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1. General Principles & Basic Science MCQs

Practice Set 632 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 12621

Topic: 1. General Principles & Basic Science

What is the recommended approach for obtaining synovial fluid cultures to avoid contamination?

. Aspirate through an existing sinus tract.
. Perform aspiration under non-sterile conditions to maximize yield.
. Perform aspiration using strict aseptic technique, discarding the first few milliliters of fluid.
. Obtain fluid only during open surgical debridement.
. Collect fluid from a joint effusion without prior skin preparation.

Correct Answer & Explanation

. Perform aspiration using strict aseptic technique, discarding the first few milliliters of fluid.

Explanation

To avoid contamination and obtain accurate synovial fluid cultures, aspiration must be performed using strict aseptic technique. It is also recommended to discard the first few milliliters of fluid collected, as this 'waste' fluid may contain skin contaminants introduced by the needle's passage. Aspirating through a sinus tract is highly prone to contamination. Non-sterile conditions or lack of skin prep are unacceptable. While fluid collected during surgery is valuable, preoperative aspiration is crucial for diagnosis and guiding initial empirical therapy.

Question 12622

Topic: Surgical Anatomy & Approaches

A 40-year-old patient with chronic lateral ankle instability is found to have significant tendinosis and longitudinal tears of the peroneal brevis tendon on MRI. How might this influence the surgical management strategy for her instability?

. It suggests that a primary repair of the lateral ligaments will be sufficient.
. It necessitates the use of a Chrisman-Snook or Watson-Jones procedure for reconstruction.
. It complicates the repair and may require concomitant peroneal tendon debridement or repair.
. It indicates that the patient likely has a medial ankle instability instead.
. It means non-operative management is the only viable option.

Correct Answer & Explanation

. It complicates the repair and may require concomitant peroneal tendon debridement or repair.

Explanation

Concomitant peroneal tendon pathology (tendinosis, tears, or subluxation) is common in patients with chronic lateral ankle instability. If present, it must be addressed during the same surgical setting, typically through debridement, repair, or tenodesis of the peroneal tendons, in addition to the lateral ligament stabilization. Ignoring significant peroneal pathology can lead to continued pain, weakness, and potentially compromise the outcome of the instability repair. It does not necessarily preclude a primary ligament repair, but it adds another component to the surgical plan. Chrisman-Snook/Watson-Jones use healthy peroneal tendons, not torn ones.

Question 12623

Topic: Physiology & Rehabilitation

In a patient with chronic lateral ankle instability, what is the 'star excursion balance test' primarily used to assess?

. Static balance and ankle range of motion.
. Dynamic balance, proprioception, and neuromuscular control.
. Strength of the peroneal muscles.
. Ligamentous laxity of the ankle joint.
. Pain levels during functional activities.

Correct Answer & Explanation

. Dynamic balance, proprioception, and neuromuscular control.

Explanation

The Star Excursion Balance Test (SEBT) is a commonly used clinical assessment tool for dynamic balance, proprioception, and neuromuscular control of the lower extremity. It requires the patient to maintain balance on one leg while reaching with the contralateral leg in various directions, thereby challenging the ankle's stability in a functional manner. It does not directly measure static balance, muscle strength, ligamentous laxity, or pain levels, though it can be influenced by these factors.

Question 12624

Topic: Physiology & Rehabilitation

Which of the following types of ankle instability is characterized by a feeling of 'giving way' without objective evidence of ligamentous laxity on examination or stress radiographs?

. Mechanical instability
. Chronic instability
. Functional instability
. Combined instability
. Acute instability

Correct Answer & Explanation

. Functional instability

Explanation

Functional instability describes the subjective sensation of the ankle 'giving way' or feeling unstable, without demonstrable objective laxity (e.g., on stress radiographs). This is often attributed to impaired proprioception and neuromuscular control deficits. Mechanical instability, on the other hand, involves objective ligamentous laxity. Chronic instability refers to persistent symptoms, which can be either mechanical, functional, or both.

Question 12625

Topic: Physiology & Rehabilitation

What aspect of chronic lateral ankle instability is most effectively addressed by a comprehensive physiotherapy program, even if mechanical laxity persists?

