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1. General Principles & Basic Science MCQs

Practice Set 417 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 8321

Topic: Biomechanics & Biomaterials

A 20-year-old collegiate baseball pitcher reports progressive medial elbow pain and decreased pitching velocity. The moving valgus stress test is positive. MRI shows a high-grade partial tear of the anterior bundle of the ulnar collateral ligament (UCL). During surgical reconstruction, where is the most appropriate anatomical insertion site on the ulna for the graft?

. Sublime tubercle
. Olecranon tip
. Coronoid tip
. Supinator crest
. Radial tuberosity

Correct Answer & Explanation

. Sublime tubercle

Explanation

The anterior bundle of the ulnar collateral ligament (UCL) is the primary restraint to valgus stress at the elbow during the throwing motion. It originates on the anteroinferior aspect of the medial epicondyle and inserts on the sublime tubercle of the proximal ulna. Reconstruction grafts must be routed through or anchored at this anatomic footprint to restore proper biomechanics.

Question 8322

Topic: 1. General Principles & Basic Science

A 25-year-old hockey player presents with groin pain exacerbated by hip flexion and internal rotation. Imaging shows a high alpha angle on the lateral radiograph. This specific hip morphology is most strongly associated with initial damage to which structure?

. Anterosuperior acetabular labrum
. Posteroinferior acetabular labrum
. Ligamentum teres
. Anterosuperior acetabular articular cartilage
. Ischiofemoral ligament

Correct Answer & Explanation

. Anterosuperior acetabular articular cartilage

Explanation

Cam impingement, characterized by a high alpha angle, causes sheer forces that typically result in the delamination of the anterosuperior acetabular articular cartilage prior to frank labral detachment.

Question 8323

Topic: Surgical Anatomy & Approaches

A 55-year-old manual laborer undergoes an arthroscopic rotator cuff repair with an open subpectoral biceps tenodesis. What nerve is at greatest risk of iatrogenic injury if medial retractors are placed too aggressively during the subpectoral exposure?

. Axillary nerve
. Radial nerve
. Musculocutaneous nerve
. Median nerve
. Ulnar nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The musculocutaneous nerve is at significant risk if medial retraction is too deep or aggressive during a subpectoral biceps tenodesis, as it pierces the coracobrachialis medial to the surgical field.

Question 8324

Topic: 1. General Principles & Basic Science

A 55-year-old man feels a "pop" in his posterior knee while descending stairs, followed by acute pain. MRI reveals a medial meniscus posterior root tear with 3 mm of extrusion. Biomechanically, this injury is most equivalent to which of the following?

. A complete total meniscectomy
. An anterior horn meniscal tear
. A longitudinal tear in the red-red zone
. A radial tear involving the inner 10%
. A bucket-handle meniscal tear

Correct Answer & Explanation

. A complete total meniscectomy

Explanation

Poster root tears disrupt the circumferential hoop stresses of the meniscus, causing extrusion under axial load. Biomechanically, a complete root avulsion transmits contact pressures across the joint identical to a total meniscectomy, predisposing the knee to rapid articular cartilage degeneration.

Question 8325

Topic: 1. General Principles & Basic Science
In the setting of a multiligamentous knee injury (KD-III-M), reconstruction of the posteromedial corner is planned. The posterior oblique ligament (POL) acts as the primary restraint to which of the following forces?
. Internal rotation near extension
. External rotation near extension
. Varus gapping at 30 degrees of flexion
. Valgus gapping at 30 degrees of flexion
. Posterior tibial translation in deep flexion

Correct Answer & Explanation

. Internal rotation near extension

Explanation

The posterior oblique ligament (POL) is the primary restraint to internal rotation of the tibia at early angles of knee flexion (0 to 30 degrees). The superficial MCL is the primary restraint to valgus at 30 degrees of flexion.

Question 8326

Topic: 1. General Principles & Basic Science

A 42-year-old manual laborer has a symptomatic type II superior labrum anterior-posterior (SLAP) tear that has failed 6 months of nonoperative management. Compared to an arthroscopic SLAP repair, proceeding with a primary biceps tenodesis in this patient demographic is associated with:

. Higher rate of postoperative stiffness
. Increased risk of deep infection
. Decreased supination strength at 1 year
. Higher rate of return to pre-injury work level
. Increased incidence of postoperative Popeye deformity

Correct Answer & Explanation

. Higher rate of return to pre-injury work level

Explanation

In older patients (typically >35-40 years) or manual laborers, SLAP repairs have higher rates of failure and postoperative stiffness. Biceps tenodesis yields more reliable pain relief and higher rates of return to work in this demographic.

