OITE Orthopedic Surgery Board Review MCQs: Part 43

Question 1

In planning an osteotomy for a uniplanar angular deformity of the tibia, placing the hinge of the osteotomy directly on the convex cortex at the center of rotation of angulation (CORA) will result in which of the following?

Explanation

According to Paley's rules of osteotomy, if the osteotomy and the hinge are both placed at the CORA on the convex side of the deformity, an opening wedge correction without translation will result. If the hinge is placed at the CORA on the concave side, a closing wedge correction without translation results.

Question 2

A 42-year-old male sustains a terrible triad injury of the elbow. During surgical reconstruction, what is the most widely accepted standard sequence of repair to restore elbow stability?

Explanation

The standard surgical algorithm for a terrible triad injury (elbow dislocation, radial head fracture, coronoid fracture) typically proceeds from deep to superficial, or anterior to posterior: 1) Fixation or capsular repair of the coronoid, 2) Fixation or replacement of the radial head, 3) Repair of the lateral collateral ligament (LCL) complex. If the elbow remains unstable after these steps, the medial collateral ligament (MCL) repair or application of a hinged external fixator may be considered.

Question 3

A 55-year-old female presents with progressive medial foot pain and a flatfoot deformity. Examination reveals a flexible hindfoot valgus and an inability to perform a single-leg heel rise. Weight-bearing radiographs demonstrate talonavicular uncoverage of 60%. Which of the following surgical strategies is most appropriate?

Explanation

The patient has Stage IIb adult-acquired flatfoot deformity (posterior tibial tendon dysfunction). Stage II indicates a flexible deformity. Stage IIa has minimal forefoot abduction, typically managed with FDL transfer and MDCO. Stage IIb is characterized by significant forefoot abduction (talonavicular uncoverage > 40-50%). Addition of a lateral column lengthening (e.g., Evans osteotomy) to the FDL transfer and MDCO is necessary to correct the severe forefoot abduction.

Question 4

Which of the following represents the correct sequence of degenerative changes seen in Scaphoid Nonunion Advanced Collapse (SNAC)?

Explanation

SNAC wrist arthritis follows a predictable pattern of progression due to abnormal kinematics of the distal scaphoid fragment. Stage I: arthritis at the radial styloid and distal scaphoid. Stage II: arthritis progresses to the scaphocapitate joint. Stage III: arthritis involves the lunocapitate joint. The radiolunate joint is characteristically spared in both SLAC and SNAC wrists due to its concentric, purely spherical articulation.

Question 5

A 6-year-old boy presents with a displaced extension-type supracondylar humerus fracture. On initial examination, the hand is pink and well-perfused, but the radial pulse is absent. After closed reduction and percutaneous pinning, the radial pulse remains absent, but the hand remains pink with a capillary refill time of less than 2 seconds. What is the most appropriate next step in management?

Explanation

A 'pink, pulseless' hand following reduction and pinning of a pediatric supracondylar humerus fracture is indicative of adequate collateral circulation despite probable brachial artery spasm, kinking, or entrapment. Current AAOS and POSNA guidelines recommend admission for close observation (typically 24-48 hours) as long as the hand remains well-perfused (warm, pink, capillary refill <2 seconds). Immediate exploration is reserved for a 'white, pulseless' hand (dysvascular) that does not improve after reduction.

Question 6

A 52-year-old male with poorly controlled diabetes presents with a swollen, erythematous, and warm right foot. He denies trauma. Radiographs show periarticular debris, joint subluxation, and fragmentation of the tarsometatarsal joints. According to the Eichenholtz classification, what is the optimal treatment at this stage?

Explanation

The patient is in Eichenholtz Stage I (Developmental/Fragmentation phase) of Charcot neuroarthropathy, characterized by acute inflammation, erythema, joint subluxation, and bony fragmentation. The standard of care for acute Stage I Charcot is immobilization in a total contact cast and strict non-weight-bearing to prevent further deformity until the acute inflammatory phase resolves (transition to Stage II - Coalescence). Surgery in the acute inflammatory phase carries high rates of failure and complication.

Question 7

A 2-year-old child presents with bilateral genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle (MDA) of 20 degrees bilaterally. What is the most appropriate initial management?

Explanation

In a child under 3 years old with suspected infantile Blount's disease, a metaphyseal-diaphyseal angle (MDA or Drennan's angle) greater than 16 degrees strongly suggests true Blount's disease rather than physiologic bowing. The initial treatment for infantile Blount's disease in children under age 3 is bracing with knee-ankle-foot orthoses (KAFOs). Surgery is indicated if bracing fails or if the child presents at an older age with advanced Langenskiöld stages.

Question 8

A 28-year-old tennis player presents with ulnar-sided wrist pain and clicking. Examination reveals instability of the distal radioulnar joint (DRUJ) in both supination and pronation. MRI arthrogram demonstrates a full-thickness tear of the triangular fibrocartilage complex (TFCC) at its foveal attachment. Which of the following is the primary stabilizing structure of the DRUJ disrupted in this patient?

Explanation

The primary stabilizers of the DRUJ are the radioulnar ligaments (volar and dorsal). However, it is the deep (proximal) fibers of these ligaments that converge to attach at the fovea of the ulna (ligamentum subcruentum) that serve as the true isometric axis of rotation and the primary restraint to DRUJ translation. Tears of the superficial attachment to the ulnar styloid (Palmer 1B) typically do not cause gross DRUJ instability, whereas deep foveal avulsions do.

