Menu

1. General Principles & Basic Science MCQs

Practice Set 85 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 1681

Topic: 1. General Principles & Basic Science

A 48-year-old male undergoes a single-incision anterior repair for an acute distal biceps tendon rupture. During the procedure, the surgeon is meticulously dissecting through the subcutaneous tissue and fascia in the antecubital fossa.

. Posterior Interosseous Nerve (PIN)
. Median Nerve
. Radial Nerve (main trunk)
. Lateral Antebrachial Cutaneous Nerve (LACN)
. Ulnar Nerve

Correct Answer & Explanation

. Lateral Antebrachial Cutaneous Nerve (LACN)

Explanation

Correct Answer: DThe 'Surgical Anatomy & Biomechanics' section highlights key anatomical structures in close proximity and at risk during surgical approaches. It specifically states:"Lateral Antebrachial Cutaneous Nerve (LACN): A terminal branch of the musculocutaneous nerve, the LACN provides sensation to the radial forearm and typically pierces the deep fascia between the biceps and brachialis muscles. It lies superficially and is susceptible to injury during skin incision and subcutaneous dissection."The PIN, Median Nerve, and main trunk of the Radial Nerve are deeper structures, at risk during deeper dissection or tunnel drilling, but not typically during the initial skin incision and subcutaneous tissue dissection. The Ulnar nerve is located medially and posteriorly to the cubital fossa and is not typically at risk with an anterior approach to the distal biceps.

Question 1682

Topic: Surgical Anatomy & Approaches

During a single-incision anterior repair of a distal biceps tendon rupture, the surgeon has retrieved the retracted tendon and is preparing the radial tuberosity for fixation. The image below depicts a surgical field during such a procedure.

. Maintaining the elbow in full extension
. Placing a deep retractor medially to protect the brachial artery
. Keeping the forearm in full supination
. Placing the forearm in full pronation and using a deep retractor laterally
. Identifying and dissecting the PIN proximally to the supinator muscle

Correct Answer & Explanation

. Placing the forearm in full pronation and using a deep retractor laterally

Explanation

Correct Answer: DThe 'Surgical Approach & Technique' section, under 'Protection of the Radial Nerve (PIN)', explicitly states:"With the forearm in full pronation, the posterior interosseous nerve (PIN)... moves away from the surgical field, typically posterior to the radial tuberosity and deep to the supinator muscle. This maneuver increases the distance between the PIN and the radial tuberosity. A deep, blunt Hohmann or cobra retractor is placed beneath the brachioradialis and supinator, hugging the anterior surface of the radius, retracting the muscle belly laterally to expose the radial tuberosity. This retractor acts as a physical barrier, protecting the PIN from drilling and reaming."Maintaining full extension or supination would place the PIN at greater risk. While protecting the brachial artery is important, it is done with careful medial retraction, not specifically for PIN protection. Identifying and dissecting the PIN proximally is not the primary protective maneuver during tuberosity preparation.

Question 1683

Topic: 1. General Principles & Basic Science

A surgeon is discussing options for distal biceps tendon repair with a 40-year-old patient. The patient is concerned about potential complications, particularly heterotopic ossification (HO). Based on the literature review in the case, which statement regarding surgical approaches and HO risk is most accurate?

. The single-incision anterior approach carries a higher risk of HO compared to the two-incision approach.
. The two-incision (Boyes-O'Brien) approach is associated with a higher incidence of HO.
. Both single-incision and two-incision approaches have similar rates of HO.
. Prophylactic NSAIDs are only effective in preventing HO with the single-incision approach.
. HO is primarily a complication of suture anchor fixation, not the surgical approach.

Correct Answer & Explanation

. The two-incision (Boyes-O'Brien) approach is associated with a higher incidence of HO.

Explanation

Correct Answer: BThe 'Key Literature & Guidelines Summary' section explicitly addresses this comparison:"Two-Incision Approach (Boyes-O'Brien): Historically popular... However, it is associated with a higher incidence of heterotopic ossification (up to 20%), a major complication limiting range of motion."In contrast, for the single-incision approach, it states:"This approach has gained widespread acceptance due to lower rates of heterotopic ossification and comparable functional outcomes."Therefore, the two-incision approach has a higher incidence of HO. Prophylactic NSAIDs are used for HO prevention regardless of the approach, and HO is a known complication related to soft tissue dissection and hematoma, not primarily the fixation method.

Question 1684

Topic: 1. General Principles & Basic Science

During a calcaneonavicular coalition resection in a 10-year-old patient, the surgeon makes an Ollier-type incision. After elevating the extensor digitorum brevis (EDB) muscle and exposing the coalition, as shown in the image, the resection is performed. Which of the following is a critical step to prevent recurrence and a common error to avoid during this procedure?

. Ensuring the resection extends to the talar head medially; incomplete medial resection is a common error.
. Protecting the posterior tibial nerve; it is in close proximity to the lateral approach.
. Resecting less than 50% of the coalition to preserve joint stability.
. Interposing the flexor hallucis longus tendon into the defect.
. Performing the resection from posterior to anterior to avoid violating the posterior facet.

