion at the fracture site. This micromotion promotes secondary bone healing through callus formation, predominantly via endochondral ossification. Constructs providing absolute stability (compression plating, lag screws, tension bands) heal via primary (intramembranous) bone healing without a cartilaginous intermediate or visible callus.

Question 4

In total hip arthroplasty, which of the following bearing surface combinations is associated with the lowest expected linear and volumetric wear rate?

Explanation

Ceramic-on-ceramic bearing surfaces possess the lowest linear and volumetric wear rates of all current total hip arthroplasty bearing combinations. However, they carry specific risks such as squeaking, stripe wear, and catastrophic component fracture.

Question 5

A 22-year-old female soccer player undergoes anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BTB) autograft. She is most at risk for which of the following complications postoperatively compared to the use of a hamstring autograft?

Explanation

BTB autograft is associated with a significantly higher incidence of anterior knee pain and kneeling pain (donor site morbidity) compared to hamstring autograft. Hamstring grafts are associated with decreased deep flexion strength. Both grafts have comparable ultimate clinical failure rates when correctly tensioned and fixed.

Question 6

A 45-year-old female undergoes an open carpal tunnel release. During the procedure, the incision is inadvertently placed too far ulnar to the axis of the ring finger. Which of the following structures is most at immediate risk?

Explanation

During an open carpal tunnel release, placing the incision too far ulnar (ulnar to the ring finger axis) places the contents of Guyon's canal (the ulnar nerve and artery) at risk. The incision is typically made in line with the radial border of the ring finger to safely avoid the palmar cutaneous branch of the median nerve radially and the ulnar neurovascular bundle ulnarly.

Question 7

A 65-year-old man presents with progressive clumsiness in his hands and difficulty walking. Examination shows positive Hoffmann's sign bilaterally and hyperreflexia in the lower extremities. MRI reveals severe cervical stenosis at C4-C5 and C5-C6. Which physical exam finding would most specifically indicate an upper motor neuron lesion resulting from cervical spine pathology?

Explanation

The inverted supinator reflex (brachioradialis reflex) is elicited by tapping the brachioradialis tendon. A positive response (finger flexion) indicates a lower motor neuron lesion at C5 and an upper motor neuron lesion below the C5 level, making it highly specific to cervical myelopathy. The Babinski sign is an UMN sign but does not specifically localize to the cervical spine (could be thoracic).

Question 8

A 15-year-old boy presents with a painful mass near his knee. Radiographs reveal a destructive metaphyseal lesion of the distal femur with a 'sunburst' periosteal reaction. Biopsy confirms high-grade, conventional osteosarcoma. Following complete staging, what is the most appropriate initial step in management?

Explanation

The standard of care for high-grade, conventional appendicular osteosarcoma is neoadjuvant chemotherapy (typically MAP: Methotrexate, Doxorubicin/Adriamycin, Cisplatin), followed by wide surgical resection (limb salvage if possible), and concluding with adjuvant chemotherapy. Osteosarcoma is generally considered radioresistant.

Question 9

A 30-year-old male sustains a severely comminuted closed tibia fracture. Several hours later in the emergency department, he complains of severe pain out of proportion to the injury. Which of the following is the most sensitive early clinical sign of acute compartment syndrome?

Explanation

Pain with passive stretch of the muscles in the affected compartment is widely regarded as the most sensitive and earliest clinical sign of acute compartment syndrome. The '5 Ps' (pain, pallor, pulselessness, paresthesias, paralysis) are classically taught, but pulselessness, pallor, and paralysis are late signs indicating irreversible ischemic damage.

Question 10

A 40-year-old male sustains an acute, complete mid-substance Achilles tendon rupture playing basketball. He elects for functional nonoperative management with early mobilization. According to recent literature, what is the primary risk associated with this approach compared to operative repair?

Explanation

Nonoperative management of Achilles tendon ruptures, even with modern functional rehabilitation protocols, historically and currently carries a slightly higher rate of re-rupture compared to operative repair. Conversely, operative repair is associated with higher rates of superficial and deep wound infections, as well as sural nerve injury.

Question 11

Articular cartilage is a highly specialized tissue designed to distribute mechanical loads. While water is the most abundant component, which of the following macromolecules is primarily responsible for providing the tensile strength of articular cartilage?

Explanation

Type II collagen is the primary collagenous component (making up 90-95% of the collagen) in articular cartilage and forms a fibrillar network that provides the tissue with its tensile strength and resistance to shear forces. Proteoglycans (such as aggrecan) draw in water via osmotic pressure, providing compressive stiffness.

