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1. General Principles & Basic Science MCQs

Practice Set 202 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 4021

Topic: Surgical Anatomy & Approaches

A 40-year-old male falls from a height and sustains a severely displaced comminuted fracture of the talar body. Surgical planning dictates that extensive exposure of the medial and central aspects of the talar dome is required for anatomical reduction.

Which surgical approach provides the most optimal visualization for this injury?

. Anterolateral approach to the ankle
. Extensile lateral approach with fibular osteotomy
. Medial approach with a medial malleolar osteotomy
. Posteromedial approach between FHL and neurovascular bundle
. Dorsal approach through the extensor retinaculum

Correct Answer & Explanation

. Medial approach with a medial malleolar osteotomy

Explanation

Talar body fractures often require excellent visualization of the talar dome for accurate articular reduction. The medial aspect and central dome are best visualized via a medial malleolar osteotomy. This osteotomy is pre-drilled, performed in a chevron or transverse fashion, and allows the medial malleolus to be retracted distally with the deltoid ligament attached, fully exposing the medial talar body and dome.

Question 4022

Topic: Surgical Anatomy & Approaches

When utilizing the posterolateral approach to the ankle for fixation of a posterior malleolus fracture, the surgical interval is developed between which of the following muscle bellies?

. Flexor hallucis longus and Peroneus brevis
. Flexor digitorum longus and Tibialis posterior
. Tibialis anterior and Extensor hallucis longus
. Extensor digitorum longus and Peroneus tertius
. Gastrocnemius and Soleus

Correct Answer & Explanation

. Flexor hallucis longus and Peroneus brevis

Explanation

The posterolateral approach utilizes the internervous plane between the peroneal tendons (superficial peroneal nerve) and the flexor hallucis longus (tibial nerve). This provides excellent access to the posterior malleolus while avoiding major neurovascular structures.

Question 4023

Topic: 1. General Principles & Basic Science

Following open reduction and internal fixation of a severe pronation-external rotation (PER) ankle fracture with syndesmotic instability, which imaging modality is considered the gold standard for evaluating the accuracy of syndesmotic reduction?

. Anteroposterior (AP) radiograph
. Mortise radiograph with external rotation stress
. Bilateral computed tomography (CT) scan
. Magnetic resonance imaging (MRI)
. Intraoperative fluoroscopy using the lateral view

Correct Answer & Explanation

. Anteroposterior (AP) radiograph

Explanation

Postoperative or intraoperative bilateral CT is the gold standard for assessing syndesmotic reduction. Plain radiographs have low sensitivity for detecting subtle, yet clinically significant, syndesmotic malreduction.

Question 4024

Topic: Surgical Anatomy & Approaches

A 33-year-old unrestrained driver sustains a posterior wall acetabular fracture with a posterior hip dislocation.

On initial evaluation, the patient has weakness in ankle dorsiflexion and great toe extension, with completely intact ankle plantar flexion. Which nerve division is most likely injured?

. Tibial division of the sciatic nerve
. Peroneal division of the sciatic nerve
. Femoral nerve
. Superior gluteal nerve
. Obturator nerve

Correct Answer & Explanation

. Peroneal division of the sciatic nerve

Explanation

The common peroneal division of the sciatic nerve is injured much more frequently than the tibial division during posterior hip dislocations or posterior wall acetabular fractures. This division is more susceptible to stretch injury because it is located laterally (closer to the displacing femoral head), is tethered at the fibular head, and possesses larger fascicles with less protective epineurial connective tissue.

Question 4025

Topic: Surgical Anatomy & Approaches

A 40-year-old male presents with a chronic anterior shoulder dislocation missed for 6 weeks. During open reduction and stabilization using a Latarjet procedure, the conjoint tendon is aggressively retracted medially to gain exposure to the glenoid. Postoperatively, the patient is unable to flex his elbow against resistance when the forearm is supinated and has sensory loss over the lateral forearm. Which nerve was most likely injured?

. Median nerve
. Ulnar nerve
. Axillary nerve
. Musculocutaneous nerve
. Radial nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The musculocutaneous nerve branches from the lateral cord and enters the coracobrachialis muscle approximately 5 to 8 cm distal to the tip of the coracoid process. Aggressive or prolonged medial retraction of the conjoint tendon during anterior shoulder approaches (like the Latarjet procedure) places this nerve at high risk for a stretch injury. Deficits include weakness of the biceps and brachialis muscles (elbow flexion) and sensory loss in the lateral antebrachial cutaneous nerve distribution.

