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

OITE & ABOS Orthopedic MCQs: Elbow, Foot, Hip & Spine | Part 14

23 Apr 2026 148 min read 59 Views
OITE & ABOS Orthopedic Board Prep: Practice Exam Part 14

Key Takeaway

This page offers Part 14 of an interactive MCQ set for orthopedic residents and surgeons preparing for OITE/AAOS/ABOS board certification. Featuring 50 high-yield questions on Elbow, Foot, Hip, and Spine, it provides two learning modes with detailed explanations and literature references to enhance exam readiness and knowledge.

OITE & ABOS Orthopedic MCQs: Elbow, Foot, Hip & Spine | Part 14

Comprehensive 100-Question Exam


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Question 1

In the surgical management of a 'terrible triad' injury of the elbow (elbow dislocation, radial head fracture, coronoid fracture), what is the most widely accepted sequential protocol to restore elbow stability?





Explanation

The standard surgical protocol for a terrible triad injury, popularized by Pugh et al., involves fixing structures from deep to superficial, typically starting anterior to posterior or inside-out. The sequence is: 1) Coronoid fracture fixation or anterior capsule repair, 2) Radial head fixation or replacement, 3) LCL repair to the lateral epicondyle. If the elbow remains unstable after these steps, the MCL is repaired or a hinged external fixator is applied.

Question 2

A 28-year-old male sustains a Hawkins type III talar neck fracture. Which of the following blood vessels provides the most significant blood supply to the body of the talus and is at highest risk of disruption leading to avascular necrosis (AVN)?





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. In talar neck fractures (especially Hawkins Types II, III, and IV), this vessel is frequently disrupted, leading to a high risk of avascular necrosis. The deltoid branch is often the only remaining blood supply in a displaced neck fracture and must be protected during medial surgical approaches.

Question 3

A 55-year-old female presents with progressive groin pain 6 years after a metal-on-metal total hip arthroplasty. MRI with MARS reveals a large cystic pseudotumor. Laboratory testing shows elevated serum cobalt and chromium levels. During revision surgery, extensive abductor muscle necrosis is noted. Which histologic feature is most characteristic of this adverse local tissue reaction (ALTR)?





Explanation

Adverse local tissue reaction (ALTR) in metal-on-metal implants, often termed ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion), is characterized histologically by a prominent perivascular lymphocytic infiltrate (suggesting a Type IV delayed hypersensitivity reaction to metal ions), macrophage infiltration, and extensive tissue necrosis. Foreign body giant cells with birefringence are characteristic of polyethylene wear, not metal-on-metal wear.

Question 4

A 60-year-old Asian male presents with progressive hand clumsiness and gait imbalance. CT of the cervical spine demonstrates continuous ossification of the posterior longitudinal ligament (OPLL) from C3 to C6 with a canal occupying ratio of 65%. The cervical spine is neutrally aligned. Which of the following is the most appropriate surgical approach with the lowest risk of direct dural injury?





Explanation

In patients with severe OPLL (occupying ratio >50-60%) and neutral or lordotic alignment, a posterior approach (laminectomy and fusion or laminoplasty) is generally preferred over an anterior approach. Anterior resection of continuous OPLL carries a very high risk of dural tear and cerebrospinal fluid leak because the ossified mass is often densely adherent to or incorporated into the dura.

Question 5

When comparing the single anterior incision to the two-incision technique for distal biceps tendon repair, the single anterior incision is associated with a higher risk of injury to which of the following nerves?





Explanation

The single-incision anterior approach for distal biceps repair is associated with a higher risk of neurapraxia to the lateral antebrachial cutaneous nerve (LABCN), which is often retracted laterally during the exposure. The two-incision technique historically carries a higher risk of heterotopic ossification and potential injury to the posterior interosseous nerve (PIN) during the posterior exposure if the forearm is not fully pronated.

Question 6

The Lisfranc ligament is a critical stabilizing interosseous ligament in the midfoot. Which two osseous structures does it connect?





Explanation

The Lisfranc ligament connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the strongest of the tarsometatarsal ligaments and its integrity is critical for the stability of the midfoot arch. There is no direct ligamentous connection between the first and second metatarsal bases.

Question 7

In a 12-year-old male presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following factors is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?





Explanation

While unilateral SCFE can progress to bilateral disease in about 20-40% of cases, patients with underlying endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency) have an exceptionally high risk of bilateral involvement (up to 100% in some series). Therefore, an underlying endocrinopathy is a strong and widely accepted absolute indication for prophylactic pinning of the contralateral hip.

Question 8

A 65-year-old female presents with severe neurogenic claudication. Upright radiographs demonstrate a Grade I degenerative spondylolisthesis at L4-L5 with 4 mm of dynamic translation on flexion-extension views. According to the Spine Patient Outcomes Research Trial (SPORT) data, which of the following outcomes is most expected if she undergoes surgical decompression and fusion compared to nonoperative management at 4-year follow-up?





Explanation

The SPORT trial for degenerative spondylolisthesis demonstrated that patients who underwent surgery (decompression and fusion) had significantly greater improvement in pain and function compared to those treated nonoperatively, and this treatment effect was maintained at 4-year and 8-year follow-ups.

Question 9

A 35-year-old female sustains a coronal shear fracture of the distal humerus. Intraoperative findings reveal the fracture involves the capitellum and the lateral half of the trochlea as a single articular piece. Which classification best describes this specific fracture pattern?





Explanation

The McKee modification to the Bryan and Morrey classification added the Type IV fracture, which describes a coronal shear fracture involving the capitellum and a large portion of the lateral trochlea as a single fragment. Type I is a large osseous capitellum fragment (Hahn-Steinthal), Type II is a thin articular cartilage fragment with minimal bone (Kocher-Lorenz), and Type III is a comminuted capitellum fracture.

Question 10

A 55-year-old female undergoes a medializing calcaneal osteotomy, flexor digitorum longus (FDL) transfer, and a lateral column lengthening (Evans osteotomy) for stage IIB adult-acquired flatfoot deformity. Which of the following complications is most specifically associated with the lateral column lengthening portion of this procedure?





Explanation

Lateral column lengthening (Evans calcaneal osteotomy) inserts a bone graft in the anterior calcaneus to correct forefoot abduction. The most specific and challenging complication associated with this procedure is increased pressure across the calcaneocuboid (CC) joint, which can lead to CC joint subluxation, postoperative pain, and eventual CC arthritis.

Question 11

When performing a total hip arthroplasty on a patient with Crowe Type IV developmental dysplasia of the hip (DDH), the true native acetabulum is characteristically deficient in which of the following regions?





Explanation

In developmental dysplasia of the hip (DDH), the true acetabulum is classically shallow, with the greatest bony deficiency located in the anterior and superior walls. This morphological abnormality necessitates careful preoperative planning for acetabular cup placement and often requires the use of structural bone grafts or specialized augments to achieve adequate superior-anterior coverage.

Question 12

An 82-year-old male with severe osteoporosis sustains a Type II odontoid fracture after a low-energy fall. He is neurologically intact, and the fracture has 2 mm of posterior displacement. Based on current evidence, what is the most appropriate management to minimize overall morbidity and mortality?





Explanation

In elderly patients (typically >80 years) with Type II odontoid fractures, rigid cervical collar immobilization is increasingly recommended. While nonunion rates are high, most nonunions are stable, fibrous nonunions, and clinical outcomes are acceptable. Operative intervention in this frail demographic carries high morbidity and mortality, as does Halo vest immobilization (associated with fatal respiratory complications in the elderly).

Question 13

A 42-year-old male sustains a comminuted radial head fracture. He also complains of severe ipsilateral wrist pain, and wrist radiographs demonstrate positive ulnar variance. If the radial head is simply resected without prosthetic replacement, which of the following biomechanical consequences is most likely to occur?





Explanation

This clinical presentation describes an Essex-Lopresti injury (radial head fracture, interosseous membrane disruption, and DRUJ dislocation). In this scenario, the radial head acts as a crucial secondary stabilizer to longitudinal forces. Resection of the radial head without replacement leads to proximal migration of the radius, resulting in symptomatic ulnocarpal impaction and chronic wrist/forearm pain.