Question 9

A 40-year-old woman falls on an outstretched hand and sustains a coronal shear fracture of the distal humerus. CT imaging reveals that the fracture fragment includes the capitellum and extends medially to include the majority of the trochlea. According to the McKee modification of the Bryan and Morrey classification, what type of fracture is this?

Explanation

The Bryan and Morrey classification describes capitellum fractures. Type I (Hahn-Steinthal) is a large capitellar fragment with substantial subchondral bone. Type II (Kocher-Lorenz) involves articular cartilage with minimal subchondral bone. Type III (Broberg-Morrey) is comminuted. McKee added Type IV, which is a coronal shear fracture that involves the capitellum and extends medially to include most or all of the trochlea.

Question 10

A 24-year-old male sustains a Hawkins Type III talar neck fracture. Which of the following arteries provides the majority of the blood supply to the body of the talus, placing it at highest risk for avascular necrosis in this injury pattern?

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, is the dominant blood supply to the body of the talus. It forms an anastomotic sling with the artery of the tarsal sinus (from the anterior tibial/dorsalis pedis and peroneal arteries). In a Hawkins Type III fracture (talar neck fracture with subluxation/dislocation of both the subtalar and tibiotalar joints), the major blood supplies are disrupted, leading to an AVN risk approaching 80-100%.

Question 11

When assessing a patient with a lower extremity deformity, the mechanical axis deviation (MAD) is measured. Which of the following accurately describes the relationship between the mechanical and anatomic axes of the normal femur and tibia?

Explanation

In a normal lower extremity, the mechanical axis of the femur runs from the center of the femoral head to the center of the knee. The anatomic axis of the femur runs down the intramedullary canal, meaning it is typically 5 to 7 degrees valgus relative to the mechanical axis. For the tibia, the mechanical and anatomic axes are normally parallel (or co-linear), running from the center of the knee down the intramedullary canal to the center of the ankle.

Question 12

A 22-year-old male presents with a scaphoid waist fracture. Avascular necrosis of the proximal pole is a known complication. Which of the following describes the primary arterial supply to the scaphoid?

Explanation

The primary blood supply to the scaphoid comes from the dorsal carpal branch of the radial artery, which enters the scaphoid distally (in the region of the distal pole and dorsal ridge) and flows retrogradely to supply the proximal pole. Because of this retrograde blood supply, fractures at the scaphoid waist or proximal pole disrupt the vascularity to the proximal fragment, significantly increasing the risk of avascular necrosis and nonunion.

Question 13

During an ulnar collateral ligament (UCL) reconstruction of the elbow using the docking technique, the surgeon must be careful to avoid injury to the primary dynamic stabilizer against valgus stress. Which of the following muscles acts as the primary dynamic valgus stabilizer of the elbow?

Explanation

While the anterior bundle of the UCL is the primary static stabilizer against valgus stress at the elbow, the flexor carpi ulnaris (FCU) and the flexor digitorum superficialis (FDS) are the primary dynamic stabilizers. Biomechanical studies have shown that the flexor carpi ulnaris provides the greatest dynamic stabilization against valgus forces during the throwing motion.

Question 14

A 45-year-old male presents with a neglected Achilles tendon rupture that occurred 4 months ago. On examination, he has a palpable gap of 6 cm and profound plantarflexion weakness. The surgeon decides to perform an open reconstruction. Which of the following tendon transfers is most commonly utilized to augment this repair?

Explanation

For chronic or neglected Achilles tendon ruptures with a large defect (typically > 5 cm), primary repair is often impossible without excessive tension. Flexor hallucis longus (FHL) tendon transfer is the procedure of choice for augmentation. The FHL is preferred because of its strength (strongest deep plantar flexor), its axis of pull, its proximity to the Achilles, and its phase of contraction (in phase with the triceps surae).

Question 15

A 14-year-old boy is undergoing tibial lengthening via distraction osteogenesis. Four weeks into the distraction phase, radiographs show poor regenerate bone formation (the gap is radiolucent, without premature consolidation). Which of the following modifications to the distraction protocol is the most appropriate next step?

Explanation

Poor regenerate bone formation (hypotrophic regenerate) during distraction osteogenesis can be addressed by the 'accordion technique,' which involves temporarily stopping distraction and compressing the site (typically 1 mm/day for several days) followed by resuming distraction. This cyclical compression and distraction mechanically stimulates osteogenesis. Increasing the rate would worsen the gap.

Question 16

A 32-year-old construction worker presents with chronic dorsal wrist pain. Radiographs reveal sclerosis and fragmentation of the lunate with a radioscaphoid angle of 65 degrees and proximal migration of the capitate. According to the Lichtman classification of Kienböck's disease, what stage does this represent?

Explanation

The Lichtman classification of Kienböck's disease is based on radiographic findings. Stage I: normal x-ray, MRI shows changes. Stage II: lunate sclerosis without collapse. Stage III: lunate collapse. Stage III is subdivided: Stage IIIA has normal carpal alignment, whereas Stage IIIB has carpal collapse (fixed scaphoid rotation/flexion with a radioscaphoid angle > 60 degrees, and proximal capitate migration). Stage IV involves degenerative arthritis of the midcarpal or radiocarpal joints.