Question 4026

Topic: Surgical Anatomy & Approaches

A 32-year-old male sustains a posterior hip dislocation. He presents with a foot drop but retains full strength in ankle plantar flexion and toe flexion. Why is the peroneal division of the sciatic nerve more frequently and severely injured than the tibial division in this clinical scenario?

. The peroneal division has larger fascicles and less supporting epineurial connective tissue, and is situated further laterally.
. The peroneal division lies more medially and is directly impacted by the displaced femoral head.
. The peroneal division is tethered by its multiple motor branches to the short external rotators.
. The tibial division has a richer, protective anastomotic blood supply from the inferior gluteal artery.
. The tibial division courses anterior to the piriformis muscle, protecting it from posterior stretch forces.

Correct Answer & Explanation

. The peroneal division has larger fascicles and less supporting epineurial connective tissue, and is situated further laterally.

Explanation

The common peroneal division of the sciatic nerve is injured more frequently in posterior hip dislocations due to its anatomical and histological properties. It lies lateral to the tibial division (closer to the posteriorly displacing femoral head), is tethered between the sciatic notch and the fibular neck, and histologically contains larger fascicles with significantly less protective epineurial connective tissue compared to the tibial division.

Question 4027

Topic: Surgical Anatomy & Approaches

A 28-year-old male is involved in a motor vehicle collision, sustaining a posterior wall acetabular fracture and a posterior hip dislocation.

Following a successful closed reduction, he demonstrates profound weakness in ankle dorsiflexion but preserved plantarflexion. Which division of the sciatic nerve is most commonly injured in this clinical scenario?

. Tibial division
. Sural nerve
. Femoral nerve
. Peroneal division
. Obturator nerve

Correct Answer & Explanation

. Tibial division

Explanation

Sciatic nerve injury occurs in 10-20% of posterior hip dislocations and is particularly common when associated with posterior wall acetabular fractures. The peroneal division of the sciatic nerve is laterally positioned and tightly tethered at the sciatic notch and fibular head, making it significantly more susceptible to stretch injury than the medial tibial division.

Question 4028

Topic: Surgical Anatomy & Approaches
A 30-year-old man sustains a severe grade IIIA open midshaft humerus fracture resulting from a motorcycle crash. On initial presentation, he has an isolated radial nerve palsy. He is scheduled for urgent surgical debridement. What is the recommended management for the radial nerve during this procedure?
. Observe the nerve, perform standard irrigation and debridement with fracture fixation
. Perform prophylactic nerve grafting
. Perform immediate tendon transfers
. Primary exploration of the nerve during irrigation and debridement
. Delay surgical intervention for 3 weeks to allow nerve recovery

Correct Answer & Explanation

. Primary exploration of the nerve during irrigation and debridement

Explanation

While closed humeral shaft fractures with radial nerve palsy are managed non-operatively initially, an open humeral shaft fracture with a radial nerve palsy is an absolute indication for primary surgical exploration of the nerve at the time of initial irrigation, debridement, and fracture stabilization to evaluate for nerve laceration or entrapment.

Question 4029

Topic: Surgical Anatomy & Approaches

A 26-year-old unrestrained driver is involved in a motor vehicle collision. He presents with his right hip flexed, adducted, and internally rotated. Following closed reduction of the hip, he is unable to dorsiflex his right foot or extend his toes, but plantar flexion is symmetric to the contralateral side. Which of the following best explains the specific pattern of this neurological deficit?

. The tibial division of the sciatic nerve is positioned more laterally.
. The obturator nerve is primarily stretched over the anterior column.
. The common peroneal division consists of larger, less organized fascicles with less connective tissue.
. The common peroneal division is tethered strictly at the lesser sciatic notch.
. The femoral nerve is directly compressed by the displaced femoral head.

Correct Answer & Explanation

. The tibial division of the sciatic nerve is positioned more laterally.

Explanation

The common peroneal division of the sciatic nerve is more susceptible to injury in posterior hip dislocations because its fascicles are larger, fewer in number, and have less protective connective tissue compared to the tibial division.

