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1. General Principles & Basic Science MCQs

Practice Set 435 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 8681

Topic: 1. General Principles & Basic Science

A 45-year-old woman presents with acute posterior knee pain after a deep squat. MRI reveals a medial meniscus posterior root tear. Which of the following is the most likely consequence if this injury is left untreated?

. Rapid development of patellofemoral osteoarthritis
. Meniscal extrusion and accelerated medial compartment osteoarthritis
. Spontaneous healing due to the robust vascularity of the root
. Chronic anterior knee instability
. Formation of a symptomatic popliteal cyst without articular changes

Correct Answer & Explanation

. Meniscal extrusion and accelerated medial compartment osteoarthritis

Explanation

Posterior root tears of the medial meniscus disrupt circumferential hoop stresses, functionally equating to a total meniscectomy. This biomechanical failure leads to meniscal extrusion and rapid acceleration of medial compartment osteoarthritis if left un repaired.

Question 8682

Topic: Surgical Anatomy & Approaches

During hip arthroscopy, the placement of the anterolateral portal is performed first. Which of the following nerves is at the greatest risk of iatrogenic injury during the establishment of this specific portal?

. Sciatic nerve
. Pudendal nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Obturator nerve

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

The lateral femoral cutaneous nerve is highly susceptible to injury during the placement of the anterolateral and mid-anterior portals in hip arthroscopy due to its anatomic proximity to these standard portal sites.

Question 8683

Topic: 1. General Principles & Basic Science

A 45-year-old active female presents with acute posterior medial knee pain after a deep squat. An MRI demonstrates a posterior root tear of the medial meniscus. Which of the following best describes the biomechanical consequence of this specific injury?

. Decreased peak contact pressure in the medial compartment.
. Loss of hoop stresses equivalent to a total meniscectomy.
. Anterior tibial translation comparable to an ACL-deficient knee.
. Decreased medial joint space narrowing under axial load.
. Increased varus laxity at 30 degrees of knee flexion.

Correct Answer & Explanation

. Loss of hoop stresses equivalent to a total meniscectomy.

Explanation

A posterior medial meniscus root tear disrupts the meniscal attachments, abolishing its ability to transmit hoop stresses. The biomechanical consequences, including increased peak contact pressures, are nearly equivalent to those of a total meniscectomy.

Question 8684

Topic: Physiology & Rehabilitation

A 28-year-old male powerlifter feels a tearing sensation in his anterior chest wall while performing a heavy bench press. Examination reveals an ecchymotic defect at the anterior axillary fold. He is diagnosed with a pectoralis major rupture. Which portion of the muscle is most commonly injured in this scenario?

. The clavicular head at the musculotendinous junction.
. The sternal head at its insertion on the humerus.
. The sternal head at its origin on the sternum.
. The clavicular head at its insertion on the humerus.
. The entire muscle belly at the midsubstance.

Correct Answer & Explanation

. The sternal head at its insertion on the humerus.

Explanation

Pectoralis major ruptures typically occur during maximal eccentric contraction, such as the lowering phase of a bench press. The most common injury pattern is the avulsion of the sternocostal head from its insertion on the proximal humerus.

Question 8685

Topic: 1. General Principles & Basic Science

Which of the following represents the primary static restraint to external rotation of the tibia at 30 degrees of knee flexion?

. Popliteofibular ligament
. Popliteus tendon
. Lateral collateral ligament
. Posterior cruciate ligament
. Iliotibial band

Correct Answer & Explanation

. Lateral collateral ligament

Explanation

The lateral collateral ligament (LCL) is the primary static restraint to varus stress and also serves as the primary restraint to external rotation at 30 degrees of knee flexion. The popliteus and popliteofibular ligament play secondary roles in resisting external rotation.

Question 8686

Topic: 1. General Principles & Basic Science

Cam impingement of the hip is primarily characterized by which of the following anatomic abnormalities?

. Acetabular retroversion
. Coxa profunda
. Decreased anterior head-neck offset
. Acetabular overcoverage
. Coxa valga

Correct Answer & Explanation

. Decreased anterior head-neck offset

Explanation

Cam impingement results from an aspherical femoral head and decreased anterior head-neck offset, leading to abnormal contact between the femoral neck and the anterosuperior acetabular rim during hip flexion and internal rotation. Acetabular retroversion and coxa profunda are associated with pincer impingement.

Question 8687

Topic: Surgical Anatomy & Approaches

A 32-year-old water skier sustains a hyperflexion injury of the hip with an extended knee. MRI demonstrates a complete proximal hamstring avulsion with 4 cm of retraction. What is the most appropriate surgical approach for repair?

. Anterior approach to the hip (Smith-Petersen)
. Anterolateral approach to the hip (Watson-Jones)
. Direct lateral approach (Hardinge)
. Posterior subgluteal approach
. Medial approach to the thigh

Correct Answer & Explanation

. Posterior subgluteal approach

Explanation

Proximal hamstring avulsions are approached via a posterior subgluteal approach, often employing a transverse gluteal crease incision. This provides direct access to the ischial tuberosity and allows for identification and protection of the adjacent sciatic nerve during repair.