Question 14

Recent high-quality randomized controlled trials (e.g., Willits et al.) comparing operative to nonoperative treatment of acute Achilles tendon ruptures, when utilizing early weight-bearing and functional rehabilitation protocols in both groups, have demonstrated which of the following?





Explanation

Historically, nonoperative treatment using prolonged cast immobilization was associated with higher re-rupture rates. However, modern high-quality RCTs have shown that when accelerated functional rehabilitation (early weight-bearing and early ROM) is employed in both groups, there is no significant difference in re-rupture rates, range of motion, or functional outcomes between operative and nonoperative management, though surgery carries a risk of wound complications.

Question 15

A 24-year-old male hockey player presents with insidious onset groin pain exacerbated by hip flexion and internal rotation. Radiographs reveal a pistol grip deformity of the proximal femur and an alpha angle of 75 degrees. Which of the following intra-articular pathologies is most commonly associated with this specific type of femoroacetabular impingement (FAI)?





Explanation

The clinical picture describes Cam-type FAI (pistol grip deformity, high alpha angle). Cam impingement generates shear forces at the chondrolabral junction of the anterosuperior acetabulum, classically causing inside-out chondral delamination while leaving the labrum relatively intact initially. In contrast, Pincer FAI (e.g., global retroversion) typically causes direct, often circumferential crushing and degeneration of the labrum.

Question 16

A 35-year-old male sustains an L1 burst fracture. He has bilateral weakness in ankle dorsiflexion (3/5) and bowel/bladder incontinence. MRI shows retropulsion of bone and complete disruption of the posterior ligamentous complex (PLC). What is his Thoracolumbar Injury Classification and Severity (TLICS) score, and what management is recommended?





Explanation

The TLICS system scores morphology, neurologic status, and PLC integrity. Burst fracture = 2 points. Neurologic status (cauda equina injury due to bowel/bladder dysfunction and lower extremity weakness) = 3 points. PLC disruption = 3 points. Total = 8 points. A score ≥ 5 recommends surgical management.

Question 17

During the late cocking and early acceleration phases of pitching, the ulnar collateral ligament (UCL) of the elbow experiences maximal stress. Which specific structure is the primary restraint to valgus stress at 30, 60, and 90 degrees of elbow flexion?





Explanation

The anterior bundle of the UCL is the primary restraint to valgus stress at the elbow. Within the anterior bundle, the anterior band is tense throughout the range of motion and provides the primary restraint up to 90 degrees of flexion, whereas the posterior band becomes taut and contributes more at flexion angles greater than 90 degrees (up to 120 degrees).

Question 18

A 58-year-old male with poorly controlled type 2 diabetes presents with a swollen, erythematous right foot. Radiographs reveal fragmentation of the midfoot joints, periarticular debris, and joint subluxation. According to the Eichenholtz classification, the patient is currently in Stage I (Fragmentation). What is the hallmark radiographic finding of the subsequent stage (Stage II)?





Explanation

The Eichenholtz classification of Charcot arthropathy consists of three stages. Stage I (Developmental/Fragmentation) involves joint edema, fragmentation, and debris. Stage II (Coalescence) is marked by the absorption of fine debris, fusion of larger fragments, and early sclerosis as the inflammatory phase resolves. Stage III (Reconstruction) involves bony consolidation, remodeling, and rounding of bone ends.

Question 19

An 80-year-old female presents with a periprosthetic femur fracture around a cemented total hip arthroplasty stem. Radiographs show a spiral fracture extending just below the tip of the stem. The stem is radiographically loose, and there is significant cortical thinning and osteolysis of the proximal femur. According to the Vancouver classification, how is this fracture classified?





Explanation

The Vancouver classification assesses fracture location, implant stability, and bone stock. Type A is trochanteric. Type B is around or just below the stem: B1 = well-fixed stem; B2 = loose stem but adequate bone stock; B3 = loose stem with poor bone stock (as described here, with severe cortical thinning and osteolysis). Type C is well below the stem tip.

Question 20

A 13-year-old premenarchal female (Risser stage 0) is diagnosed with adolescent idiopathic scoliosis (AIS). Her primary right thoracic curve measures 32 degrees on standing PA radiographs. According to the guidelines of the Scoliosis Research Society (SRS), what is the most appropriate next step in management?





Explanation

According to the SRS criteria, bracing is indicated for actively growing patients (girls who are premenarchal or <1 year postmenarchal, Risser 0-2) with a primary curve measuring between 25 and 40 degrees. The standard of care, supported by the BrAIST trial, is a rigid TLSO worn for 16-23 hours a day, which significantly decreases the risk of curve progression to the surgical threshold.

Question 21

A 45-year-old man falls from a ladder and sustains a 'terrible triad' injury of the elbow. He undergoes operative management via a single lateral incision. According to standard treatment protocols for this injury, what is the most appropriate sequence of repair?





Explanation

The standard protocol for treating a terrible triad injury of the elbow (elbow dislocation, radial head fracture, and coronoid fracture) via a single lateral approach involves working deep to superficial. The sequence is: 1) Coronoid fixation or capsular repair, 2) Radial head fixation or arthroplasty, and 3) LCL complex repair. The MCL is typically only repaired if the elbow remains unstable after these three steps are completed and a hinged external fixator is not preferred.

Question 22

A 40-year-old bodybuilder undergoes a distal biceps tendon repair utilizing a two-incision technique. Compared to a single-incision anterior approach, the two-incision technique carries a uniquely higher risk of which of the following complications?





Explanation

Historically and in comparative studies, the two-incision technique for distal biceps repair has been associated with a higher risk of radioulnar synostosis (heterotopic ossification) because of the subperiosteal dissection near the ulna. Conversely, the single-incision anterior approach places the lateral antebrachial cutaneous nerve (LABCN) and the posterior interosseous nerve (PIN) at higher risk.

Question 23

A 35-year-old female sustains a Bryan-Morrey Type I capitellum fracture. The surgeon elects to perform an open reduction and internal fixation utilizing the Kaplan approach. Which inter-nervous/inter-muscular interval is utilized in this approach, and which nerve is most at risk during distal dissection?





Explanation

The Kaplan approach to the lateral elbow utilizes the interval between the extensor carpi radialis brevis (ECRB) and the extensor digitorum communis (EDC). During distal dissection, the posterior interosseous nerve (PIN) is at risk as it courses through the supinator muscle. The Kocher approach uses the interval between the anconeus and the extensor carpi ulnaris (ECU).

Question 24

A 50-year-old female undergoes an anterior subcutaneous transposition of the ulnar nerve for severe cubital tunnel syndrome. Postoperatively, she reports worsened ulnar neuropathy symptoms. Surgical exploration reveals a new site of compression. If the initial surgeon failed to release all potential sites of tethering during the transposition, what is the most likely anatomic structure causing this new compression?





Explanation

During an anterior transposition of the ulnar nerve, the medial intermuscular septum must be excised. If it is left intact, routing the nerve anteriorly over the septum creates a sharp angulation and a new point of tethering/compression. Osborne's ligament is the primary site of compression in in situ entrapment, but is divided during the approach. The ligament of Struthers (associated with the supracondylar process) compresses the median nerve, not the ulnar nerve (arcade of Struthers is ulnar).

Question 25

A 5-year-old child falls on an outstretched arm and sustains an elbow dislocation. Post-reduction radiographs show an entrapped bony fragment within the medial joint space. Based on the chronologic appearance of elbow ossification centers, which center is most likely incarcerated in the joint, and what is its standard sequence of appearance?





Explanation

The ossification centers of the pediatric elbow appear in a predictable sequence represented by the mnemonic CRITOE: Capitellum (1st, ~1 yr), Radial head (2nd, ~3 yrs), Internal/Medial epicondyle (3rd, ~5 yrs), Trochlea (4th, ~7 yrs), Olecranon (5th, ~9 yrs), and External/Lateral epicondyle (6th, ~11 yrs). The medial epicondyle is the 3rd center to appear and is frequently avulsed and incarcerated in the joint during pediatric elbow dislocations.