Question 17

A patient complains of elbow clicking and a sense of giving way when pushing out of a chair. The lateral pivot-shift test of the elbow reproduces the symptoms. This instability pattern (PLRI) is primarily caused by insufficiency of which of the following structures?

Explanation

Posterolateral rotatory instability (PLRI) of the elbow is the most common pattern of chronic elbow instability. It is classically caused by insufficiency or rupture of the lateral ulnar collateral ligament (LUCL). The LUCL serves as the primary restraint to posterolateral subluxation of the radial head and proximal ulna relative to the humerus.

Question 18

A 30-year-old female sustains a purely ligamentous Lisfranc injury involving the first, second, and third tarsometatarsal joints. Which of the following is true regarding the surgical management of this specific injury pattern compared to open reduction and internal fixation (ORIF)?

Explanation

Level I evidence (e.g., Ly and Coetzee) has demonstrated that primary arthrodesis of the medial two or three tarsometatarsal joints for purely ligamentous Lisfranc injuries yields superior functional outcomes and requires fewer secondary surgeries compared to ORIF. ORIF in purely ligamentous injuries frequently fails or requires secondary hardware removal, often eventually necessitating a salvage arthrodesis.

Question 19

A 5-year-old child presents with severe bilateral genu varum, short stature, and waddling gait. Laboratory tests reveal low serum phosphate, normal serum calcium, normal parathyroid hormone, and elevated alkaline phosphatase. Genetic testing confirms an X-linked dominant mutation in the PHEX gene. Which of the following medications is currently considered disease-modifying and targets the underlying pathophysiology of this condition?

Explanation

The child has X-linked hypophosphatemic rickets (XLH), caused by a PHEX mutation leading to excess FGF23 production. High FGF23 causes renal phosphate wasting and impairs calcitriol synthesis. Burosumab is a monoclonal antibody that binds and inhibits FGF23, directly addressing the pathophysiology of XLH and improving phosphate homeostasis, rickets severity, and lower limb deformity.

Question 20

During surgical repair of a lacerated flexor digitorum profundus (FDP) tendon in Zone II, a surgeon performs a multi-strand core suture and an epitendinous repair. What is the primary biomechanical advantage of adding a running epitendinous suture to the core suture?

Explanation

The addition of a peripheral epitendinous suture to a core tendon repair provides two major biomechanical benefits: it significantly increases the overall tensile strength of the repair (increasing load to gap formation by 10-50%), and it smooths the repair site by tucking in frayed edges, thereby decreasing gliding resistance and work of flexion within the flexor sheath.

Question 21

A 45-year-old male sustains an acute distal biceps tendon rupture while lifting a heavy box. A double-incision (modified Boyd-Anderson) repair technique is chosen. Compared to a single-incision anterior approach, the double-incision technique carries a statistically higher risk of which of the following specific complications?

Explanation

The double-incision approach was developed to avoid the radial nerve and lateral antebrachial cutaneous (LABC) nerve injuries associated with the single anterior incision. However, it requires dissection through the interosseous membrane or around the ulna, which carries a higher risk of heterotopic ossification and proximal radioulnar synostosis compared to a single-incision approach. Single-incision approaches have a higher rate of LABC nerve neuropraxia.

Question 22

In the context of lower extremity deformity correction utilizing Paley's osteotomy rules, what is the resultant effect on the mechanical axis if both the osteotomy and the axis of correction of angulation (ACA) are performed at a level distinct from the center of rotation of angulation (CORA)?

Explanation

According to Paley's Rule 3, if the osteotomy and the ACA are placed at a level different from the CORA, the mechanical axes of the proximal and distal segments will end up parallel to each other, resulting in a secondary translation deformity. Rule 1 (osteotomy and ACA at CORA) yields pure angulation and collinear axes. Rule 2 (ACA at CORA, osteotomy at a different level) yields angulation and translation at the osteotomy site, but collinear mechanical axes.

Question 23

A 32-year-old male sustains a purely ligamentous Lisfranc injury during a football game. Based on prospective randomized data comparing open reduction internal fixation (ORIF) to primary arthrodesis for purely ligamentous Lisfranc injuries, primary arthrodesis has been shown to have a lower reoperation rate and equivalent or better functional outcomes. If primary arthrodesis is performed, which joints are typically fused?

Explanation

Primary arthrodesis for purely ligamentous Lisfranc injuries typically involves the medial and middle columns (tarsometatarsal joints 1, 2, and 3). The lateral column (TMT 4 and 5) must be preserved and left unfused (or stabilized temporarily with K-wires) to maintain essential forefoot mobility and accommodate uneven ground during the gait cycle.

Question 24

A 40-year-old female sustains a comminuted distal radius fracture with an associated distal radioulnar joint (DRUJ) dislocation. Intraoperatively, following anatomic volar plate fixation of the distal radius, the DRUJ remains grossly unstable in supination. The ulnar styloid is intact on fluoroscopy. What is the most appropriate next step in management?

Explanation

DRUJ instability after anatomic fixation of the distal radius without an ulnar styloid fracture suggests an avulsion of the deep (foveal) fibers of the TFCC, which are the primary stabilizers of the DRUJ. Direct open or arthroscopic repair of the radioulnar ligaments to their foveal footprint is the most appropriate management to restore stability.