Question 12

In the Ponseti method for correcting idiopathic congenital talipes equinovarus (clubfoot), which component of the deformity must be addressed and corrected first during serial casting?

Explanation

The sequence of correction in the Ponseti method follows the mnemonic CAVE: Cavus, Adductus, Varus, Equinus. The very first step is to correct the Cavus deformity by supinating the forefoot and elevating the first ray to align the forefoot with the hindfoot.

Question 13

During a primary posterior-stabilized total knee arthroplasty, the surgeon employs spacer blocks to assess the gaps. The knee is found to be excessively tight in flexion but perfectly balanced in extension. Which of the following surgical adjustments is most appropriate to correct this mismatch?

Explanation

If a knee is tight in flexion and balanced in extension, the flexion gap is too small while the extension gap is correct. Decreasing the AP size of the femoral component (often combined with anterior translation if needed) will increase the flexion gap without affecting the extension gap. Resecting more distal femur alters the extension gap. Resecting more tibia alters both gaps.

Question 14

According to the Young-Burgess classification, an anteroposterior compression (APC) type II pelvic ring injury is characterized by rupture of the anterior sacroiliac ligaments. What is the classic radiographic appearance of the pubic symphysis in this specific injury pattern?

Explanation

In an APC II injury, the pubic symphysis diastasis is typically greater than 2.5 cm. This represents disruption of the symphyseal ligaments as well as the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The robust posterior sacroiliac ligaments remain intact, leading to an externally rotated ('open book') but vertically stable pelvis.

Question 15

A 24-year-old male sustains a non-displaced fracture of the proximal pole of the scaphoid. The tenuous blood supply to the scaphoid makes this fracture highly prone to nonunion. This primary blood supply is delivered predominantly by branches of which artery?

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters the bone at the dorsal ridge (distal to the waist) and supplies the proximal pole via intraosseous retrograde flow. This distal-to-proximal retrograde vascularity places proximal pole fractures at a high risk for avascular necrosis and nonunion.

Question 16

In the biomechanical principles of fracture fixation using plates and screws, how is the 'working length' of a plate defined?

Explanation

The working length of a plate is defined as the distance between the two innermost screws (the first screws placed on either side of the fracture). Increasing the working length increases the relative flexibility of the construct, allowing for micro-motion which can promote secondary bone healing, particularly in bridge plating techniques.

Question 17

A 14-year-old female gymnast presents with an insidious onset of low back pain exacerbated by extension. Radiographs reveal a Grade I isthmic spondylolisthesis at L5-S1. The bilateral pars interarticularis defects are most clearly visualized on which specific radiographic view?

Explanation

The oblique radiograph of the lumbar spine is the classic view to best visualize the pars interarticularis, often described by the 'Scotty dog' sign. A defect or fracture of the pars interarticularis (spondylolysis) appears as a radiolucent line at the 'collar' of the Scotty dog.

Question 18

A 68-year-old male presents with a pathologic subtrochanteric femur fracture. Laboratory workup reveals hypercalcemia, renal insufficiency, and anemia. Radiographs show multiple punched-out lytic lesions in the pelvis and skull. What is the most definitive diagnostic test to confirm the suspected underlying systemic condition?

Explanation

The clinical presentation is classic for multiple myeloma (CRAB criteria: hypercalcemia, renal failure, anemia, bone lesions). The definitive diagnostic test to confirm multiple myeloma is a bone marrow aspirate and biopsy showing >10% clonal plasma cells. Bone scans are typically cold (false negative) because myeloma inhibits osteoblastic activity.

Question 19

A 20-year-old male sustains an anterior shoulder dislocation during a tackle. Following reduction, an MRI arthrogram reveals an avulsion of the anterior inferior labrum along with the anterior band of the inferior glenohumeral ligament (IGHL) directly off the glenoid rim. This specific lesion is termed a:

Explanation

A Bankart lesion is an avulsion of the anterior-inferior labrum and the attached inferior glenohumeral ligament (IGHL) complex from the anterior glenoid rim. It is the most common pathologic lesion (essential lesion) in traumatic anterior shoulder instability. An ALPSA lesion is similar but the labroligamentous complex is displaced medially and inferiorly along the scapular neck.

