Question 1

A 13-year-old female competitive gymnast has had pain in her lumbar spine and anterior thighs for 9 weeks. It has become significant enough to limit her activities. Radiographs of her lumbar and thoracic spine are normal and iliac crests show that she is not skeletally mature. Physical examination is essentially normal with no long tract or nerve tension signs present. What is the next appropriate step in a diagnostic work up:

Explanation

This athlete most likely has spondylolysis of the lumbar spine. Repetitive hyperextension of the lumbar spine with stress concentrated at the pars interarticularis can lead to stress fractures especially in the fourth or fifth lumbar vertebrae. Spondylolysis is the most common bony injury in the athlete's spine. The most sensitive way to delineate this injury is with technetium bone scanning. C T and MRI are not as helpful in the diagnosis or treatment of spondylolysis, unless the patient has frank radicular symptoms.

Question 2

The posterior cruciate ligament sustains from 85% to 100% of the load of a posterior directed force at 90º of flexion. Which fibers of the ligament are responsible for this:

Explanation

The posterior cruciate ligament is the primary restraint to posterior tibial translation, sustaining the majority of force across the knee at 90º of flexion. The PC L has two functional components, an anterolateral portion, and a posteromedial portion. These two "bundles" are named according to their insertions. The anterolateral bundle is tight in flexion and is biomechanically superior to the posteromedial bundle. For this reason, "one bundle techniques" attempt to reproduce the anterolateral bundle.

Question 3

A fourteen-year-old little league pitcher has lateral elbow pain that is worsened by throwing. Plain radiographs demonstrate fragmentation of the capitellum with no evidence of a loose body. A presumptive diagnosis of osteochondritis dissecans of the capitellum has been made. He has undergone rest, followed by physical therapy over the past three months. Now range of motion is from 30 to 120, and pain is present when attempting to throw. The next appropriate step is:

Explanation

This patient has osteochondritits dissecans of the capitellum from pitching. OC D of the capitellum differs from Panner's disease, which is a osteochondrosis of the capitellum which occurs at a younger age (7-12) and is less symptomatic. Initial treatment of osteochondritis dissecans of the capitellum is rest and occasional splinting. Arthroscopy is indicated for both detached lesions and those who have failed conservative therapy. The entire joint should be a assessed, loose fragments removed and the subchondral bone of the defect is debrieded to a healthy vascular bed.

Question 4

The primary stabilizer of the elbow to valgus stress is:

Explanation

The medial collateral ligament complex of the elbow consists of three parts: the anterior, posterior, and transverse segments or bundles. The anterior bundle is the most distinct portion. The posterior bundle/segment is a thickening of the capsule and notable only at 90 degrees of flexion. The transverse component or ligament of C ooper appears to contribute little to elbow stability. There are no inferior or superior bundles.

Question 5

A collegiate football player sustains a direct blow to his anterior shoulder. Physical examination reveals ecchymosis over the anterior shoulder and painful range of motion. Radiographs include an anteroposterior, scapular Y and an axillary lateral. The radiographs show the humeral head to be located with an isolated fracture at the base of the coracoid process. Treatment should consist of:

Explanation

Acute isolated fracture of the coracoid base is almost invariably treated conservatively with the expectation of a good result. If the acromioclavicular joint is sound, the basal fracture is splinted by the costoclavicular ligaments, and displacement is minimal. Treatment with a sling for comfort is sufficient. Pendulum exercises are encouraged. Overhead elevation is restricted for 4-6 weeks to allow healing. Return to sports can occur after healing of the fracture and return to full, painless range of motion. This usually requires 6 to 8 weeks.

Question 6

The infraspinatus is strengthened best by which exercise:

Explanation

The infraspinatus is primarily responsible for external rotation, humeral head depression, and posterior approximation at lower elevations, whereas the teres minor functions at higher elevations. Therefore, external rotation with the arm near the side of the body is optimal for strengthening the infraspinatus. External rotation at approximately 70º is more appropriate for strengthening the teres minor.

Question 7

When comparing male and female competitive athletes, what can be said regarding anterior cruciate ligament injuries:

Explanation

It has been shown that competitive female athletes have an increased relative risk for anterior cruciate ligament injury in college sports as well as during military training. Possible causative factors have been suggested (body movement, muscular strength, joint laxity, limb alignment, notch dimensions, effects of estrogen), but none have been proven as of yet.

