Full Question & Answer Text (for Search Engines)
Question 1:
Which of the following accurately describes the 'corona mortis' anastomosis, a critical vascular structure that may be encountered and injured during the ilioinguinal approach to the acetabulum?
Options:
- Anastomosis between the external iliac or inferior epigastric vessels and the obturator vessels
- Anastomosis between the internal iliac artery and the superior gluteal artery
- Anastomosis between the deep circumflex iliac artery and the femoral artery
- Anastomosis between the internal pudendal artery and the middle rectal artery
- Anastomosis between the external pudendal artery and the medial femoral circumflex artery
Correct Answer: Anastomosis between the external iliac or inferior epigastric vessels and the obturator vessels
Explanation:
The corona mortis ('crown of death') is a vascular connection between the obturator and external iliac (or inferior epigastric) systems. It is located over the superior pubic ramus at an average distance of 5 to 6 cm from the pubic symphysis. Injury to this structure during an ilioinguinal approach or placement of superior pubic ramus screws can result in severe, difficult-to-control hemorrhage.
Question 2:
A 12-year-old boy presents with a painful mass in the diaphysis of his left femur. Radiographs show a permeative, destructive lesion with an 'onion-skin' periosteal reaction. A core needle biopsy is performed. Which of the following chromosomal translocations is most characteristic of the suspected diagnosis?
Options:
- t(X;18)(p11;q11)
- t(11;22)(q24;q12)
- t(12;16)(q13;p11)
- t(2;13)(q35;q14)
- t(9;22)(q34;q11)
Correct Answer: t(11;22)(q24;q12)
Explanation:
The clinical and radiographic presentation is classic for Ewing sarcoma. Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma. t(12;16) is seen in myxoid liposarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma. t(9;22) is the Philadelphia chromosome seen in CML and occasionally in some chondrosarcomas.
Question 3:
In a patient presenting with a slipped capital femoral epiphysis (SCFE), which of the following is the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral hip?
Options:
- Age older than 15 years at the time of presentation
- Male gender
- Obesity (BMI > 95th percentile)
- Presence of an underlying endocrine disorder (e.g., hypothyroidism)
- Moderate-to-severe slip angle (>30 degrees) on the affected side
Correct Answer: Presence of an underlying endocrine disorder (e.g., hypothyroidism)
Explanation:
While contralateral pinning is debated in idiopathic SCFE, there is broad consensus that patients with an underlying endocrinopathy (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) have an exceptionally high risk of bilateral involvement (up to 100% in some series). Therefore, prophylactic contralateral pinning is strongly indicated in these patients. Other indications include an inability to reliably follow up or an age at presentation of less than 10 years.
Question 4:
A 55-year-old man who underwent a ceramic-on-ceramic total hip arthroplasty 3 years ago complains of a loud squeaking noise from his hip with bending and walking. Radiographs are unremarkable. Which of the following component positions is most strongly associated with this phenomenon?
Options:
- Acetabular component inclination of 35 degrees
- Acetabular component inclination of 55 degrees
- Femoral stem retroversion of 10 degrees
- Femoral stem anteversion of 15 degrees
- Increased lateral femoral offset
Correct Answer: Acetabular component inclination of 55 degrees
Explanation:
Squeaking in ceramic-on-ceramic (CoC) THA is strongly correlated with edge loading and subsequent stripe wear of the ceramic components. Edge loading is most frequently caused by malpositioning of the acetabular component, particularly cup inclination greater than 45-50 degrees, or excessive anteversion/retroversion. An inclination of 55 degrees significantly increases the risk of edge loading and squeaking.
Question 5:
A 35-year-old man presents after a motor vehicle collision with severe neck pain. Radiographs reveal a traumatic spondylolisthesis of the axis (Hangman's fracture) with 15 degrees of angulation and 2 mm of anterior translation. The fracture line is oblique from anterior-inferior to posterior-superior. Which of the following is true regarding the management of this specific fracture pattern (Effendi/Levine Type IIA)?
Options:
- Immediate longitudinal cervical traction is the first line of treatment
- It is caused primarily by a hyperextension-axial loading mechanism
- Cervical traction is strictly contraindicated due to the risk of over-distraction
- Treatment primarily consists of a soft cervical collar for 6 weeks
- Posterior C1-C2 fusion is universally required due to high rates of nonunion
Correct Answer: Cervical traction is strictly contraindicated due to the risk of over-distraction
Explanation:
This is a Type IIA Hangman's fracture, characterized by severe angulation with minimal translation. The mechanism is flexion-distraction, which disrupts the C2-C3 intervertebral disc and posterior longitudinal ligament, while the anterior longitudinal ligament remains intact. Because the posterior restraints are completely torn, applying cervical traction is strictly contraindicated as it can cause massive over-distraction and subsequent severe neurologic injury. Reduction is achieved with gentle extension and axial compression, followed by halo immobilization.
