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1. General Principles & Basic Science MCQs

Practice Set 106 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 2101

Topic: Surgical Anatomy & Approaches

Following a complex nail bed repair and distal phalanx fracture stabilization, the surgeon decides to use a splint to maintain the patency of the eponychial fold and provide a scaffold for new nail growth. If the original nail plate is too damaged, which of the following is the most appropriate alternative material and duration for this splint?

. Xeroform gauze, removed at 1 week.
. Silicone sheeting, removed at 3-4 weeks.
. Absorbable gelatin sponge, left to resorb.
. Cotton pledget, removed at 2 weeks.
. Surgical glue, no removal needed.

Correct Answer & Explanation

. Silicone sheeting, removed at 3-4 weeks.

Explanation

Correct Answer: BUnder theDetailed Surgical Approach and Techniquesection, in theNail Plate Replacement or Splintingsubsection, it states: 'If the original nail plate is too damaged or contaminated, a non-adherent material (e.g., silicone sheeting, aluminum foil cut to shape, Xeroform gauze) can be used as a stent. It is similarly tucked into the eponychial fold and secured. This alternative splint should remain in place for 3-4 weeks.'Incorrect Options:A. Xeroform gauze, removed at 1 week:While Xeroform gauze is listed as a possible material, 1 week is too short a duration to effectively maintain the eponychial fold patency and prevent synechiae.C. Absorbable gelatin sponge, left to resorb:This material is not typically used as a structural splint to maintain the eponychial fold.D. Cotton pledget, removed at 2 weeks:A cotton pledget is not ideal for maintaining the eponychial fold and 2 weeks is likely too short.E. Surgical glue, no removal needed:Surgical glue is not used as a splint to maintain the eponychial fold; it's for skin approximation.

Question 2102

Topic: 1. General Principles & Basic Science

A 45-year-old patient, 1 year post-nail unit repair for a severe crush injury, presents with a persistent, symptomatic split nail (onychoschisis). Despite initial meticulous repair, this complication has significantly impacted their quality of life. According to the case, what is the most appropriate salvage strategy for this specific complication?

. Observation and reassurance, as it often resolves spontaneously.
. Regular trimming of the non-adherent portion of the nail.
. Surgical exploration, excision of scar tissue, meticulous primary repair of the nail bed defect, potentially with local advancement flaps or free matrix grafts.
. Application of topical corticosteroids to reduce inflammation.
. Complete matricectomy with skin grafting as a first-line approach.

Correct Answer & Explanation

. Surgical exploration, excision of scar tissue, meticulous primary repair of the nail bed defect, potentially with local advancement flaps or free matrix grafts.

Explanation

Correct Answer: CUnder theComplications and Managementsection, in the table forCommon Complications and Salvage Strategies, for 'Split Nail (Onychoschisis)', the salvage strategy is described as: 'Excision of scar tissue causing the split, meticulous primary repair of the nail bed defect (with local advancement flaps or free matrix grafts if needed), and sometimes permanent nail ablation (matricectomy) if recurrent and symptomatic.' Option C provides the most comprehensive and appropriate surgical salvage strategy before considering permanent ablation.Incorrect Options:A. Observation and reassurance, as it often resolves spontaneously:While some minor issues may resolve, a persistent, symptomatic split nail 1 year post-injury is unlikely to resolve spontaneously and requires intervention.B. Regular trimming of the non-adherent portion of the nail:This is a management strategy for non-adherence/onycholyis, not a definitive salvage for a split nail caused by a scar.D. Application of topical corticosteroids to reduce inflammation:This might be used for inflammatory conditions but will not correct a structural split nail caused by scar tissue.E. Complete matricectomy with skin grafting as a first-line approach:While matricectomy is an option for recurrent and symptomatic cases, it is typically considered after attempts at reconstructive repair have failed, making it a last resort rather than a first-line approach.

Question 2103

Topic: Physiology & Rehabilitation

Beyond protection, the nail unit serves crucial biomechanical roles. Which of the following best describes a primary biomechanical function of the nail plate in conjunction with the fingertip pulp?

. Facilitating thermoregulation of the digit.
. Acting as a counterforce for the pulp, essential for precision pinch and grip.
. Producing synovial fluid for the distal interphalangeal joint.
. Anchoring the flexor digitorum profundus tendon.
. Enhancing proprioception through specialized mechanoreceptors.