Question 8

The most common location for a meniscal cyst is:

Explanation

Mensical cysts are rather uncommon and occur most frequently in the middle third of the lateral meniscus. They are less common in the medial meniscus, where they tend to occur in the posterior horn. They are often associated with horizontal, cleavage type tears of the meniscus. Lateral cysts tend to be smaller and are localized to the joint line, where medial cysts can be large and may dissect through the capsule.

Question 9

If a distal biceps tendon avulsion is not repaired or reconstructed, what is the likely result:

Explanation

Untreated distal biceps rupture results in a loss of about 20% flexion and 40% supination strength.

Question 10

The best clinical test for diagnosis of an anterior cruciate ligament (AC L) rupture is:

Explanation

The Lachman test provides the best predictive value of all clinical tests for diagnosis of an anterior cruciate ligament rupture. The diagnosis of a complete AC L rupture can be reliably made clinically without the added expense of a preoperative magnetic resonance image.

Question 11

The reason a patient with an acute rupture of the anterior cruciate ligament will usually have a hemarthrosis is due to disruption of what main blood supply to the ligament:

Explanation

The major blood supply to the anterior cruciate ligament arises from the ligamentous branches of the middle genicular artery, with minor contribution from the terminal branches of the medial and lateral inferior genicular arteries. The AC L is covered in a synovial fold that is richly supplied by the middle geniculate artery.

Question 12

A football player is down and unconscious after making a tackle. He is found lying supine. What initial management should be undertaken on the playing field:

Explanation

Prevention of further injury is the single most important objective in this patient. While maintaining immobilization of the head and neck check for airway, breathing and pulses (ABC ), followed by level of consciousness. The chin strap and helmet fastened will support the head and neck, and keep it aligned with the body, thereby reducing the risk of spinal cord injury associated with unstable fractures and dislocations. The face mask must be removed from the helmet before rescue breathing can ensue.

Question 13

A 30-year-old competitive body builder felt a severe pain in his proximal humerus after performing a bench press exercise. He has significant ecchymoses over the anterior aspect of his proximal arm and axilla. There is significant limitation of motion due to pain, with pain to palpation over the insertion of the pectoralis major and the axilla. A magnetic resonance image showed more than 80% avulsion of the pectoralis major from the humerus. What treatment should this patient undergo:

Explanation

A complete rupture of the pectoralis insertion demands early surgical treatment in the active athlete. Results of late repair are inferior when compared with primary repair. The tendon is either sutured to bone or anchors are placed to augment repair. Results of those with surgery within one week of injury have been shown to be superior compared to those with delayed surgery or no surgery.

Question 14

When making an anteromedial portal for ankle arthroscopy, which structure is most "at risk" for injury:

Explanation

The anteromedial portal is adjacent to the saphenous vein, and injury may occur if care is not taken when creating the portal. A nick in the skin is made and then blunt hemostats are used to spread in line with the neurovascular structures to decrease the likelihood of injury. The anterolateral portal is associated with injury to the superficial peroneal nerve. The anterior-central portal is associated with injury to the dorsalis pedis artery.

Question 15

Fibrinous degradation in which muscle insertion most commonly characterizes lateral epicondylitis or tennis elbow:

Explanation

Degeneration at the extensor muscle group insertion to the lateral epicondyle, primarily the extensor carpi radialis brevis, can be a result of overuse or poor technique in racket sports. Tenderness to palpation at the insertion of the extensor carpi radialis brevis and pain with resisted wrist extension are common findings.

Question 16

A patient underwent bone-patellar-bone anterior cruciate ligament reconstruction. Postoperative radiographs show the femoral tunnel has been placed too far anteriorly. What is the most likely clinical result of anterior placement of the femoral tunnel:

Explanation

A femoral tunnel that has been placed too anterior will limit extension. Numerous studies have shown the most common technical mistake intraoperatively is placement of either the tibial or the femoral tunnel, or both, too far anteriorly. Either of these aberrant placements may cause impingement of the graft and thus promote formation of a large lump of fibrous tissue, known as a Cyclops lesion. This lesion forms anterior to the graft, potentially blocking extension of the knee.

Question 17

During a wrist arthroscopy in a basketball player who has ulnar-sided wrist pain, the articular disk of the triangular fibrocartilage complex is observed. A probe is inserted and the disk is free floating without tension, (a negative "trampoline test"). What does this signify:

Explanation

A probe should be used to test the integrity of the articular disc of the TFC C . This disk should be fairly taught, similar to a trampoline. When the articular disk is floppy and floating without tension, a tear in either the central or peripheral portion must be suspected.