Question 6:
During the repair of a Zone II flexor tendon injury in the hand, preservation or reconstruction of which of the following annular pulleys is most critical to prevent bowstringing and maintain proper finger biomechanics?
Options:
- A1 and A3 pulleys
- A2 and A4 pulleys
- A3 and A5 pulleys
- A1 and A5 pulleys
- A2 and A3 pulleys
Correct Answer: A2 and A4 pulleys
Explanation:
The flexor tendon sheath contains five annular (A1-A5) and three cruciform (C1-C3) pulleys. The A2 and A4 pulleys are the most mechanically critical. They originate directly from the periosteum of the proximal and middle phalanges, respectively. Loss of the A2 or A4 pulleys leads to clinically significant bowstringing of the flexor tendons, resulting in a loss of active flexion at the IP joints and an overall decrease in the work capacity of the finger.
Question 7:
Compared to a traditional transtibial drilling technique, utilizing an independent anteromedial (AM) portal drilling technique for the femoral tunnel in an anterior cruciate ligament (ACL) reconstruction increases the risk of which of the following intraoperative complications?
Options:
- Vertical graft placement in the coronal plane
- Posterior cruciate ligament impingement
- Posterior wall blowout of the lateral femoral condyle
- Anterior placement of the femoral tunnel
- Inability to adequately tension the graft
Correct Answer: Posterior wall blowout of the lateral femoral condyle
Explanation:
The anteromedial (AM) portal technique allows for more anatomic placement of the femoral tunnel footprint compared to the transtibial technique, which often results in a more vertical and non-anatomic graft. However, drilling through the AM portal is associated with specific risks, particularly a shorter femoral tunnel length and a higher risk of posterior wall blowout of the lateral femoral condyle due to the acute angle of the drill trajectory relative to the intercondylar notch.
Question 8:
A 25-year-old athlete presents with midfoot pain after sustaining a twisting injury to his foot while playing football. Weight-bearing radiographs reveal a subtle widening between the first and second metatarsal bases, and a 'fleck sign' is visible. The injured ligament responsible for this pathognomonic finding typically originates and inserts on which of the following structures?
Options:
- Base of the 1st metatarsal to the base of the 2nd metatarsal
- Medial cuneiform to the base of the 2nd metatarsal
- Medial cuneiform to the base of the 1st metatarsal
- Intermediate cuneiform to the base of the 2nd metatarsal
- Lateral cuneiform to the cuboid
Correct Answer: Medial cuneiform to the base of the 2nd metatarsal
Explanation:
The 'fleck sign' is pathognomonic for a Lisfranc injury and represents a bony avulsion of the Lisfranc ligament. The Lisfranc ligament is a strong interosseous ligament that originates from the lateral aspect of the medial cuneiform and inserts onto the medial aspect of the base of the second metatarsal. There is no direct ligamentous connection between the bases of the first and second metatarsals.
Question 9:
Bone Morphogenetic Proteins (BMPs) play a crucial role in osteoinduction during fracture healing and spinal fusion. The cellular signaling cascade of BMPs is primarily initiated by the ligand binding to which of the following types of receptors on the cell surface?
Options:
- Tyrosine kinase receptors
- G-protein coupled receptors
- Serine/threonine kinase receptors
- Intracellular nuclear receptors
- Ion channel-linked receptors
Correct Answer: Serine/threonine kinase receptors
Explanation:
Bone Morphogenetic Proteins (BMPs) are members of the TGF-beta superfamily. They bind to type I and type II transmembrane receptors, which are serine/threonine kinase receptors. Upon ligand binding, these receptors phosphorylate intracellular Smad proteins (typically Smad 1, 5, and 8), which then complex with Smad 4, translocate to the nucleus, and regulate the transcription of osteogenic genes (e.g., Runx2).
Question 10:
A 32-year-old man sustains a closed highly-comminuted tibial shaft fracture. He complains of severe pain out of proportion to the injury that worsens with passive stretch. His blood pressure is 120/80 mmHg. Intracompartmental pressure monitoring is performed. According to the 'Delta P' theory, what is the critical threshold indicating the need for emergent four-compartment fasciotomy?