Question 25

A 55-year-old female sustains a terrible triad injury of the elbow. Intraoperatively, the coronoid fracture is fixed with a suture lasso, the irreparable radial head is replaced with a metallic arthroplasty, and the lateral ulnar collateral ligament (LUCL) is repaired to the lateral epicondyle. During examination under anesthesia, the elbow hinges open on the medial side and subluxates when extended beyond 30 degrees. What is the most appropriate next step?

Explanation

The standard surgical algorithm for a terrible triad injury is deep to superficial, fixing the coronoid, then addressing the radial head, and finally repairing the lateral collateral ligament complex. If the elbow remains unstable in extension after these steps, the next appropriate step is exploration and repair of the medial ulnar collateral ligament (MUCL). If instability persists despite MUCL repair, a hinged external fixator is indicated.

Question 26

A 2-year-old obese boy presents with bilateral genu varum. Radiographs demonstrate medial metaphyseal beaking of the proximal tibia. Measurement of the metaphyseal-diaphyseal angle of Drennan is performed. Which of the following values is most highly predictive of progression to infantile Blount disease rather than physiologic bowing?

Explanation

The metaphyseal-diaphyseal angle (Drennan's angle) is measured between a line drawn through the transverse plane of the proximal tibial metaphysis and a line perpendicular to the anatomical axis of the tibial diaphysis. An angle greater than 16 degrees is highly predictive (95% probability) of progression to infantile Blount disease, whereas an angle less than 10 degrees typically indicates physiologic bowing that will resolve spontaneously.

Question 27

A 55-year-old male with long-standing poorly controlled type 2 diabetes and peripheral neuropathy presents with a red, hot, swollen foot for 3 weeks. He denies any trauma or fever. Radiographs show periarticular osteopenia, fragmentation of the talonavicular joint, and subluxation, but no osteomyelitis. What Eichenholtz stage of Charcot arthropathy is this, and what is the standard initial treatment?

Explanation

Eichenholtz Stage 1 (development/fragmentation) is characterized clinically by a red, hot, swollen foot and radiographically by periarticular osteopenia, fragmentation, debris formation, and subluxation. The standard of care for acute active Charcot (Stage 0 and Stage 1) is immobilization with a total contact cast (TCC) and restricted weight-bearing to prevent further deformity until the acute inflammatory phase resolves (transition to Stage 2/3).

Question 28

A 50-year-old male presents with chronic wrist pain and a known history of an untreated scapholunate ligament tear. Radiographs reveal narrowing and sclerosis at the radioscaphoid joint as well as the capitolunate joint. The radiolunate joint is well-preserved. According to the SLAC (Scapholunate Advanced Collapse) classification, which stage is this, and what is an appropriate surgical treatment?

Explanation

This patient has SLAC III arthritis, which involves the radioscaphoid and capitolunate joints while sparing the radiolunate joint. (SLAC I involves only the radial styloid-scaphoid articulation; SLAC II involves the entire radioscaphoid fossa). The standard surgical treatment options for SLAC III are proximal row carpectomy (PRC) or scaphoid excision with 4-corner fusion. Total wrist fusion is typically reserved for SLAC IV (pancarpal, including radiolunate arthritis) or failed salvage.

Question 29

A 45-year-old male presents with progressive hand clumsiness, intrinsic muscle atrophy, and a positive Froment's sign. He reports a childhood elbow fracture that was treated non-operatively. Current elbow radiographs reveal a severe cubitus valgus deformity and a nonunion of the lateral humeral condyle. What is the pathomechanism of his current neurologic deficit?

Explanation

Nonunion of a pediatric lateral condyle fracture leads to a progressive cubitus valgus deformity over time. This increased carrying angle produces chronic stretching and traction on the ulnar nerve as it passes behind the medial epicondyle, resulting in a 'tardy ulnar nerve palsy.' The symptoms described (intrinsic atrophy, positive Froment's sign) are classic for ulnar neuropathy.

Question 30

A 9-year-old girl undergoes tension band plating (guided growth) for idiopathic genu valgum. Following clinical and radiographic correction of the mechanical axis, the plates and screws are removed. She returns to the clinic 18 months later with recurrent genu valgum. What is the most likely cause of this recurrent deformity?

Explanation

The 'rebound phenomenon' is a well-documented complication following implant removal in guided growth (tension band plating), particularly in younger patients with significant remaining growth potential. The physis 'rebounds' and grows at an accelerated rate, causing a recurrence of the original deformity. Some surgeons intentionally overcorrect by a few degrees to account for this expected rebound.

Question 31

A 35-year-old male sustains an intra-articular calcaneus fracture after falling from a ladder. A coronal CT scan is obtained. At the level showing the widest portion of the posterior facet, there are two distinct primary fracture lines crossing the posterior facet, dividing it into three articular fragments. According to the Sanders classification, what type of fracture is this?

Explanation

The Sanders classification for intra-articular calcaneus fractures is based on the number of fracture lines through the posterior facet on a coronal CT scan. Type I is non-displaced. Type II has one fracture line (two articular fragments). Type III has two fracture lines (three articular fragments). Type IV is highly comminuted with more than three fracture lines (four or more articular fragments).

Question 32

A 30-year-old manual laborer presents with dorsal wrist pain and decreased grip strength. Radiographs show sclerosis and collapse of the lunate, with proximal migration of the capitate and fixed scaphoid rotation. The patient has ulnar neutral variance. MRI confirms Kienböck's disease. According to the Lichtman classification, this represents Stage IIIB. Which of the following is the most appropriate surgical intervention?