Question 18

A football player has suffered a concussion. It is his first such injury. He suffered loss of consciousness for about 30 seconds and was confused after for 45 minutes. He is now fully asymptomatic at the end of the football game (1 hour after injury). When should he return to play:

Explanation

This patient has suffered a grade 2, or moderate concussion. These patients may return to play after one week if asymptomatic. Grade 1: No LOC , posttraumatic amnesia <30 minutes; return to play when symptoms resolve Grade 2: LOC <5 minutes or posttraumatic amnesia >30 minutes; return to play after one week if asymptomatic. Grade 3: LOC >5 minutes, or posttraumatic amnesia >24 hours; minimum delay of 1 month, then may return if asymptomatic.

Question 19

A collegiate tennis player has undergone surgery for recalcitrant tennis elbow (lateral epicondylitis). He now complains of clicking, catching, and "slipping out of joint" of the elbow. Examination reveals a positive "pivot shift" test of the elbow with normal motion. Radiograph examination is normal. The primary stabilizer of the elbow that is damaged in this patient giving rise to his symptoms of posterolateral rotatory instability is:

Explanation

This patient has incompetence of the lateral ligamentous constraint to the elbow. The most common causes for this injury are previous dislocations and iatrogenic approaches to the lateral elbow. Up to 25% of cases of failed tennis elbow surgery are associated with lateral ligamentous insufficiency. The lateral ulnar collateral ligament has been shown to be the primary restraint to posterolateral instability of the elbow.

Question 20

A 56-year-old competitive triathelete fell off his bicycle and sustained a traumatic anterior shoulder dislocation. The dislocation was reduced in the emergency room. No associated fractures were noted. A magnetic resonance image examination would be judicious in this patient to:

Explanation

Rotator cuff tears may accompany anterior and inferior glenohumeral dislocations. The frequency of this complication increases with age. In patients older than 40 years incidence exceeds 30%; in patients older than 60 years, the incidence exceeds 80%. Shoulder ultrasound, arthrography or MRI is indicated in patients over 40 years of age, with a shoulder dislocation. Prompt repair of these lesions is usually indicated.

Question 21

The anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) function synergistically. Which of the following best describes the primary biomechanical role of the posterolateral bundle?

Explanation

The PL bundle is tight in extension and provides the primary restraint against rotatory loads. Conversely, the AM bundle tightens in flexion and serves as the primary restraint to anterior tibial translation at 90 degrees of flexion.

Question 22

An 8-year-old boy presents with an atraumatic limp and left groin pain. Radiographs reveal a slipped capital femoral epiphysis (SCFE). His weight is in the 45th percentile for his age. Which of the following tests is most appropriate as part of his initial evaluation?

Explanation

A patient presenting with SCFE before the age of 10 or with atypical physical features (weight less than 50th percentile) requires a thorough endocrine workup. Hypothyroidism and renal osteodystrophy are among the most common associated endocrine disorders.

Question 23

A 6-year-old girl falls from the monkey bars and sustains an extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, she is unable to flex the interphalangeal joint of her thumb and the distal interphalangeal joint of her index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury results in the inability to make an 'OK' sign due to weakness of the flexor pollicis longus and the flexor digitorum profundus to the index finger.

Question 24

A 14-year-old boy presents with a painful, enlarging mass in his diaphyseal femur. Biopsy reveals uniform small round blue cells. Genetic analysis demonstrates a t(11;22) chromosomal translocation. Which fusion protein is characteristic of this tumor?

Explanation

Ewing sarcoma is characterized histologically by small round blue cells and genetically by the t(11;22) translocation. This specific chromosomal abnormality results in the oncogenic EWS-FLI1 fusion protein.

Question 25

Aseptic loosening secondary to osteolysis is a primary cause of long-term failure in total hip arthroplasty. The cellular cascade leading to periprosthetic osteolysis is primarily initiated by the activation of which of the following cell types upon phagocytizing polyethylene wear debris?

Explanation

Macrophages phagocytize particulate polyethylene wear debris, leading to the release of inflammatory cytokines like TNF-alpha and IL-1. This cascade stimulates RANKL expression, which drives osteoclast activation and subsequent periprosthetic osteolysis.

Question 26

When treating an infant with a severe rigid clubfoot (talipes equinovarus) using the Ponseti method, the very first step in the serial casting process targets which component of the deformity?

Explanation

The Ponseti method systematically addresses the CAVE deformities (Cavus, Adductus, Varus, Equinus). The critical first step is to correct the cavus by elevating the first metatarsal, which aligns the forefoot properly with the hindfoot.

Question 27

A 68-year-old woman on long-term alendronate therapy presents with sudden onset thigh pain after a minor trip. Radiographs show a transverse fracture in the subtrochanteric region with lateral cortical thickening. This fracture pattern is primarily attributed to which cellular mechanism?