Question 20

A 4-month-old female infant is being evaluated for developmental dysplasia of the hip (DDH). She has been treated with a properly applied Pavlik harness for 4 weeks; however, follow-up clinical examination and ultrasound show no improvement, and the hip remains dislocated. What is the next most appropriate step in management?

Explanation

Failure of Pavlik harness treatment for DDH is typically defined if the hip remains dislocated after 3-4 weeks of proper wear. Continuing the harness in a persistently dislocated hip places the infant at high risk for 'Pavlik harness disease' (erosion of the posterior acetabular wall). The next most appropriate step for an infant of this age is a closed reduction and spica casting under general anesthesia, usually confirmed with an intraoperative arthrogram.

Question 21

What is the final deformity corrected in the serial casting phase of the Ponseti method for idiopathic clubfoot?

Explanation

The sequence of correction in Ponseti casting follows the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. The equinus deformity is typically the last to be addressed and often requires a percutaneous Achilles tenotomy to achieve adequate dorsiflexion.

Question 22

A 45-year-old male sustains a high-energy injury resulting in a bicondylar tibial plateau fracture with dissociation of the metaphysis from the diaphysis. Which Schatzker classification does this represent?

Explanation

Schatzker Type VI is defined by a tibial plateau fracture with metaphyseal-diaphyseal dissociation. It is a severe, high-energy injury. Type V is a bicondylar fracture but maintains continuity between the metaphysis and diaphysis.

Question 23

When selecting an autograft for an anterior cruciate ligament (ACL) reconstruction, which of the following provides the highest initial ultimate tensile load compared to the native ACL?

Explanation

A quadrupled hamstring graft has an initial ultimate tensile load of approximately 4000-4100 N, which is significantly higher than the native ACL (~2160 N) and a 10mm BPTB graft (~2977 N). However, graft healing, incorporation, and fixation strength also play critical roles in long-term clinical outcomes.

Question 24

Which of the following genetic alterations is most frequently associated with classic high-grade intramedullary osteosarcoma?

Explanation

Mutations in the tumor suppressor genes RB1 (retinoblastoma) and TP53 (Li-Fraumeni syndrome) are strongly linked to the development of osteosarcoma. t(11;22) is characteristic of Ewing sarcoma, t(X;18) is seen in synovial sarcoma, EXT1/2 mutations cause multiple hereditary exostoses, and t(12;16) is associated with myxoid liposarcoma.

Question 25

In total hip arthroplasty, the use of highly cross-linked polyethylene significantly improves implant longevity primarily by reducing which specific type of wear?

Explanation

Highly cross-linked polyethylene primarily decreases adhesive wear, which is the main mechanism of volumetric wear in standard ultra-high-molecular-weight polyethylene (UHMWPE) bearings. The cross-linking process restricts polymer chain mobility. Note that while wear resistance increases, fatigue strength may decrease slightly.

Question 26

A patient presents with weakness in wrist flexion and finger extension, a diminished triceps reflex, and numbness isolated to the middle finger. Which cervical nerve root is most likely compressed?

Explanation

C7 radiculopathy classically presents with sensory deficits in the middle finger, a diminished triceps reflex, and motor weakness in the triceps, wrist flexors, and finger extensors. This is the most common cervical radiculopathy.

Question 27

Which artery provides the predominant blood supply to the adult femoral head?

Explanation

The lateral epiphyseal artery, which is the terminal branch of the medial femoral circumflex artery (MFCA), provides the vast majority of the blood supply to the adult femoral head. Damage to this vessel during trauma or surgery significantly increases the risk of avascular necrosis.

Question 28

A flexor tendon laceration occurs in the region extending from the distal palmar crease to the middle of the middle phalanx. This injury falls into which anatomical flexor tendon zone?

Explanation

Zone II, historically termed 'no man's land' due to poor surgical outcomes in the past, extends from the A1 pulley (distal palmar crease) to the insertion of the flexor digitorum superficialis (FDS) at the mid-middle phalanx. Both FDS and FDP tendons run tightly within the flexor sheath in this zone.

Question 29

Which of the following processes accurately characterizes intramembranous ossification during bone formation?

Explanation

Intramembranous ossification involves the direct differentiation of mesenchymal stem cells into osteoblasts, bypassing any cartilaginous intermediate. This process forms the flat bones of the skull, the clavicle, and the periosteal outer layer of long bones (appositional growth).

Question 30

The Lisfranc ligament is a critical stabilizing structure of the midfoot. Which two osseous structures does it directly connect?

