ABOS Part I & AAOS OITE Orthopedic Review Questions

Question 1

A 68-year-old male presents with a 2-year history of progressive right shoulder pain, pseudoparalysis (active elevation to 45 degrees, passive 90 degrees), and significant night pain refractory to NSAIDs and corticosteroid injections. Radiographs demonstrate severe glenohumeral osteoarthritis with superior migration of the humeral head and an acromiohumeral interval of 4mm. What is the most appropriate surgical intervention?

Explanation

Correct Answer: C

This patient presents with signs and symptoms consistent with rotator cuff tear arthropathy (RCAT), characterized by chronic shoulder pain, pseudoparalysis, superior migration of the humeral head, and glenohumeral arthritis. In such cases, the deltoid muscle becomes the primary elevator of the arm, and a reverse total shoulder arthroplasty (RTSA) is indicated to medialize and distalize the center of rotation, increasing the deltoid's lever arm and restoring function. Anatomic total shoulder arthroplasty is contraindicated in the presence of an irreparable rotator cuff tear with superior migration as it relies on an intact rotator cuff for stability and function. Arthroscopic repair is not feasible given the chronic nature, pseudoparalysis, and arthritic changes. Hemiarthroplasty alone would not address the deltoid's mechanical disadvantage.

Question 2

A 32-year-old competitive runner presents with 6 months of worsening posteromedial ankle pain, exacerbated by push-off and toe-off activities. Clinical examination reveals pain with resisted plantarflexion and inversion. MRI shows tenosynovitis and thickening of the tendon sheath. Which tendon is most likely affected?

Explanation

Correct Answer: C

The clinical presentation of posteromedial ankle pain, exacerbated by push-off/toe-off, and pain with resisted plantarflexion and inversion, is classic for tibialis posterior tendon dysfunction (TPTD). The tibialis posterior tendon is a primary dynamic stabilizer of the medial longitudinal arch and is crucial for plantarflexion and inversion. Tenosynovitis and thickening on MRI further support this diagnosis. Achilles tendon pain is typically posterior, peroneus brevis pain is lateral, FHL pain is posteromedial but typically associated with hallux rigidus or dance, and tibialis anterior pain is anterior.

Question 3

A 7-year-old male falls from a tree, sustaining a supracondylar humerus fracture. On arrival, he has a pulseless but warm and pink hand. There is no evidence of motor or sensory deficit. What is the MOST appropriate initial management step?

Explanation

Correct Answer: C

A pulseless but warm and pink hand with good capillary refill following a supracondylar humerus fracture in a child suggests a vascular spasm, not complete arterial transection. The most appropriate initial step is a gentle closed reduction of the fracture. If the pulse returns after reduction, the limb should be pinned. If the pulse does not return after reduction, then further vascular assessment (e.g., Doppler, potentially angiography) and possibly exploration would be warranted. Immediate angiography or fasciotomy is premature. Observation without attempting reduction delays appropriate treatment and risks worsening ischemia.

Question 4

Which of the following surgical approaches to the hip carries the highest risk of injury to the superior gluteal nerve?

Explanation

Correct Answer: C

The direct lateral approach (Hardinge approach) involves incising the fascia lata and splitting the gluteus medius abductor insertion, which places the superior gluteal nerve at risk. The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and tensor fascia lata. Injury to this nerve can lead to a Trendelenburg gait. While all approaches have specific nerve risks, the direct lateral approach is particularly known for this risk due to its dissection plane. The posterior approach risks the sciatic nerve, the direct anterior approach risks the lateral femoral cutaneous nerve, and the anterolateral approach carries a lower risk of superior gluteal nerve injury compared to the direct lateral but still involves the abductors.

Question 5

A 55-year-old male with a history of diabetes mellitus and chronic kidney disease presents with acute onset, severe left foot pain and swelling, warmth, and erythema, but no history of trauma. Radiographs show disorganization of the midfoot joints, fragmentation, and 'rocker-bottom' deformity. What is the most likely diagnosis?

Explanation

Correct Answer: D

The clinical presentation (acute onset, severe pain, swelling, warmth, erythema in a diabetic patient) combined with the radiographic findings (disorganization of midfoot joints, fragmentation, rocker-bottom deformity) is highly characteristic of Charcot neuroarthropathy. This condition results from an underlying neuropathy (common in diabetes) leading to repetitive microtrauma and subsequent destructive changes in the joints. While gout, septic arthritis, osteomyelitis, and cellulitis can present with similar acute inflammatory signs, the radiographic findings of joint disorganization and fragmentation, particularly the 'rocker-bottom' deformity, are pathognomonic for Charcot arthropathy.

Question 6

What is the most common primary malignant bone tumor in children and young adults?

Explanation

Correct Answer: B

Osteosarcoma is the most common primary malignant bone tumor in children and young adults, typically presenting in the metaphysis of long bones (e.g., distal femur, proximal tibia, proximal humerus). Ewing's sarcoma is the second most common, often affecting the diaphysis. Chondrosarcoma is more common in older adults, and multiple myeloma is a plasma cell dyscrasia primarily affecting older individuals. Fibrosarcoma is a rare soft tissue sarcoma that can occasionally arise from bone.

Question 7

A 28-year-old professional basketball player sustains an acute knee injury after an awkward landing. He reports hearing a 'pop' and describes immediate swelling and difficulty bearing weight. Lachman test is positive, and there is a positive pivot shift. What is the most appropriate next step in management?

Explanation

Correct Answer: C

The clinical presentation (pop, swelling, difficulty bearing weight, positive Lachman and pivot shift) is highly indicative of an ACL tear. However, the most appropriate next step is an MRI of the knee to confirm the diagnosis, evaluate for associated meniscal tears, collateral ligament injuries, and chondral damage, which will influence treatment planning. While an ACL tear is likely, imaging provides crucial information for shared decision-making regarding operative versus non-operative management, timing of surgery, and potential concomitant procedures. Immediate surgery is not typically indicated acutely due to swelling and inflammation. Immobilization alone is not definitive treatment for a young athlete. Corticosteroid injections are not indicated for acute ligamentous injury.

