Menu

1. General Principles & Basic Science MCQs

Practice Set 523 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 10441

Topic: Infection, Pharmacology & VTE

A 60-year-old male presents with sudden, excruciating pain in his left knee, accompanied by erythema, swelling, and warmth. He has a history of hypertension and hyperuricemia but has never had a prior attack like this. Aspiration of the knee joint reveals negatively birefringent needle-shaped crystals under polarized light microscopy. What is the most appropriate acute management?

. Intra-articular corticosteroid injection.
. Systemic antibiotics.
. NSAIDs, colchicine, or systemic corticosteroids.
. Joint lavage and debridement.
. Allopurinol.

Correct Answer & Explanation

. NSAIDs, colchicine, or systemic corticosteroids.

Explanation

The clinical presentation (acute, excruciating monoarticular arthritis with erythema, swelling, warmth) and the finding of negatively birefringent needle-shaped crystals on joint fluid analysis are diagnostic of acute gouty arthritis. The most appropriate acute management involves NSAIDs (e.g., indomethacin), colchicine, or systemic corticosteroids. Intra-articular corticosteroid injection is an alternative for monoarticular attacks if systemic agents are contraindicated or ineffective. Systemic antibiotics are for septic arthritis (which is in the differential but ruled out by crystal analysis and lack of bacteria). Joint lavage and debridement are for septic arthritis. Allopurinol is a uric acid-lowering therapy used for long-term prevention of gout attacks, not for acute attack management (and can sometimes worsen acute attacks if initiated during one).

Question 10442

Topic: Biology, Genetics & Bone Healing

What is the primary mechanism of action of bone morphogenetic proteins (BMPs) in promoting fracture healing?

. Inhibition of osteoclast activity.
. Stimulation of osteoblast apoptosis.
. Induction of mesenchymal stem cell differentiation into osteoblasts and chondroblasts.
. Enhancement of vascular permeability at the fracture site.
. Direct structural bridging of fracture gaps.

Correct Answer & Explanation

. Induction of mesenchymal stem cell differentiation into osteoblasts and chondroblasts.

Explanation

Bone morphogenetic proteins (BMPs) are powerful osteoinductive proteins. Their primary mechanism of action in promoting fracture healing is the induction of mesenchymal stem cells (MSCs) to differentiate into osteoblasts (bone-forming cells) and chondroblasts (cartilage-forming cells), thereby initiating and accelerating the bone repair process. They also recruit undifferentiated mesenchymal cells to the site. BMPs do not primarily inhibit osteoclast activity, stimulate osteoblast apoptosis, enhance vascular permeability, or directly structurally bridge fracture gaps; rather, they stimulate the biological cascade that leads to new bone formation.

Question 10443

Topic: Infection, Pharmacology & VTE

Which organism is the most common causative agent of acute hematogenous osteomyelitis in healthy children?

. Pseudomonas aeruginosa.
. Staphylococcus aureus.
. Streptococcus pyogenes.
. Kingella kingae.
. Escherichia coli.

Correct Answer & Explanation

. Staphylococcus aureus.

Explanation

Staphylococcus aureus is by far the most common causative organism of acute hematogenous osteomyelitis in healthy children across all age groups. While other organisms can cause osteomyelitis (e.g., Kingella kingae in infants/toddlers, Pseudomonas in puncture wounds through athletic shoes, E. coli in neonates or immunocompromised), S. aureus remains predominant in the general pediatric population.

Question 10444

Topic: Biology, Genetics & Bone Healing
Which of the following growth factors is most commonly used in clinical practice to enhance bone healing, particularly in non-union scenarios?
. Fibroblast Growth Factor (FGF).
. Vascular Endothelial Growth Factor (VEGF).
. Transforming Growth Factor-beta (TGF-ฮฒ).
. Bone Morphogenetic Protein-2 (BMP-2).
. Insulin-like Growth Factor-1 (IGF-1).

Correct Answer & Explanation

. Bone Morphogenetic Protein-2 (BMP-2).

Explanation

Bone Morphogenetic Protein-2 (BMP-2), often delivered in a collagen sponge (e.g., Infuse Bone Graft), is currently the most commonly used growth factor in clinical orthopedic practice to enhance bone healing, particularly in treating recalcitrant non-unions, open tibial fractures, and lumbar spinal fusions. BMPs are potent osteoinductive agents. While other growth factors like FGF, VEGF, TGF-ฮฒ, and IGF-1 play roles in bone healing, they are not as widely used or approved for direct clinical application as an osteoinductive agent for fracture healing/fusion augmentation as BMP-2 (and BMP-7).