Correct Answer & Explanation

. Ensuring the resection extends to the talar head medially; incomplete medial resection is a common error.

Explanation

Correct Answer: AFor calcaneonavicular (CN) coalition resection, the case highlights that the resection must be generous, extending proximally to the normal anterior calcaneal wall, distally to the normal navicular surface, and crucially, medially to the talar head. It explicitly states, "A common error is incomplete medial resection." This incomplete resection is a significant factor in recurrence. Options B, D, and E describe considerations for a medial approach (posterior tibial nerve, FHL interposition, posterior facet protection), which is used for talocalcaneal coalitions, not CN. Option C is incorrect; a generous resection is required, and the 50% rule applies to talocalcaneal coalitions, not CN.

Question 1685

Topic: 1. General Principles & Basic Science

Which muscle is most commonly utilized for interposition grafting after resection of a symptomatic calcaneonavicular coalition to prevent recurrence?

. Flexor digitorum brevis
. Extensor digitorum brevis
. Abductor hallucis
. Peroneus brevis
. Tibialis anterior

Correct Answer & Explanation

. Extensor digitorum brevis

Explanation

Following resection of a calcaneonavicular coalition, the extensor digitorum brevis (EDB) muscle belly is frequently detached proximally and interposed into the defect to prevent re-ossification and recurrence.

Question 1686

Topic: Infection, Pharmacology & VTE

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

. Gouty arthritis
. Septic arthritis
. Osteomyelitis
. Charcot arthropathy
. Cellulitis

Correct Answer & Explanation

. Charcot arthropathy

Explanation

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

Question 1687

Topic: Infection, Pharmacology & VTE

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

. Oral antibiotics
. Intra-articular steroid injection
. NSAIDs and colchicine
. Surgical debridement
. Long-term allopurinol

Correct Answer & Explanation

. NSAIDs and colchicine

Explanation

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

Question 1688

Topic: Biomechanics & Biomaterials

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

. Stress relaxation
. Fatigue failure
. Creep
. Hysteresis
. Yield point

Correct Answer & Explanation

. Creep

Explanation

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

Question 1689

Topic: Biology, Genetics & Bone Healing

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

. Bone morphogenetic protein-2 (BMP-2)
. Transforming growth factor-beta (TGF-b)
. Platelet-derived growth factor (PDGF)
. Fibroblast growth factor (FGF)
. Vascular endothelial growth factor (VEGF)

Correct Answer & Explanation

. Transforming growth factor-beta (TGF-b)

Explanation

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

Question 1690

Topic: Infection, Pharmacology & VTE

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

. Vancomycin
. Cefazolin
. Rifampin
. Linezolid
. Daptomycin

Correct Answer & Explanation

. Rifampin

Explanation

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

Question 1691

Topic: Biology, Genetics & Bone Healing

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

. Endochondral ossification
. Intramembranous ossification
. Primary bone healing
. Secondary bone healing with callus formation
. Chondrogenesis

Correct Answer & Explanation

. Primary bone healing

Explanation

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

Question 1692

Topic: Biology, Genetics & Bone Healing

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

. Vascular Endothelial Growth Factor (VEGF)
. Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL)
. Human Epidermal Growth Factor Receptor 2 (HER2)
. Epidermal Growth Factor Receptor (EGFR)
. BRAF V600E

Correct Answer & Explanation

. Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL)

Explanation

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

Question 1693

Topic: 1. General Principles & Basic Science

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

. Superficial (tangential) zone
. Middle (transitional) zone
. Deep (radial) zone
. Calcified cartilage zone
. The tidemark

Correct Answer & Explanation

. Deep (radial) zone

Explanation

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

Question 1694

Topic: Biology, Genetics & Bone Healing

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

. Prophylactic intramedullary nailing
. Discontinuation of alendronate and observation
. Plate osteosynthesis
. Teriparatide therapy alone
. Non-weight bearing in a hip spica cast

Correct Answer & Explanation

. Prophylactic intramedullary nailing

Explanation

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

Question 1695

Topic: 1. General Principles & Basic Science

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

. Titanium and Cobalt-Chrome
. Stainless Steel and Titanium
. Ceramic and Titanium
. Cobalt-Chrome and Ceramic
. Tantalum and Titanium

Correct Answer & Explanation

. Stainless Steel and Titanium

Explanation

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

Question 1696

Topic: Biomechanics & Biomaterials

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

. Stress relaxation
. Creep
. Hysteresis
. Fatigue failure
. Toughness

Correct Answer & Explanation

. Creep

Explanation

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

Question 1697

Topic: 1. General Principles & Basic Science

A 56-year-old mason presents with acute swelling of his left knee after prolonged kneeling. He has a firm, non-tender prepatellar bursa without erythema. Which physical finding would be LEAST suggestive of septic bursitis if it were present?