Question 8

Which of the following describes the anatomical structure primarily responsible for providing a 'rotary stability' to the knee, especially against external tibial rotation in a valgus stress?

Explanation

Correct Answer: E

The posteromedial corner (PMC) of the knee, which includes the superficial MCL, posterior oblique ligament, and semimembranosus attachments, is crucial for controlling valgus and external rotational stability, particularly at 30 degrees of knee flexion. While the MCL resists valgus stress, the complete 'rotary stability' against combined valgus and external rotation (often seen in complex knee injuries) is attributed to the integrity of the PMC. The ACL primarily resists anterior translation and internal rotation. The LCL resists varus stress. The PCL resists posterior translation.

Question 9

A 4-year-old child presents with a painless limp. Examination reveals limited abduction and internal rotation of the hip. Radiographs show increased density and flattening of the femoral epiphysis. What is the most likely diagnosis?

Explanation

Correct Answer: D

The clinical picture of a painless limp in a 4-year-old with limited hip abduction and internal rotation, coupled with radiographic findings of increased density (sclerosis) and flattening (fragmentation/collapse) of the femoral epiphysis, is characteristic of Legg-Calvé-Perthes disease. This condition is idiopathic avascular necrosis of the femoral head. SCFE typically occurs in older, often obese adolescents. DDH presents earlier and with different radiographic findings. Septic arthritis and transient synovitis are acute painful conditions.

Question 10

What is the primary role of the annulus fibrosus in the intervertebral disc?

Explanation

Correct Answer: C

The annulus fibrosus, composed of concentric lamellae of collagen fibers, primarily functions to contain the nucleus pulposus and resist tensile forces during spinal movements. While it contributes to bearing axial load and spinal flexibility, its most critical role is to encapsulate the highly hydrated nucleus pulposus. The nucleus pulposus itself acts more as the shock absorber, and the annulus maintains its position. Fibroblasts within the annulus produce collagen and proteoglycans, but this is a cellular function, not the primary structural role.

Question 11

A 45-year-old male presents with acute onset of right shoulder pain and weakness after attempting to lift a heavy object. On examination, he has significant weakness in external rotation and abduction. Deltoid function is intact. Radiographs are normal. Which of the following is the most likely diagnosis?

Right shoulder pain and weakness

Explanation

Correct Answer: B

The patient presents with acute shoulder pain and weakness, specifically in external rotation and abduction. While the supraspinatus initiates abduction, the infraspinatus is the primary external rotator. Given the intact deltoid (ruling out axillary nerve palsy) and significant weakness in external rotation, a tear of the infraspinatus is the most likely diagnosis. Subscapularis tears primarily affect internal rotation, and long head of biceps rupture typically presents with a 'Popeye' deformity and weakness in elbow flexion/supination, not primarily shoulder abduction/external rotation.

Question 12

A 62-year-old female with a history of osteoporosis sustains a displaced intra-articular fracture of the distal radius (AO type C3). She is active and has good functional demands. What is the most appropriate definitive management strategy?

$Distal radius fracture X-ray$

Explanation

Correct Answer: D

For a displaced intra-articular distal radius fracture (AO type C3) in an active patient with good functional demands, open reduction and internal fixation with a volar locking plate is considered the gold standard. This approach allows for stable anatomical reduction, early range of motion, and addresses the challenge of comminution and osteopenia often seen in C3 fractures. Closed reduction and splinting is inadequate for displaced intra-articular fractures. Percutaneous pinning or external fixation alone may not provide sufficient stability or allow for direct visualization and reduction of articular fragments, especially in complex, comminuted patterns.

Question 13

A 7-year-old boy presents with a 3-week history of right hip pain and a limp. He denies trauma. On examination, he has decreased internal rotation and abduction of the right hip. Radiographs show increased density of the right femoral epiphysis and a flattened appearance. What is the most likely diagnosis?

Pediatric hip X-ray with epiphyseal changes

Explanation

Correct Answer: D

The clinical presentation of a 7-year-old boy with hip pain, limp, and decreased hip motion (especially internal rotation and abduction), combined with radiographic findings of increased density (sclerosis) and flattening (fragmentation) of the femoral epiphysis, is classic for Legg-Calvé-Perthes disease. Septic arthritis would present acutely with systemic signs and extreme pain, transient synovitis is usually self-limiting with normal radiographs after a few days, SCFE typically occurs in older, often obese adolescents, and DDH is usually diagnosed in infancy or early childhood.

Question 14

A 32-year-old competitive runner presents with chronic pain along the medial aspect of her left foot, exacerbated by activity. Examination reveals tenderness just distal to the medial malleolus, reproducible pain with resisted plantarflexion and inversion, and a pes planus foot posture. What is the most likely diagnosis?

Medial aspect of foot with pes planus

Explanation

Correct Answer: D

The symptoms of chronic medial foot pain exacerbated by activity, tenderness distal to the medial malleolus, pain with resisted plantarflexion and inversion, and an associated pes planus deformity are highly suggestive of Posterior Tibial Tendon Dysfunction (PTTD). PTTD is a progressive condition that can lead to adult-acquired flatfoot. Plantar fasciitis causes heel pain. Achilles tendinopathy causes pain in the posterior ankle/heel. Tarsal tunnel syndrome involves nerve compression, often with burning/tingling. A navicular stress fracture would typically present with localized dorsal midfoot pain and often swelling.

Question 15

A 55-year-old female presents with severe, progressive back pain radiating down both legs, worsening with standing and walking, and relieved by sitting or leaning forward. She also reports bilateral leg numbness and weakness. On examination, she has diminished patellar and Achilles reflexes bilaterally. What is the most likely diagnosis?