Explanation

Lichtman Stage IIIB Kienböck's disease is characterized by lunate collapse with fixed scaphoid rotation and carpal height loss (carpal collapse). Because carpal kinematics are significantly altered, joint-leveling procedures (like radial shortening) or revascularization are no longer effective. Salvage procedures such as proximal row carpectomy (PRC), scaphoid-trapezium-trapezoid (STT) fusion, or scaphocapitate fusion are indicated for Stage IIIB.

Question 33

A 42-year-old bodybuilder feels a pop in his posterior elbow during a heavy bench press. Examination reveals a palpable gap and loss of active elbow extension against gravity. Surgical repair of the distal triceps tendon is planned. Based on biomechanical studies, which repair construct provides the highest load to failure and restores the largest anatomic footprint?

Explanation

Biomechanical studies have shown that a cruciate double-row or anatomic transosseous cruciate repair technique provides the highest load to failure, minimizes gap formation, and optimally restores the broad anatomic footprint of the distal triceps tendon on the olecranon, compared to single-row suture anchor repairs or simple transosseous knots.

Question 34

A 6-year-old boy is brought to the clinic by his parents due to an in-toeing gait. He frequently sits in a 'W' position. On physical examination, his hips exhibit 85 degrees of internal rotation and 10 degrees of external rotation. The thigh-foot angle is +10 degrees. There is no pain or limitation in activities. What is the most appropriate management?

Explanation

The clinical picture describes classic increased femoral anteversion, common in children ages 3-6. The thigh-foot angle is normal (+10 degrees), ruling out tibial torsion. The vast majority of cases resolve spontaneously by age 8-10 as normal derotation occurs with growth. Reassurance and observation is the standard of care. Bracing and special shoes are ineffective. Surgery (proximal femoral osteotomy) is rarely indicated, and only for severe, symptomatic cases in children over age 8-10.

Question 35

A 55-year-old female presents with a flexible, acquired flatfoot deformity secondary to Stage IIb posterior tibial tendon dysfunction. Radiographs demonstrate >40% talonavicular uncoverage and severe forefoot abduction. The planned procedure includes a flexor digitorum longus (FDL) transfer to the navicular. To optimally address the severe transverse plane deformity (forefoot abduction), which structural osteotomy is most commonly indicated?

Explanation

Stage IIb posterior tibial tendon dysfunction (PTTD) is characterized by a flexible flatfoot with significant forefoot abduction (>40% talonavicular uncoverage on AP radiograph). A lateral column lengthening (Evans osteotomy) effectively corrects the severe transverse plane deformity by pushing the forefoot into adduction. A medializing calcaneal osteotomy (MCO) primarily corrects hindfoot valgus (coronal plane) but has limited effect on severe transverse plane abduction.

Question 36

A 25-year-old male sustains a trans-scaphoid perilunate dislocation. During emergent open reduction and internal fixation, the surgeon notes that the lunate is completely extruded and entirely devoid of any capsular or ligamentous soft-tissue attachments. Despite this finding, what is the accepted standard of care regarding the lunate?

Explanation

Even when the lunate is completely extruded and devoid of soft-tissue attachments, the standard of care is immediate reduction and stabilization (with K-wires or screws) combined with ligamentous repair. While the risk of avascular necrosis (AVN) is high, the lunate often revascularizes or functions reasonably well without significant collapse. Primary salvage procedures (PRC or fusion) are not indicated in the acute setting.

Question 37

A 22-year-old elite baseball pitcher presents with medial elbow pain during the late cocking phase of throwing. MRI demonstrates a high-grade partial tear of the medial ulnar collateral ligament (MUCL). Which component of the MUCL is the primary restraint to valgus stress at the elbow between 30 and 120 degrees of flexion?

Explanation

The anterior bundle of the medial ulnar collateral ligament (MUCL) is the primary restraint to valgus stress at the elbow from 30 to 120 degrees of flexion. The posterior bundle acts as a secondary restraint, becoming taut in higher degrees of flexion. The transverse bundle provides no significant contribution to elbow stability.

Question 38

A 2-year-old boy presents with an anterolateral bow of the tibia and a radiolucent area in the diaphysis. Examination reveals 6 café-au-lait macules measuring >5 mm. He is diagnosed with congenital pseudarthrosis of the tibia (CPT). Histological analysis of the tissue resected from the pseudarthrosis site during surgery is most likely to reveal which of the following?

Explanation

Congenital pseudarthrosis of the tibia (CPT) is strongly associated with Neurofibromatosis type 1 (NF1). The pathology at the pseudarthrosis site typically demonstrates a thick, constricting band of highly cellular, dense fibrous tissue (a hamartoma) that replaces the normal periosteum and prevents normal bone formation and healing, leading to persistent nonunion.

Question 39

A 14-year-old boy with Charcot-Marie-Tooth disease presents with bilateral progressive cavovarus feet. Examination reveals a plantarflexed first ray and a positive Coleman block test indicating a flexible hindfoot. During the surgical reconstruction, which specific tendon transfer is utilized to remove the primary deforming force driving the first ray plantarflexion while augmenting foot eversion?

