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1. General Principles & Basic Science MCQs

Practice Set 58 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 1141

Topic: 1. General Principles & Basic Science

C omplications post-replantation include:

. C old intolerance
. Stiffness
. Excessive laxity of the digit
. A and B only
. All of the above

Correct Answer & Explanation

. All of the above

Explanation

Complications after replantation include cold intolerance, which may improve over time, and stiffness of the replanted digit, which is generally due to immobility, tendon adhesions, and joint contracture.

Question 1142

Topic: 1. General Principles & Basic Science

Placing some tension on a flexor tendon repair increases the ultimate tensile strength of the repair.

. True
. False Tension on the repair site of a flexor tendon laceration has been shown experimentally to increase the tensile strength of the repair.

Correct Answer & Explanation

. True

Explanation

Question 1143

Topic: 1. General Principles & Basic Science

Flexor tendon nutrition is derived from:

. The vincula
. The pulleys
. Synovial diffusion
. All of the above
. A and C only

Correct Answer & Explanation

. A and C only

Explanation

Flexor tendon nutrition in the uninjured state is derived via the vincula, which contain blood vessels for nutrition. Injured tendons obtain nutrition via diffusion of synovial fluid. The pulley system does not contribute to flexor tendon nutrition.

Question 1144

Topic: Surgical Anatomy & Approaches

The radial nerve is at risk during a lateral approach to the distal humerus. At approximately what distance proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum to transition from the posterior to the anterior compartment?

. 5 cm
. 10 cm
. 15 cm
. 20 cm
. 25 cm

Correct Answer & Explanation

. 10 cm

Explanation

The radial nerve courses from posterior to anterior by piercing the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle. This anatomical landmark is critical when extending surgical exposures of the distal humerus.

Question 1145

Topic: Surgical Anatomy & Approaches

A 42-year-old male undergoes a single-incision anterior approach for the repair of an acute distal biceps tendon rupture. Postoperatively, he complains of numbness along the lateral aspect of his forearm. Which nerve was most likely injured?

. Posterior interosseous nerve
. Lateral antebrachial cutaneous nerve
. Superficial radial nerve
. Anterior interosseous nerve
. Musculocutaneous nerve proper

Correct Answer & Explanation

. Lateral antebrachial cutaneous nerve

Explanation

The lateral antebrachial cutaneous nerve (LABCN) is the terminal sensory branch of the musculocutaneous nerve. It exits the deep fascia lateral to the biceps tendon and is the most commonly injured nerve in an anterior single-incision distal biceps repair.

Question 1146

Topic: Surgical Anatomy & Approaches

During a posterior approach to the shoulder, the axillary nerve is visualized emerging through the quadrangular space. Which muscle forms the inferior border of this anatomical space?

. Teres minor
. Teres major
. Long head of the triceps
. Surgical neck of the humerus
. Subscapularis

Correct Answer & Explanation

. Teres minor

Explanation

The quadrangular space is bordered superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the surgical neck of the humerus. It transmits the axillary nerve and the posterior circumflex humeral artery.

Question 1147

Topic: Surgical Anatomy & Approaches

During hip arthroscopy, establishing the anteroinferior portal carries the highest risk of injury to which of the following neurological structures?

. Lateral femoral cutaneous nerve
. Femoral nerve
. Sciatic nerve
. Superior gluteal nerve
. Obturator nerve

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

The anteroinferior portal in hip arthroscopy places the lateral femoral cutaneous nerve (LFCN) at greatest risk. The nerve courses near the anterior superior iliac spine (ASIS) and can be easily injured if portal placement is poorly controlled.

Question 1148

Topic: Biomechanics & Biomaterials
Highly cross-linked ultra-high-molecular-weight polyethylene (UHMWPE) is widely used in total hip arthroplasty to reduce volumetric wear. Which step in its manufacturing process significantly reduces the risk of in vivo oxidation but comes at the cost of decreasing the ultimate tensile strength?
. Gamma irradiation in an inert gas
. Remelting above the melting temperature
. Sub-melting annealing
. Vitamin E doping
. Ethylene oxide sterilization

Correct Answer & Explanation

. Remelting above the melting temperature

Explanation

Remelting highly cross-linked polyethylene eliminates free radicals, thereby preventing long-term oxidation and structural degradation. However, this thermal process decreases crystallinity, which reduces the material's ultimate tensile and yield strength.

Question 1149

Topic: 1. General Principles & Basic Science

A patient presents with an inability to make an "OK" sign with their thumb and index finger following a forearm injury. Which of the following muscles is primarily innervated by the affected nerve?

. Flexor digitorum superficialis
. Flexor carpi radialis
. Pronator quadratus
. Abductor pollicis brevis
. Lumbricals to the index and long fingers

Correct Answer & Explanation

. Pronator quadratus

Explanation

The anterior interosseous nerve (AIN) innervates the flexor pollicis longus, the radial half of the flexor digitorum profundus, and the pronator quadratus. It is a pure motor nerve and does not provide cutaneous sensory innervation.

Question 1150

Topic: Biology, Genetics & Bone Healing

During secondary fracture healing, the cartilaginous soft callus is eventually replaced by hard woven bone. Which of the following transcription factors is most essential for the initial differentiation of multipotent mesenchymal stem cells into the osteoblastic lineage?

. Sox9
. Runx2 (Cbfa1)
. HIF-1 alpha
. RANKL
. Osteoprotegerin (OPG)

Correct Answer & Explanation

. Runx2 (Cbfa1)

Explanation

Runx2 (Cbfa1) is the master transcription factor responsible for committing mesenchymal stem cells to the osteoblast lineage. In contrast, Sox9 is the primary transcription factor driving chondrogenic differentiation during soft callus formation.