Lumbar spine MRI showing stenosis

Explanation

Correct Answer: B

The classic symptoms of neurogenic claudication – bilateral leg pain, numbness, and weakness exacerbated by standing/walking and relieved by sitting/leaning forward (shopping cart sign) – are highly indicative of lumbar spinal stenosis. While a large disc herniation or spondylolisthesis can cause radiculopathy, bilateral symptoms relieved by flexion strongly point towards stenosis. Cauda equina syndrome would involve acute urinary retention, saddle anesthesia, and severe, progressive neurological deficits. Facet arthropathy typically causes axial back pain, potentially referred pain, but not classic neurogenic claudication.

Question 16

Which of the following describes the most common mechanism of injury for an anterior cruciate ligament (ACL) rupture?

Diagram of knee injury mechanism

Explanation

Correct Answer: C

The most common mechanism for ACL rupture is a non-contact injury involving deceleration, cutting, or pivoting maneuvers, typically with the knee in slight flexion, valgus, and external rotation of the tibia on the femur. This creates significant tension on the ACL. A direct blow to the anterior tibia (dashboard injury) can cause a posterior cruciate ligament (PCL) injury. Hyperextension with varus force might stress the posterolateral corner, while a direct posterior force to the tibia causes PCL injury. Landing in full extension is less common than dynamic valgus loading for ACL rupture.

Question 17

A 28-year-old male sustains an open Schatzker type VI tibial plateau fracture with significant soft tissue compromise. After initial debridement and external fixation, what is the optimal timing for definitive internal fixation?

$Tibial plateau fracture X-ray$

Explanation

Correct Answer: C

For complex open tibial plateau fractures with significant soft tissue injury, the 'staged protocol' is generally preferred. This involves initial debridement, provisional stabilization with an external fixator, and then delayed definitive internal fixation once the soft tissues have adequately recovered and the 'wrinkle sign' is present (indicating decreased edema). This typically occurs between 5-10 days. Operating immediately in compromised soft tissues increases the risk of wound complications and infection. Waiting too long (3 weeks) might lead to fracture stiffness and more difficult reduction. The question specifically asks for definitive internal fixation, not initial debridement or external fixation, which should happen urgently. The 'wrinkle sign' is key to timing definitive fixation in such injuries.

Question 18

What is the most common benign bone tumor of the hand?

Hand X-ray showing bone tumor

Explanation

Correct Answer: A

Enchondroma is by far the most common benign bone tumor of the hand, frequently found in the phalanges and metacarpals. Osteochondromas are common benign tumors but less frequent in the hand than enchondromas. Giant cell tumors are rare in the hand, and aneurysmal bone cysts and osteoid osteomas are also less common in this location compared to enchondromas.

Question 19

In the management of a displaced femoral shaft fracture in a 3-year-old child, which of the following is the most appropriate initial treatment?

$Pediatric femoral shaft fracture X-ray$

Explanation

Correct Answer: B

For a displaced femoral shaft fracture in a 3-year-old child, spica cast immobilization is the preferred initial treatment. Children in this age group have excellent remodeling potential and tolerate cast immobilization well. Intramedullary nailing is typically reserved for older children (usually >5-6 years) or specific fracture patterns. External fixation is generally reserved for open fractures, polytrauma, or significant soft tissue compromise. Open reduction and plating is used in specific circumstances but not as first-line for this age group. Skeletal traction followed by cast is an older method, largely supplanted by immediate spica casting for this age group.

Question 20

A 68-year-old male presents with sudden onset of right knee pain and swelling. On aspiration, the synovial fluid is cloudy and contains negatively birefringent, needle-shaped crystals. What is the most appropriate management for this condition?

Knee aspiration procedure

Explanation

Correct Answer: C

The description of cloudy synovial fluid with negatively birefringent, needle-shaped crystals is pathognomonic for gout (monosodium urate crystal arthropathy). Acute attacks are best managed with NSAIDs and/or colchicine. Intra-articular steroid injection can also be used but NSAIDs/colchicine are often first-line. Oral antibiotics are for septic arthritis (which would show positive gram stain and high WBC count, not crystals). Surgical debridement is not indicated for acute gout. Allopurinol is a long-term urate-lowering therapy used for chronic gout prevention, not for acute attack management.

Question 21

A 35-year-old polytrauma patient presents in hemorrhagic shock with an anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is to be applied. At what anatomic landmark should the binder be centered to optimally reduce the pelvic volume?

Explanation

Pelvic binders should be centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests or ASIS can paradoxically widen the pelvis in anteroposterior compression injuries.

Question 22

A 3-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the mother notes the child is no longer kicking her leg on the affected side. Examination reveals absent active knee extension but intact ankle movements. What is the most appropriate next step in management?

Explanation

The patient has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The most appropriate immediate step is to discontinue the harness to allow for nerve recovery before attempting alternative treatments.

Question 23

A 14-year-old boy presents with a painful mass in his distal femur. Biopsy reveals small round blue cells. Cytogenetic analysis demonstrates a t(11;22)(q24;q12) translocation. Which of the following fusion proteins is highly characteristic of this tumor?

Explanation

The t(11;22) translocation is characteristic of Ewing sarcoma, resulting in the EWS-FLI1 fusion protein. This drives the pathogenesis of the tumor, which typically presents as a small round blue cell tumor in the diaphysis or metaphysis of long bones.

Question 24

A 42-year-old carpenter presents with a swollen, painful index finger 3 days after sustaining a puncture wound. Examination reveals a fusiform swollen digit that is held in slight flexion. What is considered the earliest and most sensitive Kanavel sign for pyogenic flexor tenosynovitis?

Explanation

Pain with passive extension is considered the earliest and most sensitive of the four Kanavel signs for pyogenic flexor tenosynovitis. The other signs include fusiform swelling, flexed resting posture, and tenderness along the tendon sheath.

Question 25

During a primary total knee arthroplasty, the surgeon notes the knee is balanced in extension but is tight in flexion. Which of the following steps is the most appropriate next maneuver to balance the knee?

Explanation

A tight flexion gap with a balanced extension gap implies the posterior condyles of the femoral component are excessively prominent. Downsizing the femoral component or translating it anteriorly will increase the flexion gap without affecting the extension gap.