Explanation

The Lisfranc ligament is an interosseous ligament that runs obliquely from the lateral aspect of the medial (first) cuneiform to the medial aspect of the base of the second metatarsal. There is no direct ligamentous connection between the first and second metatarsal bases, making the Lisfranc ligament crucial for stabilizing the tarsometatarsal joint.

Question 31

When utilizing a Pavlik harness for the treatment of Developmental Dysplasia of the Hip (DDH), hyperflexion of the hips most commonly places the infant at risk for which complication?

Explanation

Femoral nerve palsy is the most common nerve injury associated with the Pavlik harness and is typically caused by excessive hip flexion. Avascular necrosis is a devastating complication usually associated with extreme hyperabduction rather than hyperflexion.

Question 32

A 30-year-old sustains an open tibial shaft fracture with an 11 cm soft tissue laceration due to a motorcycle collision. Following thorough surgical debridement, there is adequate soft tissue to close over the bone without the need for a local or free flap. What is the correct Gustilo-Anderson classification?

Explanation

Type IIIA open fractures involve high-energy trauma with extensive soft tissue laceration (often >10 cm) but retain adequate soft tissue coverage over the fractured bone, not requiring flap coverage. Type IIIB requires a rotational or free flap for soft tissue coverage, and Type IIIC involves an arterial injury requiring repair.

Question 33

Denosumab is an effective targeted medical therapy used in the treatment of Giant Cell Tumor of Bone. It exerts its effect by binding directly to which of the following molecules?

Explanation

Denosumab is a fully human monoclonal antibody that binds directly to RANKL (Receptor Activator of Nuclear factor Kappa-B Ligand). In Giant Cell Tumor of Bone, the neoplastic mononuclear stromal cells overexpress RANKL, which recruits and activates the reactive osteoclast-like giant cells. Denosumab blocks this interaction.

Question 34

According to the Snyder classification, a Type II SLAP (Superior Labrum Anterior to Posterior) tear is best characterized by which of the following descriptions?

Explanation

Type II SLAP lesions involve the detachment of the superior labrum and the origin of the long head of the biceps tendon from the superior glenoid tubercle, resulting in a pathological instability of the biceps-labral complex. Type I is fraying; Type III is a bucket-handle tear with an intact anchor; Type IV is a bucket-handle tear extending into the biceps tendon.

Question 35

Which specific type of collagen is the predominant structural protein in articular hyaline cartilage, responsible for its tensile strength?

Explanation

Type II collagen makes up 90-95% of the collagen found in articular (hyaline) cartilage and provides the structural framework that resists tensile and shear forces. Type I collagen is predominant in bone, tendon, and fibrocartilage (e.g., meniscus). Type X is found in the hypertrophic zone of the epiphyseal plate.

Question 36

Based on the Meyerding classification for spondylolisthesis, a Grade III slip indicates what percentage of anterior translation of the superior vertebral body over the inferior vertebral body?

Explanation

The Meyerding classification grades the severity of spondylolisthesis based on the percentage of slippage: Grade I (1-25%), Grade II (26-50%), Grade III (51-75%), Grade IV (76-100%), and Grade V (spondyloptosis, >100%).

Question 37

During deep flexion of the normal native human knee joint, how does the center of rotation of the distal femur move relative to the tibial plateau?

Explanation

During normal knee flexion, the femoral condyles exhibit 'posterior rollback' relative to the tibia. This kinematic mechanism, primarily driven by the posterior cruciate ligament (PCL) and meniscal geometry, maximizes flexion by delaying posterior impingement between the femur and the posterior tibial plateau.

Question 38

Which of the following physical examination maneuvers is considered the most sensitive for the clinical diagnosis of Carpal Tunnel Syndrome?

Explanation

Durkan's carpal compression test, which involves applying direct pressure over the carpal tunnel for 30 seconds to elicit paresthesias, has been shown to be the most sensitive and specific physical examination provocative test for diagnosing Carpal Tunnel Syndrome, outperforming both Tinel's and Phalen's tests.

Question 39

In the treatment of severe Slipped Capital Femoral Epiphysis (SCFE), an intracapsular cuneiform osteotomy of the femoral neck is performed. This aggressive over-correction most significantly increases the risk of which devastating complication?

Explanation

Avascular necrosis (AVN) is the most severe and devastating complication of SCFE treatment. Intracapsular base-of-neck or cuneiform osteotomies aggressively stretch or transect the retinacular vessels (branches of the MFCA), leading to a high rate of AVN compared to in-situ pinning or extracapsular osteotomies.