Explanation

Bisphosphonates inhibit osteoclast function, severely suppressing bone turnover and impairing the physiological repair of microdamage. Over years of therapy, this leads to the accumulation of microfractures on the tension side (lateral cortex) of the femur, eventually resulting in an atypical complete fracture.

Question 28

During surgical evaluation of a midfoot injury, the surgeon identifies an avulsion fracture at the base of the second metatarsal (the "fleck sign"). The Lisfranc ligament, which is disrupted in this injury, natively connects which two osseous structures?

Explanation

The Lisfranc ligament is a robust interosseous ligament that runs from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is critical for the stability of the tarsometatarsal articulation, and its avulsion produces the classic "fleck sign."

Question 29

A 35-year-old carpenter sustains a puncture wound to his right index finger. Two days later, he presents with severe throbbing pain. Which of the following Kanavel signs is typically the earliest clinical indicator of acute infectious flexor tenosynovitis?

Explanation

Pain out of proportion with passive extension of the involved digit is generally considered the earliest and most sensitive of Kanavel's four classic signs for infectious flexor tenosynovitis. Prompt recognition is critical to prevent tendon necrosis.

Question 30

A 72-year-old man undergoes a primary total hip arthroplasty via a standard posterior approach. Six weeks postoperatively, he presents to the Emergency Department with severe hip pain after bending over to tie his shoes. His leg is noted to be shortened and internally rotated. Which of the following is the most likely diagnosis?

Explanation

A posterior hip dislocation classically presents with the affected limb shortened, internally rotated, and adducted. This complication is a known risk following THA via a posterior approach, particularly when the hip undergoes combined excessive flexion and internal rotation.

Question 31

During a diagnostic shoulder arthroscopy, the surgeon notes an absent anterosuperior labrum and a thick, cord-like middle glenohumeral ligament. This anatomic variant, which should not be surgically repaired to the glenoid, is known as:

Explanation

The Buford complex is a normal anatomic variant seen in a small percentage of shoulders. It consists of a cord-like middle glenohumeral ligament and an absent anterosuperior labrum, and erroneously "repairing" it to the glenoid will severely restrict external rotation.

Question 32

A 45-year-old motorcyclist is brought to the trauma bay hemodynamically unstable with a suspected anterior-posterior compression (APC) pelvic ring injury. In applying a pelvic binder to reduce pelvic volume, over which specific anatomical landmark should the binder be centered?

Explanation

To effectively close an "open-book" pelvic fracture and correctly reduce pelvic volume, a pelvic binder must be applied and centered directly over the greater trochanters. Placing the binder too high (e.g., over the iliac crests) can paradoxically worsen the deformity.

Question 33

A 24-year-old male sustains a knee injury during a soccer match. Physical exam reveals a positive Dial test with 15 degrees of increased external rotation at 30 degrees of knee flexion compared to the uninjured side, but symmetric external rotation at 90 degrees. Which structure is most likely isolated in this injury?

Explanation

Increased external rotation at 30 degrees of flexion but not at 90 degrees indicates an isolated posterolateral corner (PLC) injury. If external rotation is increased at both 30 and 90 degrees, it suggests a combined PCL and PLC injury.

Question 34

A 14-year-old male baseball pitcher complains of right shoulder pain while throwing. Radiographs demonstrate widening and irregularity of the proximal humeral physis compared to the contralateral side. What is the most appropriate initial management?

Explanation

Little League Shoulder is a stress fracture or epiphysiolysis of the proximal humeral physis caused by repetitive rotational stresses. The standard treatment is complete cessation of throwing for 3 months, followed by physical therapy and a graduated throwing program.

Question 35

A 30-year-old male sustains a displaced talar neck fracture requiring open reduction and internal fixation. At 8 weeks postoperatively, a subchondral radiolucent band is noted in the talar dome on the AP mortise radiograph. What does this radiographic finding indicate?

Explanation

Hawkins sign is a subchondral radiolucency of the talar dome that appears 6 to 8 weeks after injury due to subchondral atrophy from disuse. Its presence is a positive prognostic indicator demonstrating that the vascular supply to the talar body remains intact.

Question 36

During a total hip arthroplasty, the surgeon opts to use a highly cross-linked polyethylene liner to reduce wear rates. What is the primary mechanism by which cross-linking improves the tribological properties of the polyethylene?