Question 26

A 19-year-old female gymnast complains of bilateral shoulder pain and a sensation of her shoulders "slipping." Examination demonstrates a positive sulcus sign and a positive apprehension test bilaterally, without a discrete history of trauma. Initial management should primarily consist of:

Explanation

The patient has multidirectional instability (MDI), characterized by generalized ligamentous laxity and atraumatic instability. The mainstay of initial treatment is a prolonged course of physical therapy focusing on periscapular and rotator cuff strengthening.

Question 27

A 28-year-old male sustains a closed midshaft tibia fracture. Twelve hours later, he complains of severe pain out of proportion to the injury. His diastolic blood pressure is 75 mmHg. Intracompartmental pressure monitoring reveals an anterior compartment pressure of 50 mmHg. What is the delta pressure, and what is the indication for fasciotomy?

Explanation

Delta pressure is calculated as Diastolic Blood Pressure minus Compartment Pressure (75 - 50 = 25 mmHg). A delta pressure of less than 30 mmHg is the accepted threshold indicating the need for emergent four-compartment fasciotomy.

Question 28

When treating a 2-week-old infant with idiopathic clubfoot using the Ponseti method, what is the correct sequence of deformity correction?

Explanation

The Ponseti method corrects the components of clubfoot in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by elevating the first ray to supinate the forefoot.

Question 29

In orthopedic biomechanics, what term describes the phenomenon where a viscoelastic material undergoes increasing deformation over time under a constant applied load?

Explanation

Creep is defined as the progressive deformation of a viscoelastic material when subjected to a constant load over time. This is distinct from stress relaxation, which is the decrease in stress over time under a constant deformation.

Question 30

A 65-year-old male presents with bilateral lower extremity pain and cramping that worsens with walking and prolonged standing. He notes the symptoms are reliably relieved when leaning forward on a shopping cart. Which of the following differentiates neurogenic claudication from vascular claudication?

Explanation

Neurogenic claudication is classically relieved by lumbar flexion (e.g., leaning on a shopping cart), which increases the cross-sectional area of the spinal canal. Vascular claudication is typically relieved simply by resting or standing still, without a change in posture.

Question 31

A 22-year-old male falls on an outstretched hand and sustains a fracture of the scaphoid proximal pole. He is at high risk for avascular necrosis (AVN). The blood supply to the proximal pole of the scaphoid is primarily derived from which of the following vessels?

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters at the distal pole and flows retrogradely to the proximal pole. Fractures at the proximal pole disrupt this retrograde supply, leading to a high rate of AVN.

Question 32

A 55-year-old active male undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing surface. Which of the following is the most commonly cited specific complication unique to this hard-on-hard bearing articulation?

Explanation

Squeaking is a unique and potentially bothersome complication of ceramic-on-ceramic total hip arthroplasties, occurring in up to 10% of patients. While stripe wear can occur, squeaking is the classic clinical manifestation distinct to this bearing.

Question 33

A 58-year-old patient with poorly controlled diabetes mellitus presents with a red, hot, swollen foot without breaks in the skin. Radiographs show periarticular osteopenia, debris, and fragmentation of the midfoot. According to the Eichenholtz classification, what stage does this represent and what is the best initial treatment?

Explanation

Eichenholtz Stage 1 (Developmental/Fragmentation) is characterized by a red, hot, swollen foot with radiographic debris and fragmentation. The mainstay of initial treatment is immobilization and offloading, typically utilizing a total contact cast until the acute inflammatory phase resolves.

Question 34

A 16-year-old boy complains of progressive right thigh pain that is distinctly worse at night and dramatically relieved by ibuprofen. Radiographs reveal a cortical thickening with a small 8mm radiolucent nidus. What is the most appropriate definitive minimally invasive treatment?

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. Radiofrequency ablation (RFA) is the current gold standard minimally invasive definitive treatment, offering high success rates and low morbidity compared to surgical resection.

Question 35

An obese 13-year-old male presents with right knee pain and an antalgic limp. Examination reveals obligate external rotation of the right hip with passive flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most recognized complication of in-situ percutaneous pinning of a stable SCFE?

Explanation

Chondrolysis is a severe complication associated with SCFE treatment, often linked to unrecognized intra-articular hardware penetration during in-situ pinning. AVN is much more commonly associated with unstable SCFE or aggressive reduction attempts rather than standard pinning of a stable slip.

Question 36

A 25-year-old male sustains a Pauwels type III femoral neck fracture. Which of the following internal fixation constructs provides the highest biomechanical stability for this specific fracture pattern?

Explanation

For vertical (Pauwels type III) femoral neck fractures, a sliding hip screw (dynamic hip screw) combined with a derotational screw provides superior biomechanical stability and higher failure loads compared to parallel cancellous screws.

Question 37

A 12-year-old obese male presents with a stable left 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 is highly recommended in patients with an underlying endocrinopathy (e.g., hypothyroidism) or prior pelvic radiation, as their risk for bilateral involvement is significantly elevated.

Question 38

Six months after an uncomplicated anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone autograft, a 22-year-old athlete complains of an inability to achieve full terminal extension. MRI reveals a nodular mass anterior to the ACL graft in the intercondylar notch. What is the most likely etiology?

Explanation

A "cyclops lesion" (localized anterior arthrofibrosis) often presents as an extension deficit. Anterior placement of the tibial tunnel can lead to roof impingement and subsequent formation of this fibrovascular nodule.

Question 39

A 65-year-old male presents with groin pain 4 years after a total hip arthroplasty utilizing a titanium stem and a 36-mm cobalt-chromium head. Inflammatory markers are normal, but metal ion levels (cobalt) are elevated. What is the most likely source of the elevated metal ions?

Explanation

Trunnionosis (fretting and corrosion at the modular head-neck junction) is associated with large-diameter cobalt-chromium heads on titanium stems. It leads to elevated serum cobalt levels and adverse local tissue reactions.

Question 40

A 45-year-old female presents with neck pain radiating down her right arm. Examination reveals weakness in wrist extension, a diminished brachioradialis reflex, and numbness over the dorsal radial aspect of the hand and thumb. Which cervical nerve root is most likely compressed?