Explanation

In Charcot-Marie-Tooth disease, the peroneus longus (PL) is typically relatively strong compared to a weak anterior tibialis, leading to a rigidly plantarflexed first ray (which drives the hindfoot into varus). Transferring the PL to the peroneus brevis (PB) removes this deforming plantarflexion force on the first metatarsal and simultaneously augments the weak PB to assist in eversion.

Question 40

A 35-year-old competitive rower presents with dorsal forearm pain and swelling, approximately 4-5 cm proximal to the radiocarpal joint. Examination reveals crepitus and swelling with active wrist flexion and extension. He is diagnosed with intersection syndrome, caused by friction between the muscle bellies of the first extensor compartment and the tendons of the second extensor compartment. Which tendons constitute the second extensor compartment?

Explanation

Intersection syndrome is characterized by tenosynovitis at the crossing point where the muscle bellies of the first extensor compartment (abductor pollicis longus and extensor pollicis brevis) cross over the tendons of the second extensor compartment (extensor carpi radialis longus and extensor carpi radialis brevis). It typically occurs 4-5 cm proximal to the wrist joint.

Question 41

According to Paley's rules of osteotomy, if the osteotomy and the hinge are placed on the transverse bisector line but at a distance from the center of rotation of angulation (CORA), what is the resultant effect on the bone segments?

Explanation

Paley's Rule 2 states that placing the hinge on the bisector line but away from the CORA results in both angular correction and translation, producing colinear mechanical axes. Rule 1 yields pure angulation, while Rule 3 results in non-colinear axes.

Question 42

A 30-month-old child presents with bilateral symmetric genu varum. Radiographs reveal a metaphyseal-diaphyseal angle of 18 degrees and lateral thrust during ambulation. Which of the following is the most appropriate initial management?

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees strongly suggests infantile Blount's disease rather than physiologic bowing. In children under 3 years old with Langenskiöld stage I or II, full-time bracing with a KAFO is the recommended initial management.

Question 43

When performing tibial lengthening over an intramedullary nail (LON) compared to classic Ilizarov circular frame lengthening alone, LON provides which of the following primary advantages?

Explanation

Lengthening over a nail (LON) allows the external fixator to be removed immediately after the distraction phase, relying on the locked nail to support the regenerate during consolidation. This significantly decreases the time spent in the external fixator, improving patient comfort.

Question 44

Which of the following radiographic or clinical parameters is uniquely essential for programming a hexapod circular external fixator (e.g., Taylor Spatial Frame) but is not explicitly required for building a standard Ilizarov frame?

Explanation

Hexapod fixators utilize computer software to generate a prescription for 6-axis deformity correction. This requires precise mounting parameters, which describe the spatial relationship between the reference ring and the reference bone segment.

Question 45

A 10-year-old boy with X-linked hypophosphatemic (XLH) rickets presents with severe genu varum. Prior to surgical deformity correction, medical optimization should ideally include which of the following targeted therapies?

Explanation

XLH is characterized by excess FGF23, which leads to renal phosphate wasting and impaired bone mineralization. Burosumab, an anti-FGF23 monoclonal antibody, normalizes phosphate homeostasis and optimizes bone quality before osteotomy.

Question 46

A 35-year-old female complains of recurrent elbow clicking and a sense of instability when pushing up from a chair. Examination reveals a positive lateral pivot-shift test of the elbow. This condition is most directly caused by insufficiency of which of the following structures?

Explanation

Posterolateral rotatory instability (PLRI) is the most common form of recurrent elbow instability. It is caused by insufficiency of the lateral ulnar collateral ligament (LUCL), which allows the radial head to subluxate posterolaterally.

Question 47

A 40-year-old male undergoes a two-incision distal biceps tendon repair. Compared to a single-incision anterior approach, the two-incision technique is historically associated with a higher risk of which of the following complications?

Explanation

The two-incision (modified Boyd-Anderson) approach was developed to decrease radial nerve injuries but is associated with a higher risk of heterotopic ossification and radioulnar synostosis due to subperiosteal dissection near the ulna. Single-incision repairs carry a higher risk to the lateral antebrachial cutaneous nerve (LABCN).

Question 48

A patient sustains a traumatic elbow subluxation resulting in an anteromedial facet fracture of the coronoid. This specific fracture pattern is highly predictive of an associated injury to which of the following ligamentous structures?

Explanation

Anteromedial facet fractures of the coronoid result from varus posteromedial rotatory instability. The mechanism involves varus stress that tears the lateral collateral ligament (LCL) complex, followed by posteromedial subluxation that shears the anteromedial coronoid facet.

Question 49

When performing an osteotomy for angular deformity, if the osteotomy and the hinge are both placed away from the Center of Rotation of Angulation (CORA) but parallel to the transverse bisector line, which of the following is true regarding the resulting mechanical axis?

Explanation

According to Paley's rules of deformity correction (Rule 2), if the osteotomy axis (hinge) is away from the CORA, angular correction is accompanied by a translation of the axis. This can be used intentionally to correct pre-existing translation.

Question 50

A 45-year-old manual laborer presents with advanced scaphoid nonunion advanced collapse (SNAC). Radiographs reveal arthritis involving the radioscaphoid and capitolunate joints, with absolute preservation of the radiolunate joint. Which of the following surgical options is most appropriate?

Explanation

This patient has Stage III SNAC wrist characterized by capitolunate arthritis. PRC is contraindicated when the capitate articular surface is degenerate; therefore, scaphoid excision and four-corner arthrodesis is the preferred motion-preserving procedure.