Question 8327

Topic: Surgical Anatomy & Approaches

During an ulnar collateral ligament (UCL) reconstruction using the docking technique, a muscle-splitting approach through the flexor pronator mass is utilized. Which nerve is most at risk of iatrogenic injury during this specific surgical approach?

. Median nerve
. Radial nerve
. Anterior interosseous nerve
. Medial antebrachial cutaneous nerve
. Posterior interosseous nerve

Correct Answer & Explanation

. Medial antebrachial cutaneous nerve

Explanation

The medial antebrachial cutaneous nerve (MABC) and its branches run superficially over the medial epicondyle and are highly vulnerable during the surgical approach to the ulnar collateral ligament.

Question 8328

Topic: Physiology & Rehabilitation

A 17-year-old female soccer player is 9 months post-ACL reconstruction. Which of the following sets of objective criteria is most significantly associated with a reduced risk of graft rupture upon return to sport?

. Limb symmetry index >90% on single-leg hop testing and isokinetic quadriceps strength
. A negative Lachman test and negative pivot shift test
. MRI demonstrating full graft ligamentization
. Completion of a mandatory 12-month postoperative timeframe
. Return of full active range of motion equal to the contralateral knee

Correct Answer & Explanation

. Limb symmetry index >90% on single-leg hop testing and isokinetic quadriceps strength

Explanation

Functional testing is paramount for assessing return-to-play readiness. A limb symmetry index (LSI) >90% on single-leg hop tests and isokinetic quadriceps strength correlates strongly with successful return to sport and drastically reduces re-injury risk compared to timeframes or static exams alone.

Question 8329

Topic: 1. General Principles & Basic Science

A 28-year-old powerlifter feels a sharp "pop" in his anterior axilla while performing a one-rep max bench press. Examination reveals loss of the anterior axillary fold contour and marked weakness in internal rotation. At what location does the classic distal tear of this muscle typically occur?

. At the musculotendinous junction
. Avulsion from its insertion on the lateral lip of the bicipital groove
. Avulsion from its insertion on the medial lip of the bicipital groove
. Avulsion from the sternocostal origin
. Avulsion from the clavicular origin

Correct Answer & Explanation

. Avulsion from its insertion on the lateral lip of the bicipital groove

Explanation

The patient has sustained a pectoralis major rupture. The most common site of injury in weightlifters performing the bench press is an avulsion of the tendon from its insertion site on the lateral lip of the bicipital groove of the humerus.

Question 8330

Topic: 1. General Principles & Basic Science

A 45-year-old male develops acute posterior knee pain after a deep squat. MRI reveals a complete radial tear at the posterior root of the medial meniscus with 4 mm of meniscal extrusion. What is the primary biomechanical consequence of leaving this injury untreated?

. It is biomechanically equivalent to an intact meniscus
. It is biomechanically equivalent to a partial meniscectomy
. It is biomechanically equivalent to a total meniscectomy
. It decreases peak contact pressure in the medial compartment
. It primarily increases anterior tibial translation

Correct Answer & Explanation

. It is biomechanically equivalent to a total meniscectomy

Explanation

A complete posterior root tear disrupts the circumferential hoop stresses of the meniscus. Biomechanically, this is equivalent to a total meniscectomy and leads to rapid deterioration of the medial compartment cartilage.

Question 8331

Topic: 1. General Principles & Basic Science

A 29-year-old male weightlifter felt a 'tearing' sensation in his anterior chest while attempting a maximal bench press. On examination, there is loss of the normal anterior axillary fold contour and significant weakness in internal rotation. Which anatomical location is most common for a complete pectoralis major rupture in this scenario?

. Clavicular head muscle belly
. Clavicular head origin at the sternum
. Sternal head insertion at the humerus
. Sternal head origin at the sternoclavicular joint
. Mid-substance of the combined conjoined tendon

Correct Answer & Explanation

. Sternal head insertion at the humerus

Explanation

Pectoralis major ruptures typically occur during eccentric loading, such as the bottom phase of a bench press. The sternal head is placed under maximum tension in extension and external rotation, making it most susceptible to avulsion at or near its humeral insertion.

Question 8332

Topic: Biology, Genetics & Bone Healing

A 4-year-old girl is evaluated for recurrent fractures following minimal trauma. Clinical examination reveals blue sclerae and evidence of dentinogenesis imperfecta. Genetic testing confirms a mutation in COL1A1. Which of the following mechanisms best describes the action of the medical therapy most commonly used to decrease fracture burden in this patient?