Explanation

Compression of the C6 nerve root causes weakness in wrist extension and elbow flexion, a diminished brachioradialis reflex, and sensory deficits over the lateral forearm and thumb.

Question 41

When performing a Zone II flexor tendon repair, which of the following biomechanical factors most significantly increases the tensile strength of the repair?

Explanation

The ultimate tensile strength of a flexor tendon repair is directly proportional to the number of core suture strands crossing the repair site. A 4-strand or 6-strand repair allows for safe early active motion protocols.

Question 42

A 15-year-old male is diagnosed with high-grade conventional osteosarcoma of the distal femur. Following neoadjuvant chemotherapy, what histological finding in the resected specimen is the most important independent prognostic factor for long-term survival?

Explanation

The percentage of tumor necrosis in the resection specimen following neoadjuvant chemotherapy is the single most important histological prognostic factor in conventional osteosarcoma. Greater than 90% necrosis indicates a good response.

Question 43

A 55-year-old diabetic male presents with a swollen, warm, and erythematous left foot. Radiographs show periarticular debris, fragmentation of the navicular, and subluxation of the talonavicular joint. According to the Eichenholtz classification, what is the most appropriate initial management?

Explanation

The patient is in the acute fragmentation phase (Stage 1) of Charcot arthropathy. The standard of care is immobilization with a total contact cast and strict non-weight-bearing until the inflammatory phase resolves.

Question 44

A 30-year-old male is brought in after a motorcycle collision with a heart rate of 130 bpm and blood pressure of 80/50 mmHg. Radiographs show a widened pubic symphysis (4 cm) and completely displaced bilateral sacroiliac joints. Where is the most anatomically correct location to place a pelvic circumferential compression device?

Explanation

A pelvic binder should be centered directly over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is less effective and can paradoxically widen the pelvis in certain fracture patterns.

Question 45

During secondary bone healing, which growth factor is primarily responsible for stimulating the differentiation of mesenchymal stem cells into chondrocytes during the formation of the soft callus?

Explanation

TGF-beta is released by platelets and macrophages early in the fracture healing process. It plays a critical role in the proliferation and differentiation of mesenchymal stem cells into chondrocytes to form the soft callus.

Question 46

A 34-year-old carpenter presents with chronic dorsal wrist pain. Radiographs reveal sclerosis and fragmentation of the lunate with preservation of carpal height, and a negative ulnar variance of 3mm. What is the most appropriate surgical treatment?

Explanation

The patient has Lichtman Stage IIIA Kienbock's disease with negative ulnar variance. A joint-leveling procedure, such as a radial shortening osteotomy, effectively unloads the radiolunate joint and is the treatment of choice.

Question 47

A 6-month-old female with developmental dysplasia of the hip has failed 4 weeks of Pavlik harness treatment. Ultrasound demonstrates continued posterior dislocation of the femoral head. What is the most appropriate next step in management?

Explanation

If a Pavlik harness fails to achieve reduction within 3-4 weeks, it should be discontinued to prevent Pavlik harness disease (damage to the posterior acetabular wall). The next appropriate step is closed reduction and spica casting under general anesthesia with an arthrogram.

Question 48

A 65-year-old female presents 1 year after a posterior-stabilized total knee arthroplasty with a painful catching sensation when extending her knee from a flexed position. What is the underlying etiology of this condition?

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKA when a fibrous nodule forms on the undersurface of the distal quadriceps tendon. This nodule catches in the intercondylar box of the femoral component during extension from a flexed position.

Question 49

A 16-year-old gymnast complains of chronic low back pain. Radiographs show a Grade II L5-S1 isthmic spondylolisthesis. If the patient develops radicular symptoms, which nerve root is most commonly affected due to foraminal compression?

Explanation

In an L5-S1 isthmic spondylolisthesis, the slip occurs through the pars interarticularis. The exiting L5 nerve root is most commonly compressed within the neural foramen by the fibrocartilaginous mass at the pars defect.

Question 50

A 24-year-old rugby player undergoes arthroscopic Bankart repair for recurrent anterior shoulder instability. Intraoperatively, an engaging Hill-Sachs lesion is identified with a glenoid bone loss of 10%. Which of the following adjunct procedures is most appropriate?

Explanation

An engaging Hill-Sachs lesion with subcritical glenoid bone loss (<20-25%) is an indication for an arthroscopic remplissage combined with an anterior Bankart repair. This involves infraspinatus tenodesis and posterior capsulodesis into the humeral defect.

Question 51

Six weeks after open reduction and internal fixation of a distal radius fracture with a volar locking plate, a patient suddenly loses the ability to actively extend the interphalangeal joint of the thumb. Which technical error most likely caused this complication?

Explanation

Extensor pollicis longus (EPL) rupture is a known complication of volar plating of the distal radius. It is most commonly caused by over-penetration of dorsal cortical screws, leading to mechanical attrition of the tendon in the third extensor compartment.

Question 52

A 72-year-old male is undergoing debridement and implant retention (DAIR) for an acute staphylococcal periprosthetic joint infection of the hip. Which of the following antibiotics is most critical to include in the postoperative regimen due to its specific efficacy against organisms in a biofilm?

Explanation

Rifampin has a unique ability to penetrate bacterial biofilms and kill stationary-phase staphylococci. It is routinely used as a critical adjunct in the treatment of periprosthetic joint infections when hardware is retained.

Question 53

During a minimally invasive percutaneous repair of an acute Achilles tendon rupture, the surgeon places a suture 10 cm proximal to the calcaneal insertion. Which structure is at highest risk of iatrogenic injury at this level?

Explanation

The sural nerve crosses from lateral to medial across the lateral border of the Achilles tendon. It is at the highest risk of injury during percutaneous repair, particularly when placing sutures in the proximal stump.

Question 54

During an open carpal tunnel release, the surgeon carefully dissects the distal extent of the transverse carpal ligament to avoid injuring the recurrent motor branch of the median nerve. Which variation of this nerve's anatomy is most common?