Question 8688

Topic: 1. General Principles & Basic Science

A 30-year-old weightlifter feels a "pop" in his anterior chest wall while performing a heavy bench press. Examination reveals ecchymosis and a palpable defect in the anterior axillary fold. He is diagnosed with a pectoralis major rupture. Which portion of the tendon is most commonly injured and where does it insert relative to the other head?

. Clavicular head; inserts deep and proximal to the sternal head
. Clavicular head; inserts superficial and distal to the sternal head
. Sternal head; inserts deep and proximal to the clavicular head
. Sternal head; inserts superficial and distal to the clavicular head
. Costal head; inserts deep and distal to the clavicular head

Correct Answer & Explanation

. Sternal head; inserts deep and proximal to the clavicular head

Explanation

Pectoralis major tears most commonly involve the sternal head. Due to a 180-degree twist of the tendon, the sternal head inserts deep and proximal to the clavicular head on the lateral lip of the bicipital groove.

Question 8689

Topic: Biomechanics & Biomaterials

A 45-year-old active male feels a 'pop' in his posterior knee while squatting. MRI demonstrates a complete radial tear of the posterior horn of the medial meniscus exactly at its tibial attachment. Biomechanically, this injury is equivalent to which of the following?

. A 25% partial meniscectomy
. A total medial meniscectomy
. An isolated MCL sprain
. An ACL rupture
. Normal knee kinematics

Correct Answer & Explanation

. A total medial meniscectomy

Explanation

Medial meniscus posterior root tears completely disrupt the hoop stresses of the meniscus. Biomechanically, this effectively renders the knee equivalent to one that has undergone a total meniscectomy.

Question 8690

Topic: 1. General Principles & Basic Science

A 28-year-old weightlifter experiences a sudden tearing sensation in his anterior chest while performing a heavy bench press. Examination reveals loss of the anterior axillary fold. MRI confirms a complete rupture of the pectoralis major. Which head of the muscle is most commonly injured, and where does it typically fail?

. Clavicular head at the musculotendinous junction
. Sternal head at the sternal origin
. Clavicular head at the humeral insertion
. Sternal head at the humeral insertion
. Sternal head at the musculotendinous junction

Correct Answer & Explanation

. Sternal head at the humeral insertion

Explanation

Pectoralis major ruptures almost exclusively occur during heavy eccentric loading like bench pressing. The most common site of failure is the sternocostal (sternal) head avulsing from its humeral insertion.

Question 8691

Topic: Biology, Genetics & Bone Healing

A 19-year-old female cross-country runner presents with a femoral neck stress fracture. She has a BMI of 17.5 and reports amenorrhea for the last 8 months. What is the third component of the clinical triad most commonly associated with her condition?

. Anemia
. Decreased bone mineral density
. Hypothyroidism
. Polycystic ovarian syndrome
. Hypercortisolism

Correct Answer & Explanation

. Decreased bone mineral density

Explanation

The Female Athlete Triad consists of low energy availability (with or without disordered eating), menstrual dysfunction (amenorrhea), and decreased bone mineral density (osteopenia or osteoporosis).

Question 8692

Topic: Biomechanics & Biomaterials

A 52-year-old woman experiences a sharp pop in her posterior knee while squatting. MRI reveals a complete posterior root tear of the medial meniscus with 4 mm of radial meniscal extrusion. Which of the following best describes the biomechanical consequence of this injury if left untreated?

. It is biomechanically equivalent to a normal meniscus due to preserved anterior horn attachments.
. It results in altered kinematics but preserves normal joint contact pressures.
. It is best treated with partial meniscectomy to prevent accelerated osteoarthritis.
. It disrupts circumferential hoop stresses, generating contact pressures equivalent to a total meniscectomy.
. It primarily increases lateral compartment contact pressures via a compensatory varus shift.

Correct Answer & Explanation

. It disrupts circumferential hoop stresses, generating contact pressures equivalent to a total meniscectomy.

Explanation

A posterior root tear of the medial meniscus completely disrupts the circumferential hoop stresses, leading to radial extrusion. Biomechanically, this results in peak tibiofemoral contact pressures equivalent to those seen after a total meniscectomy, rapidly accelerating osteoarthritis.

Question 8693

Topic: 1. General Principles & Basic Science

A 6-year-old boy presents with painless limping. Radiographs show sclerosis and fragmentation of the lateral pillar of the femoral head, with 60% of the lateral pillar height maintained. According to the Herring lateral pillar classification, what is the appropriate group and typical recommendation for this patient?

. Group A, symptomatic treatment
. Group B, symptomatic treatment
. Group B, containment surgery
. Group C, containment surgery
. Group C, symptomatic treatment

Correct Answer & Explanation

. Group B, symptomatic treatment

Explanation

This is a Herring Group B classification (>50% lateral pillar height). In children under 8 years of age, Group B hips generally do well with symptomatic nonoperative management.