Question 40

In a conscious patient with suspected acute compartment syndrome of the leg, which 'delta pressure' threshold is generally accepted as an objective indication for an urgent surgical fasciotomy?

Explanation

The delta pressure, calculated as the patient's diastolic blood pressure minus the measured compartment pressure, is considered the most reliable threshold. A delta pressure of less than 30 mmHg (some sources say <20-30 mmHg) indicates inadequate tissue perfusion and is a strong indication for fasciotomy, regardless of the absolute pressure.

Question 41

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up visit, the parents report she has stopped spontaneously kicking her affected leg. Physical examination reveals an absence of active knee extension. Which of the following is the most appropriate next step in management?

Explanation

The patient has developed a femoral nerve palsy, a known complication of the Pavlik harness typically caused by excessive hip flexion. The standard management is to remove the harness or significantly relax the straps until spontaneous active knee extension returns, after which the harness can often be carefully reapplied or an alternative brace considered.

Question 42

Which of the following bone grafting materials inherently possesses osteogenic, osteoinductive, and osteoconductive properties?

Explanation

Iliac crest bone autograft is the 'gold standard' because it is the only option listed that provides all three essential properties for bone healing: osteoconduction (scaffold), osteoinduction (growth factors like BMPs), and osteogenesis (live osteoprogenitor cells). DBM is osteoconductive and osteoinductive but lacks live cells. Allograft is only osteoconductive. BMP-2 is purely osteoinductive.

Question 43

A 35-year-old male is struck by a motor vehicle and sustains a closed displaced acetabular fracture. Examination reveals a large, fluctuant soft-tissue swelling over the greater trochanter. Aspiration yields serosanguinous fluid. What is the most likely composition of the boundary of this fluid collection?

Explanation

The patient has a Morel-Lavallée lesion, which is a closed degloving injury where the skin and subcutaneous tissue are separated from the underlying fascia. The resulting potential space fills with blood, lymph, and necrotic fat, eventually forming a pseudocapsule made of compressed fibrous tissue, which often prevents spontaneous resolution and may require surgical excision or sclerodesis.

Question 44

A 22-year-old soccer player sustains a twisting knee injury. Radiographs reveal a small avulsion fracture of the lateral tibial plateau. This radiographic finding is pathognomonic for an injury to which of the following structures?

Explanation

A Segond fracture is an avulsion fracture of the lateral tibial plateau at the insertion of the anterolateral ligament (ALL) and lateral capsular ligament. It is highly associated (pathognomonic) with an anterior cruciate ligament (ACL) tear.

Question 45

When comparing operative versus nonoperative management of acute Achilles tendon ruptures using modern functional rehabilitation protocols, which of the following statements is most accurate?

Explanation

Recent high-quality studies demonstrate that when functional rehabilitation (early weight-bearing and range of motion) is employed, the re-rupture rates between operative and nonoperative management of acute Achilles tendon ruptures are comparable. However, operative management carries a higher risk of complications such as infection, wound breakdown, and sural nerve injury.

Question 46

A 14-year-old boy undergoes neoadjuvant chemotherapy followed by wide surgical resection for a conventional high-grade osteosarcoma of the distal femur. Which of the following histologic findings in the resected specimen is the most important prognostic factor for his long-term overall survival?

Explanation

The most significant prognostic factor for long-term survival in conventional high-grade osteosarcoma is the tumor's histologic response to neoadjuvant chemotherapy. A good response, defined as greater than 90% tumor necrosis (Huvos grade III or IV) in the resected specimen, correlates with significantly improved survival.

Question 47

A 55-year-old active female undergoes a primary total hip arthroplasty. At her 2-year follow-up, she complains of a reproducible 'squeaking' noise coming from her hip during walking, though she denies any pain. Which of the following bearing surface combinations was most likely used?

Explanation

Squeaking is a well-documented phenomenon unique to ceramic-on-ceramic total hip arthroplasty bearings. It occurs in a small percentage of patients and is thought to be related to stripe wear, component malposition, microseparation, or loss of fluid lubrication.

Question 48

A 28-year-old carpenter sustains a laceration over the volar aspect of the proximal phalanx of his index finger, resulting in an inability to flex the distal and proximal interphalangeal joints. This injury is located in which of the following flexor tendon zones?