Explanation

The extraligamentous with recurrent course is the most common anatomic variation of the motor branch of the median nerve. It branches distal to the transverse carpal ligament and curves back to innervate the thenar musculature.

Question 55

A 50-year-old male presents with dull, aching thigh pain. Radiographs reveal a large destructive lesion in the proximal femur with endosteal scalloping and "rings and arcs" of calcification. Biopsy confirms grade II chondrosarcoma. What is the most appropriate definitive management?

Explanation

Conventional chondrosarcomas are notably resistant to both chemotherapy and radiation. The standard of care for an intermediate or high-grade (Grade II/III) chondrosarcoma is wide surgical resection alone.

Question 56

A 25-year-old male sustains a vertically oriented femoral neck fracture (Pauwels type III). What biomechanical force is most responsible for failure of fixation in this specific fracture pattern?

Explanation

Pauwels type III fractures are highly vertical (>50 degrees), which subjects the fracture site to significant shear forces. This increases the risk of varus collapse, nonunion, and fixation failure.

Question 57

An obese 12-year-old boy presents with right groin pain and an obligate external rotation of the hip during passive flexion. He is diagnosed with a stable slipped capital femoral epiphysis (SCFE). Which complication is most closely associated with the natural history of the altered anatomy if left untreated?

Explanation

The metaphyseal prominence resulting from the slipped epiphysis creates a cam lesion, leading to anterior femoroacetabular impingement. While AVN and chondrolysis are common complications of severe slips or treatment, FAI is the most common sequela of the altered bony morphology.

Question 58

A 65-year-old female presents with deteriorating handwriting and difficulty buttoning her shirt. Exam reveals a positive Hoffmann sign and hyperreflexia in the lower extremities. MRI confirms severe cervical stenosis with cord signal changes at C4-C5 and C5-C6. What is the most appropriate next step in management?

Explanation

This patient presents with progressive cervical spondylotic myelopathy. Surgical decompression and stabilization (e.g., ACDF) is indicated to halt progression, as non-operative management typically leads to stepwise neurologic decline.

Question 59

A 22-year-old soccer player sustains a twisting knee injury. Radiographs reveal an avulsion fracture of the lateral tibial plateau (Segond fracture). In addition to the anterior cruciate ligament, which of the following structures is most likely injured?

Explanation

A Segond fracture is a pathognomonic avulsion fracture of the anterolateral tibial plateau, highly associated with an ACL tear. The avulsed bony fragment typically involves the tibial attachment of the anterolateral ligament (ALL) and lateral capsule.

Question 60

A 45-year-old male undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing. At a 2-year follow-up, he complains of an audible squeaking noise with hip flexion but denies pain. Radiographs show a well-fixed implant. What is the most common cause of this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is typically related to edge loading, often resulting from cup malposition (excessive anteversion or inclination). If asymptomatic and well-fixed, no immediate revision is necessary, but the patient should be monitored.

Question 61

A 40-year-old male presents with chronic wrist pain and is diagnosed with a stage III scaphoid nonunion advanced collapse (SNAC). Radiographs show arthritis involving the radioscaphoid and capitolunate joints, with a preserved radiolunate joint. What is the most appropriate surgical treatment?

Explanation

In Stage III SNAC, the capitolunate joint is arthritic, making a proximal row carpectomy contraindicated due to a lack of a preserved proximal capitate articular surface. A four-corner arthrodesis (capitate, hamate, lunate, triquetrum) with scaphoid excision successfully relies on the preserved radiolunate joint.

Question 62

A 28-year-old athlete sustains an axial load to a plantarflexed foot. Weight-bearing radiographs demonstrate a 3mm diastasis between the medial and middle cuneiforms. What is the most appropriate initial management?

Explanation

A true Lisfranc injury with >2mm of displacement or diastasis on weight-bearing views in an active patient warrants operative stabilization. The choice between ORIF and primary fusion depends on the degree of ligamentous vs. bony injury, but non-operative management is contraindicated for displaced injuries.

Question 63

A 14-year-old boy presents with progressive knee pain. Radiographs reveal a sunburst periosteal reaction and Codman's triangle in the distal femoral metaphysis. A biopsy confirms high-grade osteosarcoma. What is the standard sequence of treatment?

Explanation

The standard of care for high-grade osteosarcoma includes neoadjuvant chemotherapy, followed by wide surgical resection (limb salvage if possible), and then adjuvant chemotherapy. Radiation has a minimal role as osteosarcoma is highly radioresistant.

Question 64

Which type of bone healing occurs under conditions of absolute stability, such as following rigid compression plating of a transverse forearm fracture?

Explanation

Absolute stability via rigid internal fixation (e.g., compression plating) leads to primary bone healing. This occurs through direct osteonal remodeling via cutting cones without intermediate callus formation.

Question 65

A 40-year-old male is involved in a high-speed motorcycle collision and is hemodynamically unstable. Pelvic radiographs show an anteroposterior compression (APC) type III injury with total disruption of the anterior and posterior sacroiliac ligaments. What is the most appropriate first step in emergent orthopedic management?

Explanation

In a hemodynamically unstable patient with an open-book pelvic fracture, the immediate first step is mechanical stabilization of the pelvic volume. This is most rapidly and effectively achieved with a pelvic binder placed at the level of the greater trochanters.

Question 66

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed treatment with a Pavlik harness. Ultrasound confirms persistent dislocation. What is the next most appropriate step in management?

Explanation

For infants between 6 and 18 months, or those who fail Pavlik harness treatment, closed reduction under anesthesia followed by spica casting is the standard next step. An intraoperative arthrogram is typically performed to assess the adequacy of reduction.

Question 67

A 19-year-old female swimmer presents with bilateral shoulder pain and a sensation of her shoulders slipping out of place. Examination reveals a positive sulcus sign bilaterally, apprehension and relocation tests, and generalized ligamentous laxity. What is the most appropriate initial management?