Question 1151

Topic: 1. General Principles & Basic Science

All of the following medications are indicated in the early treatment of frostbite injury except:

. Ibuprofen
. Tetanus booster
. Antibiotic prophylaxis
. Narcotic pain medications
. Intravenous beta blocker

Correct Answer & Explanation

. Intravenous beta blocker

Explanation

Peripheral beta-blockade has minimal effect on peripheral vasculature and is not typically used in patients with frostbite injury. Ibuprofen, tetanus booster, antibiotic prophylaxis, and appropriate pain medication are routinely used in the treatment of frostbite injuries.

Question 1152

Topic: Biology, Genetics & Bone Healing

Orthopedic sequelae of frostbite injury include all of the following except:

. Joint contractures
. Localized osteoporosis
. Decreased risk of future frostbite injury
. Punched-out subchondral bony lesions
. C old intolerance

Correct Answer & Explanation

. Decreased risk of future frostbite injury

Explanation

People who have had previous frostbite injuries are at increased risk of thermal injury, whether cold or heat related. Joint contractures, localized osteoporosis, punched-out subchondral bony lesions, and cold intolerance are often present after frostbite injury.

Question 1153

Topic: 1. General Principles & Basic Science

Initial treatment of an acute frostbite injury should include:

. Rapid rewarming in circulating 34° C to 36° C water
. Rapid rewarming in circulating 40° C to 42° C water
. Rapid rewarming in steam
. Slow rewarming with intermittent 50° C to 55° C water
. Slow rewarming in room air

Correct Answer & Explanation

. Rapid rewarming in circulating 40° C to 42° C water

Explanation

Rapid rewarming in a 40° C to 42° C circulating water bath is the most effective early treatment of frostbite injury. Slow or fast rewarming in other temperatures and/or rewarming in air is not indicated.

Question 1154

Topic: 1. General Principles & Basic Science

All of the following except _ increase the risk of frostbite injury.

. Altitude higher than 17,000 feet
. History of smoking
. Increased humidity
. Prolonged exposure
. Peripheral vascular disease

Correct Answer & Explanation

. Increased humidity

Explanation

High altitudes, prolonged exposure, and anything that would cause peripheral vasoconstriction increase the risk of frostbite injury. Humidity does not play a significant role in the development of frostbite injury.

Question 1155

Topic: Surgical Anatomy & Approaches

What is the most common site of posterior interosseous nerve entrapment:

. The arcade of Frohse
. The flexor retinaculum
. The first cervical rib
. In the spiral groove of the humerus
. Ligament of Struthers

Correct Answer & Explanation

. The arcade of Frohse

Explanation

The most common site of posterior interosseous nerve entrapment is at the arcade of Frohse, which is a fibrotendinous ring found within the fibers of the supinator muscle as the posterior interosseous nerve originates from the radial nerve.

Question 1156

Topic: 1. General Principles & Basic Science

Which of the following muscles is innervated by the posterior interosseous nerve:

. Extensor carpi ulnaris
. Extensor digiti minimi
. Extensor pollicis brevis and longus
. Abductor pollicis longus
. All of the above

Correct Answer & Explanation

. All of the above

Explanation

The posterior interosseous nerve innervates a number of muscles involved primarily in finger extension, including the extensor carpi ulnaris, extensor digitorum, extensor digiti minimi, extensor pollicis brevis and longus, abductor pollicis longus, and extensor indices.

Question 1157

Topic: 1. General Principles & Basic Science
The use of clostridial collagenase for Dupuytren's contracture is performed by:
. Injecting collagenase into the affected joint
. Injecting collagenase into the Dupuytren's cord
. Performing a subcutaneous wheal injection of collagenase
. Using a patch of collagenase on the skin
. Applying collagenase to the Dupuytren's cords during surgery

Correct Answer & Explanation

. Injecting collagenase into the Dupuytren's cord

Explanation

Clostridial collagenase works by breaking the collagen connections. The Dupuytren's cord is ruptured manually; surgery is not necessary.

Question 1158

Topic: Physiology & Rehabilitation

A 33-year-old woman with a history of a traumatic fall onto her wrist and tenderness over the scapholunate (SL) interval presents to the clinic. Radiographs are normal, and magnetic resonance imaging reveals a partial tear of the SL ligament. The remaining wrist ligaments are normal. If conservative therapy is attempted, then it should consist of:

. Short arm casting for 2 months
. Activity modification and wrist extension stretching
. Splinting and flexor carpi radialis training
. Splinting and flexor carpi ulnaris training
. C orticosteroid injection into the midcarpal space

Correct Answer & Explanation

. Splinting and flexor carpi radialis training

Explanation

Conservative management includes a period of splinting and activity modification, followed by proprioception training of the flexor carpi radialis to act as a dynamic scaphoid stabilizer.

Question 1159

Topic: 1. General Principles & Basic Science

Ultrasound therapy delivers superficial heat to the tissue and has a penetration depth of 5 mm.

. True
. False Ultrasound is considered a deep heat modality and does not heat the superficial tissues.

Correct Answer & Explanation

. True

Explanation

Question 1160

Topic: 1. General Principles & Basic Science
Thermal ultrasound is used for all of the following purposes EXCEPT:
. Increasing capsular extensibility
. Decreasing scar
. Increasing pain threshold
. Reversing Dupuytren's contracture
. Increasing ligament stretch ability

Correct Answer & Explanation

. Increasing capsular extensibility

Explanation

Thermal uses of ultrasound include increasing pain threshold, decreasing scar, and improving extensibility of the ligaments and joint capsule. Ultrasound has not been shown to have an effect in reversing Dupuytren's contracture.

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