Question 26

A 30-year-old male sustains a strictly ligamentous Lisfranc injury. Based on randomized controlled trials comparing primary arthrodesis versus open reduction and internal fixation (ORIF) for purely ligamentous Lisfranc injuries, primary arthrodesis is associated with which of the following outcomes?





Explanation

Level I evidence (e.g., Ly and Coetzee, Henning et al.) has demonstrated that for purely ligamentous Lisfranc injuries, primary arthrodesis results in superior functional outcomes and significantly lower rates of secondary surgeries (such as hardware removal or salvage arthrodesis for post-traumatic arthritis) compared to ORIF.

Question 27

A 55-year-old male with long-standing poorly controlled diabetes presents with a warm, swollen, erythematous right foot. He denies trauma or fever. Radiographs show early fragmentation of the navicular and cuneiforms. Blood work reveals a normal erythrocyte sedimentation rate (ESR). What is the most appropriate initial management?





Explanation

This is a classic presentation of acute Charcot neuroarthropathy (Eichenholtz Stage I - Fragmentation phase). The normal ESR helps differentiate this from acute osteomyelitis. The gold standard initial management for acute Charcot arthropathy is immobilization in a total contact cast (TCC) and protected weight bearing to arrest the inflammatory process and prevent further bone destruction and deformity. Surgery is generally contraindicated in the acute phase.

Question 28

A 28-year-old male is 6 weeks post-operative from open reduction and internal fixation of a Hawkins Type III talar neck fracture. An AP radiograph of the ankle demonstrates a subchondral radiolucent band in the dome of the talus. What does this radiographic finding signify?





Explanation

The subchondral radiolucent band seen on the AP ankle view at 6-8 weeks post-injury is known as Hawkins' sign. It represents subchondral bone resorption (disuse osteopenia), a process that requires an intact vascular supply. Therefore, the presence of a Hawkins sign is a highly reliable prognostic indicator of revascularization and the absence of widespread avascular necrosis (AVN) of the talar body.

Question 29

A 45-year-old obese female presents with progressive medial foot pain and an inability to perform a single-leg heel rise. Examination reveals a flexible pes planovalgus deformity. She has failed 6 months of orthotics and physical therapy. What is the most appropriate surgical management for this stage of her condition?





Explanation

The patient has Stage II adult-acquired flatfoot deformity (posterior tibial tendon dysfunction), characterized by medial pain, a flexible deformity, and inability to perform a single heel rise. The standard surgical treatment for Stage II disease after failed conservative management involves a flexor digitorum longus (FDL) tendon transfer to replace the diseased posterior tibial tendon, combined with a medial displacement calcaneal osteotomy (MDCO) to correct the valgus malalignment. Triple arthrodesis is reserved for Stage III (rigid) deformity.

Question 30

A 35-year-old recreational athlete sustains an acute mid-substance Achilles tendon rupture. He inquires about the differences between operative and non-operative treatment. Based on recent high-level evidence utilizing early functional rehabilitation protocols, which of the following is true?





Explanation

Recent high-level randomized controlled trials (e.g., Willits et al.) have demonstrated that when an early functional rehabilitation protocol (early weight-bearing and active range of motion in a brace) is employed, non-operative management of acute Achilles tendon ruptures yields a re-rupture rate similar to operative management. Non-operative management also avoids surgical complications such as infection and sural nerve injury.

Question 31

A 25-year-old male hockey player presents with chronic anterior groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate a lateral center edge angle (LCEA) of 30 degrees and an alpha angle of 75 degrees. Which morphological abnormality is most likely responsible for his symptoms?





Explanation

An alpha angle greater than 50-55 degrees on a lateral or Dunn view radiograph is diagnostic of Cam morphology, which represents an aspherical femoral head with decreased head-neck offset (typically anterosuperiorly). This leads to cam-type femoroacetabular impingement (FAI). His LCEA of 30 degrees is normal (25-39 degrees), making pincer impingement (overcoverage) less likely.

Question 32

A 13-year-old obese male presents to the emergency department with acute-on-chronic left knee pain and an absolute inability to bear weight on the left lower extremity. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following factors is the most significant predictor for the development of avascular necrosis (AVN) in this patient?





Explanation

According to the Loder classification, SCFE is divided into stable (able to bear weight) and unstable (unable to bear weight, even with crutches). Unstable slips carry a significantly higher risk of avascular necrosis (AVN), reported to be up to 47%, whereas stable slips have an AVN rate approaching zero. This clinical feature is the most important prognostic factor for AVN.

Question 33

A 4-month-old infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, the mother reports that the infant has stopped kicking the leg on the affected side. Examination reveals an absent patellar reflex and profound quadriceps weakness. What is the most likely cause of this finding, and what is the next best step in management?





Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, caused by hyperflexion of the hip which compresses the nerve against the pelvis. It presents with decreased active knee extension and an absent patellar reflex. The appropriate management is to loosen the anterior flexion straps or temporarily discontinue the harness to allow the nerve to recover, which it typically does within days to weeks.

Question 34

A 65-year-old male who underwent a metal-on-metal total hip arthroplasty 8 years ago presents with new-onset groin pain and a palpable anterior mass. Joint aspiration yields sterile fluid with a high macrophage count. Blood cobalt and chromium levels are markedly elevated. Histological examination of the periprosthetic tissue during revision surgery is most likely to reveal which of the following?





Explanation

Adverse local tissue reactions (ALTR) or adverse reactions to metal debris (ARMD), often seen with metal-on-metal implants or severe trunnionosis, are characterized histologically by an Aseptic Lymphocytic Vasculitis-Associated Lesion (ALVAL). This represents a delayed Type IV hypersensitivity reaction to metal ions, featuring perivascular lymphocytic infiltrates and macrophage predominance. Birefringent wear debris is classic for polyethylene wear, not metal.

Question 35

A 35-year-old male sustains a posterior hip dislocation following a high-speed motor vehicle collision. CT imaging post-reduction reveals an associated fracture of the femoral head that is located inferior to the fovea capitis. According to the Pipkin classification, what type of fracture is this, and what is the preferred surgical approach if open reduction and internal fixation is indicated?





Explanation

According to the Pipkin classification, a Type I fracture involves the femoral head inferior to the fovea capitis (non-weight-bearing portion). If ORIF is indicated (e.g., irreducible fragment, joint incongruity), an anterior approach (Smith-Petersen or Hueter) is preferred. A posterior approach in the setting of a posterior dislocation further jeopardizes the already tenuous medial femoral circumflex artery (MFCA) blood supply, significantly increasing the risk of avascular necrosis.

Question 36

A 70-year-old male presents with cervical spondylotic myelopathy. He reports bilateral hand clumsiness and significant difficulty walking, which forced him to retire from his job as a mechanic. However, he remains able to ambulate around his home and in the community without the use of a cane or walker. According to the Nurick classification system, what grade best describes this patient's condition?





Explanation

The Nurick classification for cervical myelopathy is based on gait abnormality. Grade 0 = root signs only. Grade 1 = signs of cord involvement but normal gait. Grade 2 = mild gait involvement, able to be employed. Grade 3 = gait abnormality prevents employment, but can walk unassisted. Grade 4 = requires assistance (cane/walker) to ambulate. Grade 5 = wheelchair-bound or bedridden. Because he is unemployed due to his gait but walks unassisted, he is Grade 3.

Question 37

A 65-year-old male complains of bilateral posterior calf pain that consistently occurs after walking two blocks. The pain is rapidly relieved by sitting or leaning forward over a shopping cart. The patient notes no pain when riding a stationary bicycle. Which of the following is the most reliable clinical or historical finding to differentiate his condition from vascular claudication?





Explanation

The patient's symptoms are classic for neurogenic claudication secondary to lumbar spinal stenosis. The most reliable differentiator from vascular claudication is that neurogenic claudication is position-dependent; it is relieved by lumbar flexion (which increases the cross-sectional area of the spinal canal) and exacerbated by extension. Therefore, riding a stationary bicycle (which involves lumbar flexion) is well-tolerated in neurogenic claudication, whereas it provokes pain in vascular claudication due to increased muscle oxygen demand.