Correct Answer & Explanation

. Acting as a counterforce for the pulp, essential for precision pinch and grip.

Explanation

Correct Answer: BUnder theSurgical Anatomy and Biomechanicssection, in theBiomechanical Considerationssubsection, it states: 'The rigid nail plate provides dorsal support, acting as a counterforce to the tactile pulp, which is essential for precision pinch, grip, and fine motor manipulation.'Incorrect Options:A. Facilitating thermoregulation of the digit:While the digit has vascularity for thermoregulation, this is not a primary biomechanical function of the nail plate itself.C. Producing synovial fluid for the distal interphalangeal joint:Synovial fluid is produced by the synovial membrane lining the joint capsule, not the nail unit.D. Anchoring the flexor digitorum profundus tendon:The flexor digitorum profundus tendon inserts into the volar base of the distal phalanx, not the nail unit.E. Enhancing proprioception through specialized mechanoreceptors:While the fingertip is highly innervated and sensitive, the primary biomechanical role described for the nail plate is as a counterforce, not primarily proprioception enhancement.

Question 2104

Topic: Surgical Anatomy & Approaches
A 3-year-old patient undergoes reconstruction for a Blauth Type IIIA hypoplastic thumb. The procedure includes a comprehensive web space deepening, CMC joint stabilization, and an FDS ring finger tendon transfer for opposition. The image shows the thumb positioned during the critical step of tensioning the tendon transfer. What is the primary reason for positioning the thumb in full abduction, full flexion, and full pronation during this step?
. To prevent post-operative stiffness of the interphalangeal joint.
. To ensure adequate blood supply to the transferred tendon.
. To achieve the pronation component of opposition and optimize the mechanical advantage of the transfer.
. To facilitate easier skin closure of the web space.
. To minimize tension on the CMC joint capsulodesis.

Correct Answer & Explanation

. To achieve the pronation component of opposition and optimize the mechanical advantage of the transfer.

Explanation

To achieve the pronation component of opposition, the thumb should be positioned in full abduction, full flexion, and full pronation during tensioning. This is a critical step in restoring thumb function, ensuring that the transferred tendon is tensioned to provide all three components of opposition effectively.

Question 2105

Topic: 1. General Principles & Basic Science
During an index finger pollicization for Blauth Type IIIB thumb hypoplasia, the extrinsic and intrinsic muscles of the index finger are reassigned to replicate thumb function. The first dorsal interosseous muscle is typically transferred to function as which of the following?
. Abductor pollicis brevis
. Adductor pollicis
. Flexor pollicis brevis
. Opponens pollicis
. Abductor pollicis longus

Correct Answer & Explanation

. Abductor pollicis brevis

Explanation

In Buck-Gramcko's pollicization technique, the first dorsal interosseous (which normally abducts the index finger) is attached to the radial lateral band to function as the abductor pollicis brevis. The first volar interosseous is transferred to function as the adductor pollicis.

Question 2106

Topic: 1. General Principles & Basic Science

A 24-year-old machinist sustains an avulsion injury to the thumb nail unit, resulting in a 60% loss of the sterile matrix. The germinal matrix is intact. Bone is completely covered by a thin layer of healthy tissue. What is the most appropriate source for reconstruction of this defect?

. Full-thickness germinal matrix graft from the great toe
. Split-thickness sterile matrix graft from the great toe
. Split-thickness skin graft from the hypothenar eminence
. Reverse cross-finger flap
. Volar advancement flap (Moberg)

Correct Answer & Explanation

. Split-thickness sterile matrix graft from the great toe

Explanation

For a sterile matrix defect lacking sufficient adjacent tissue but with an intact vascular bed, a split-thickness sterile matrix graft is the gold standard. The great toe is the preferred donor site, as it provides a large area of sterile matrix with minimal morbidity.

Question 2107

Topic: 1. General Principles & Basic Science

During a Buck-Gramcko pollicization of the index finger, careful mobilization of the neurovascular bundles is required. To allow adequate mobilization and rotation of the index finger, which vascular structure is typically ligated?

. Radial proper digital artery of the index finger
. Ulnar proper digital artery of the index finger
. Proper digital artery to the radial side of the long finger
. Proper digital artery to the ulnar side of the long finger
. Princeps pollicis artery

Correct Answer & Explanation

. Proper digital artery to the radial side of the long finger

Explanation

To fully mobilize the index finger on its neurovascular pedicles, the common digital artery to the second web space must be separated. This requires ligating the proper digital artery to the radial side of the long finger, keeping the vascular supply to the index finger intact.