Options:
- Absolute compartment pressure > 30 mmHg
- Absolute compartment pressure > 45 mmHg
- Diastolic blood pressure minus compartment pressure < 30 mmHg
- Mean arterial pressure minus compartment pressure < 40 mmHg
- Systolic blood pressure minus compartment pressure < 30 mmHg
Correct Answer: Diastolic blood pressure minus compartment pressure < 30 mmHg
Explanation:
The 'Delta P' concept for diagnosing acute compartment syndrome states that the difference between the diastolic blood pressure and the absolute compartment pressure (Delta P = Diastolic BP - Compartment Pressure) is a more accurate predictor of muscle ischemia than absolute compartment pressure alone. A Delta P of less than 30 mmHg is the widely accepted threshold that dictates the need for emergent fasciotomy, as capillary perfusion is severely compromised below this pressure gradient.
Question 11:
In the Ponseti method for the treatment of idiopathic clubfoot, the sequence of deformity correction is critical for a successful outcome. Which of the following represents the correct first step in the manipulation and casting process?
Options:
- Dorsiflexion of the ankle to correct equinus
- Abduction of the forefoot to correct adductus
- Pronation of the forefoot to correct varus
- Elevation of the first ray to correct cavus
- Eversion of the calcaneus to correct hindfoot varus
Correct Answer: Elevation of the first ray to correct cavus
Explanation:
The sequence of correction in the Ponseti method follows the acronym CAVE: Cavus, Adductus, Varus, Equinus. The very first step must be the correction of the cavus deformity. This is achieved by elevating the first ray (supinating the forefoot), which aligns the forefoot with the hindfoot. Pronating the forefoot, a common error, worsens the cavus deformity.
Question 12:
During a posterior-stabilized total knee arthroplasty, the trial components are inserted. The surgeon notes that the knee is well-balanced and stable in full extension, but the joint is excessively tight and difficult to bring past 90 degrees of flexion. Which of the following intraoperative maneuvers is the most appropriate next step to resolve this specific kinematic mismatch?
Options:
- Resect additional bone from the distal femur
- Downsize the femoral component and use a thicker polyethylene insert
- Downsize the femoral component
- Release the posterior cruciate ligament
- Recut the proximal tibia with less posterior slope
Correct Answer: Downsize the femoral component
Explanation:
A knee that is balanced in extension but tight in flexion has a tight flexion gap. To increase the flexion gap without affecting the extension gap, the surgeon must either downsize the femoral component (which decreases the anterior-posterior dimension and thus the posterior condylar offset) or increase the posterior slope of the tibial cut. Since the knee is a posterior-stabilized design, the PCL is already resected. Resecting more distal femur would loosen the extension gap. Simply downsizing the femoral component effectively opens the flexion gap.
Question 13:
A 45-year-old woman presents with isolated weakness in her right hand. On examination, she is unable to form an 'OK' sign with her thumb and index finger, instead demonstrating an extended posture of the distal interphalangeal joint of the index finger and the interphalangeal joint of the thumb. She reports no sensory deficits. Entrapment of the affected nerve most commonly occurs at which of the following anatomical structures?
Options:
- Ligament of Struthers
- Arcade of Frohse
- Tendinous edge of the deep head of the pronator teres
- Cubital tunnel retinaculum
- Guyon's canal
Correct Answer: Tendinous edge of the deep head of the pronator teres
Explanation:
The patient is presenting with Anterior Interosseous Nerve (AIN) syndrome, characterized by weakness of the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index (and sometimes middle) finger, and the pronator quadratus. This results in the inability to make the 'OK' sign, leading to a pinch with extended distal joints (Kiloh-Nevin sign). Because the AIN is a purely motor branch, there is no sensory loss. The most common site of AIN entrapment is the tendinous edge of the deep head of the pronator teres (or the fibrous arcade of the FDS).
Question 14:
A 52-year-old man presents with acute onset, severe left-sided radiating leg pain. Physical examination reveals weakness in knee extension, an asymmetric depressed patellar tendon reflex on the left, and numbness over the medial aspect of the left lower leg. An MRI of the lumbar spine reveals a far-lateral (extraforaminal) disc herniation. At which of the following disc levels is this herniation most likely located?
Options:
- L2-L3
- L3-L4
- L4-L5
- L5-S1
- S1-S2
Correct Answer: L4-L5
Explanation:
The patient exhibits classic signs of an L4 nerve root radiculopathy: weakness in quadriceps (knee extension), a depressed patellar reflex, and sensory deficits over the medial leg. In the lumbar spine, a typical paracentral disc herniation compresses the traversing nerve root (e.g., L4-L5 paracentral disc hits the L5 root). However, a far-lateral (foraminal/extraforaminal) disc herniation compresses the exiting nerve root at that level. Therefore, to compress the exiting L4 nerve root, the far-lateral disc herniation must be located at the L4-L5 level.