Question 4030

Topic: Surgical Anatomy & Approaches

A 45-year-old man is undergoing open reduction and internal fixation of a posterior wall acetabular fracture via a Kocher-Langenbeck approach. What intraoperative leg position is most critical to minimize iatrogenic tension on the sciatic nerve?

. Hip extension and knee flexion
. Hip flexion and knee extension
. Hip flexion and knee flexion
. Hip extension and knee extension
. Neutral hip and knee extension

Correct Answer & Explanation

. Hip extension and knee flexion

Explanation

During the Kocher-Langenbeck approach, the sciatic nerve is at significant risk of iatrogenic stretch injury. Extending the hip and flexing the knee minimizes tension on the sciatic nerve.

Question 4031

Topic: Surgical Anatomy & Approaches

A 28-year-old male sustains a posterior hip dislocation. Following successful closed reduction, he is noted to have a dense foot drop and absent sensation over the dorsal aspect of his foot. Which anatomic characteristic makes the primarily involved nerve division most susceptible to this specific injury?

. Nutrient artery arising directly from the inferior gluteal artery
. Medial position within the sciatic sheath
. Larger size with more connective tissue relative to fascicular area
. Larger fascicles with less supportive perineurium and a lateral position
. Direct tethering to the posterior wall of the acetabulum

Correct Answer & Explanation

. Nutrient artery arising directly from the inferior gluteal artery

Explanation

The common peroneal division of the sciatic nerve is laterally positioned and has larger fascicles with less protective connective tissue (perineurium). This makes it highly susceptible to traction injury during a posterior hip dislocation.

Question 4032

Topic: Surgical Anatomy & Approaches

A 45-year-old man is involved in a motor vehicle collision, sustaining a posterior hip dislocation and a posterior wall acetabular fracture. Following closed reduction, he is unable to dorsiflex his ankle or extend his great toe, though plantar flexion remains intact. Which division of the affected nerve is most likely injured, and what is its typical relative prognosis?

. Peroneal division, poor prognosis compared to the tibial division
. Peroneal division, excellent prognosis compared to the tibial division
. Tibial division, poor prognosis compared to the peroneal division
. Tibial division, excellent prognosis compared to the peroneal division
. Complete sciatic nerve transection with an inevitably poor prognosis

Correct Answer & Explanation

. Peroneal division, poor prognosis compared to the tibial division

Explanation

Posterior hip dislocations most commonly injure the sciatic nerve, specifically the peroneal division due to its lateral position and secure tethering at the sciatic notch. The peroneal division has a significantly poorer prognosis for spontaneous recovery compared to the tibial division.

Question 4033

Topic: Surgical Anatomy & Approaches

A 40-year-old man sustains a Pipkin IV fracture-dislocation of the hip with an immediate, profound sciatic nerve palsy. He is reduced and placed in skeletal traction. A post-reduction CT scan clearly demonstrates a large posterior wall fragment directly impinging upon the sciatic nerve. What is the next best step in management?

. Observation and delayed EMG at 3 weeks
. Urgent surgical decompression of the nerve and ORIF of the posterior wall
. Administration of high-dose IV methylprednisolone
. Immediate total hip arthroplasty
. Application of a hip spica cast

Correct Answer & Explanation

. Observation and delayed EMG at 3 weeks

Explanation

While post-traumatic sciatic nerve palsies are often observed, documented direct mechanical compression of the nerve by a fracture fragment (such as a posterior wall segment) is an absolute indication for urgent surgical decompression and fracture fixation.

Question 4034

Topic: 1. General Principles & Basic Science
Which of the following is true regarding anterior sternoclavicular joint dislocations?
. Reduction may result in tracheal injury
. They are usually stable following closed reduction
. They require fusion to hold the reduction
. They are rarely symptomatic when left unreduced
. They should be treated acutely with medial clavicle excision

Correct Answer & Explanation

. They are rarely symptomatic when left unreduced

Explanation

From the Bicos article, โ€œAnterior SC joint instability should primarily be treated conservatively. The patients should be informed that there is a high risk of persistent instability with nonoperative or operative care, but that the persistent instability will be well tolerated and have little functional impact in the vast majority. Therefore, operative intervention for anterior SC joint instability is mainly cosmetic in nature.โ€

Question 4035

Topic: Biology, Genetics & Bone Healing
Which treatment of the current fracture will provide the best long-term outcome?
. Casting it in its current position, which is acceptable alignment
. Closed reduction and casting
. Functional brace because this is a stable fracture
. Open reduction with revision of the current implants

Correct Answer & Explanation

. Open reduction with revision of the current implants

Explanation

This fracture is in unacceptable alignment with subluxation of the radiocapitellar joint. The plates are bent, so closed reduction will not solve the alignment problem. In early childhood, load-sharing implants (flexible rods or wires) should be used to solve the elasticity mismatch that contributed to the current fracture.