Explanation

Highly cross-linked polyethylene is manufactured using gamma or electron beam irradiation, which breaks polymer chains to create free radicals that subsequently form covalent bonds between adjacent chains. This cross-linking significantly reduces volumetric wear in total joint arthroplasty.

Question 37

A 45-year-old woman presents with an unresectable recurrence of a giant cell tumor of the sacrum. She is started on denosumab therapy. What is the specific mechanism of action of this medication?

Explanation

Denosumab is a fully human monoclonal antibody that binds directly to RANKL, preventing its interaction with the RANK receptor on osteoclast precursors. This prevents osteoclast formation, function, and survival, severely inhibiting the bone resorption characteristic of giant cell tumors.

Question 38

A 25-year-old male undergoes intramedullary nailing for a closed midshaft tibial fracture. One year postoperatively, his fracture has fully healed, but he complains of significant pain that limits his ability to kneel or squat. What is the most common complication following intramedullary nailing of tibial shaft fractures?

Explanation

Anterior knee pain is the most frequent complication following intramedullary nailing of the tibia, occurring in up to 40-50% of patients. Its etiology is multifactorial and it can occur regardless of whether a parapatellar or transtendinous surgical approach was utilized.

Question 39

In the Ponseti method for the treatment of idiopathic clubfoot, the sequence of correction is paramount to achieve a successful plantigrade foot. Which of the following represents the correct sequential order for correcting the deformities?

Explanation

The Ponseti method sequentially corrects the components of clubfoot deformity using the mnemonic CAVE: Cavus, Adductus, Varus, and Equinus. The cavus is corrected first by elevating the first ray to align the forefoot with the hindfoot.

Question 40

A 19-year-old female athlete experiences recurrent patellar instability. An MRI confirms an incompetent medial patellofemoral ligament (MPFL). During anatomic reconstruction, where should the femoral attachment of the graft be placed?

Explanation

Schottle's point defines the anatomic femoral footprint of the MPFL. It is located radiographically between the adductor tubercle (proximal) and the medial epicondyle (distal), and slightly posterior to the posterior cortex line of the femoral diaphysis.

Question 41

During a posterior-stabilized total knee arthroplasty, trial components are placed. The knee is perfectly balanced in 90 degrees of flexion, but the extension gap is tight medially and loose laterally. Which of the following is the most appropriate next step to balance the knee?

Explanation

A tight medial extension gap with a balanced flexion gap indicates an asymmetric extension space requiring a specific medial release. Releasing the deep medial collateral ligament or performing a posteromedial capsular release will selectively open the medial side in extension without affecting flexion.

Question 42

A 30-year-old construction worker sustains a deep, 10-cm laceration over the anterior tibia with an underlying, highly comminuted midshaft tibia fracture. There is extensive periosteal stripping, but the wound can be primarily closed without requiring a flap. According to the Gustilo-Anderson classification, what type of open fracture is this?

Explanation

A Gustilo-Anderson Type IIIA fracture involves high-energy trauma and extensive soft tissue damage, but retains adequate soft tissue coverage for the fractured bone despite extensive laceration or periosteal stripping. Type IIIB would require a local or free flap for soft tissue coverage.

Question 43

A 28-year-old carpenter sustains a puncture wound to the volar aspect of his index finger. Three days later, he presents to the emergency department with a swollen, exquisitely painful finger. Which of the following is NOT one of Kanavel's four cardinal signs of flexor tenosynovitis?

Explanation

Kanavel's four cardinal signs of flexor tenosynovitis are: flexed resting posture, fusiform (sausage) swelling, exquisite tenderness along the flexor tendon sheath, and severe pain with passive extension. Pain with active flexion is not a defining cardinal sign.

Question 44

A 65-year-old woman is prescribed alendronate after a dual-energy X-ray absorptiometry (DEXA) scan reveals a T-score of -2.7 in her lumbar spine. Which of the following describes the primary molecular target of this bisphosphonate therapy?

Explanation

Nitrogen-containing bisphosphonates (such as alendronate) inhibit the farnesyl pyrophosphate synthase enzyme within the mevalonate pathway. This disruption prevents the prenylation of small GTPases in osteoclasts, leading to impaired osteoclast function and enhanced apoptosis.

Question 45

A 12-year-old obese male presents with left knee pain and an obligate external rotation of the hip during passive hip flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is a recognized specific indication for prophylactic pinning of the contralateral, asymptomatic hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy). These patients have a significantly higher risk of developing bilateral slip compared to the idiopathic population.

Question 46

A 45-year-old male presents with severe lower back pain, bilateral lower extremity weakness, and saddle anesthesia after lifting a heavy box. Which of the following is the most consistent and sensitive early clinical finding of cauda equina syndrome?