. Inhibition of osteoclast-mediated bone resorption
. Stimulation of osteoblast differentiation
. Direct stimulation of type I collagen synthesis
. Antagonism of the RANKL pathway
. Enhancement of intestinal calcium absorption

Correct Answer & Explanation

. Inhibition of osteoclast-mediated bone resorption

Explanation

The patient has Osteogenesis Imperfecta (OI), characterized by defective type I collagen. The mainstay of medical management to reduce fracture burden is the use of bisphosphonates (e.g., pamidronate or zoledronic acid). Bisphosphonates act by inducing osteoclast apoptosis and inhibiting osteoclast-mediated bone resorption, thereby increasing cortical thickness and trabecular bone density, though they do not correct the underlying collagen defect.

Question 8333

Topic: Biology, Genetics & Bone Healing
A 5-year-old girl with Osteogenesis Imperfecta (Type III) has a history of recurrent long bone fractures and progressive bowing deformities. She is receiving cyclical intravenous pamidronate therapy. This pharmacological agent decreases the incidence of fractures primarily through which of the following cellular mechanisms?
. Stimulating mesenchymal stem cell differentiation into osteoblasts
. Increasing the cross-linking of Type I collagen molecules
. Inhibiting farnesyl pyrophosphate synthase, leading to osteoclast apoptosis
. Acting as a selective estrogen receptor modulator (SERM) on bone tissue
. Directly binding to RANKL to prevent osteoclastogenesis

Correct Answer & Explanation

. Inhibiting farnesyl pyrophosphate synthase, leading to osteoclast apoptosis

Explanation

Pamidronate is a nitrogen-containing bisphosphonate widely used in the medical management of moderate to severe Osteogenesis Imperfecta. These agents work by being internalized by osteoclasts during bone resorption. Inside the osteoclast, they inhibit the enzyme farnesyl pyrophosphate (FPP) synthase in the mevalonate pathway. This disruption prevents the prenylation of small GTPase proteins essential for osteoclast function and survival, ultimately leading to osteoclast apoptosis and decreased bone turnover. They do not correct the underlying Type I collagen defect.

Question 8334

Topic: Biology, Genetics & Bone Healing

A 4-year-old child with a known history of recurrent fractures and blue sclerae is being treated with intravenous bisphosphonate therapy (pamidronate).

Radiographs of the long bones demonstrate multiple dense horizontal bands ('zebra lines') in the metaphyses. What is the primary mechanism by which this medication produces these radiographic findings?

. Stimulation of osteoblast differentiation and proliferation
. Inhibition of osteoclast-mediated bone resorption
. Direct inhibition of type 1 collagen synthesis
. Upregulation of the runx2 gene expression
. Inhibition of tissue non-specific alkaline phosphatase activity

Correct Answer & Explanation

. Inhibition of osteoclast-mediated bone resorption

Explanation

The patient has Osteogenesis Imperfecta (OI). Bisphosphonates, such as pamidronate, act by inhibiting osteoclast activity and inducing osteoclast apoptosis, thereby decreasing bone resorption. When administered cyclically, the periods of osteoclast inhibition leave behind bands of unresorbed calcified cartilage in the growing metaphyses, appearing as parallel radiodense lines known as 'zebra lines'.

Question 8335

Topic: Physiology & Rehabilitation

A 7-year-old child with spastic diplegic cerebral palsy undergoes comprehensive 3D gait analysis. The kinematic data reveals a characteristic stiff-knee gait with significantly decreased peak knee flexion during the swing phase. Spasticity and overactivity of which of the following muscles is primarily responsible for this gait abnormality?

. Psoas major
. Medial hamstrings
. Rectus femoris
. Gastrocnemius
. Anterior tibialis

Correct Answer & Explanation

. Rectus femoris

Explanation

Stiff-knee gait in cerebral palsy is characterized by reduced peak knee flexion during the swing phase, which impairs foot clearance. This is classically caused by spasticity or prolonged firing (overactivity) of the rectus femoris muscle during the swing phase, preventing the knee from flexing adequately. Treatment often involves a distal rectus femoris transfer to the sartorius or gracilis to augment knee flexion.

Question 8336

Topic: Physiology & Rehabilitation

A 9-year-old boy with spastic diplegic cerebral palsy is evaluated for a worsening crouch gait. He has a history of prior bilateral Achilles tendon lengthenings performed at age 5. Physical exam reveals bilateral knee flexion contractures of 15 degrees. Which of the following findings is most likely to be seen on three-dimensional computerized gait analysis?