Question 15:
A 28-year-old woman presents with knee pain. Radiographs reveal an eccentric, lytic lesion in the distal femoral epiphysis extending to the subchondral bone, with no sclerotic margin. Biopsy confirms a giant cell tumor of bone (GCTB). Which of the following statements regarding the pathogenesis and targeted medical therapy for this tumor is true?
Options:
- The multinucleated giant cells are the primary neoplastic cells and express high levels of RANK
- The mononuclear stromal cells are the primary neoplastic cells and secrete excessive amounts of RANKL
- Imatinib mesylate is the preferred targeted therapy for unresectable lesions
- Denosumab therapy is a monoclonal antibody directed against the RANK receptor on the surface of the mononuclear stromal cells
- The tumor cells characteristically exhibit the t(X;18) chromosomal translocation
Correct Answer: The mononuclear stromal cells are the primary neoplastic cells and secrete excessive amounts of RANKL
Explanation:
In Giant Cell Tumor of Bone (GCTB), the neoplastic cells are actually the mononuclear stromal cells, not the multinucleated giant cells. The neoplastic stromal cells secrete large amounts of Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL), which recruits and activates normal osteoclast precursors into the reactive, multinucleated giant cells that cause the characteristic bone destruction. Denosumab is a monoclonal antibody that targets and binds RANKL (not the RANK receptor), inhibiting this process and is used for advanced or unresectable GCTB.
Question 16:
A 40-year-old man falls while skiing and sustains an isolated full-thickness tear of the subscapularis tendon. Which of the following physical examination findings has the highest sensitivity for identifying a lesion specifically involving the upper portion of the subscapularis tendon footprint?
Options:
- Positive Jobe's (empty can) test
- Positive Hornblower's sign
- Positive Belly-press test
- Positive Bear-hug test
- Positive Lift-off test
Correct Answer: Positive Bear-hug test
Explanation:
The bear-hug test has been shown in multiple biomechanical and clinical studies (such as Barth et al.) to be the most sensitive test for evaluating tears of the upper footprint of the subscapularis tendon. The lift-off test is highly specific but evaluates primarily the lower portion of the subscapularis. The belly-press test evaluates the middle/upper portions but is generally less sensitive than the bear-hug test for isolated upper tears. Hornblower's is for the teres minor, and Jobe's is for the supraspinatus.
Question 17:
'Trunnionosis' in modern total hip arthroplasty primarily occurs at the modular head-neck taper junction. This phenomenon, which can lead to adverse local tissue reactions (ALTR) even with metal-on-polyethylene bearings, is mechanically initiated by micro-motion at the taper interface. This micro-motion primarily leads to which of the following modes of implant degradation?
Options:
- Pitting corrosion
- Galvanic corrosion
- Fretting corrosion
- Intergranular corrosion
- Stress corrosion cracking
Correct Answer: Fretting corrosion
Explanation:
Trunnionosis refers to the wear and corrosion at the modular head-neck taper junction in a total hip arthroplasty. It is initiated by micro-motion under load, which constantly disrupts the protective passive oxide layer on the metal surface. This specific process of mechanically assisted crevice corrosion initiated by oscillatory micro-motion is termed 'fretting corrosion'. While galvanic corrosion plays a secondary role once the passivating layer is breached (especially with mixed metals like CoCr on Ti), the mechanical initiator is fretting.
Question 18:
An infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a 2-week follow-up visit, the mother notes that the infant is no longer actively kicking the right leg. Physical examination reveals decreased active knee extension on the right side, with an absent patellar reflex, but normal active ankle and toe motion. Which of the following harness adjustments is the most appropriate next step to resolve this complication?
Options:
- Decrease the abduction angle of the posterior straps
- Increase the flexion angle of the anterior straps
- Decrease the flexion angle of the anterior straps
- Discontinue the harness entirely and place the child in a spica cast
- Add an anti-rotation strap to the affected side
Correct Answer: Decrease the flexion angle of the anterior straps
Explanation:
The infant has developed a femoral nerve palsy, which is the most common nerve palsy associated with Pavlik harness use. It is caused by excessive hyperflexion of the hip, which compresses the femoral nerve against the inguinal ligament. The appropriate management is to decrease the flexion angle of the anterior straps. If the palsy does not resolve within a few days to a week after adjustment, the harness should be temporarily discontinued. Excessive abduction (posterior straps) is associated with a vascular complication—avascular necrosis (AVN) of the femoral head.
Question 19:
A 60-year-old woman undergoes volar locking plate fixation for a displaced, comminuted distal radius fracture. Six months postoperatively, she presents with the sudden inability to actively flex the interphalangeal joint of her thumb. She denies any new trauma. This complication is most strongly associated with which of the following intraoperative technical errors?