Explanation

Multidirectional instability (MDI) is typically atraumatic and characterized by generalized ligamentous laxity. The cornerstone of initial management is an extended, structured course of physical therapy focusing on the dynamic stabilizers and periscapular musculature.

Question 68

According to the Musculoskeletal Infection Society (MSIS) criteria, which of the following is considered a major criterion for diagnosing a periprosthetic joint infection (PJI)?

Explanation

The major diagnostic criteria for PJI include a sinus tract communicating with the prosthesis or two positive periprosthetic cultures with phenotypically identical organisms. The other listed options represent minor criteria.

Question 69

A 25-year-old carpenter suffers a laceration to the volar aspect of his index finger at the level of the proximal phalanx, transecting both the FDS and FDP tendons. Into which flexor tendon zone does this injury fall?

Explanation

Zone II, historically referred to as "no man's land", extends from the A1 pulley (distal palmar crease) to the insertion of the flexor digitorum superficialis (FDS) on the middle phalanx. Both the FDS and FDP tendons lie within the tight fibro-osseous flexor sheath in this region.

Question 70

A 45-year-old recreational athlete sustains an acute Achilles tendon rupture and elects for non-operative management. Compared to operative repair, which of the following outcomes is most statistically associated with non-operative management?

Explanation

Non-operative management of Achilles tendon ruptures carries a slightly higher risk of re-rupture compared to surgical repair, although modern early functional rehabilitation protocols are narrowing this gap. Operative repair has a higher risk of wound complications and iatrogenic nerve injury.

Question 71

A 30-year-old female presents with a destructive, eccentric, lytic lesion in the proximal tibial epiphysis extending to the subchondral bone. Biopsy reveals multinucleated giant cells interspersed with mononuclear stromal cells. If systemic therapy is considered, which molecular target is most appropriate to inhibit?

Explanation

Giant Cell Tumor of bone is characterized by neoplastic mononuclear stromal cells that overexpress RANKL, driving the recruitment of osteoclast-like giant cells. Denosumab, a monoclonal antibody against RANKL, is highly effective in reducing the tumor's osteolytic activity.

Question 72

In healthy articular cartilage, the highest concentration of proteoglycans and the lowest water content are found in which specific histologic layer?

Explanation

The deep (radial) zone of articular cartilage is responsible for resisting compressive forces. It contains the highest concentration of proteoglycans, the lowest water content, and thick collagen fibers oriented perpendicular to the articular surface.

Question 73

A 55-year-old male sustains a severe bicondylar tibial plateau fracture (Schatzker VI) with massive soft tissue swelling. Compartment pressures measure 45 mmHg in the anterior compartment with a diastolic blood pressure of 60 mmHg. What is the required definitive intervention?

Explanation

The patient has a delta-P (diastolic pressure minus compartment pressure) of 15 mmHg, clearly indicating acute compartment syndrome (threshold typically <30 mmHg). Emergent four-compartment fasciotomy of the leg is the definitive treatment to prevent irreversible muscle ischemia.

Question 74

A 14-year-old boy presents with severe, aching pain in his right thigh that is worse at night and rapidly relieved by ibuprofen. Radiographs demonstrate diaphyseal cortical thickening with a 1-centimeter radiolucent nidus. What is the primary biochemical mediator responsible for this patient's pain?

Explanation

Osteoid osteoma nidus cells produce high levels of Prostaglandin E2, which causes the characteristic night pain. This is the mechanism by which NSAIDs provide rapid and effective pain relief.

Question 75

A 25-year-old male undergoes an anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone autograft. Postoperatively, he lacks full knee flexion but easily achieves full extension. The surgeon suspects malpositioning of the femoral tunnel. Where was the femoral tunnel most likely placed?

Explanation

An anteriorly placed femoral tunnel during ACL reconstruction results in a graft that is tight in flexion and loose in extension, leading to a loss of knee flexion. Conversely, a posterior femoral tunnel leads to a graft that is tight in extension.

Question 76

A 55-year-old male with poorly controlled diabetes mellitus presents with a severely swollen, erythematous, and warm left foot. He denies any recent trauma, systemic fevers, or pain. Radiographs reveal fragmentation and early subluxation of the navicular and cuneiforms without open wounds. What is the most appropriate initial management?

Explanation

This patient presents with acute Eichenholtz Stage I (fragmentation) Charcot arthropathy. The gold standard initial treatment to prevent further deformity is strict immobilization and offloading, most effectively achieved with total contact casting.

Question 77

A 60-year-old male presents with an audible squeaking sound from his right hip, which underwent a ceramic-on-ceramic total hip arthroplasty 3 years ago. What biomechanical phenomenon is most frequently associated with squeaking in this specific bearing surface?

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading due to component malposition (e.g., excessive cup anteversion or steep inclination). This edge loading leads to stripe wear and subsequent loss of fluid-film lubrication.

Question 78

A 70-year-old female on alendronate for 12 years presents with persistent right thigh pain for 3 months. Radiographs reveal lateral cortical thickening and a transverse radiolucent line in the subtrochanteric femur without complete displacement. What is the most appropriate primary management step?

Explanation

This is an impending atypical femur fracture secondary to long-term bisphosphonate use. Because she has a cortical radiolucency with prodromal pain, prophylactic intramedullary nailing is indicated to prevent catastrophic complete fracture.

Question 79

A 22-year-old rugby player aggressively grabs an opponent's jersey and feels a pop in his right ring finger. He is unable to actively flex the distal interphalangeal (DIP) joint. On examination, a tender mass is palpable in the proximal palm. According to the Leddy and Packer classification, what is the recommended timeframe for surgical repair?

Explanation

This is a Type I flexor digitorum profundus (FDP) avulsion (Jersey finger) where the tendon retracts into the palm, compromising its blood supply from the vincula. Early surgical repair within 7-10 days is required to prevent myostatic contracture and tendon necrosis.

Question 80

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the mother notes the child is no longer actively extending her left knee. Which nerve is most likely affected by incorrect harness positioning?

Explanation

Excessive hyperflexion in a Pavlik harness can cause compression of the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy (loss of active knee extension). Treatment involves altering the harness to reduce flexion.