. Premature plantar flexor muscle firing during swing phase
. Excessive ankle dorsiflexion during the stance phase
. Decreased hip flexion during the swing phase
. Internal foot progression angle during initial contact
. Excessive knee extension in mid-stance

Correct Answer & Explanation

. Excessive ankle dorsiflexion during the stance phase

Explanation

Crouch gait in spastic diplegia is often characterized by excessive ankle dorsiflexion (frequently iatrogenic secondary to over-lengthening of the Achilles tendon), coupled with excessive knee and hip flexion during the stance phase. The lack of the normal plantarflexion-knee extension couple allows the tibia to fall forward into excessive dorsiflexion, which biomechanically forces the knee into increased flexion (crouch).

Question 8337

Topic: Biology, Genetics & Bone Healing

A 3-year-old boy presents with a history of 4 low-energy fractures. Physical examination reveals blue sclerae, joint hyperlaxity, and mild dentinogenesis imperfecta. Genetic testing confirms a mutation in the COL1A1 gene. The patient is initiated on intravenous pamidronate therapy. Which of the following best describes the expected radiographic changes following treatment and the specific cellular mechanism of this medication?

. Dense metaphyseal bands due to inhibition of osteoclast-mediated bone resorption
. Widened physes due to direct stimulation of osteoblast proliferation
. Cortical thinning due to down-regulation of type 1 collagen synthesis
. Sclerotic diaphyseal lesions due to inhibition of matrix metalloproteinases
. Periosteal reaction due to a secondary inflammatory cascade

Correct Answer & Explanation

. Dense metaphyseal bands due to inhibition of osteoclast-mediated bone resorption

Explanation

The patient has Osteogenesis Imperfecta (OI). Bisphosphonates, such as pamidronate, are the medical treatment of choice for moderate to severe OI. They are antiresorptive agents that act by inhibiting osteoclast activity and inducing osteoclast apoptosis. Because the normal resorption of calcified cartilage at the physis is inhibited during cyclical IV bisphosphonate therapy, horizontal sclerotic lines form parallel to the growth plate. These are known as 'zebra lines' or dense metaphyseal bands. Bisphosphonates do not directly stimulate osteoblasts or down-regulate collagen synthesis.

Question 8338

Topic: Infection, Pharmacology & VTE

A 4-year-old girl presents with acute onset of right hip pain and a limp. Which of the following parameters is NOT included in the original Kocher criteria for differentiating septic arthritis from transient synovitis?

. Non-weight-bearing on the affected side
. Erythrocyte sedimentation rate (ESR) > 40 mm/hr
. C-reactive protein (CRP) > 20 mg/L
. Temperature > 38.5 C (101.3 F)
. White blood cell (WBC) count > 12,000/mm3

Correct Answer & Explanation

. C-reactive protein (CRP) > 20 mg/L

Explanation

The classic Kocher criteria include history of non-weight-bearing, ESR > 40, temperature > 38.5 C, and WBC > 12,000. Although CRP is highly predictive and used in modified criteria, it was not part of the original four-part Kocher criteria.

Question 8339

Topic: 1. General Principles & Basic Science

A 7-year-old boy presents with a painful, snapping right knee. MRI confirms a Wrisberg-variant discoid lateral meniscus. What is the primary anatomical deficiency in this specific variant?

. Absence of the anterior horn attachment
. Absence of the posterior meniscotibial (coronary) ligaments
. Complete absence of the meniscofemoral ligament of Wrisberg
. Hypertrophy of the anterior meniscofemoral ligament
. A tear in the peripheral blood supply zone

Correct Answer & Explanation

. Absence of the posterior meniscotibial (coronary) ligaments

Explanation

The Wrisberg-variant discoid meniscus lacks the normal posterior meniscotibial (coronary) ligament attachments, making it hypermobile. Its only posterior attachment is the meniscofemoral ligament of Wrisberg, leading to subluxation and the classic "snapping" knee.

Question 8340

Topic: Infection, Pharmacology & VTE
An 8-year-old boy presents with a 2-day history of right knee pain, limp, and a fever of 38.8°C. Labs show a WBC of 16,000/mm³, ESR of 65 mm/hr, and CRP of 5.2 mg/dL. Knee aspiration yields turbid fluid with 85,000 WBCs/mm³ (>90% polymorphonuclear cells). Which of the following is the most appropriate definitive management?
. Intravenous antibiotics and splinting
. Serial needle aspirations of the knee
. Urgent arthrotomy and irrigation of the knee joint
. MRI of the knee with and without contrast
. Outpatient oral antibiotics and follow-up in 48 hours

Correct Answer & Explanation

. Urgent arthrotomy and irrigation of the knee joint

Explanation

The clinical presentation and aspirate findings (>50,000 WBCs with >75% PMNs) are highly diagnostic of septic arthritis. This is a surgical emergency requiring urgent joint irrigation and debridement to prevent irreversible cartilage destruction.

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