Question 2108

Topic: 1. General Principles & Basic Science

During a Buck-Gramcko index finger pollicization for Blauth Type IV thumb hypoplasia, the first dorsal interosseous (FDI) muscle of the index finger is typically transferred to function as which thumb muscle?

. Adductor pollicis
. Abductor pollicis brevis
. Opponens pollicis
. Extensor pollicis longus
. Flexor pollicis longus

Correct Answer & Explanation

. Adductor pollicis

Explanation

In the Buck-Gramcko pollicization, the first dorsal interosseous (FDI) is transferred to act as the abductor pollicis brevis (APB). The first palmar interosseous acts as the adductor pollicis.

Question 2109

Topic: 1. General Principles & Basic Science

Which of the following statements best describes the primary function of the sterile matrix in the human nail unit?

. It produces 90% of the nail plate volume and thickness.
. It generates the eponychial fold.
. It is responsible for the firm adherence of the nail plate to the nail bed.
. It forms the opaque, crescent-shaped lunula.
. It synthesizes the paronychium.

Correct Answer & Explanation

. It is responsible for the firm adherence of the nail plate to the nail bed.

Explanation

The primary function of the sterile matrix is to provide adherence of the nail plate to the nail bed. The germinal matrix is responsible for producing the vast majority (90%) of the nail plate volume.

Question 2110

Topic: 1. General Principles & Basic Science

In the Buck-Gramcko index finger pollicization technique, the transferred digit is fixed in approximately what degree of palmar abduction and pronation to optimize functional thumb opposition?

. 90 degrees palmar abduction and 90 degrees pronation
. 40 degrees palmar abduction and 120 degrees pronation
. 20 degrees palmar abduction and 45 degrees pronation
. 0 degrees palmar abduction and 180 degrees pronation
. 60 degrees palmar abduction and 60 degrees pronation

Correct Answer & Explanation

. 40 degrees palmar abduction and 120 degrees pronation

Explanation

Proper positioning is critical in pollicization. The new thumb should be placed in approximately 40 degrees of palmar abduction and 100 to 120 degrees of pronation to replicate the natural resting posture of the thumb.

Question 2111

Topic: 1. General Principles & Basic Science

A patient presents with an infection localizing to the junction of the distal nail bed and the fingertip skin. This specific anatomic area, which normally acts as a waterproof barrier preventing pathogens from entering the subungual space, is known as the:

. Eponychium
. Lunula
. Hyponychium
. Germinal matrix
. Paronychium

Correct Answer & Explanation

. Hyponychium

Explanation

The hyponychium is the junction between the distal nail bed and the fingertip epidermis. It forms a highly specialized keratinous plug that functions as a waterproof, mechanical barrier to infection.

Question 2112

Topic: 1. General Principles & Basic Science

During reconstruction of a Blauth Type II thumb hypoplasia, an opponensplasty (Huber transfer) is planned to restore opposition and thenar bulk. Which of the following muscles is transferred in this specific procedure?

. Extensor indicis proprius (EIP)
. Flexor digitorum superficialis (FDS) of the ring finger
. Abductor digiti minimi (ADM)
. Flexor carpi radialis (FCR)
. Palmaris longus

Correct Answer & Explanation

. Abductor digiti minimi (ADM)

Explanation

The Huber transfer utilizes the abductor digiti minimi (ADM) muscle. It is particularly advantageous in thumb hypoplasia reconstruction because it restores opposition while simultaneously providing bulk to the hypoplastic thenar eminence.

Question 2113

Topic: Biology, Genetics & Bone Healing

A 30-year-old female presents with a lytic, epiphyseal lesion of the proximal tibia extending to the subchondral bone. Biopsy confirms a Giant Cell Tumor. Prior to joint-sparing curettage, she is given a medication that targets the RANKL pathway. What is the mechanism of this drug?