Question 51

A 32-year-old gymnast reports recurrent clicking and catching in her lateral elbow when pushing up from a chair. The lateral pivot-shift test of the elbow is positive. Which ligamentous structure is primarily incompetent?

Explanation

Posterolateral rotatory instability (PLRI) of the elbow is caused by insufficiency of the lateral ulnar collateral ligament (LUCL). The patient typically presents with symptoms during axial loading, supination, and valgus stress (e.g., pushing off a chair).

Question 52

A 24-year-old athlete sustains a purely ligamentous Lisfranc injury. Weight-bearing radiographs show a 3 mm diastasis between the medial cuneiform and the base of the second metatarsal. Current evidence suggests that which of the following treatments provides the most predictable long-term functional outcome for this specific injury pattern?

Explanation

For purely ligamentous Lisfranc injuries, multiple studies have demonstrated that primary arthrodesis yields superior functional outcomes and lower reoperation rates compared to ORIF. ORIF is generally preferred for bony fracture-dislocations.

Question 53

During distraction osteogenesis using the Ilizarov method, what is the optimal biological environment for regenerate bone formation?

Explanation

Optimal regenerate formation in distraction osteogenesis requires a low-energy corticotomy preserving the periosteum, a 7-10 day latency period to allow soft callus formation, and a distraction rate of roughly 1 mm per day in small, divided increments.

Question 54

A 65-year-old woman undergoes volar locked plating for a displaced intra-articular distal radius fracture. Six months postoperatively, she suddenly loses the ability to flex her thumb interphalangeal joint. What is the most likely cause?

Explanation

Placement of a volar plate distal to the watershed line can cause prominence and attritional rupture of the flexor pollicis longus (FPL) tendon. Sudden loss of thumb IP joint flexion months after fixation strongly suggests tendon rupture rather than a nerve palsy.

Question 55

A 40-year-old female presents with an elbow injury. Lateral radiographs show the "double-arc" sign. Which of the following best describes this fracture pattern?

Explanation

The "double-arc" sign on a lateral elbow radiograph is pathognomonic for a Type IV (McKee) coronal shear fracture, indicating involvement of both the capitellum and the lateral trochlear ridge. Anatomic reduction and rigid internal fixation are required.

Question 56

A 55-year-old patient with long-standing diabetes presents with a warm, swollen, and erythematous left foot. Radiographs demonstrate periarticular debris, fragmentation of the navicular, and subluxation of the midtarsal joints. There are no systemic signs of infection. What is the most appropriate initial management?

Explanation

This patient is in the acute fragmentation phase (Eichenholtz Stage I) of Charcot arthropathy. The gold standard of initial treatment is strict offloading and immobilization using a total contact cast until the acute inflammatory phase resolves.

Question 57

You are planning an eight-plate hemiepiphysiodesis for a 9-year-old girl with idiopathic genu valgum. To achieve the best mechanical advantage and minimize joint line distortion, where should the plates be placed?

Explanation

For genu valgum (knock-knees), medial hemiepiphysiodesis tethers the faster-growing medial side, allowing the lateral physis to continue growing and correct the deformity. Addressing both the femur and tibia (if both contribute) limits joint line obliquity.

Question 58

In a progressive perilunate instability pattern (Mayfield classification), which ligamentous disruption occurs immediately after the scapholunate ligament fails?

Explanation

According to Mayfield's stages of perilunate instability, the injury progresses sequentially around the lunate: scapholunate (Stage I), capitolunate (Stage II), lunotriquetral (Stage III), and finally volar dislocation of the lunate (Stage IV).

Question 59

A 42-year-old bodybuilder undergoes a two-incision repair for an acute distal biceps tendon rupture. Postoperatively, he has normal elbow flexion but struggles with forearm pronation and supination due to a mechanical block. Which complication is most likely responsible?

Explanation

A known complication of the two-incision technique for distal biceps repair is radioulnar synostosis, which presents as a mechanical block to pronation/supination. The risk is minimized by avoiding subperiosteal dissection of the ulna and muscle-splitting of the supinator.

Question 60

A 45-year-old male laborer presents with chronic right wrist pain. Radiographs reveal advanced narrowing and sclerosis of the radioscaphoid and capitolunate joints, with a completely preserved radiolunate joint. What is the most appropriate motion-preserving surgical intervention?

Explanation

This patient has Stage III Scapholunate Advanced Collapse (SLAC) wrist, characterized by capitolunate involvement with a preserved radiolunate joint. Scaphoid excision and four-corner fusion is the procedure of choice, as proximal row carpectomy is contraindicated when the capitate articular surface is degenerate.

Question 61

In a Dubberley Type 3B fracture of the capitellum, what specific anatomic characteristic dictates the need for a more complex reconstructive strategy compared to a Type 3A fracture?

Explanation

The Dubberley classification differentiates capitellar/trochlear fractures based on the presence (Type B) or absence (Type A) of posterior capitellar comminution. Type B fractures lack a stable posterior bony buttress, often requiring structural bone grafting or specialized posterior to anterior fixation to prevent collapse.

Question 62

A 58-year-old patient with long-standing diabetes presents with an acutely swollen, erythematous, and warm foot but denies significant pain. Radiographs demonstrate periarticular debris, bony fragmentation, and early subluxation at the tarsometatarsal joints. According to the Eichenholtz classification, what is the most appropriate initial management?