Question 81

An 8-week postoperative AP radiograph of the ankle in a patient who underwent ORIF for a talar neck fracture demonstrates a subchondral radiolucent band in the talar dome. What is the clinical significance of this radiographic finding?

Explanation

This finding is known as the Hawkins sign, representing subchondral osteopenia. It indicates that the vascular supply to the talus is intact, as hyperemia is required to resorb the bone.

Question 82

A 25-year-old male sustains a closed tibial shaft fracture. He complains of excruciating pain out of proportion to the injury. Which pressure measurement threshold is the most reliable indication for emergent fasciotomies?

Explanation

The delta pressure (Diastolic BP - Compartment Pressure) is the most reliable indicator for acute compartment syndrome. A delta pressure of less than 30 mmHg necessitates emergent fasciotomies.

Question 83

A 40-year-old mechanic presents with an inability to make an "OK" sign, instead forming a flat pinch between his thumb and index finger. Sensation in the hand is completely normal. Compression of which nerve is responsible for this deficit?

Explanation

The anterior interosseous nerve (AIN) innervates the flexor pollicis longus (FPL), flexor digitorum profundus (FDP) to the index/middle fingers, and pronator quadratus. AIN syndrome causes a pure motor deficit, preventing flexion of the IP joint of the thumb and DIP of the index finger.

Question 84

A 15-year-old elite gymnast presents with mechanical low back pain. Radiographs demonstrate a Grade 1 isthmic spondylolisthesis at L5-S1. She is neurologically intact. What is the most appropriate initial management?

Explanation

For low-grade isthmic spondylolisthesis in adolescents without neurologic deficits, initial management should be nonoperative. This includes a temporary cessation of hyperextension activities, bracing if acutely symptomatic, and core-strengthening physical therapy.

Question 85

A trauma patient arrives hypotensive with a mechanically unstable anteroposterior compression (APC) pelvic ring injury. A commercial pelvic binder is applied in the trauma bay. To maximize the reduction force on the pelvic ring, over which anatomic landmark should the binder be centered?

Explanation

Pelvic binders are most effective at reducing pelvic volume and stabilizing the ring when placed directly over the greater trochanters. Placement over the iliac crests is less effective and can paradoxically open the pelvis in some fracture patterns.

Question 86

In orthopedic basic science, mixing different metal alloys in an implant construct can lead to accelerated corrosion in vivo. Which of the following material combinations is most susceptible to significant galvanic corrosion?

Explanation

Galvanic corrosion occurs when two metals with significantly different anodic indices are in electrical contact within an electrolyte solution. Stainless steel and titanium have vastly different potentials, making this combination highly susceptible to galvanic corrosion.

Question 87

A 12-year-old obese male presents with acute severe hip pain and inability to bear weight. Radiographs show a severe slipped capital femoral epiphysis (SCFE). Which of the following treatments is associated with the highest risk of iatrogenic avascular necrosis (AVN) of the femoral head?

Explanation

Forceful closed reduction or overzealous manipulation of an acute or unstable SCFE severely compromises the already tenuous epiphyseal blood supply. This drastically increases the rate of avascular necrosis and is strictly contraindicated.

Question 88

A 35-year-old male sustains a spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). On initial presentation, his radial nerve function is intact. Following closed reduction and splint application, he is found to have a complete wrist drop and inability to extend his MCP joints. What is the most appropriate management?

Explanation

While radial nerve palsies present at the time of injury can often be observed, a secondary radial nerve palsy that develops AFTER closed reduction strongly suggests the nerve has become entrapped in the fracture site. This is an absolute indication for surgical exploration.

Question 89

A 15-year-old male presents with persistent knee pain. Radiographs reveal a destructive metaphyseal lesion in the distal femur with a "sunburst" periosteal reaction. Biopsy confirms malignant spindle cells producing unmineralized osteoid. What is the standard of care for this condition?

Explanation

The diagnosis is classic osteosarcoma. The standard of care to maximize survival and allow for limb salvage involves neoadjuvant (preoperative) chemotherapy, wide surgical resection, and adjuvant (postoperative) chemotherapy.

Question 90

When evaluating a patient for early, mild carpal tunnel syndrome, which physical examination test is considered the most sensitive for detecting early sensory deficits?

Explanation

Semmes-Weinstein monofilament testing measures light touch threshold and is the most sensitive test for identifying early sensory nerve compression. Two-point discrimination assesses innervation density and usually remains normal until late in the disease process.

Question 91

During the Ponseti method of serial casting for a congenital clubfoot, the sequence of deformity correction is critical. Which component of the deformity is corrected last, typically requiring a surgical intervention to fully resolve?

Explanation

The Ponseti method corrects the deformities in the order of CAVE: Cavus, Adductus, Varus, and finally Equinus. The equinus deformity is corrected last and requires a percutaneous Achilles tenotomy in approximately 80-90% of cases.

Question 92

In orthopedic biomechanics, the gradual and progressive deformation of a viscoelastic material over time when subjected to a constant, sustained load is defined as what?

Explanation

Creep is the time-dependent deformation of a material under a constant applied load or stress. This is distinct from stress relaxation, which is the decrease in stress over time when a material is held at a constant strain or length.

Question 93

During a total knee arthroplasty (TKA), the surgeon inadvertently places the femoral component in excessive internal rotation. What is the most likely biomechanical consequence of this specific malpositioning?

Explanation

Internal rotation of the femoral component moves the trochlear groove medially relative to the patella. This effectively increases the Q-angle dynamically, leading to lateral patellar maltracking, tilt, and potential subluxation.

Orthopaedic Surgery Board Exam Review: ABOS Part I & AAOS OITE Prep Questions | Part 22210

ABOS Part I & AAOS OITE Orthopedic Surgery Board Review Questions - Comprehensive Module | Part 22156

Key Takeaway

ABOS Part I & AAOS OITE Orthopedic Surgery Board Review Questions - Comprehensive Module | Part 22156

Chapter Index