Options:
- Screws penetrating the dorsal cortex of the distal radius
- Placement of the volar plate distal to the watershed line
- Failure to repair the pronator quadratus during closure
- Over-distraction of the radiocarpal joint during reduction
- Use of a non-locking screw in the most ulnar distal plate hole
Correct Answer: Placement of the volar plate distal to the watershed line
Explanation:
The patient has experienced an attritional rupture of the flexor pollicis longus (FPL) tendon. In volar plating of the distal radius, the FPL tendon is at high risk of attrition and rupture if the plate is positioned too far distally, crossing the 'watershed line' (the bony ridge marking the volar margin of the distal radius articular surface). Prominent hardware at this level directly rubs against the flexor tendons. Dorsal screw penetration causes extensor tendon ruptures (most commonly EPL).
Question 20:
A 55-year-old man with a 15-year history of poorly controlled type 2 diabetes mellitus presents with a swollen, warm, and erythematous left foot. He denies fevers, chills, or any open wounds. His inflammatory markers are normal. Radiographs demonstrate periarticular osteopenia, osseous debris, and fragmentation of the tarsometatarsal joints. According to the Eichenholtz classification of Charcot arthropathy, what is the most appropriate initial management for this patient?
Options:
- Urgent surgical debridement and intravenous antibiotics
- Open reduction and rigid internal fixation of the midfoot
- Total contact casting and strict non-weight-bearing
- Prescribing custom accommodative footwear and allowing full weight-bearing
- Intravenous bisphosphonates and immediate physical therapy
Correct Answer: Total contact casting and strict non-weight-bearing
Explanation:
The patient's clinical presentation and radiographic findings (fragmentation, debris, periarticular osteopenia) correspond to Eichenholtz Stage 1 (Development/Fragmentation stage) of Charcot arthropathy. In this acute inflammatory stage, the primary treatment is strict immobilization and offloading to prevent further structural collapse. The gold standard is total contact casting (TCC) and non-weight-bearing. Surgery is generally contraindicated during the acute inflammatory phase due to poor bone quality and high risk of failure, unless there is an unstable deformity causing imminent skin breakdown.
Question 21:
A 28-year-old male presents after a high-speed motor vehicle accident with a Hawkins type III fracture of the talar neck. What is the approximate rate of avascular necrosis (AVN) associated with this specific injury pattern?
Options:
- 0-10%
- 20-50%
- 70-100%
- Always occurs
- 15-20%
Correct Answer: 70-100%
Explanation:
Hawkins type III fractures involve the talar neck with dislocation of the subtalar and tibiotalar joints. Because the three main sources of blood supply (artery of the tarsal canal, artery of the sinus tarsi, and deltoid branches) are typically disrupted in this displacement pattern, the rate of AVN is reported to be near 70-100%.
Question 22:
In the evaluation of developmental dysplasia of the hip (DDH) in a 6-month-old child, the ossific nucleus of the femoral head is delayed. Which radiographic landmark combination correctly defines the normal anatomical position of the proximal femur?
Options:
- Superior to Hilgenreiner's line and medial to Perkin's line
- Inferior to Hilgenreiner's line and medial to Perkin's line
- Inferior to Hilgenreiner's line and lateral to Perkin's line
- Superior to Hilgenreiner's line and lateral to Perkin's line
- Medial to the teardrop and superior to Hilgenreiner's line
Correct Answer: Inferior to Hilgenreiner's line and medial to Perkin's line
Explanation:
On an AP pelvis radiograph, the normal femoral head (or its expected unossified cartilaginous analogue) should reside in the inferomedial quadrant formed by the intersection of Hilgenreiner's line (horizontal through the triradiate cartilages) and Perkin's line (vertical descending from the lateral margin of the ossified acetabulum).
Question 23:
A 14-year-old boy presents with a destructive diaphyseal lesion of the femur with a multilamellated 'onion-skin' periosteal reaction. Biopsy reveals uniform small round blue cells. Which chromosomal translocation is most characteristically associated with this tumor?
Options:
- t(11;22)
- t(9;22)
- t(X;18)
- t(2;13)
- t(12;16)
Correct Answer: t(11;22)
Explanation:
The clinical and histological picture describes Ewing sarcoma. The most common chromosomal translocation is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein and is found in approximately 85-90% of Ewing sarcoma cases. The t(X;18) translocation is associated with synovial sarcoma, and t(2;13) is associated with alveolar rhabdomyosarcoma.
Question 24:
A 55-year-old male underwent a primary total hip arthroplasty utilizing a ceramic-on-ceramic bearing. At 2-year follow-up, he complains of an audible 'squeaking' noise when walking, though he has no pain. Which factor is most strongly associated with the development of squeaking in this specific bearing couple?