Explanation

Flexor tendon Zone II, historically called 'no man/'s land', extends from the proximal edge of the A1 pulley to the insertion of the flexor digitorum superficialis (FDS) on the middle phalanx. Injuries here involve both the FDS and FDP tendons within the narrow fibro-osseous sheath, making surgical repair challenging.

Question 49

In healthy articular cartilage, which structural zone is characterized by collagen fibers aligned perpendicular to the joint surface and contains the highest concentration of proteoglycans?

Explanation

The deep (radial) zone of articular cartilage is characterized by thick collagen fibers (primarily Type II) aligned perpendicularly to the articular surface. This zone provides the greatest resistance to compressive forces due to its high concentration of water-retaining proteoglycans.

Question 50

A 30-year-old male sustains a closed tibial shaft fracture. Two hours later, he complains of severe leg pain out of proportion to the injury. Compartment pressures are measured. Which of the following criteria is the most reliable threshold for diagnosing acute compartment syndrome and indicating emergent fasciotomy?

Explanation

The Delta P (diastolic blood pressure minus the measured compartment pressure) is the most reliable indicator for acute compartment syndrome. A Delta P of less than 30 mmHg signifies that local tissue perfusion pressure is inadequate, establishing the need for emergent fasciotomies.

Question 51

A 12-year-old obese male presents with a unilateral slipped capital femoral epiphysis (SCFE) of the left hip. Which of the following patient profiles is a strongly accepted indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is generally indicated for patients at high risk for a future contralateral slip. These include patients with underlying endocrinopathies (e.g., hypothyroidism, growth hormone deficiency), metabolic bone disease, prior pelvic radiation, and very young age (typically < 10 years).

Question 52

A 65-year-old male presents with a painful total knee arthroplasty 3 years after the index procedure. Joint aspiration yields synovial fluid. Which of the following synovial fluid biomarkers has the highest specificity for diagnosing a periprosthetic joint infection (PJI)?

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It has been shown to have extremely high sensitivity and specificity for diagnosing periprosthetic joint infection, making it a highly reliable synovial fluid biomarker.

Question 53

A 60-year-old male complains of deteriorating handwriting, dropping objects, and a stiff-legged gait. Physical examination reveals a positive Hoffmann's sign and an inverted supinator reflex. What is the most likely diagnosis?

Explanation

The combination of fine motor skill deterioration, gait disturbance, and upper motor neuron signs (Hoffmann's sign, inverted supinator reflex, hyperreflexia) is the classic presentation for cervical spondylotic myelopathy (CSM).

Question 54

A 25-year-old male presents with chronic wrist pain following an untreated injury 2 years ago. Radiographs reveal a scaphoid nonunion with advanced carpal collapse. Which of the following articulations is classically spared from arthritic changes in a Scaphoid Nonunion Advanced Collapse (SNAC) wrist?

Explanation

In both Scapholunate Advanced Collapse (SLAC) and Scaphoid Nonunion Advanced Collapse (SNAC) patterns of wrist arthritis, the radiolunate joint is characteristically spared. This is due to the concentric, spherical articulation of the lunate fossa and the lunate, which avoids abnormal shear forces even when carpal kinematics are altered.

Question 55

A 24-year-old football player sustains an axial load to a plantarflexed foot. Weight-bearing radiographs demonstrate a 3 mm diastasis between the base of the first and second metatarsals. The primary stabilizing structure that is injured connects which two bones?

Explanation

The Lisfranc ligament is an intra-articular ligament that connects the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. There is no transverse intermetatarsal ligament between the bases of the first and second metatarsals, making the Lisfranc ligament the critical stabilizer of this complex.

Question 56

During the preoperative planning for a patient with recurrent anterior shoulder instability, the 'glenoid track' concept is utilized. An 'off-track' Hill-Sachs lesion without critical glenoid bone loss is best managed by which of the following soft-tissue procedures in addition to an arthroscopic Bankart repair?

Explanation

An 'off-track' Hill-Sachs lesion is one that engages the anterior glenoid rim during shoulder abduction and external rotation. When glenoid bone loss is subcritical, adding a Remplissage (insetting the infraspinatus tendon and posterior capsule into the Hill-Sachs defect) to the Bankart repair effectively converts the lesion to an 'on-track' lesion, preventing engagement.

Question 57

A 32-year-old female presents with a lytic, eccentrically located lesion in the distal femoral epiphysis. Biopsy confirms a Giant Cell Tumor of bone. She is treated preoperatively with denosumab to consolidate the tumor and reduce its vascularity. What is the specific molecular target of this medication?