Question 10445

Topic: Infection, Pharmacology & VTE

A 4-year-old child presents with a limp, fever, and refusal to bear weight on the left leg. On examination, the left hip is held in flexion, abduction, and external rotation. Passive range of motion is severely painful, especially internal rotation. Blood tests show a WBC count of 75,000 cells/ยตL, 90% neutrophils, and positive Gram stain for Gram-positive cocci in clusters. What is the most appropriate management?

. Immediate intravenous antibiotics and observation.
. Aspiration, culture, and non-weight bearing.
. Urgent surgical irrigation and debridement of the knee.
. Intra-articular corticosteroid injection.
. Arthroscopy with synovectomy.

Correct Answer & Explanation

. Urgent surgical irrigation and debridement of the knee.

Explanation

This is a clear case of septic arthritis of the knee, an orthopedic emergency in children. The presentation (limp, fever, swollen/warm/painful joint), and particularly the synovial fluid analysis (high WBC count, high neutrophils, positive Gram stain) confirms the diagnosis. Urgent surgical irrigation and debridement (arthrotomy or arthroscopy) of the knee is the most appropriate management to remove purulent material, reduce bacterial load, and prevent cartilage destruction. This should be combined with intravenous antibiotics. While aspiration is part of diagnosis, surgical washout is definitive for septic arthritis of a large joint. Immediate IV antibiotics alone without surgical debridement are insufficient to treat severe septic arthritis. Corticosteroid injection is contraindicated. Synovectomy is not the primary goal; debridement and irrigation are.

Question 10446

Topic: Surgical Anatomy & Approaches

Which nerve is most at risk of injury during surgical exposure of the anterior column of the acetabulum through an ilioinguinal approach?

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

Correct Answer & Explanation

. Femoral nerve.

Explanation

During an ilioinguinal approach for anterior column acetabular fractures, the femoral nerve is most at risk of injury. It lies within the middle window of the ilioinguinal approach, deep to the iliopsoas muscle and lateral to the femoral artery. The sciatic nerve is posterior. The obturator nerve is more medial within the pelvis. The lateral femoral cutaneous nerve is also at risk, but femoral nerve injury can be more devastating. The superior gluteal nerve is superior and lateral, typically associated with posterior approaches.

Question 10447

Topic: 1. General Principles & Basic Science

Which of the following is the most effective intervention to reduce the risk of surgical site infection (SSI) in orthopedic surgery, specifically related to the operating room environment?

. Administration of prophylactic broad-spectrum antibiotics for 7 days post-operatively.
. Use of laminar flow operating rooms with ultra-clean air.
. Strict control of operating room traffic and door openings.
. Routine application of topical antibiotics to surgical wounds.
. Increased concentration of povidone-iodine in surgical skin prep.

Correct Answer & Explanation

. Strict control of operating room traffic and door openings.

Explanation

Strict control of operating room traffic and minimizing door openings is considered one of the most effective and easily implemented strategies to reduce the risk of surgical site infection (SSI). Each door opening can introduce airborne contaminants into the sterile field. While laminar flow operating rooms can be beneficial, their routine use is debated and expensive. Prophylactic antibiotics are crucial but should be discontinued shortly after surgery (typically within 24 hours). Topical antibiotics have limited evidence for reducing SSI in orthopedic surgery, and increasing povidone-iodine concentration beyond standard recommendations does not confer additional benefit and may cause irritation. Environmental control through traffic restriction is a high-yield intervention.

Question 10448

Topic: Infection, Pharmacology & VTE

Which of the following is the most common cause of non-traumatic amputation in adults globally?

. Trauma.
. Malignancy (e.g., osteosarcoma).
. Peripheral vascular disease and diabetes.
. Chronic osteomyelitis.
. Neurological disorders (e.g., severe spasticity).

Correct Answer & Explanation

. Peripheral vascular disease and diabetes.

Explanation

Globally, peripheral vascular disease (PVD) and diabetes mellitus are by far the most common causes of non-traumatic amputations in adults. These conditions lead to critical limb ischemia, diabetic foot ulcers, and infection, ultimately necessitating amputation. While trauma is a significant cause of amputation, it is typically traumatic. Malignancy, chronic osteomyelitis, and neurological disorders also lead to amputation but are less common than PVD/diabetes combined.

Question 10449

Topic: Infection, Pharmacology & VTE

A 3-year-old child presents with a limp, fever, and refusal to bear weight on the left leg. On examination, the left hip is held in flexion, abduction, and external rotation. Passive range of motion is severely painful, especially internal rotation. Blood tests show cloudy fluid with a WBC count of 75,000 cells/ยตL, 90% neutrophils, and positive Gram stain for Gram-positive cocci in clusters. What is the most appropriate management?