. Inhibits osteoblast apoptosis
. Monoclonal antibody against RANKL preventing osteoclast activation
. Directly induces apoptosis of the neoplastic mononuclear cells
. Bisphosphonate that inhibits osteoclast ruffled border formation
. Antagonist of the Wnt/beta-catenin pathway

Correct Answer & Explanation

. Monoclonal antibody against RANKL preventing osteoclast activation

Explanation

Denosumab is a monoclonal antibody that binds to RANKL, preventing it from binding to the RANK receptor on osteoclasts and their precursors. In Giant Cell Tumors, this reduces osteoclast-mediated bone destruction and helps ossify the tumor margins to facilitate curettage.

Question 2114

Topic: Biology, Genetics & Bone Healing

A 28-year-old female presents with knee pain. Radiographs show an eccentric, lytic epiphyseal lesion in the proximal tibia. Biopsy reveals mononuclear cells and multinucleated giant cells. Which of the following describes the mechanism of action of the targeted biologic therapy commonly used for this condition?

. Inhibits vascular endothelial growth factor (VEGF)
. Binds to and inhibits RANK ligand (RANKL)
. Blocks the mammalian target of rapamycin (mTOR)
. Acts as an antagonist to the estrogen receptor
. Inhibits platelet-derived growth factor receptor (PDGFR)

Correct Answer & Explanation

. Binds to and inhibits RANK ligand (RANKL)

Explanation

Denosumab is a monoclonal antibody that binds to RANKL, preventing the activation of osteoclast-like giant cells by the neoplastic mononuclear stromal cells in Giant Cell Tumor of Bone. This leads to tumor necrosis and woven bone formation.

Question 2115

Topic: Surgical Anatomy & Approaches

What is the most common serious complication following posterior hip dislocation, even after successful reduction?

. Sciatic nerve injury.
. Avascular necrosis of the femoral head.
. Post-traumatic osteoarthritis.
. Heterotopic ossification.
. Recurrent dislocation.

Correct Answer & Explanation

. Avascular necrosis of the femoral head.

Explanation

Correct Answer: BAvascular necrosis (AVN) of the femoral head is the most common serious long-term complication following posterior hip dislocation, with incidence increasing with prolonged dislocation time. Sciatic nerve injury is common acutely but usually resolves partially or completely. Post-traumatic osteoarthritis is also a long-term sequela but AVN is more directly linked to the initial insult. Heterotopic ossification can occur but is less common and less debilitating than AVN or severe osteoarthritis. Recurrent dislocation is rare after a single, well-reduced dislocation without associated bony injury.

Question 2116

Topic: Biology, Genetics & Bone Healing

A 32-year-old female presents with knee pain. Radiographs show an eccentric, lytic epiphyseal lesion in the distal femur without a sclerotic rim. Biopsy confirms a Giant Cell Tumor of bone. If medical therapy is considered, denosumab acts by directly inhibiting which of the following?

. Osteoprotegerin (OPG)
. Receptor activator of nuclear factor kappa-B (RANK)
. Receptor activator of nuclear factor kappa-B ligand (RANKL)
. Vascular endothelial growth factor (VEGF)
. Tumor necrosis factor alpha (TNF-alpha)

Correct Answer & Explanation

. Receptor activator of nuclear factor kappa-B ligand (RANKL)

Explanation

Denosumab is a monoclonal antibody that binds to RANKL, preventing it from interacting with RANK on the surface of osteoclasts and osteoclast precursors. This inhibits the recruitment and activation of the multinucleated giant cells characteristic of this tumor.

Question 2117

Topic: 1. General Principles & Basic Science

During open reduction and internal fixation of a high-energy tibial plateau fracture with a posteromedial fragment, the surgeon decides to use a direct posteromedial approach. To safely expose the bone, the deep dissection utilizes an internervous plane between which of the following two structures?

. Semimembranosus and medial head of the gastrocnemius
. Pes anserinus and medial head of the gastrocnemius
. Popliteus and soleus
. Tibialis posterior and flexor digitorum longus
. Iliotibial band and biceps femoris

Correct Answer & Explanation

. Pes anserinus and medial head of the gastrocnemius

Explanation

The posteromedial approach to the tibial plateau classically utilizes the internervous plane between the pes anserinus (supplied by the femoral nerve) anteriorly and the medial head of the gastrocnemius (supplied by the tibial nerve) posteriorly. Retracting the gastrocnemius laterally protects the popliteal neurovascular bundle.

Question 2118

Topic: Infection, Pharmacology & VTE

A 15-year-old non-ambulatory patient with Duchenne Muscular Dystrophy is recovering from a posterior spinal fusion. On postoperative day 2, the patient develops increasing shortness of breath, decreased oxygen saturation, and a weak cough. Which of the following is the most likely early postoperative complication in this patient, and what is the immediate management strategy?