Options:
- Increased femoral offset
- Acetabular component retroversion or malposition
- Use of a 28 mm rather than 36 mm femoral head
- Titanium femoral stem
- Excessive polyethylene wear
Correct Answer: Acetabular component retroversion or malposition
Explanation:
Squeaking in ceramic-on-ceramic THA is highly associated with edge loading caused by acetabular component malposition (e.g., excessive anteversion, retroversion, or high inclination angles), which leads to loss of fluid film lubrication and subsequent stripe wear.
Question 25:
A 40-year-old male presents with chronic wrist pain and an untreated scaphoid fracture sustained 10 years ago. Radiographs reveal osteoarthritis involving the radioscaphoid joint and the capitolunate joint, but the radiolunate joint is remarkably spared. What is the correct stage of Scaphoid Nonunion Advanced Collapse (SNAC)?
Options:
- Stage I
- Stage II
- Stage III
- Stage IV
- SLAC Stage III
Correct Answer: Stage III
Explanation:
SNAC staging describes the predictable progression of wrist arthritis following a scaphoid nonunion. Stage I involves the radial styloid and distal scaphoid. Stage II involves the entire radioscaphoid joint. Stage III adds involvement of the capitolunate joint. Stage IV involves the entire carpus. The radiolunate joint is typically spared in both SNAC and SLAC due to the spherical congruency of that articulation.
Question 26:
A 35-year-old male is involved in a motor vehicle accident and sustains a traumatic spondylolisthesis of the axis (Hangman's fracture). Radiographs show a fracture through the pars interarticularis of C2 with 4 mm of translation and 12 degrees of angulation. According to the Levine and Edwards classification, what is the most appropriate initial management?
Options:
- Rigid cervical collar for 6 weeks
- Halo vest immobilization
- Anterior cervical discectomy and fusion of C2-C3
- Posterior C1-C2 fusion
- Transoral odontoid resection
Correct Answer: Halo vest immobilization
Explanation:
This is a Type II Hangman's fracture (characterized by significant angulation >11 degrees or translation >3 mm due to disruption of the C2-C3 disc and posterior longitudinal ligament). The recommended treatment is closed reduction and application of a Halo vest. Type I fractures (minimal displacement) are treated with a rigid collar. Type III fractures (associated with bilateral C2-C3 facet dislocations) require open reduction and surgical stabilization.
Question 27:
A 22-year-old female soccer player sustains a twisting injury to her knee. Radiographs reveal an avulsion fracture of the lateral tibial plateau (Segond fracture). This radiographic finding is pathognomonic for a major injury to which of the following structures?
Options:
- Posterior cruciate ligament
- Medial collateral ligament
- Anterior cruciate ligament
- Lateral meniscus
- Iliotibial band
Correct Answer: Anterior cruciate ligament
Explanation:
A Segond fracture is an avulsion of the anterolateral ligament (ALL) or lateral capsular ligament from the lateral tibial plateau. It results from excessive internal rotation and varus stress, and is highly associated (often considered pathognomonic) with an anterior cruciate ligament (ACL) tear.
Question 28:
A 50-year-old female presents with medial ankle pain, a progressively flattening arch, and an inability to perform a single-leg heel rise. Examination reveals a flexible pes planovalgus deformity. Radiographs show no degenerative changes in the subtalar or talonavicular joints. What is the standard surgical treatment if non-operative management fails?
Options:
- Isolated talonavicular fusion
- Subtalar fusion
- Flexor digitorum longus (FDL) transfer to the navicular and medial displacement calcaneal osteotomy
- Triple arthrodesis
- Ankle arthrodesis
Correct Answer: Flexor digitorum longus (FDL) transfer to the navicular and medial displacement calcaneal osteotomy
Explanation:
The patient has Stage II posterior tibial tendon dysfunction (PTTD), defined by a flexible flatfoot deformity and loss of PTT function. Standard joint-sparing surgical treatment consists of an FDL tendon transfer to replace the dysfunctional PTT, combined with a medializing calcaneal osteotomy to correct the valgus heel alignment and protect the transfer. Triple arthrodesis is indicated for Stage III, where the deformity becomes rigid with arthritic changes.
Question 29:
In orthopedic biomechanics, what term describes the progressive deformation of a viscoelastic material over time when it is subjected to a constant load?
Options:
- Stress relaxation
- Creep
- Hysteresis
- Fatigue failure
- Isotropic behavior
Correct Answer: Creep
Explanation:
Creep is the property of a viscoelastic material wherein it undergoes progressive, time-dependent deformation when subjected to a constant force or stress. Conversely, stress relaxation refers to the decrease in stress over time when a material is held at a constant strain.