Question 38

During preoperative planning for a posterior spinal fusion in a 14-year-old girl with an adolescent idiopathic scoliosis (Lenke 1A curve), the surgeon aims to identify the Stable Vertebra to help determine the distal extent of the fusion. How is the Stable Vertebra defined on standard standing AP radiographs?





Explanation

In the evaluation of scoliosis, the Stable Vertebra is defined as the most proximal (cephalad) vertebra below the curve that is bisected by the Center Sacral Vertical Line (CSVL). The Neutral Vertebra is the most cephalad vertebra without axial rotation. The End Vertebra is the most tilted vertebra at the cephalad or caudal end of the curve. The Apical Vertebra is the most laterally deviated.

Question 39

An 80-year-old man falls from a standing height and sustains an Anderson and D'Alonzo Type II odontoid fracture with 3 mm of posterior displacement. He is neurologically intact. DEXA scan reveals severe osteoporosis (T-score -3.1). He is a community ambulator and has no other major medical comorbidities. What is the most appropriate definitive management?





Explanation

In an elderly patient with a Type II odontoid fracture, conservative management (halo or collar) is associated with unacceptably high rates of nonunion, morbidity, and mortality (especially halo vests, which are poorly tolerated in the elderly). Anterior odontoid screw fixation is contraindicated in the setting of severe osteoporosis due to poor screw purchase, and is less successful with posterior displacement. Posterior C1-C2 instrumental fusion provides rigid fixation with high fusion rates and is the gold standard for definitive surgical management in this population.

Question 40

A 50-year-old male with a history of intravenous drug use presents with severe, unrelenting mid-back pain, a low-grade fever, and progressive paraparesis. Blood cultures are drawn. An emergent MRI of the thoracic spine with and without gadolinium contrast is obtained to evaluate for a spinal epidural abscess. Which of the following MRI findings is most characteristic of this diagnosis?





Explanation

A spinal epidural abscess classically appears on MRI as an epidural mass that is isointense to hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging. Following the administration of gadolinium contrast, the liquid purulent center does not enhance, but the highly vascularized inflammatory capsule surrounding the pus does, resulting in a characteristic peripheral or 'rim' enhancement pattern.

Question 41

A 65-year-old female presents with progressive hand clumsiness and gait imbalance. Lateral cervical radiographs reveal continuous ossification of the posterior longitudinal ligament (OPLL) from C3-C6 with a kyphotic alignment (K-line negative). Sagittal MRI confirms severe cord compression. Which of the following surgical approaches is most appropriate?





Explanation

In patients with OPLL and a kyphotic cervical spine (K-line negative), posterior decompression (laminoplasty or laminectomy alone) is generally insufficient because the spinal cord will not drift back posteriorly away from the anterior compressive pathology. An anterior approach (corpectomy and fusion) or a combined anterior-posterior approach is indicated to directly decompress the cord and correct the kyphosis.

Question 42

A 72-year-old male with a history of a multi-level lumbar fusion (L2-Pelvis) is planned for a total hip arthroplasty. Preoperative sitting and standing lateral spinopelvic radiographs show a change in pelvic tilt of 3 degrees. To minimize the risk of posterior dislocation during sitting, how should the acetabular component be positioned compared to a patient with normal spinopelvic mobility?





Explanation

A patient with a prior lumbar fusion to the pelvis has a 'stiff' spinopelvic junction (less than 10 degrees of pelvic tilt change between standing and sitting). Normally, the pelvis retroverts during sitting, opening the acetabulum anteriorly to accommodate hip flexion. In a stiff spine, this retroversion does not occur, increasing the risk of anterior impingement and posterior dislocation during sitting. Therefore, the acetabular component should be placed in greater anteversion and inclination to compensate for the lack of dynamic pelvic retroversion.

Question 43

A 35-year-old male requires ligamentous reconstruction for chronic posterolateral rotatory instability (PLRI) of the elbow. During reconstruction of the lateral ulnar collateral ligament (LUCL), where should the femoral tunnel be placed to best approximate the isometric point of the native ligament?





Explanation

The isometric point for the origin of the lateral ulnar collateral ligament (LUCL) is located at the isometric center of rotation of the capitellum, which corresponds anatomically to the lateral epicondyle. Improper placement, particularly anterior to the axis of rotation, results in the graft being tight in flexion and loose in extension, leading to recurrent instability or loss of motion.

Question 44

A 14-year-old male presents with recurrent ankle sprains and a rigid flat foot. Oblique radiographs of the foot demonstrate an 'anteater nose' sign. Which of the following is the most likely diagnosis?





Explanation

The 'anteater nose' sign on an oblique radiograph of the foot is a classic finding of a calcaneonavicular coalition. It represents an elongation of the anterior process of the calcaneus extending toward the navicular. Talocalcaneal coalitions are typically best visualized on a Harris axial view or CT scan, and may demonstrate the 'C-sign' on a lateral radiograph.

Question 45

A 12-year-old obese boy presents with a left-sided stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the asymptomatic right hip?





Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) due to the exceedingly high risk of bilateral involvement. Age less than 10, open triradiate cartilage, and prior radiation therapy are also considered indications for prophylactic fixation.

Question 46

According to the Wiltse classification of spondylolisthesis, which type is characterized by congenital abnormalities of the upper sacrum or the neural arch of L5, leading to progressive slipping primarily seen in pediatric patients?





Explanation

The Wiltse classification categorizes spondylolisthesis. Type I is Dysplastic, caused by congenital anomalies of the lumbosacral junction (e.g., attenuated pars, maloriented facets) and has a high rate of progression. Type II is Isthmic (pars defect). Type III is Degenerative. Type IV is Traumatic (fracture in areas other than the pars). Type V is Pathologic (generalized or localized bone disease).

Question 47

A 40-year-old female sustains a fall on an outstretched hand and incurs a complex coronal shear fracture of the distal humerus involving the capitellum and trochlea. Based on the Dubberley classification, what defines a Type 3 capitellum fracture?





Explanation

In the Dubberley classification of coronal shear fractures of the distal humerus: Type 1 involves the capitellum with or without the lateral trochlear ridge. Type 2 involves the capitellum and extends medially into the trochlea in a single piece. Type 3 involves fractures extending across the capitellum and the entire trochlea (communited or separate fragments). The addition of 'A' means the posterior condyle is intact, and 'B' means there is posterior condylar comminution.

Question 48

The Lisfranc ligament is an essential stabilizing structure of the tarsometatarsal joint complex. From which two bony structures does the primary intra-articular band of the Lisfranc ligament span?





Explanation

The Lisfranc ligament connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the largest and strongest ligament of the tarsometatarsal joint complex and is critical for midfoot stability. There is no direct ligamentous connection between the first and second metatarsal bases.

Question 49

A 45-year-old female presents with insidious onset groin pain. Radiographs reveal a 'cross-over sign' and an alpha angle of 45 degrees. These findings are most characteristic of which of the following?





Explanation

The 'cross-over sign' on an AP pelvis radiograph indicates acetabular retroversion or focal anterior overcoverage, which is the hallmark of Pincer-type femoroacetabular impingement (FAI). An alpha angle of 45 degrees is within normal limits (typically < 50-55 degrees), making a Cam lesion (femoral-sided abnormality) less likely.

Question 50

A 78-year-old male sustains a Type II odontoid fracture after a low-energy fall. Which of the following factors is most strongly associated with a high risk of non-union if treated conservatively with a halo vest?





Explanation

Risk factors for non-union of Type II odontoid fractures treated non-operatively include initial displacement > 5 mm, age > 65 years, angulation > 10 degrees, and delayed treatment. Posterior displacement versus anterior displacement is debated, but displacement > 5mm and advanced age are well-established primary risk factors for failure of conservative management.

Question 51

A 45-year-old weightlifter feels a pop in the posterior aspect of his elbow during a heavy bench press. Which of the following physical examination findings is most specific for a complete acute distal triceps tendon rupture?





Explanation

A complete distal triceps rupture typically presents with an inability to actively extend the elbow against gravity (often tested with the arm abducted to 90 degrees). A palpable gap may be felt proximal to the olecranon. The Hook test is used for distal biceps ruptures. Pain with resisted supination is also associated with biceps pathology or lateral epicondylitis.