Question 4036

Topic: Infection, Pharmacology & VTE

An adult patient has had low-grade fevers, malaise, and joint pain for the past several days. Examination reveals an erythematous "bulls eye" rash over the right thigh (erythema migrans). What is the organism associated with this infection? Review Topic

. Borrelia burgdorferi
. Bartonella henselae
. Nocardia
. Kingella kingae
. Brucella

Correct Answer & Explanation

. Borrelia burgdorferi

Explanation

Erythema migrans is typically found in patients with Lyme's disease, which is caused by Borrelia burgdorferi and is usually transmitted by ticks. Bartonella henselae is associated with cat-scratch fever. Kingella kingae can be a cause of pediatric osteomyelitis; whereas, Nocardia and Brucella cause mono-articular forms of septic arthritis in adults, and are not associated with erythema migrans.

Question 4037

Topic: 1. General Principles & Basic Science

A 45-year-old active male presents with medial compartment osteoarthritis of the knee and 8 degrees of varus alignment. A medial opening wedge high tibial osteotomy (HTO) is planned. To maintain the native posterior tibial slope during the osteotomy, the surgeon should:

. Make the anterior gap larger than the posterior gap
. Make the posterior gap larger than the anterior gap
. Open the anterior and posterior gaps equally
. Release the superficial medial collateral ligament completely
. Perform an associated tibial tubercle osteotomy

Correct Answer & Explanation

. Make the posterior gap larger than the anterior gap

Explanation

The proximal tibia has a triangular shape in the axial plane. To maintain the native posterior slope during a medial opening wedge HTO, the posterior gap must be opened approximately twice as much as the anterior gap. Opening them equally will inadvertently increase the posterior tibial slope.

Question 4038

Topic: Surgical Anatomy & Approaches

During a direct anterior approach for total hip arthroplasty, the superficial internervous plane utilized is between muscles innervated by which of the following nerves?

. Superior gluteal nerve and inferior gluteal nerve
. Superior gluteal nerve and femoral nerve
. Femoral nerve and obturator nerve
. Femoral nerve and sciatic nerve
. Superior gluteal nerve and sciatic nerve

Correct Answer & Explanation

. Superior gluteal nerve and femoral nerve

Explanation

The direct anterior approach (Smith-Petersen) utilizes the superficial internervous plane between the tensor fasciae latae (innervated by the superior gluteal nerve) and the sartorius (innervated by the femoral nerve).

Question 4039

Topic: 1. General Principles & Basic Science

During a medial opening wedge high tibial osteotomy (HTO), the surgeon inadvertently distracts the anterior aspect of the osteotomy gap significantly more than the posterior aspect. What biomechanical consequence will this have on the knee?

. Increased posterior tibial slope
. Decreased posterior tibial slope
. Increased varus malalignment
. External rotation of the tibial tubercle
. Decreased patellar height (patella baja)

Correct Answer & Explanation

. Increased posterior tibial slope

Explanation

Distracting the anterior aspect of the osteotomy greater than the posterior aspect in a medial opening wedge HTO increases the posterior tibial slope. To maintain normal slope, the anterior gap should generally be half the size of the posterior gap.

Question 4040

Topic: 1. General Principles & Basic Science

When correcting a complex multi-planar lower extremity deformity using a hexapod circular external fixator, what mathematically defines the origin from which all spatial corrections are generated by the software?

. The center of rotation of angulation (CORA)
. The reference ring
. The moving ring
. The apex of the diaphyseal bow
. The osteotomy site

Correct Answer & Explanation

. The reference ring

Explanation

In 6-axis spatial frame software, the reference ring (usually the proximal ring) defines the Cartesian coordinate system and serves as the mathematical origin for calculating strut lengths to reposition the moving ring.

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