Explanation

Urinary retention, eventually leading to overflow incontinence, is the most consistent and sensitive early finding in cauda equina syndrome. A post-void residual bladder volume greater than 100-200 mL is highly suggestive of the condition in the proper clinical setting.

Question 47

A 35-year-old professional volleyball player presents with painless weakness in external rotation of his right shoulder. MRI reveals a paralabral cyst located strictly in the spinoglenoid notch. Which muscle or muscles are most likely affected by this specific nerve entrapment?

Explanation

Entrapment of the suprascapular nerve at the spinoglenoid notch affects only the infraspinatus muscle, leading to isolated external rotation weakness. Entrapment at the more proximal suprascapular notch affects both the supraspinatus and the infraspinatus.

Question 48

A 14-year-old male with an L5-S1 isthmic spondylolisthesis presents with persistent low back pain. Which of the following radiographic parameters is most highly associated with the risk of slip progression?

Explanation

High pelvic incidence is a primary biomechanical risk factor for the development and progression of isthmic spondylolisthesis. It results in increased shear forces across the lumbosacral junction.

Question 49

Which of the following describes the functional anatomy of the anterior cruciate ligament (ACL) bundles during knee motion?

Explanation

The anteromedial (AM) bundle of the ACL is tightest in flexion and primarily controls anterior translation. The posterolateral (PL) bundle is tightest in extension and provides primary control against rotatory loads.

Question 50

A 21-year-old collegiate baseball pitcher undergoes ulnar collateral ligament (UCL) reconstruction using a palmaris longus autograft. Which of the following technical factors is most associated with postoperative ulnar neuropathy?

Explanation

Routine ulnar nerve transposition during UCL reconstruction increases the risk of postoperative ulnar neuropathy compared to in situ decompression. Current trends favor leaving the nerve undisturbed unless significant preoperative neuropathy exists.

Question 51

During a primary total knee arthroplasty, the surgeon notes that the joint is excessively tight in flexion but well-balanced in extension. Which of the following is the most appropriate next step to balance the knee?

Explanation

A knee that is tight in flexion and well-balanced in extension has an asymmetric tight flexion gap. Downsizing the femoral component increases the flexion gap without affecting the extension gap.

Question 52

A 12-year-old boy presents with a destructive diaphyseal lesion of the femur. Biopsy reveals small round blue cells, and molecular testing shows a t(11;22) chromosomal translocation. Which fusion protein is characteristic of this tumor?

Explanation

The clinical and histologic picture describes Ewing sarcoma, which is characterized by the t(11;22) translocation. This chromosomal abnormality results in the oncogenic EWS-FLI1 fusion protein.

Question 53

A 35-year-old male is brought to the trauma bay with a mechanically unstable pelvis and a blood pressure of 80/50 mmHg following a motorcycle collision. A pelvic binder is applied. To achieve maximal volume reduction, the binder should be centered over which anatomic landmark?

Explanation

Pelvic binders must be centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can paradoxically open the pelvis in certain fracture patterns.

Question 54

A 13-year-old obese boy is diagnosed with a mild stable slipped capital femoral epiphysis (SCFE). Which of the following is an accepted absolute indication for prophylactic pinning of the contralateral asymptomatic hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrinopathies (e.g., hypothyroidism) or metabolic disorders due to a nearly 100% risk of bilateral involvement. Young age is also considered a relative indication.

Question 55

A 24-year-old manual laborer presents with a scaphoid waist nonunion demonstrating sclerosis at the fracture margins but no avascular necrosis or carpal collapse. What is the gold standard surgical management?

Explanation

For a scaphoid waist nonunion without avascular necrosis or significant carpal collapse, non-vascularized structural bone grafting (e.g., iliac crest) with rigid internal screw fixation is the treatment of choice. Vascularized grafts are reserved for cases with proximal pole avascular necrosis.

Question 56

A 55-year-old male with a metal-on-metal total hip arthroplasty presents with progressive groin pain. Workup reveals a solid pseudotumor and elevated serum metal ions. Which histologic finding is most characteristic of this adverse local tissue reaction?

Explanation

Adverse local tissue reaction (ALTR) in metal-on-metal implants is characterized histologically by ALVAL. This represents a delayed-type (Type IV) hypersensitivity reaction to metal ions.

Question 57

Following a Zone II flexor tendon repair of the index finger, a patient is started on an early active mobilization protocol. What is the primary biomechanical rationale for incorporating early active motion compared to passive-only protocols?