. Immediate intravenous antibiotics and observation.
. Aspiration, culture, and non-weight bearing.
. Urgent surgical irrigation and debridement of the knee.
. Intra-articular corticosteroid injection.
. Arthroscopy with synovectomy.

Correct Answer & Explanation

. Urgent surgical irrigation and debridement of the knee.

Explanation

This is a clear case of septic arthritis of the knee, an orthopedic emergency in children. The presentation (limp, fever, swollen/warm/painful joint), and particularly the synovial fluid analysis (high WBC count, high neutrophils, positive Gram stain) confirms the diagnosis. Urgent surgical irrigation and debridement (arthrotomy or arthroscopy) of the knee is the most appropriate management to remove purulent material, reduce bacterial load, and prevent cartilage destruction. This should be combined with intravenous antibiotics. While aspiration is part of diagnosis, surgical washout is definitive for septic arthritis of a large joint. Immediate IV antibiotics alone without surgical debridement are insufficient to treat severe septic arthritis. Corticosteroid injection is contraindicated. Synovectomy is not the primary goal; debridement and irrigation are.

Question 10450

Topic: Infection, Pharmacology & VTE

Which of the following is a common orthopedic manifestation of renal osteodystrophy in a patient with chronic kidney disease?

. Gouty arthritis.
. Pseudogout.
. Osteomalacia and adynamic bone disease.
. Rheumatoid arthritis.
. Septic arthritis.

Correct Answer & Explanation

. Osteomalacia and adynamic bone disease.

Explanation

Renal osteodystrophy is a complex bone disease that occurs in patients with chronic kidney disease (CKD). It encompasses several bone disorders, including osteomalacia (impaired mineralization), secondary hyperparathyroidism (high bone turnover), and adynamic bone disease (low bone turnover). These conditions lead to bone pain, fractures, and muscle weakness. Gout, pseudogout, rheumatoid arthritis, and septic arthritis are not primary orthopedic manifestations of renal osteodystrophy, although patients with CKD may suffer from them independently. Among the choices, osteomalacia and adynamic bone disease are direct components of renal osteodystrophy.

Question 10451

Topic: Biology, Genetics & Bone Healing

What is the primary orthopedic complication associated with an untreated symptomatic pectus excavatum?

. Scoliosis.
. Increased risk of rib fractures.
. Compromised cardiopulmonary function.
. Osteoporosis.
. Patellar instability.

Correct Answer & Explanation

. Compromised cardiopulmonary function.

Explanation

Severe pectus excavatum, a congenital deformity of the sternum and costal cartilages leading to a sunken chest, can cause compression of the heart and lungs. This compression can lead to compromised cardiopulmonary function, including reduced exercise tolerance, shortness of breath, and in severe cases, mitral valve prolapse or arrhythmias due to cardiac displacement. While scoliosis can coexist or be exacerbated by pectus excavatum, the primary concern directly attributable to the pectus deformity itself, particularly if symptomatic, is the impact on the heart and lungs. Rib fractures, osteoporosis, and patellar instability are not direct complications of pectus excavatum.

Question 10452

Topic: Surgical Anatomy & Approaches

Which of the following is a potential late complication of chronic pelvic trauma or pelvic surgery that can lead to persistent perineal or pelvic pain?

. Meralgia paresthetica.
. Piriformis syndrome.
. Pudendal neuralgia.
. Obturator nerve entrapment.
. Sciatica.

Correct Answer & Explanation

. Pudendal neuralgia.

Explanation

Pudendal neuralgia is characterized by chronic neuropathic pain in the perineum, external genitalia, or anorectal region, often exacerbated by sitting. It can result from direct trauma, nerve compression (e.g., from scar tissue or hematoma after pelvic trauma or surgery), or entrapment in Alcock's canal. While the other listed conditions are types of nerve entrapment or pain syndromes, pudendal neuralgia specifically correlates with perineal/pelvic pain and is a known, albeit uncommon, late complication of pelvic trauma or surgery. Meralgia paresthetica involves the lateral femoral cutaneous nerve (thigh), piriformis syndrome involves the sciatic nerve (buttock/leg), obturator nerve entrapment causes groin/medial thigh pain, and sciatica is general sciatic nerve pain.