Question 52

Most acute Achilles tendon ruptures occur in a relatively hypovascular 'watershed' area. Where is this region typically located relative to the calcaneal insertion?





Explanation

The Achilles tendon has a relative hypovascular zone located approximately 2 to 6 cm proximal to its insertion on the calcaneus. This area is supplied by branches from the posterior tibial and peroneal arteries but has the poorest blood supply, making it the most common site for degeneration and spontaneous rupture.

Question 53

According to the Young-Burgess classification, which injured ligamentous structure differentiates an Anteroposterior Compression Type III (APC-III) pelvic ring injury from an APC-II injury?





Explanation

In the Young-Burgess classification, an APC-II injury involves disruption of the pubic symphysis, anterior sacroiliac ligaments, sacrospinous, and sacrotuberous ligaments, causing an 'open book' pelvis with rotational instability but preserved vertical stability. An APC-III injury includes all the above plus disruption of the strong posterior sacroiliac ligaments, resulting in both rotational and complete vertical instability.

Question 54

A 35-year-old male sustains an L1 burst fracture in a motor vehicle collision. He is neurologically intact. MRI demonstrates an intact posterior ligamentous complex (PLC). According to the Thoracolumbar Injury Classification and Severity Score (TLICS), what is his total score, and what is the recommended management?





Explanation

The TLICS system assigns points based on morphology, neurologic status, and posterior ligamentous complex (PLC) integrity. Burst fracture morphology = 2 points. Neurologically intact = 0 points. Intact PLC = 0 points. Total score = 2. A score of 3 or less is an indication for non-operative management. A score of 4 is indeterminate (surgeon's choice), and 5 or more warrants surgical intervention.

Question 55

A 42-year-old female presents with a highly comminuted, displaced radial head fracture (Mason Type III) and an associated tear of the medial ulnar collateral ligament, causing elbow instability. Which of the following is the most appropriate surgical treatment?





Explanation

In a Mason Type III (comminuted) radial head fracture with associated ligamentous instability (e.g., Essex-Lopresti, terrible triad, or MUCL tear), radial head excision alone is contraindicated because the radial head is a crucial secondary stabilizer to valgus stress and longitudinal forearm stability. If ORIF is not possible due to severe comminution, radial head excision with prosthetic replacement is the treatment of choice to restore stability.

Question 56

A 55-year-old diabetic patient with peripheral neuropathy presents with a red, hot, swollen foot without open ulcers. Radiographs reveal fragmentation of the tarsometatarsal joints, periarticular debris, and subluxation. There is no systemic fever or leukocytosis. According to the Eichenholtz classification of Charcot arthropathy, which stage does this represent?





Explanation

The Eichenholtz classification of Charcot neuroarthropathy includes: Stage 0 (clinically red, hot, swollen, but normal radiographs); Stage 1 (Development/Fragmentation: joint dislocation, subchondral fragmentation, debris formation); Stage 2 (Coalescence: absorption of debris, early fusion of fragments); and Stage 3 (Consolidation/Remodeling: remodeling of bone ends, solid fusion). This patient has radiographic evidence of fragmentation, consistent with Stage 1.

Question 57

A 22-year-old female is evaluated for symptomatic developmental dysplasia of the hip (DDH). Preoperative planning for a Bernese periacetabular osteotomy (PAO) is underway. Which of the following is a strict prerequisite for a successful PAO in this patient?





Explanation

The Bernese periacetabular osteotomy (PAO) is indicated for symptomatic DDH in adolescents and young adults. A strict prerequisite is a closed triradiate cartilage to prevent growth arrest, as the osteotomy cuts through the ilium, ischium, and pubis around the acetabulum. Advanced osteoarthritis (Tonnis grade 2 or 3) is a relative contraindication, and the joint must demonstrate congruency on functional (abduction/internal rotation) views to ensure the redirected acetabulum will articulate properly.

Question 58

In the Lenke classification for adolescent idiopathic scoliosis (AIS), which of the following criteria determines whether a secondary (minor) curve is considered 'structural' and therefore necessitates inclusion in the fusion construct?





Explanation

According to the Lenke classification of AIS, a minor curve is considered structural if it fails to correct to < 25 degrees on supine side-bending radiographs, or if there is regional kyphosis > 20 degrees. Structural minor curves must generally be included in the surgical fusion construct to achieve optimal coronal and sagittal balance.

Question 59

A 35-year-old carpenter presents with aching pain in the proximal volar forearm and numbness in the radial three-and-a-half digits. Sensation over the thenar eminence is decreased. Electromyography reveals normal conduction at the wrist. Compression of the median nerve is suspected. Which anatomical structure is most likely responsible for this specific sensory deficit?





Explanation

The patient has Pronator Syndrome, an entrapment of the median nerve in the proximal forearm, most commonly between the two heads of the pronator teres. Decreased sensation over the thenar eminence distinguishes this from Carpal Tunnel Syndrome, because the palmar cutaneous branch of the median nerve (which supplies the thenar eminence) branches off proximal to the transverse carpal ligament. The Ligament of Struthers is a rarer proximal median nerve compression site associated with a supracondylar process.

Question 60

A 21-year-old collegiate basketball player sustains a fracture of the fifth metatarsal located at the metaphyseal-diaphyseal junction, extending into the fourth-fifth intermetatarsal articulation. He wishes to return to play as safely and quickly as possible. What is the most appropriate management?





Explanation

The patient has a Zone 2 (Jones) fracture of the fifth metatarsal. Because this is an intra-articular fracture at the metaphyseal-diaphyseal junction in a high-demand athlete, intramedullary screw fixation is the gold standard. It offers the highest union rate, fastest return to play, and lowest risk of non-union or re-fracture compared to conservative management, which has a higher rate of delayed union or non-union in this hypovascular zone.

Question 61

A 35-year-old male falls on an outstretched hand and sustains a fracture of the anteromedial facet of the coronoid process. Which of the following injury mechanisms and associated ligamentous injuries is most classically associated with this fracture pattern?





Explanation

Fractures of the anteromedial facet of the coronoid process are the hallmark of varus posteromedial rotatory instability (VPMRI) of the elbow. The mechanism involves an axial load combined with varus and posteromedial rotatory forces. This causes the anteromedial coronoid facet to impact the medial trochlea, resulting in a fracture, and invariably causes rupture of the lateral collateral ligament (LCL) complex, including the LUCL. Failure to recognize and treat the LUCL injury and the facet fracture can lead to rapid post-traumatic arthrosis and chronic subluxation.

Question 62

Which of the following is the primary advantage of primary arthrodesis compared to open reduction and internal fixation (ORIF) for the treatment of a purely ligamentous Lisfranc injury?





Explanation

Multiple studies (such as the landmark RCT by Ly and Coetzee) have demonstrated that primary arthrodesis of the first, second, and third tarsometatarsal joints for purely ligamentous Lisfranc injuries results in superior functional outcomes and a significantly decreased rate of hardware removal and reoperation compared to ORIF. ORIF of ligamentous injuries often fails due to hardware breakage or loss of reduction once weight-bearing begins, often necessitating a secondary fusion.

Question 63

A 65-year-old male with a ceramic-on-ceramic total hip arthroplasty presents with a squeaking hip. Radiographs demonstrate a steep acetabular cup with an inclination angle of 60 degrees. Which of the following wear patterns is most likely occurring at the bearing surface?





Explanation

Squeaking in ceramic-on-ceramic THA is highly correlated with edge loading, which typically occurs due to component malposition (such as a steep cup with high inclination, >50 degrees, or excessive retroversion). Edge loading leads to 'stripe wear,' a specific pattern of localized linear wear on the ceramic femoral head caused by contact with the edge of the ceramic acetabular liner during the swing phase or microseparation.

Question 64

A 72-year-old male with long-standing ankylosing spondylitis presents to the emergency department after a minor fall from a standing height. He reports severe neck pain but has a normal neurologic examination. CT scan reveals a displaced fracture through the C6-C7 disc space extending through the posterior elements. What is the most appropriate definitive management?