Explanation

Early active motion protocols promote tendon gliding and limit restrictive peritendinous adhesions, effectively decreasing the work of flexion. Controlled stress also stimulates intrinsic healing and improves longitudinal collagen alignment.

Question 58

A 65-year-old female undergoes arthroscopic repair for a massive, retracted supraspinatus and infraspinatus tear. To minimize the risk of postoperative retear, which biomechanical principle is most critical?

Explanation

Minimizing tension on the repair site is the single most critical factor for biological healing in massive rotator cuff tears. Over-tensioning compromises blood flow and significantly increases the risk of structural failure.

Question 59

A 72-year-old male presents with deteriorating handwriting, frequent falls, and a broad-based gait. Examination demonstrates hyperreflexia, a positive Hoffmann sign bilaterally, and a positive inverted radial reflex. What is the most likely diagnosis?

Explanation

The combination of upper motor neuron signs, gait dysfunction, and upper extremity clumsiness strongly suggests cervical spondylotic myelopathy. The inverted radial reflex is a localizing upper motor neuron sign highly specific for a lesion at the C5-C6 level.

Question 60

A 6-week-old female is being treated for developmental dysplasia of the hip with a Pavlik harness. She develops an absent knee jerk and lack of active knee extension on the treated side. What is the most appropriate next step in management?

Explanation

The patient has developed a femoral nerve palsy, a known complication of extreme hip flexion in a Pavlik harness. Immediate management requires loosening the anterior flexion straps or temporarily discontinuing the harness until nerve function recovers.

Question 61

A 28-year-old male sustains a vertically oriented, displaced basicervical femoral neck fracture (Pauwels Type III). If fixed with standard parallel cannulated screws, which complication is this fracture pattern most at risk for?

Explanation

Pauwels Type III femoral neck fractures have a vertical fracture angle (>50 degrees), subjecting the fracture site to high shear forces. This significantly increases the risk of varus collapse, nonunion, and hardware failure when fixed with parallel screws.

Question 62

A tibial shaft fracture is treated with absolute stability using a properly tensioned compression plate. Which of the following best describes the primary mode of bone healing expected in this scenario?

Explanation

Absolute stability minimizes interfragmentary strain and allows for primary bone healing. This occurs via Haversian remodeling (cutting cones) directly across the fracture site, which skips the cartilaginous phase and forms no visible callus.

Question 63

A 22-year-old athlete sustains an axial load to a plantarflexed foot. Radiographs reveal the medial border of the second metatarsal base does not align with the middle cuneiform, and a "fleck sign" is present. Which ligament is primarily disrupted?

Explanation

The Lisfranc ligament is an interosseous ligament connecting the medial cuneiform to the base of the second metatarsal. The "fleck sign" is pathognomonic for an avulsion fracture at the attachment site of this critical stabilizing structure.

Question 64

A 6-year-old boy presents with an extension-type displaced supracondylar humerus fracture (Gartland Type III). He is unable to flex the interphalangeal joint of his thumb or the distal interphalangeal joint of his index finger. Which nerve is most likely injured?

Explanation

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

Question 65

The anterior cruciate ligament (ACL) consists of two distinct functional bundles. Which of the following statements correctly describes the biomechanical role of the posterolateral bundle?

Explanation

The posterolateral (PL) bundle of the ACL is tightest in extension and provides the primary restraint to internal rotation. The anteromedial (AM) bundle is tightest in flexion and resists anterior translation.

Question 66

A 12-year-old obese male presents with a slipped capital femoral epiphysis (SCFE) of the left hip. Prophylactic pinning of the asymptomatic right hip is most strongly indicated if the patient has a history of:

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated in patients with underlying endocrine or metabolic disorders, such as hypothyroidism or renal osteodystrophy, due to the high risk of bilateral involvement.

Question 67

A 6-year-old boy sustains an extension-type supracondylar humerus fracture. Upon presentation, he is unable to flex the interphalangeal joint of his thumb or the distal interphalangeal joint of his index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury presents with the inability to form an "OK" sign due to weakness of the FPL and FDP to the index finger.

Question 68

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. Which of the following is considered the most significant prognostic factor for the long-term development of osteoarthritis?

Explanation

Age at the onset of symptoms is the most important prognostic factor in Legg-Calve-Perthes disease. Children who develop the disease before age 6 generally have a better prognosis due to greater remodeling potential of the femoral head.

Question 69

In the design and biomechanics of a reverse total shoulder arthroplasty (RTSA), moving the center of rotation medially and inferiorly achieves which of the following?