Question 30:
A 32-year-old male sustains a closed tibia fracture and presents with severe pain out of proportion to the injury. Which of the following pressure criteria is widely considered the threshold to indicate a fasciotomy for acute compartment syndrome?
Options:
- Absolute compartment pressure of 15 mm Hg
- Absolute compartment pressure of 20 mm Hg
- Delta pressure (Diastolic blood pressure minus compartment pressure) of less than 30 mm Hg
- Delta pressure (Mean arterial pressure minus compartment pressure) of less than 10 mm Hg
- Systolic blood pressure minus compartment pressure of less than 40 mm Hg
Correct Answer: Delta pressure (Diastolic blood pressure minus compartment pressure) of less than 30 mm Hg
Explanation:
The currently accepted threshold for diagnosing and treating acute compartment syndrome is a delta pressure (diastolic blood pressure minus intracompartmental pressure) of ≤ 30 mm Hg. Using absolute compartment pressures is less reliable because capillary perfusion depends on the gradient between systemic diastolic pressure and local tissue pressure.
Question 31:
A 12-year-old obese boy is diagnosed with a stable slipped capital femoral epiphysis (SCFE) and undergoes in-situ percutaneous screw fixation. If a prominent anterior metaphyseal bump remains, what is the most common long-term complication associated with the natural history of his hip?
Options:
- Avascular necrosis of the femoral head
- Chondrolysis
- Femoroacetabular impingement (cam-type)
- Premature osteoarthritis due to pincer impingement
- Leg length discrepancy > 3 cm
Correct Answer: Femoroacetabular impingement (cam-type)
Explanation:
Following SCFE, the persistent retroverted orientation of the femoral head relative to the neck leaves a prominent anterior metaphyseal bump. This altered anatomy classically leads to cam-type femoroacetabular impingement (FAI) during hip flexion, which is the most common cause of premature secondary osteoarthritis in these patients.
Question 32:
During a total knee arthroplasty, the surgeon utilizes tensioners and notes that the knee is excessively tight in flexion but correctly balanced in extension. Which of the following steps is the most appropriate maneuver to correct this isolated flexion gap imbalance?
Options:
- Increase the distal femoral resection
- Decrease the posterior slope of the tibial cut
- Resect more posterior femoral condyle (downsize the femoral component)
- Release the posterior cruciate ligament completely
- Recut the tibia with increased varus
Correct Answer: Resect more posterior femoral condyle (downsize the femoral component)
Explanation:
An isolated tight flexion gap indicates that too much bone or implant is occupying the space when the knee is flexed. Because the extension gap is fine, the distal femur and tibial cuts are correct in those planes. To selectively enlarge the flexion gap, the surgeon can downsize the femoral component (which resects more posterior condylar bone), increase the posterior slope of the tibial cut, or release the PCL if it is retained.
Question 33:
A 45-year-old male sustains an anteroposterior compression (APC) type II pelvic ring injury. Based on the Young-Burgess classification, an APC II injury is characterized by disruption of the symphysis pubis and which of the following posterior structures?
Options:
- Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
- Posterior sacroiliac ligaments only
- Both anterior and posterior sacroiliac ligaments
- Iliolumbar ligaments only
- Complete disruption of the pelvic floor and all sacroiliac ligaments
Correct Answer: Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
Explanation:
In an APC II injury, the 'open book' mechanism causes widening of the symphysis pubis (>2.5 cm) and tearing of the anterior sacroiliac ligaments, as well as the sacrotuberous and sacrospinous ligaments. The strong posterior sacroiliac ligaments remain intact, leaving the pelvis rotationally unstable but vertically stable. Complete disruption involving the posterior SI ligaments defines an APC III injury.
Question 34:
A 45-year-old male presents with severe right lower extremity radiculopathy. Examination reveals notable weakness in ankle dorsiflexion and decreased pinprick sensation over the dorsal aspect of the first web space of the foot. The patellar and Achilles reflexes are normal. A paracentral disc herniation at which intervertebral level is most likely responsible?
Options:
- L3-L4
- L4-L5
- L5-S1
- L2-L3
- S1-S2
Correct Answer: L4-L5
Explanation:
The clinical findings describe an L5 radiculopathy (extensor hallucis longus weakness and numbness in the first dorsal web space). In the lumbar spine, a typical paracentral disc herniation impinges the traversing nerve root. Therefore, a paracentral herniation at the L4-L5 disc space compresses the descending L5 nerve root.
Question 35:
Which biomechanical mechanism is primarily responsible for the development of a Type II SLAP (Superior Labrum Anterior to Posterior) tear in an elite overhead throwing athlete?