Explanation

Spinal fractures in patients with ankylosing spondylitis are highly unstable due to the altered biomechanics of the completely fused spinal column, acting like a long bone. They are prone to translation and shear forces, leading to high rates of neurologic deterioration if not definitively stabilized. Conservative management (collar, halo) is associated with high mortality and failure rates. The standard of care is long-segment posterior instrumentation and fusion (typically spanning at least 3 levels above and 3 levels below the fracture) to provide adequate lever-arm control.

Question 65

A lateral radiograph of the elbow in a trauma patient reveals a 'double-arc sign.' This radiographic finding indicates which of the following injury patterns?





Explanation

The 'double-arc sign' on a true lateral radiograph of the elbow is pathognomonic for a capitellum fracture that extends medially to include the lateral portion of the trochlea (lateral trochlear ridge), known as a McKee Type IV fracture. One arc represents the subchondral bone of the capitellum, and the second arc represents the lateral trochlear ridge.

Question 66

A 35-year-old female is evaluated 8 weeks after open reduction and internal fixation of a Hawkins Type II talar neck fracture. An AP mortise radiograph demonstrates a subchondral radiolucent band in the talar dome. What does this radiographic finding indicate?





Explanation

The presence of a subchondral radiolucent band in the talar dome 6 to 8 weeks after a talar neck fracture is known as Hawkins' sign. It represents subchondral osteopenia (bone resorption) secondary to disuse. Because bone resorption is an active cellular process that requires an intact blood supply, its presence is a highly reliable indicator that the talar body remains vascularized, thus effectively excluding the diagnosis of complete avascular necrosis (AVN).

Question 67

In a patient with cam-type femoroacetabular impingement (FAI), where is the primary site of articular cartilage damage most commonly located?





Explanation

Cam-type FAI is caused by an aspherical femoral head (often with a decreased head-neck offset or increased alpha angle). During hip flexion and internal rotation, this prominent cam lesion engages the acetabulum, causing shear forces. The resulting chondral damage typically occurs at the anterosuperior aspect of the acetabulum, frequently causing cartilage delamination at the chondrolabral junction.

Question 68

A 60-year-old male with severe cervical spondylotic myelopathy is being evaluated for surgical decompression. Which of the following preoperative MRI findings of the spinal cord is most strongly associated with a poor potential for neurologic recovery?





Explanation

In the context of cervical spondylotic myelopathy, T2-weighted hyperintensity in the spinal cord indicates edema, ischemia, or gliosis, and has a variable prognostic value. However, T1-weighted hypointensity indicates permanent tissue destruction (myelomalacia or cystic necrosis) and is strongly associated with permanent neurologic deficits and poor recovery potential following surgical decompression.

Question 69

What is the most common mode of long-term failure in a semiconstrained (linked) total elbow arthroplasty (TEA)?





Explanation

Aseptic loosening is the most common cause of long-term failure in semiconstrained (linked) total elbow arthroplasty. The linked design inherently transfers more varus, valgus, and rotational stresses to the cement-bone interface compared to an unlinked (resurfacing) prosthesis, leading to a higher rate of mechanical loosening over time. Unlinked TEA, conversely, relies on intact ligamentous structures and has a higher rate of instability but lower rates of long-term aseptic loosening.

Question 70

When performing an extensile lateral approach for the open reduction and internal fixation of a displaced intra-articular calcaneus fracture, the viability of the lateral soft tissue flap is primarily dependent on which of the following arteries?





Explanation

The lateral soft tissue flap used in the extensile lateral approach to the calcaneus receives its primary blood supply from the lateral calcaneal artery, which is a terminal branch of the peroneal artery. To preserve this delicate vascular network and minimize the risk of marginal skin necrosis or wound breakdown, it is critical to raise a full-thickness subperiosteal flap without violating the tissue planes within the flap itself.

Question 71

A 9-year-old boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. Prophylactic pinning of the asymptomatic, radiographically normal contralateral right hip is strongly indicated if the patient has a history of which of the following?





Explanation

The overall risk of a contralateral slip in patients with SCFE is approximately 20-25%. However, prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in patients with specific high-risk profiles, including underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or growth hormone therapy), previous pelvic radiation therapy, or presentation at an unusually young age (typically under 10 years for boys).

Question 72

Pathologic examination of the hypertrophied ligamentum flavum in a patient with degenerative lumbar spinal stenosis is most likely to demonstrate which of the following histologic changes?





Explanation

The normal ligamentum flavum is composed predominantly of elastic fibers (roughly 80% elastin and 20% collagen). In the pathogenesis of degenerative lumbar spinal stenosis, mechanical stress and aging lead to a loss of elastic fibers and a corresponding increase in collagen (fibrosis). This fibrotic change causes the ligament to lose its elasticity, leading to hypertrophy and buckling into the spinal canal during extension, thereby contributing to neural compression.

Question 73

A patient demonstrates posterolateral rotatory instability (PLRI) of the elbow. The primary pathomechanical lesion involves the avulsion of the lateral ulnar collateral ligament (LUCL) from which specific anatomic structure?





Explanation

Posterolateral rotatory instability (PLRI) of the elbow is primarily caused by an insufficiency of the lateral ulnar collateral ligament (LUCL). The LUCL originates on the lateral epicondyle of the humerus and inserts on the supinator crest of the ulna. The most common site of avulsion or disruption resulting in PLRI is at its humeral origin on the lateral epicondyle.

Question 74

During flatfoot reconstruction for Stage IIb posterior tibial tendon dysfunction (PTTD), a surgeon performs a flexor digitorum longus (FDL) transfer to the navicular, a medializing calcaneal osteotomy, and a lateral column lengthening (Evans osteotomy). Which of the following complications is most uniquely and commonly associated with the lateral column lengthening procedure?





Explanation

A lateral column lengthening (such as an Evans calcaneal osteotomy) corrects significant forefoot abduction in Stage IIb PTTD by wedging open the anterior calcaneus. However, this anatomically lengthens the lateral column, which increases contact pressures at the calcaneocuboid (CC) joint. Consequently, the most common specific complication of this procedure is CC joint arthrosis, lateral foot pain, and lateral column overload (which may also manifest as fifth metatarsal stress fractures).

Question 75

During a Bernese periacetabular osteotomy (PAO) for symptomatic developmental dysplasia of the hip, the posterior column of the pelvis is deliberately preserved to maintain pelvic stability and allow for early mobilization. Which of the following osteotomy cuts is NOT performed during a standard PAO?





Explanation

The Bernese periacetabular osteotomy (PAO) reorients the acetabulum while preserving the mechanical integrity of the pelvic ring. This is achieved by keeping the posterior column of the hemipelvis intact. Therefore, a complete osteotomy of the posterior column is NOT performed. The cuts include an incomplete ischial osteotomy (stopping short of the posterior column), a complete pubic root osteotomy, and an incomplete iliac osteotomy that joins the ischial cut, freeing the acetabular fragment while maintaining posterior pelvic continuity.

Question 76

A 45-year-old male presents with acute onset of severe low back pain and bilateral leg radiculopathy. Which of the following clinical findings has the highest sensitivity for the diagnosis of cauda equina syndrome?





Explanation

Urinary retention is considered the most sensitive early clinical sign for cauda equina syndrome (CES), with a sensitivity of approximately 90%. While saddle anesthesia and decreased anal sphincter tone are highly specific and classically associated with the condition, they may present later. A patient with normal bladder function (specifically, a post-void residual volume of less than 100-200 mL) is highly unlikely to have established cauda equina syndrome.

Question 77

During a single-incision anterior approach for the repair of a retracted distal biceps tendon rupture, the surgeon places Hohmann retractors around the radial neck to facilitate visualization of the radial tuberosity. Which nerve is at the highest risk of injury with this maneuver?





Explanation

The posterior interosseous nerve (PIN), which is the deep branch of the radial nerve, courses through the two heads of the supinator muscle around the lateral aspect of the proximal radius. Blind or overly aggressive placement of retractors (such as Hohmann retractors) around the radial neck during the anterior single-incision approach to the distal biceps firmly compresses the PIN against the bone, putting it at high risk for a neuropraxia or structural injury.