Question 8694

Topic: Infection, Pharmacology & VTE

A 4-year-old boy presents with a 2-day history of right hip pain, fever of 38.8°C (101.8°F), and refusal to bear weight. His WBC count is 14,000/mm3 and ESR is 55 mm/hr. According to Kocher's criteria, what is the approximate probability that this child has septic arthritis?

. 10%
. 40%
. 70%
. 93%
. 99%

Correct Answer & Explanation

. 99%

Explanation

The patient has 4 of 4 Kocher criteria (fever >38.5°C, non-weight-bearing, WBC >12,000, ESR >40). This correlates with a 99% probability of septic arthritis.

Question 8695

Topic: 1. General Principles & Basic Science

A 10-year-old boy complains of bilateral snapping and pain on the lateral aspect of the right knee during terminal extension. MRI shows a continuous band of meniscal tissue extending from the anterior to the posterior horn. Which type of discoid meniscus is characterized by an absent posterior meniscofemoral attachment?

. Incomplete type
. Complete type
. Wrisberg variant
. Ligament of Humphrey variant
. Anterior variant

Correct Answer & Explanation

. Wrisberg variant

Explanation

The Wrisberg variant of a discoid meniscus lacks normal posterior capsular attachments. This hypermobility causes the characteristic snapping knee.

Question 8696

Topic: Biology, Genetics & Bone Healing

A 13-year-old boy with a history of multiple fractures and blue sclerae is being treated for osteogenesis imperfecta with intravenous bisphosphonates. What is the primary mechanism of action of this medication?

. Stimulates osteoblast activity
. Inhibits osteoclast-mediated bone resorption
. Enhances calcium absorption in the gut
. Promotes type I collagen cross-linking
. Stimulates renal reabsorption of calcium

Correct Answer & Explanation

. Inhibits osteoclast-mediated bone resorption

Explanation

Bisphosphonates induce osteoclast apoptosis, thereby inhibiting bone resorption. This increases overall bone density and reduces fracture burden in osteogenesis imperfecta.

Question 8697

Topic: Infection, Pharmacology & VTE
A 5-year-old boy presents with an atraumatic limp and refuses to bear weight on his right leg. His temperature is 38.0°C (100.4°F), WBC count is 13,000/mm³, and ESR is 45 mm/hr. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?
. 3%
. 40%
. 71%
. 93%
. 99%

Correct Answer & Explanation

. 93%

Explanation

This patient meets three of the four Kocher criteria: non-weight-bearing, WBC >12,000/mm³, and ESR >40 mm/hr (his temperature is below the 38.5°C threshold). Having three criteria yields a 93% probability of septic arthritis.

Question 8698

Topic: Infection, Pharmacology & VTE
A 5-year-old girl presents with a 2-day history of right hip pain, a limp, and a fever of 38.6°C (101.5°F). She is refusing to bear weight. Her serum WBC count is 13,000/mm³, and ESR is 45 mm/hr. According to the Kocher criteria, what is the probability of septic arthritis?
. Less than 10%
. 30%
. 50%
. 93%
. 99%

Correct Answer & Explanation

. 93%

Explanation

The patient meets 4 out of 4 Kocher criteria (fever >38.5°C, non-weight-bearing, WBC >12,000, ESR >40). The probability of septic arthritis with 4 criteria is approximately 93-99%, mandating immediate hip aspiration.

Question 8699

Topic: Biology, Genetics & Bone Healing

A 4-year-old girl with blue sclerae and a history of multiple low-energy fractures is treated with intravenous pamidronate. What is the primary mechanism of action of this medication in treating her underlying genetic condition?

. Stimulation of osteoblast-mediated bone formation
. Inhibition of osteoclast-mediated bone resorption
. Upregulation of type 1 collagen synthesis
. Enhancement of gastrointestinal calcium absorption
. Inhibition of parathyroid hormone secretion

Correct Answer & Explanation

. Inhibition of osteoclast-mediated bone resorption

Explanation

The patient has osteogenesis imperfecta. Bisphosphonates, such as pamidronate, treat the osteopenia associated with this condition by inhibiting osteoclast-mediated bone resorption, thereby increasing bone mineral density.

Question 8700

Topic: Infection, Pharmacology & VTE
A 5-year-old boy presents with an inability to bear weight on his right leg. His oral temperature is 38.6°C (101.5°F), ESR is 45 mm/hr, and peripheral WBC is 13,500/mm³. Radiographs of the hip are normal. According to the Kocher criteria, what is the most appropriate next step in management?
. Prescribe oral NSAIDs and observe at home
. Initiate empiric oral antibiotics
. Perform an MRI of the right hip with contrast
. Perform an ultrasound-guided aspiration of the right hip joint
. Apply a Pavlik harness for pain relief

Correct Answer & Explanation

. Perform an ultrasound-guided aspiration of the right hip joint

Explanation

This patient meets all four Kocher criteria (fever, inability to bear weight, ESR >40, WBC >12,000), giving him a 99% probability of septic arthritis. The essential next step is an urgent joint aspiration to confirm the diagnosis and obtain cultures before surgical debridement.

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