Explanation

The patient is in Eichenholtz Stage I (Developmental/Fragmentation phase) of Charcot neuroarthropathy. The gold standard of initial treatment is strict offloading and immobilization using a total contact cast to prevent further deformity until the acute inflammatory phase resolves (Stage II).

Question 63

An 8-year-old severely obese male presents with worsening unilateral tibia vara. Radiographs reveal a depressed medial tibial plateau, profound metaphyseal beaking, and an established physeal bar (Langenskiöld stage VI). What is the most definitive surgical management?

Explanation

In advanced infantile Blount disease (Langenskiöld stage V-VI), a bony bar crosses the physis and causes intra-articular depression. Treatment requires resection of the physeal bar, elevation of the depressed medial plateau, and a proximal tibial osteotomy to restore mechanical alignment.

Question 64

According to Mayfield's stages of progressive perilunate instability, what is the sequential anatomic progression of ligamentous disruption that ultimately results in a volar lunate dislocation (Stage IV)?

Explanation

Mayfield described a progressive sequence of injury starting radially and progressing ulnarward: 1) Scapholunate, 2) Lunocapitate (Space of Poirier), 3) Lunotriquetral, and 4) Dorsal radiocarpal ligament, which allows the lunate to dislocate completely into the carpal tunnel.

Question 65

During surgical reconstruction of the lateral ulnar collateral ligament (LUCL) for posterolateral rotatory instability of the elbow, accurate placement of the humeral tunnel is critical. Where is the optimal isometric point for the humeral attachment?

Explanation

The isometric point for LUCL reconstruction on the humerus is located at the center of curvature of the capitellum, which typically lies just distal and anterior to the lateral epicondyle tip. Non-isometric placement will result in graft stretching or restricted range of motion.

Question 66

A 25-year-old football player sustains a pure ligamentous Lisfranc injury. Which of the following statements regarding the normal anatomy of the Lisfranc ligament is correct?

Explanation

The primary Lisfranc ligament is a strong interosseous ligament that originates from the lateral aspect of the medial cuneiform and attaches to the medial aspect of the plantar base of the second metatarsal. There is no direct ligamentous connection between the bases of the first and second metatarsals.

Question 67

When utilizing the principles of distraction osteogenesis (Ilizarov method) for a tibial lengthening procedure in a healthy adult, what is the optimal latency period and rate of distraction to ensure ideal regenerate bone formation?

Explanation

Ilizarov established that a latency period of 7-10 days allows for early callus formation before distraction begins. The ideal distraction rate is 1.0 mm per day (typically divided into 0.25 mm increments four times daily) to prevent premature consolidation or poor regenerate formation.

Question 68

A 30-year-old manual laborer presents with progressive wrist pain. Radiographs reveal ulnar minus variance and lunate sclerosis with early fragmentation, but no signs of carpal collapse or radiocarpal arthritis (Lichtman Stage IIIa). What is the preferred surgical intervention?

Explanation

In Kienböck's disease with ulnar negative variance and no carpal collapse or advanced arthritis (Lichtman Stage I, II, or IIIa), joint-leveling procedures such as a radial shortening osteotomy are indicated to decompress the lunate and halt disease progression.

Question 69

When performing a single-incision anterior approach for the repair of a distal biceps tendon rupture, excessive traction on the lateral soft-tissue retractors most commonly places which of the following nerves at risk of injury?

Explanation

The lateral antebrachial cutaneous nerve (LABC) is the most commonly injured nerve in a single-incision distal biceps repair due to lateral retraction. The posterior interosseous nerve (PIN) is more at risk during the deep, distal part of the exposure or during a two-incision approach if dissection violates the supinator.

Question 70

During the extensile lateral approach for open reduction and internal fixation of a displaced intra-articular calcaneus fracture, a full-thickness subperiosteal flap is created. Which artery provides the primary blood supply to the corner of this flap and must be protected to prevent wound necrosis?

Explanation

The lateral calcaneal artery, a branch of the peroneal artery, supplies the apex of the extensile lateral flap. A 'no touch' subperiosteal elevation technique is strictly advised to protect this vascular supply and minimize the risk of wound edge necrosis.

Question 71

In evaluating coronal plane alignment of the lower extremity on a standing long-leg radiograph, the mechanical axis line connects the center of the femoral head to the center of the ankle mortise. In a normally aligned knee, where should this line pass?

Explanation

The normal mechanical axis line of the lower extremity passes approximately 8 to 10 mm medial to the center of the knee joint. This medial deviation naturally loads the medial compartment slightly more than the lateral compartment.

Question 72

What is the most common tendon rupture associated with the placement of a volar locking plate for a distal radius fracture if the plate is positioned distal to the watershed line?

Explanation

Placement of a volar plate distal to the watershed line on the distal radius causes prominent hardware to impinge on the flexor tendons, most commonly leading to attritional rupture of the flexor pollicis longus (FPL) tendon.

Orthopedic Surgery Board Review MCQs: Arthroplasty, Trauma & Spine Part 255

Orthopedic Surgery Board Review MCQs: Deformity, Elbow, Foot & Wrist | Part 43

Key Takeaway

Orthopedic Surgery Board Review MCQs: Deformity, Elbow, Foot & Wrist | Part 43

Chapter Index