Question 78

A 55-year-old poorly controlled diabetic patient presents with a severely swollen, erythematous, and warm left foot. Radiographs reveal fragmentation of the midfoot joints and subluxation, but no skin ulceration is present. The erythrocyte sedimentation rate (ESR) and WBC count are normal. What is the most appropriate initial management?





Explanation

This patient is presenting with acute Eichenholtz Stage I (Developmental/Fragmentation) Charcot neuroarthropathy. The hallmark is a red, hot, swollen foot without systemic signs of infection or ulceration. The preferred initial management is immediate off-loading and immobilization, most effectively achieved with total contact casting (TCC). Surgery (arthrodesis) in the acute inflammatory stage is highly prone to failure and is generally contraindicated until the process reaches Stage III (Reconstruction/Consolidation).

Question 79

A 62-year-old female with a metal-on-polyethylene total hip arthroplasty utilizing a large-diameter modular cobalt-chrome head presents with new-onset groin pain and an enlarging cystic pelvic mass on MRI. Aspiration yields sterile, cloudy, greenish fluid. What is the most likely primary etiology of this adverse local tissue reaction?





Explanation

This scenario describes trunnionosis, an adverse local tissue reaction (ALTR/ALVAL) occurring in metal-on-polyethylene (or metal-on-metal) total hip arthroplasties. It is caused by mechanically assisted crevice corrosion at the modular head-neck junction (the trunnion). This risk is increased with large-diameter, heavy metal (cobalt-chrome) heads on smaller trunnions, which increases the micromotion and corrosive wear at the taper interface, leading to the formation of metal debris, pseudotumors, and cystic masses.

Question 80

The Achilles tendon is most susceptible to spontaneous rupture in its relative hypovascular 'watershed' zone. Where is this critical zone anatomically located?





Explanation

The Achilles tendon receives its blood supply from the musculotendinous junction proximally, the bone distally, and the paratenon (specifically the anterior mesotenon) longitudinally. Anatomic injection studies have consistently demonstrated a relative hypovascular 'watershed' zone located approximately 2 to 6 cm proximal to the tendon's insertion on the calcaneus. This region is the most frequent site of degenerative tendinopathy and acute rupture.

Question 81

A 35-year-old male sustains a severely comminuted, irreparable radial head fracture and reports right wrist pain after falling on an outstretched hand. Examination reveals instability of the distal radioulnar joint (DRUJ) and wrist radiographs demonstrate proximal migration of the radius. To restore longitudinal stability of the forearm and prevent chronic wrist pain, what is the most critical surgical intervention?





Explanation

This patient has an Essex-Lopresti injury, characterized by a radial head fracture, disruption of the interosseous membrane (IOM), and DRUJ instability. The radial head is a critical secondary stabilizer to longitudinal forearm forces. When the IOM is disrupted, the radial head becomes the primary stabilizer. Excision without replacement inevitably leads to proximal radial migration, ulnar impaction syndrome, and chronic wrist pain. Placement of a metallic radial head arthroplasty is essential to restore longitudinal stability. Silastic implants cannot withstand the compressive forces and will fail.

Question 82

A 25-year-old male sustains a Hawkins Type III talar neck fracture following a motor vehicle collision. Which of the following vascular structures, responsible for the majority of the blood supply to the talar body, has almost certainly been disrupted in this injury?





Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, supplies the majority of the talar body. In a Hawkins Type III fracture (talar neck fracture with dislocation of both the subtalar and tibiotalar joints), the blood supply from the artery of the tarsal canal, the artery of the tarsal sinus (branch of the dorsalis pedis/peroneal), and vessels entering the talar neck are typically disrupted. The deltoid branches may be the only remaining blood supply, but the primary supplier disrupted is the artery of the tarsal canal, leading to an extremely high rate of avascular necrosis (AVN).

Question 83

An AP pelvis radiograph of a 30-year-old male with chronic groin pain demonstrates the anterior rim of the acetabulum crossing the posterior rim superiorly, but the medial aspect of the acetabulum does not cross the ilioischial line. What is this radiographic 'crossover sign' indicative of?





Explanation

The crossover sign on a well-centered AP pelvis radiograph indicates focal cranial retroversion of the acetabulum, which is a common cause of Pincer-type femoroacetabular impingement (FAI). In a normal hip, the anterior rim line should lie medial to the posterior rim line. When they cross, it indicates that the superior-anterior acetabulum is over-covering the femoral head. Coxa profunda is characterized by the acetabular fossa medial to the ilioischial line, while protrusio occurs when the femoral head itself crosses medial to the ilioischial line.

Question 84

A 60-year-old Asian male presents with progressive hand clumsiness and gait disturbances. Radiographs and MRI demonstrate a continuous band of ossification along the posterior aspect of the cervical vertebral bodies, causing severe spinal canal stenosis. Which of the following molecular factors is most significantly implicated in the pathogenesis of this condition?





Explanation

Ossification of the posterior longitudinal ligament (OPLL) is characterized by ectopic bone formation in the spinal ligaments. Research has shown that overexpression of osteogenic factors, particularly Bone Morphogenetic Proteins (BMP-2) and TGF-beta, plays a crucial role in the hyperostotic process of the posterior longitudinal ligament. It is highly prevalent in East Asian populations, and while genetics (like ENPP1 variants) play a role, BMP/TGF-beta signaling is a central downstream mechanism of the ossification process.

Question 85

A 28-year-old gymnast sustains an elbow injury. CT imaging reveals a fracture of the anteromedial facet of the coronoid. This specific fracture pattern is most closely associated with which mechanism of injury and corresponding ligamentous disruption?





Explanation

Anteromedial facet coronoid fractures occur via a mechanism of varus force coupled with posteromedial rotation (Varus Posteromedial Rotatory Instability, VPMRI). As the elbow subluxates, the anteromedial facet of the coronoid impacts the medial trochlea, causing the fracture. This mechanism inherently involves rupture of the lateral collateral ligament (LCL) complex, which must be addressed surgically to restore stability.

Question 86

A 55-year-old patient with uncontrolled diabetes presents with a unilaterally warm, swollen, and erythematous foot. There are no ulcers. Radiographs reveal fragmentation of the navicular and cuneiforms with periarticular debris and subluxation. Based on the Eichenholtz classification, what stage does this represent and what is the most appropriate initial management?





Explanation

The patient has Charcot neuroarthropathy. The Eichenholtz classification includes: Stage 0 (clinical signs of inflammation, normal x-rays), Stage I (Development/Fragmentation - debris, periarticular fragmentation, joint subluxation), Stage II (Coalescence - absorption of debris, early fusion), and Stage III (Consolidation/Remodeling - osteopenia resolves, mature bone forms). The patient is in Stage I. The gold standard initial treatment for acute Stage I Charcot is immobilization with a total contact cast (TCC) to prevent further deformity while the inflammatory process runs its course.

Question 87

During a total hip arthroplasty, the surgeon elects to use a ceramic-on-ceramic bearing surface. Postoperatively, the patient returns complaining of a loud 'squeaking' noise from the hip during specific movements. Which of the following technical factors is most strongly associated with an increased risk of squeaking in ceramic-on-ceramic hips?





Explanation

Squeaking is a well-documented complication of ceramic-on-ceramic THA, occurring in up to 10% of cases. The primary biomechanical cause is 'edge loading', which leads to stripe wear and loss of fluid film lubrication. Edge loading typically occurs due to component malposition, specifically high acetabular inclination (e.g., >55 degrees) or insufficient anteversion/retroversion, which uncovers the femoral head during certain arcs of motion.

Question 88

A 75-year-old male sustains an Anderson and D'Alonzo Type II odontoid fracture after a ground-level fall. The fracture is displaced 6 mm posteriorly. If treated non-operatively with a rigid cervical collar, which of the following characteristics is the strongest predictor of nonunion?





Explanation

Type II odontoid fractures have a high rate of nonunion. Risk factors for nonunion include fracture displacement > 5 mm, patient age > 50 years, posterior displacement, and comminution. Displacement greater than 5 mm is a classically tested, major independent risk factor that often directs surgeons toward operative management (e.g., posterior C1-C2 fusion or anterior odontoid screw) in surgical candidates.