Explanation

Denosumab is a human monoclonal antibody that binds to RANKL, preventing it from activating RANK on the surface of osteoclasts. In Giant Cell Tumor of bone, the neoplastic stromal cells express RANKL, which recruits and activates the reactive, bone-destroying multinucleated giant cells.

Question 58

According to the Gustilo-Anderson classification, a 4 cm laceration over a tibial shaft fracture with moderate soft tissue damage, but adequate periosteal coverage and no massive contamination, is classified as which of the following?

Explanation

A Gustilo-Anderson Type II open fracture is defined as having an open wound > 1 cm and < 10 cm without extensive soft tissue damage, flaps, or avulsions. There is adequate soft tissue coverage of the bone and no massive contamination.

Question 59

During the normal biological process of tendon healing, which of the following best describes the predominant collagen type synthesized and deposited during the early proliferative phase (typically days 5 to 28)?

Explanation

Tendon healing occurs in overlapping phases: inflammatory, proliferative, and remodeling. During the proliferative phase, fibroblasts primarily synthesize Type III collagen, which forms a disorganized extracellular matrix. During the later remodeling phase, this is gradually replaced by the stronger, highly organized Type I collagen.

Question 60

A 2-week-old infant with congenital talipes equinovarus (clubfoot) is undergoing the Ponseti casting method. What is the correct sequence of deformity correction utilizing this technique?

Explanation

The Ponseti method follows a strict sequence of deformity correction summarized by the mnemonic CAVE: Cavus (corrected by supinating the forefoot to align with the hindfoot), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 61

Which of the following bone graft options possesses osteogenic, osteoinductive, and osteoconductive properties?

Explanation

Autogenous bone graft is the only option that contains live cells (osteogenic), growth factors (osteoinductive), and a structural scaffold (osteoconductive). Allografts lack osteogenic properties due to processing.

Question 62

A 45-year-old male sustains a midshaft tibial fracture. Which of the following cytokines is primarily responsible for the initial recruitment of mesenchymal stem cells to the fracture site?

Explanation

PDGF is released from degranulating platelets in the fracture hematoma immediately after injury. It acts as a powerful chemoattractant and mitogen for mesenchymal stem cells, initiating the healing cascade.

Question 63

A 55-year-old female presents with an anterior shoulder dislocation and an associated greater tuberosity fracture. Following closed reduction, radiographs demonstrate the greater tuberosity is displaced superiorly by 8 mm. What is the most appropriate management?

Explanation

In active patients, greater tuberosity displacement of more than 5 mm after reduction of an anterior shoulder dislocation is generally an indication for surgical fixation. This prevents subacromial impingement and restores rotator cuff function.

Question 64

A 4-month-old infant has been treated with a Pavlik harness for 4 weeks for a completely dislocated left hip. Ultrasound evaluation today shows the hip remains persistently dislocated. What is the most appropriate next step in management?

Explanation

Failure to achieve reduction after 3-4 weeks of Pavlik harness treatment requires cessation of the harness to prevent "Pavlik harness disease" (posterior acetabular wear). The next appropriate step is typically a closed reduction and spica casting under general anesthesia.

Question 65

A 22-year-old collegiate soccer player undergoes anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BPTB) autograft. Compared to hamstring autograft, the BPTB graft is associated with a higher incidence of which of the following?

Explanation

Bone-patellar tendon-bone (BPTB) autografts have excellent clinical outcomes but are consistently associated with a higher incidence of donor-site morbidity, specifically anterior knee pain and pain with kneeling, compared to hamstring autografts.

Question 66

A 24-year-old male falls on an outstretched hand and sustains a non-displaced fracture of the scaphoid waist. Which of the following best describes the blood supply to the proximal pole of the scaphoid?

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters the distal pole and flows in a retrograde fashion. This retrograde blood supply puts proximal pole fractures at high risk for avascular necrosis.

Question 67

A 35-year-old male sustains a burst fracture of the atlas (Jefferson fracture) after a diving accident. On the open-mouth odontoid radiograph, the rule of Spence is evaluated. Transverse atlantal ligament rupture is highly suspected if the combined overhang of the C1 lateral masses on C2 exceeds what value?

Explanation

According to the rule of Spence, a combined lateral overhang of the C1 lateral masses on C2 of greater than 6.9 mm on an open-mouth radiograph indicates a rupture of the transverse atlantal ligament. This implies C1-C2 instability requiring rigid immobilization or surgical fusion.