Options:
- Direct impact to the anterior shoulder in an abducted position
- Excessive translation of the humeral head during the follow-through phase
- The peel-back mechanism during late cocking and early acceleration phases
- Eccentric overload of the biceps tendon during deceleration
- Subacromial impingement during the wind-up phase
Correct Answer: The peel-back mechanism during late cocking and early acceleration phases
Explanation:
In overhead throwers, the most widely accepted mechanism for a Type II SLAP tear is the 'peel-back' mechanism. During the late cocking and early acceleration phases, the shoulder is in maximum abduction and external rotation. This shifts the vector of the biceps tendon, creating a severe torsional force that 'peels back' the posterosuperior labrum from the glenoid.
Question 36:
Bone morphogenetic proteins (BMPs) play a crucial role in osteoinduction and fracture healing. They exert their primary intracellular osteogenic effects through which of the following signaling pathways?
Options:
- Wnt/beta-catenin pathway
- JAK-STAT pathway
- Smad signaling pathway
- cAMP-dependent protein kinase pathway
- MAPK/ERK pathway
Correct Answer: Smad signaling pathway
Explanation:
BMPs are members of the TGF-beta superfamily. Upon binding to their specific transmembrane serine/threonine kinase receptors, they induce phosphorylation of intracellular Smad proteins (specifically receptor-regulated Smads 1, 5, and 8). These form a complex with the co-Smad (Smad 4), which translocates to the nucleus to regulate the transcription of osteogenic target genes like Runx2.
Question 37:
A 25-year-old butcher sustains a knife laceration to the palmar aspect of his index finger at the level of the proximal phalanx, transecting both the FDS and FDP tendons. According to the Verdan classification, in which zone did this flexor tendon injury occur?
Options:
- Zone I
- Zone II
- Zone III
- Zone IV
- Zone V
Correct Answer: Zone II
Explanation:
Flexor tendon Zone II, historically called 'no man's land', extends from the proximal edge of the A1 pulley (at the level of the distal palmar crease) to the insertion of the FDS tendon on the middle phalanx. Lacerations at the level of the proximal phalanx fall into this zone and frequently involve both the FDS and FDP tendons.
Question 38:
In the Ponseti method for the treatment of congenital idiopathic clubfoot, what is the proper sequence of deformity correction during the serial casting phase?
Options:
- Equinus, Varus, Adduction, Cavus
- Cavus, Adduction, Varus, Equinus
- Adduction, Cavus, Varus, Equinus
- Cavus, Varus, Adduction, Equinus
- Equinus, Cavus, Adduction, Varus
Correct Answer: Cavus, Adduction, Varus, Equinus
Explanation:
The correct sequence of correction in the Ponseti method follows the acronym CAVE: Cavus (corrected first by supinating the forefoot to align it with the hindfoot), Adduction, Varus, and lastly Equinus. The equinus is corrected last and often requires a percutaneous Achilles tenotomy to achieve full dorsiflexion.
Question 39:
An intra-articular fracture of the distal radius characterized by a volar shear fracture of the lunate facet, typically resulting in volar subluxation of the carpus along with the fracture fragment, is known by which eponym?
Options:
- Colles fracture
- Smith fracture
- Volar Barton fracture
- Chauffeur's fracture
- Die-punch fracture
Correct Answer: Volar Barton fracture
Explanation:
A volar Barton fracture is an intra-articular shear fracture of the volar rim of the distal radius, classically accompanied by volar subluxation or dislocation of the radiocarpal joint. A Colles fracture is extra-articular with dorsal angulation. A Smith fracture is extra-articular with volar angulation. A Chauffeur's fracture is an intra-articular fracture of the radial styloid.
Question 40:
A 30-year-old equestrian sustains an axial load to a plantarflexed foot. On anteroposterior (AP) and oblique radiographs, which specific alignment is the most reliable indicator of an intact, normal Lisfranc joint complex?
Options:
- The medial border of the second metatarsal aligns with the medial border of the middle cuneiform on the AP view
- The medial border of the third metatarsal aligns with the medial border of the lateral cuneiform on the AP view
- The medial border of the fourth metatarsal aligns with the medial border of the cuboid on the oblique view
- The lateral border of the first metatarsal aligns with the lateral border of the medial cuneiform on the oblique view
- The medial border of the fifth metatarsal aligns with the medial border of the cuboid on the lateral view
Correct Answer: The medial border of the second metatarsal aligns with the medial border of the middle cuneiform on the AP view
Explanation:
To rule out a subtle Lisfranc injury, critical radiographic alignments must be confirmed. On the AP view, the medial border of the base of the 2nd metatarsal must align continuously with the medial border of the middle cuneiform. On the 30-degree internal oblique view, the medial border of the 3rd metatarsal aligns with the medial border of the lateral cuneiform, and the medial border of the 4th metatarsal aligns with the medial border of the cuboid.