Explanation

RTSA medializes and distalizes the center of rotation, which increases the deltoid muscle's moment arm and tension. This allows the deltoid to effectively elevate the arm in the absence of a functioning rotator cuff.

Question 70

In the natural progression of Scapholunate Advanced Collapse (SLAC) wrist, which joint or articulation is classically spared until the latest stages of the disease?

Explanation

In SLAC wrist, the radiolunate joint is classically spared because the lunate fossa is spherical and maintains a concentric articulation with the lunate. This prevents early degenerative changes compared to the elliptical scaphoid fossa.

Question 71

A 45-year-old patient suffers an acute posterior root tear of the medial meniscus. Biomechanically, this injury is most equivalent to which of the following conditions?

Explanation

A posterior root tear of the medial meniscus disrupts the hoop stresses, causing the meniscus to extrude under load. Biomechanically, this completely eliminates the load-sharing function, rendering the knee equivalent to one with a total medial meniscectomy.

Question 72

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At a follow-up visit, the infant exhibits decreased spontaneous active extension of the knee. Which of the following adjustments or actions is most appropriate?

Explanation

Decreased active knee extension in a Pavlik harness indicates a femoral nerve palsy, typically caused by excessive hip flexion. The appropriate management is to loosen the anterior straps to decrease the degree of hip flexion.

Question 73

The medial patellofemoral ligament (MPFL) provides the primary soft tissue restraint to lateral patellar translation at which of the following knee flexion angles?

Explanation

The MPFL is the primary restraint to lateral patellar displacement in early flexion (0 to 30 degrees). Beyond 30 degrees, the patella engages the trochlear groove, and bony stability becomes the primary restraint.

Question 74

A 16-year-old boy presents with a destructive diaphyseal lesion of the femur with an "onion skin" periosteal reaction. A biopsy reveals small blue round cells. Which of the following genetic translocations is most characteristic of this tumor?

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The most common genetic abnormality associated with Ewing sarcoma is the t(11;22) translocation, which forms the EWS-FLI1 fusion protein.

Question 75

A 35-year-old male sustains an anteroposterior compression (APC) type II pelvic ring injury. Based on the Young-Burgess classification, which of the following accurately describes the status of the sacroiliac (SI) ligaments?

Explanation

In an APC II pelvic ring injury, there is symphyseal diastasis and disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The strong posterior sacroiliac ligaments remain intact, maintaining vertical stability.

Question 76

Following open reduction and internal fixation of a distal radius fracture with a volar locking plate, a patient develops an inability to actively flex the interphalangeal joint of the thumb 6 months postoperatively. What technical error is most likely responsible?

Explanation

Placement of a volar plate distal to the watershed line of the distal radius can cause mechanical irritation and subsequent attrition rupture of the flexor pollicis longus (FPL) tendon.

Question 77

During the late cocking phase of the throwing motion in an elite baseball pitcher, which structure is subjected to the highest tensile forces?

Explanation

The anterior bundle of the ulnar collateral ligament (UCL) is the primary restraint to valgus stress at the elbow. It experiences the highest tensile forces during the late cocking and early acceleration phases of throwing.

Question 78

A 45-year-old bodybuilder undergoes a two-incision surgical repair of a distal biceps tendon rupture. Compared to the single-incision anterior approach, the two-incision approach is historically associated with a higher risk of which of the following complications?

Explanation

The two-incision technique avoids anterior structures, lowering LACN and PIN injury rates, but carries a higher risk of heterotopic ossification and radioulnar synostosis due to subperiosteal dissection of the ulna.

Question 79

A 22-year-old collegiate baseball pitcher presents with shoulder pain and a Glenohumeral Internal Rotation Deficit (GIRD) of 25 degrees compared to his non-throwing shoulder. This deficit is most commonly attributed to contracture of which anatomical structure?

Explanation

GIRD in overhead throwers is primarily caused by repetitive microtrauma leading to contracture and thickening of the posterior inferior glenohumeral capsule.

Question 80

A 14-year-old male sustains a severely displaced avulsion fracture of the tibial tubercle (Ogden Type III) while playing basketball. Because of the specific regional anatomy, he is at highest risk for which of the following acute complications?

Explanation

Displaced tibial tubercle avulsion fractures are uniquely associated with acute anterior compartment syndrome. This is due to bleeding from branches of the anterior tibial recurrent artery directly into the rigid anterior compartment.

Orthopedic Prometric MCQs - Chapter 3 Part 1

Orthopedic Prometric MCQs - Chapter 3 Part 42

Orthopedic Prometric MCQs - Chapter 3 Part 42

Chapter Index