Question 68

A 60-year-old male undergoes total hip arthroplasty using a ceramic-on-ceramic bearing surface. Three years later, he complains of an audible squeaking sound from the hip during movement, though he is pain-free. What is the most common mechanical etiology associated with this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is often associated with edge loading, which leads to "stripe wear" on the femoral head. Edge loading typically occurs due to component malposition, particularly excessive cup anteversion or inclination.

Question 69

A 27-year-old male sustains a foot injury while playing football. Weight-bearing radiographs reveal widening of the space between the medial cuneiform and the base of the second metatarsal, with a small avulsion fracture noted in this interval. What is the primary stabilizing structure that has been disrupted?

Explanation

The Lisfranc ligament connects the medial cuneiform to the base of the second metatarsal and is essential for midfoot stability. An avulsion fracture in this space (the "fleck sign") is pathognomonic for a Lisfranc injury.

Question 70

A 14-year-old boy presents with night pain in his right femur. Radiographs reveal a permeative, diaphyseal lytic lesion with an "onion-skin" periosteal reaction. Biopsy confirms small blue cells. Which of the following cytogenetic abnormalities is most characteristic of this diagnosis?

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The most common chromosomal translocation associated with Ewing sarcoma is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein.

Question 71

A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture with posteromedial displacement of the distal fragment. Which nerve is most at risk of injury in this specific displacement pattern?

Explanation

In posteromedially displaced supracondylar humerus fractures, the proximal fragment goes anterolaterally, putting the radial nerve at the greatest risk of tethering or injury. Posterolateral displacement puts the median nerve (specifically AIN) at greatest risk.

Question 72

A 38-year-old male is brought to the trauma bay in hemorrhagic shock after a motorcycle crash. Pelvic radiographs show an APC-III pelvic ring injury. A pelvic binder is applied to reduce pelvic volume. Over which anatomic landmark should the binder be centered for maximal effectiveness?

Explanation

To effectively reduce pelvic volume in anteroposterior compression (open book) injuries, a pelvic binder or sheet must be centered directly over the greater trochanters. Placement higher over the iliac crests is less effective and can paradoxically open the pelvis further in certain fracture patterns.

Question 73

During a posterior-stabilized total knee arthroplasty, the surgeon prepares to make the proximal tibial bone cut. The popliteal artery is at risk during this step. At the level of the knee joint, what is the anatomical relationship of the popliteal artery to the posterior capsule?

Explanation

At the level of the joint line, the popliteal artery is separated from the posterior capsule only by a thin layer of fat, making it highly vulnerable to injury during the proximal tibial cut or posterior retractor placement.

Question 74

A 25-year-old athlete undergoes arthroscopic repair of a medial meniscus tear. Which of the following best describes the vascularity of the meniscus and its potential for healing?

Explanation

The adult meniscus has a limited blood supply, with only the peripheral 10-30% (the red-red zone) being vascularized by branches of the medial, lateral, and middle geniculate arteries. Tears in this peripheral zone have the best healing capacity following repair.

Question 75

A 29-year-old rugby player injures his ring finger. Examination reveals inability to actively flex the distal interphalangeal (DIP) joint. Radiographs are negative. MRI shows the flexor digitorum profundus (FDP) tendon is retracted into the palm. What is the optimal timeframe for surgical repair?

Explanation

This is a Zone 1 FDP avulsion (Jersey finger) retracted into the palm (Leddy-Packer Type 1). The vincula are torn, compromising blood supply, so repair must be performed within 7-10 days to prevent tendon necrosis and irreversible contracture.

Question 76

During revision of a failed internal fixation, a surgeon contemplates using titanium screws in conjunction with a stainless steel plate. Which of the following biomaterial principles makes this combination potentially problematic?

Explanation

Mixing dissimilar metals, such as stainless steel and titanium, in an electrolytic environment (like the human body) can lead to galvanic corrosion. The less noble metal acts as an anode and corrodes at an accelerated rate.

Question 77

A 68-year-old female presents with bilateral leg pain that worsens with walking and prolonged standing. She notes that leaning forward on a shopping cart relieves the pain. Which of the following diagnostic findings is most likely to be present?

Explanation

The patient's symptoms are classic for neurogenic claudication due to lumbar spinal stenosis, commonly relieved by flexion (shopping cart sign) and exacerbated by extension. Hypertrophy of the ligamentum flavum, facet arthropathy, and disc bulging are the primary causes of acquired central canal stenosis.

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