Question 89

A 42-year-old female falls onto an outstretched hand and sustains an elbow fracture. The lateral radiograph demonstrates a 'double-arc' sign. According to the Bryan and Morrey classification modified by McKee, what does this radiographic sign pathognomonically represent?





Explanation

The 'double-arc' sign on a lateral elbow radiograph is pathognomonic for a McKee modification Type IV coronal shear fracture. The two arcs represent the subchondral bone of the capitellum and the lateral ridge of the trochlea, which are fractured and displaced as a single unit. It is critical to recognize this, as it indicates a more extensive medial extension of the fracture that requires adequate surgical exposure and fixation to restore the radiocapitellar and ulnohumeral articulations.

Question 90

A 22-year-old collegiate football player sustains a purely ligamentous Lisfranc injury. Weight-bearing radiographs demonstrate 3 mm of diastasis between the medial and middle cuneiforms with no associated fractures. Based on Level 1 evidence (e.g., Ly and Coetzee), what is the most appropriate surgical management?





Explanation

The landmark prospective randomized study by Ly and Coetzee demonstrated that for strictly ligamentous Lisfranc injuries, primary arthrodesis of the medial 2 or 3 rays yields superior functional outcomes and a lower rate of planned/unplanned reoperations compared to traditional ORIF with transarticular screws. Ligamentous injuries heal poorly, and ORIF often leads to late collapse and post-traumatic arthritis requiring salvage arthrodesis.

Question 91

During a modified Stoppa (anterior intrapelvic) approach for fixation of an anterior column acetabular fracture, significant hemorrhage occurs when dissecting superior to the superior pubic ramus. Which vascular anastomosis was most likely injured?





Explanation

The 'corona mortis' (crown of death) is a vascular anastomosis between the obturator system (internal iliac) and the external iliac system (most commonly the inferior epigastric artery or vein). It typically crosses the superior pubic ramus at an average distance of 5-6 cm from the pubic symphysis. Dissection in this area during ilioinguinal or modified Stoppa approaches must be done meticulously to identify and ligate these vessels to prevent life-threatening hemorrhage.

Question 92

A 45-year-old female presents with an L1 burst fracture following a fall from height. Neurological examination is completely normal. MRI reveals an intact posterior ligamentous complex (PLC). According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is her total score and the recommended management?





Explanation

The TLICS system scores three categories: Morphology, Neurology, and PLC integrity. Morphology: Burst fracture = 2 points. Neurological status: Intact = 0 points. PLC: Intact = 0 points. Total score = 2. A score of 3 or less indicates non-operative management. A score of 4 can be treated non-operatively or operatively based on surgeon preference/clinical scenario. A score of 5 or more favors operative treatment.

Question 93

A 13-year-old elite baseball pitcher presents with chronic medial elbow pain and decreased pitching velocity. Radiographs demonstrate widening of the medial epicondyle apophysis. Which phase of the throwing motion is associated with the highest valgus stress on the medial elbow structures, exacerbating this condition?





Explanation

Little League elbow (medial epicondyle apophysitis) is caused by repetitive valgus overload. During the throwing motion, the late cocking and early acceleration phases generate the maximum valgus torque on the elbow. This results in tremendous tensile stress across the medial elbow structures (UCL, medial epicondyle apophysis, flexor-pronator mass) and compressive forces laterally (radiocapitellar joint).

Question 94

A 50-year-old female presents with a progressive, painful flatfoot deformity. Examination reveals a flexible hindfoot valgus, but she is unable to perform a single-leg heel rise. Weight-bearing radiographs demonstrate a talonavicular coverage angle indicating >50% lateral subluxation of the navicular on the talus. Based on this Stage IIb posterior tibial tendon dysfunction (PTTD), what is the most appropriate surgical treatment algorithm?





Explanation

Stage II PTTD is a flexible deformity. Stage IIa has minimal forefoot abduction (<30-40% talonavicular uncoverage) and is typically treated with a medial displacement calcaneal osteotomy (MDCO) and FDL transfer. Stage IIb has significant forefoot abduction (>40-50% TN uncoverage). To adequately correct the forefoot abduction, a lateral column lengthening (Evans osteotomy) is required in addition to MDCO and FDL transfer. Rigid deformities (Stage III) require triple arthrodesis.

Question 95

A 6-week-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. Her hips were noted to be dislocated and irreducible (Ortolani negative) at presentation. Ultrasound at 3 weeks shows persistent dislocation. What is the most appropriate next step in management?





Explanation

Continued use of a Pavlik harness in an persistently dislocated (irreducible) hip beyond 3 to 4 weeks is strictly contraindicated. Prolonged use in this setting compresses the femoral head against the posterior acetabular rim, causing 'Pavlik harness disease' (erosion of the posterior acetabulum) and a significantly increased risk of avascular necrosis. The harness must be abandoned in favor of rigid bracing or transition to closed reduction and spica casting.

Question 96

In a pediatric patient with an L5-S1 isthmic spondylolisthesis, which of the following spinopelvic parameters is typically fixed morphologically, significantly increased compared to the general population, and strongly correlates with progression of the slip?





Explanation

Pelvic incidence (PI) is a fixed morphological parameter unique to each individual, defined as the angle between a line perpendicular to the sacral plate and a line connecting the midpoint of the sacral plate to the center of the bicoxofemoral axis. Patients with developmental isthmic spondylolisthesis generally have a significantly higher PI. A high PI leads to an increased sacral slope and higher shear forces at the lumbosacral junction, predisposing to slip progression.

Question 97

Following an ulnar collateral ligament (UCL) reconstruction ('Tommy John' surgery) using a palmaris longus autograft via the docking technique, what is the most frequent postoperative complication reported in the literature?





Explanation

Ulnar neuropathy is the most common complication following UCL reconstruction, reported in approximately 5-10% of cases. The ulnar nerve lies in the cubital tunnel immediately posterior to the UCL and is at high risk of irritation, traction, or compression during surgical exposure and tunnel drilling. Modern techniques, such as the docking technique with meticulous handling of the nerve or formal transposition when indicated, have helped minimize, but not eliminate, this risk.

Question 98

A 55-year-old male with hallux rigidus complains of severe pain throughout the entire range of motion of the first metatarsophalangeal (MTP) joint, including pain in the mid-range. Radiographs show severe joint space narrowing, large dorsal osteophytes, and subchondral cysts. Based on the Coughlin and Shurnas classification, which grade does this represent and what is the definitive surgical option?





Explanation

The Coughlin and Shurnas classification for hallux rigidus defines Grade 4 by the presence of pain in the mid-range of motion (unlike Grade 3, where pain is only at the extremes of motion), severe joint space loss, and large osteophytes. While cheilectomy is acceptable for Grades 1-3, Grade 4 implies global joint destruction and mid-ROM pain, making 1st MTP arthrodesis the gold standard surgical treatment.

Question 99

A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. During surgical planning, prophylactic pinning of the asymptomatic right hip is discussed. Which of the following is the strongest specific indication for prophylactic pinning of the contralateral hip?





Explanation

While there is ongoing debate regarding universal prophylactic pinning of the contralateral hip in SCFE, strong, generally accepted indications include the presence of an underlying endocrine or metabolic disorder (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or previous radiation therapy. These conditions carry a much higher risk (often >50%) of bilateral involvement compared to idiopathic cases.

Question 100

A 62-year-old male with a history of uncontrolled diabetes mellitus presents with severe back pain, fever, and radicular leg pain. MRI with contrast reveals a lumbar epidural abscess. The patient is neurologically intact. A trial of non-operative management with IV antibiotics is considered. Which of the following factors at presentation is most strongly predictive of failure of medical management?





Explanation

Non-operative management of a spinal epidural abscess (SEA) can be attempted in neurologically intact patients. However, risk factors for failure of medical management (leading to neurological deterioration requiring emergency decompression) include: age > 65, diabetes, MRSA infection, positive blood cultures, and a highly elevated CRP (> 115 mg/L) or ESR (> 85 mm/hr). A CRP > 115 mg/L is a very strong independent predictor of medical failure.

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Dr. Mohammed Hutaif
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