. Deep Vein Thrombosis (DVT); Initiate immediate systemic anticoagulation.
. Wound infection; Administer broad-spectrum antibiotics and consider wound debridement.
. Respiratory insufficiency/failure; Prolonged mechanical ventilation and aggressive pulmonary hygiene.
. Cardiac decompensation; Optimize cardiac medications and transfer to ICU.
. Pseudarthrosis; Plan for revision surgery with additional bone graft.

Correct Answer & Explanation

. Respiratory insufficiency/failure; Prolonged mechanical ventilation and aggressive pulmonary hygiene.

Explanation

Correct Answer: CThe case identifies respiratory insufficiency/failure as a moderate-to-high incidence early postoperative complication in DMD patients, especially after major surgery like spinal fusion. Symptoms like increasing shortness of breath, decreased oxygen saturation, and a weak cough are classic signs. The recommended management strategy includes prolonged mechanical ventilation (invasive/non-invasive), aggressive pulmonary hygiene, early mobilization, and respiratory consult.Option A (Deep Vein Thrombosis (DVT); Initiate immediate systemic anticoagulation):DVT is a possible complication, but the symptoms described (shortness of breath, decreased O2 sat, weak cough) are more indicative of primary respiratory compromise rather than a DVT/PE as the initial event. While DVT prophylaxis is important, this is not the most likely immediate cause of these specific symptoms.Option B (Wound infection; Administer broad-spectrum antibiotics and consider wound debridement):Wound infection is a possibility, but it typically presents with local signs (redness, warmth, drainage, fever) and usually manifests a few days later. The described symptoms are not typical for an early wound infection.Option D (Cardiac decompensation; Optimize cardiac medications and transfer to ICU):Cardiac decompensation is a risk, but the symptoms (shortness of breath, decreased O2 sat, weak cough) are more directly related to pulmonary mechanics and respiratory muscle weakness, which are profoundly affected in DMD, especially post-spinal surgery. While cardiac monitoring is crucial, respiratory issues are often the more immediate and direct concern in this scenario.Option E (Pseudarthrosis; Plan for revision surgery with additional bone graft):Pseudarthrosis (non-union) is a late postoperative complication, occurring months to years after surgery, not on postoperative day 2.

Question 2119

Topic: Physiology & Rehabilitation

A 5-year-old boy presents with calf pseudohypertrophy and proximal muscle weakness. Genetic testing confirms a mutation in the dystrophin gene. Which of the following best describes the inheritance pattern and the normal cellular function of the affected protein?

. Autosomal dominant; anchors actin to the sarcolemma
. X-linked recessive; anchors actin to the extracellular matrix via the dystroglycan complex
. Autosomal recessive; regulates calcium release from the sarcoplasmic reticulum
. X-linked dominant; forms gap junctions between myofibrils
. X-linked recessive; facilitates ATP binding during muscle contraction

Correct Answer & Explanation

. X-linked recessive; anchors actin to the extracellular matrix via the dystroglycan complex

Explanation

Duchenne Muscular Dystrophy is inherited in an X-linked recessive pattern. Dystrophin connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix through the cell membrane.

Question 2120

Topic: Physiology & Rehabilitation

Duchenne Muscular Dystrophy (DMD) is caused by an X-linked recessive mutation that leads to the absence of dystrophin. At the cellular level, what is the primary structural role of the dystrophin protein in healthy skeletal muscle?

. It acts as a voltage-gated calcium channel in the sarcoplasmic reticulum.
. It directly binds myosin heads to the actin filaments during contraction.
. It links the intracellular actin cytoskeleton to the extracellular matrix via the dystroglycan complex.
. It provides the structural framework for the Z-disc of the sarcomere.
. It regulates ATP hydrolysis within the mitochondria of type I muscle fibers.

Correct Answer & Explanation

. It links the intracellular actin cytoskeleton to the extracellular matrix via the dystroglycan complex.

Explanation

Dystrophin is a critical structural protein that stabilizes the sarcolemma by linking the intracellular actin cytoskeleton to the extracellular matrix through the dystrophin-associated glycoprotein complex. Its absence leads to membrane fragility, calcium influx, and eventual muscle necrosis.

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