Question 10453

Topic: Infection, Pharmacology & VTE
A 4-year-old child presents with a limp, fever, and refusal to bear weight. X-rays are normal. MRI shows fluid in the hip joint and a small lesion in the adjacent ilium. Labs show elevated CRP and ESR. Urine culture is positive for E. coli. What is the most likely diagnosis?
. Transient synovitis.
. Legg-Calvรฉ-Perthes disease.
. Septic arthritis of the hip.
. Osteomyelitis of the ilium with reactive effusion.
. Juvenile idiopathic arthritis.

Correct Answer & Explanation

. Osteomyelitis of the ilium with reactive effusion.

Explanation

Given the child's fever, limp, refusal to bear weight, elevated inflammatory markers, and a positive urine culture, the presence of a lesion in the ilium along with joint fluid points strongly to osteomyelitis of the ilium with a sympathetic (reactive) effusion in the hip joint. Hematogenous spread from the urinary tract (E. coli UTI) is a common source for osteomyelitis in children. While septic arthritis of the hip is also a possibility, the specific mention of a lesion in the ilium makes osteomyelitis a more fitting primary diagnosis, with the joint effusion being reactive. Transient synovitis typically has normal labs. Legg-Calvรฉ-Perthes disease is avascular necrosis, and JIA is a chronic inflammatory arthritis, neither of which presents acutely with fever and positive cultures like this.

Question 10454

Topic: Infection, Pharmacology & VTE
Which of the following statements regarding the management of pressure ulcers in a patient with a T10 complete spinal cord injury is most accurate from an orthopedic perspective?
. Surgical debridement and closure is always the primary treatment for deep pressure ulcers.
. Routine repositioning and specialized mattresses are sufficient for prevention and early stage ulcers.
. Osteomyelitis of underlying bone is a common and serious complication of chronic pressure ulcers.
. Topical antibiotics are the most effective treatment for deep pressure ulcers.
. All pressure ulcers require a full-thickness skin graft for definitive closure.

Correct Answer & Explanation

. Osteomyelitis of underlying bone is a common and serious complication of chronic pressure ulcers.

Explanation

For patients with SCI, chronic deep pressure ulcers (Stage III and IV) frequently involve the underlying bone, leading to osteomyelitis. This is a very common and serious complication that can result in systemic sepsis and requires aggressive management, often including surgical debridement of infected bone and long-term antibiotics. While repositioning and specialized mattresses are crucial for prevention and early stage ulcers, and surgical debridement/closure is often needed for deep ulcers, the orthopedic relevance lies particularly in the high risk of underlying osteomyelitis. Topical antibiotics alone are insufficient for deep ulcers with potential osteomyelitis. Not all ulcers require skin grafts; flaps are often used for deeper wounds.

Question 10455

Topic: Infection, Pharmacology & VTE

A 30-year-old male sustains a traumatic complete T4 spinal cord injury. Which of the following is the most significant long-term cardiovascular risk related to his level of injury?

. Peripheral vascular disease.
. Hypertension secondary to renal dysfunction.
. Autonomic dysreflexia.
. Deep vein thrombosis (DVT) and pulmonary embolism (PE).
. Coronary artery disease.

Correct Answer & Explanation

. Autonomic dysreflexia.

Explanation

For spinal cord injuries at or above T6, autonomic dysreflexia is a significant and life-threatening long-term cardiovascular risk. It is a sudden, uncontrolled sympathetic response to noxious stimuli below the level of injury, leading to severe hypertension, bradycardia, headache, and sweating above the injury. While DVT/PE risk is high initially and can persist, and other cardiovascular issues can occur, autonomic dysreflexia is a unique and acute life-threatening phenomenon specific to high-level SCI. Hypertension secondary to renal dysfunction is possible but not the most significant or direct cardiovascular risk stemming from the SCI level itself. Peripheral vascular disease and coronary artery disease are general risks, not specific to this level of SCI.

Question 10456

Topic: Surgical Anatomy & Approaches

Which surgical approach for a lumbar discectomy carries the highest risk of iatrogenic injury to the ureter?

. Posterior midline microdiscectomy.
. Transforaminal lumbar interbody fusion (TLIF).
. Posterolateral fusion.
. Direct anterior lumbar interbody fusion (ALIF).
. Oblique lumbar interbody fusion (OLIF).

Correct Answer & Explanation

. Direct anterior lumbar interbody fusion (ALIF).

Explanation

The direct anterior lumbar interbody fusion (ALIF) approach requires significant retroperitoneal dissection and mobilization of the great vessels. The ureters lie within the retroperitoneum and are at risk of injury (laceration, clamping, kinking) during this extensive exposure. While OLIF also involves a retroperitoneal approach, it is generally considered less invasive than a direct ALIF and potentially carries a lower risk for ureteral injury if carefully performed. Posterior, transforaminal, and posterolateral approaches are far removed from the ureters and thus carry negligible risk of ureteral injury.