. Fever >37.8°C
. Pre-bursal temperature difference greater than 2.2°C
. Pain with passive range of motion of the knee
. Overlying skin lesions
. Significant local erythema

Correct Answer & Explanation

. Pain with passive range of motion of the knee

Explanation

Correct Answer: CSeptic bursitis is an infection of the bursa, often presenting with signs of inflammation and systemic symptoms. Findings highly suggestive of septic bursitis include fever (>37.8°C), a significant temperature difference over the bursa compared to surrounding skin (>2.2°C), and overlying skin lesions (e.g., cellulitis, abrasions). Significant local erythema is also a classic sign of infection. Pain with passive range of motion of the knee, however, is more characteristic of an intra-articular process (e.g., arthritis, meniscal tear) rather than an isolated bursitis, whether septic or aseptic. Bursitis pain is typically worse with direct pressure or active motion involving the bursa.

Question 1698

Topic: Biology, Genetics & Bone Healing

A 17-year-old female runner presents with increased leg pain and is diagnosed with a stress fracture. Her physician is concerned about the female athlete triad. Which of the following is NOT considered one of the three core components of the female athlete triad?

. Amenorrhea
. Disordered eating
. Osteoporosis
. Abulia
. Low energy availability

Correct Answer & Explanation

. Low energy availability

Explanation

Correct Answer: DThe female athlete triad is a syndrome characterized by three interrelated components: 1) Low energy availability (with or without disordered eating), 2) Menstrual dysfunction (e.g., amenorrhea), and 3) Low bone mineral density (e.g., osteoporosis). Abulia refers to a lack of will or initiative and is a neurological or psychological symptom not directly part of the triad. Low energy availability is now recognized as the underlying cause that links disordered eating to menstrual dysfunction and low bone mineral density.

Question 1699

Topic: Infection, Pharmacology & VTE

Upon arrival at the emergency department, the patient with an acute flexor tendon laceration in Zone II received prophylactic intravenous antibiotics. Given the mechanism of injury (kitchen knife) and the location, which of the following antibiotic choices is most appropriate for initial empiric coverage?

. Vancomycin and Piperacillin-Tazobactam
. Ciprofloxacin and Metronidazole
. Cefazolin
. Clindamycin and Gentamicin
. Doxycycline

Correct Answer & Explanation

. Cefazolin

Explanation

Correct Answer: CFor acute penetrating injuries to the hand, particularly those involving flexor tendons, the primary concern for infection is typically skin flora, most commonlyStaphylococcus aureusandStreptococcusspecies. A first-generation cephalosporin, such as Cefazolin, provides excellent coverage against these common gram-positive organisms and is generally well-tolerated. The case specifically mentions the administration of a first-generation cephalosporin, aligning with standard practice for clean-contaminated wounds.Option A (Vancomycin and Piperacillin-Tazobactam) would be overly broad for an initial empiric choice in this scenario, typically reserved for more severe infections, immunocompromised patients, or those with specific risk factors for MRSA or polymicrobial infections (e.g., human/animal bites, farm injuries). Option B (Ciprofloxacin and Metronidazole) targets gram-negative and anaerobic bacteria, which are not the primary concern for a clean knife injury. Option D (Clindamycin and Gentamicin) is also a broad-spectrum combination, with gentamicin covering gram-negatives and clindamycin covering anaerobes and some gram-positives, but Cefazolin is simpler and usually sufficient. Option E (Doxycycline) is not a first-line empiric choice for acute penetrating hand injuries.

Question 1700

Topic: 1. General Principles & Basic Science

During the clinical examination, the patient demonstrated diminished sensation along the radial digital nerve distribution of the left middle finger, with a static two-point discrimination of 8 mm. Sensation along the ulnar digital nerve was intact (4 mm). What is the most appropriate management strategy for this radial digital nerve injury in the acute setting?

. Observation and serial neurological examinations, as partial injuries often recover spontaneously.
. Immediate surgical exploration and primary microsurgical repair during the same setting as tendon repair.
. Delayed nerve grafting at 6 months if no recovery is observed.
. Administration of high-dose corticosteroids to reduce nerve edema and promote healing.
. Referral for nerve conduction studies and electromyography (NCS/EMG) prior to any intervention.

Correct Answer & Explanation

. Immediate surgical exploration and primary microsurgical repair during the same setting as tendon repair.

Explanation

Correct Answer: BThe case explicitly states that the radial digital nerve was found to be approximately 80% transected during surgical exploration, confirming the clinical suspicion of a severe partial laceration. A two-point discrimination of 8 mm is abnormal and indicates a significant sensory deficit. In the setting of an open wound and a clear clinical deficit, a digital nerve laceration, whether partial or complete, warrants immediate surgical exploration and microsurgical repair. Performing this repair during the same surgical setting as the flexor tendon repair is the standard of care. This allows for primary repair, which generally yields the best outcomes, and avoids the complications of delayed repair such as nerve retraction and scar tissue formation.Option A is incorrect; while some very minor neuropraxic injuries might recover, a significant laceration (80% transection) will not spontaneously recover adequate function. Option C is incorrect; delayed nerve grafting is reserved for cases where primary repair is not possible due to significant nerve gap or chronic injury. Option D is incorrect; corticosteroids are not indicated for nerve lacerations. Option E is incorrect; NCS/EMG are typically used for chronic nerve compression or entrapment neuropathies, not for acute, open lacerations where the diagnosis is clinically evident and confirmed by exploration.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page