Question 10457

Topic: Biology, Genetics & Bone Healing

A 70-year-old female with osteoporosis and chronic steroid use for rheumatoid arthritis presents with sudden severe back pain after a minor fall. X-rays show a new compression fracture at T12. Which of the following is an important associated risk to consider, particularly given her steroid use?

. Increased risk of deep vein thrombosis.
. Compromised bone healing.
. Increased susceptibility to gastrointestinal bleeding.
. Worsening of pre-existing diabetes.
. All of the above.

Correct Answer & Explanation

. All of the above.

Explanation

Chronic steroid use (common in rheumatoid arthritis patients) for prolonged periods leads to severe osteoporosis, increasing fracture risk. Steroids also impair bone healing, increase the risk of gastrointestinal bleeding (especially if NSAIDs are also used), and can worsen glucose control in diabetic patients or induce steroid-induced diabetes. Therefore, all these risks are important associated considerations when managing an elderly patient with osteoporosis and chronic steroid use who sustains a compression fracture. The question asks for an associated risk, not just the primary risk, making 'All of the above' the most comprehensive answer.

Question 10458

Topic: Infection, Pharmacology & VTE

A patient with a T8 spinal cord injury has developed a chronic non-healing sacral pressure ulcer. What specific orthopedic complication might be present underneath the ulcer that requires surgical debridement and long-term antibiotic therapy?

. Heterotopic ossification.
. Deep vein thrombosis.
. Osteomyelitis.
. Septic arthritis.
. Neuropathic joint (Charcot arthropathy).

Correct Answer & Explanation

. Osteomyelitis.

Explanation

Chronic, non-healing deep pressure ulcers, especially over bony prominences like the sacrum in a patient with spinal cord injury, frequently lead to osteomyelitis of the underlying bone (sacrum or ischium). This infection is a serious complication that mandates surgical debridement of necrotic and infected bone along with long-term systemic antibiotic therapy for eradication. Heterotopic ossification is bone formation in soft tissues, DVT is a vascular complication, septic arthritis is infection of a joint, and Charcot arthropathy is neurogenic joint destruction; while these can occur in SCI, osteomyelitis directly beneath a chronic pressure ulcer is the most common and relevant orthopedic complication in this specific scenario.

Question 10459

Topic: Biology, Genetics & Bone Healing

Which of the following metabolic bone disorders, often seen in patients with end-stage renal disease, is characterized by brown tumors and subperiosteal bone resorption, especially in the phalanges?

. Osteomalacia.
. Renal osteodystrophy (specifically secondary hyperparathyroidism).
. Adynamic bone disease.
. Osteoporosis.
. Paget's disease of bone.

Correct Answer & Explanation

. Renal osteodystrophy (specifically secondary hyperparathyroidism).

Explanation

Renal osteodystrophy encompasses several bone abnormalities in chronic kidney disease. Specifically, secondary hyperparathyroidism is characterized by excessive parathyroid hormone secretion in response to hypocalcemia and hyperphosphatemia. This leads to high bone turnover, osteoclastic resorption, subperiosteal bone resorption (classic in phalanges, distal clavicle), and the formation of brown tumors (osteitis fibrosa cystica). Osteomalacia involves impaired mineralization. Adynamic bone disease is low bone turnover. Osteoporosis is generalized bone loss, and Paget's is a localized disorder of bone remodeling.

Question 10460

Topic: 1. General Principles & Basic Science

A 60-year-old male with a history of chronic alcoholism presents with atraumatic right hip pain and a limp. Radiographs show a crescent sign and collapse of the superior aspect of the femoral head. What is the most likely diagnosis?

. Osteoarthritis of the hip
. Septic arthritis
. Transient osteoporosis of the hip
. Avascular Necrosis (AVN) of the femoral head
. Stress fracture of the femoral neck

Correct Answer & Explanation

. Avascular Necrosis (AVN) of the femoral head

Explanation

The history of chronic alcoholism is a significant risk factor for Avascular Necrosis (AVN) of the femoral head. The radiographic finding of a crescent sign (subchondral collapse) is pathognomonic for late-stage AVN, preceding femoral head collapse. Osteoarthritis would show diffuse joint space narrowing and osteophytes. Septic arthritis would be acute with systemic signs. Transient osteoporosis is self-limiting and less severe. Stress fracture has a different radiographic appearance and history.

Test Yourself

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

On this Page