. Complete restoration of torn ligamentous structures.
. Correction of significant cavovarus foot deformity.
. Improvement of functional stability through enhanced proprioception and neuromuscular control.
. Elimination of all pain and swelling completely.
. Direct repair of associated osteochondral lesions.

Correct Answer & Explanation

. Improvement of functional stability through enhanced proprioception and neuromuscular control.

Explanation

A comprehensive physiotherapy program is highly effective in improving functional stability, even when some degree of mechanical laxity persists. This is achieved by enhancing proprioception, strengthening dynamic stabilizers (peroneals), and improving neuromuscular control. Physiotherapy cannot directly restore torn ligaments, correct structural deformities like cavovarus foot, or directly repair OCLs. While it aims to reduce pain and swelling, complete elimination is not always possible without addressing underlying mechanical issues or other pathologies.

Question 12626

Topic: 1. General Principles & Basic Science

Which of the following describes the 'Whiteside's Line' used in rotational alignment of the femoral component?

. A line parallel to the posterior femoral condyles
. A line connecting the medial and lateral epicondyles of the femur
. A line perpendicular to the transepicondylar axis, passing through the deepest part of the trochlear groove anteriorly and the intercondylar notch posteriorly
. A line passing through the center of the femoral head and the center of the intercondylar notch
. A line tangential to the anterior femoral cortex

Correct Answer & Explanation

. A line perpendicular to the transepicondylar axis, passing through the deepest part of the trochlear groove anteriorly and the intercondylar notch posteriorly

Explanation

Whiteside's Line is an important reference for femoral rotation. It is defined as a line perpendicular to the transepicondylar axis (TEA), typically passing through the deepest part of the trochlear groove anteriorly and the intercondylar notch posteriorly. It is used as an axis for femoral component rotation, ideally aligning with the AP axis of the femoral component. The TEA connects the medial and lateral epicondyles.

Question 12627

Topic: 1. General Principles & Basic Science

Failure to externally rotate the femoral component adequately, relative to the surgical epicondylar axis, results in what common alignment issue?

. Valgus malalignment of the femoral component
. Flexion malalignment of the femoral component
. Internal rotation of the femoral component
. Excessive anterior slope of the tibial component
. Patella baja

Correct Answer & Explanation

. Internal rotation of the femoral component

Explanation

Failure to externally rotate the femoral component adequately (or internally rotating it) relative to the surgical epicondylar axis is a common cause of femoral component internal rotation. This can lead to patellofemoral maltracking, lateral patellar subluxation, and an asymmetric flexion gap (tight medially, loose laterally). Valgus or flexion malalignment are different planes of malalignment. Excessive anterior tibial slope and patella baja are unrelated to femoral rotational errors.

Question 12628

Topic: 1. General Principles & Basic Science

Which of the following is most strongly associated with the 'opening up' of the medial compartment in flexion and leading to medial laxity?

. Femoral component internal rotation
. Excessive femoral component external rotation
. Excessive tibial posterior slope
. Insufficient distal femoral resection
. Tibial component varus alignment

Correct Answer & Explanation

. Excessive femoral component external rotation

Explanation

Excessive femoral component external rotation leads to an asymmetrical flexion gap where the medial side becomes loose and the lateral side becomes tight. This causes medial laxity, particularly in flexion, and can result in medial instability or varus stress laxity in flexion. Femoral internal rotation would tighten the medial side. Excessive tibial posterior slope primarily affects overall gap balance and hyperextension. Insufficient distal femoral resection affects the extension gap. Tibial component varus affects coronal stability in extension mainly.

Question 12629

Topic: 1. General Principles & Basic Science

What is a potential consequence of placing the patellar component with excessive medial tilt?

. Increased lateral patellofemoral pressure and anterior knee pain
. Increased medial patellofemoral pressure and anterior knee pain
. Lateral patellar subluxation
. Patellar clunk syndrome
. Reduced range of motion due to impingement

Correct Answer & Explanation

. Increased medial patellofemoral pressure and anterior knee pain

Explanation

Placing the patellar component with excessive medial tilt leads to increased pressure on the medial facet of the patella against the femoral trochlea. This results in increased medial patellofemoral pressure and can cause anterior knee pain, crepitus, and accelerated wear of the medial patellar polyethylene. Lateral tilt would cause increased lateral pressure. Lateral patellar subluxation is usually due to femoral rotational malalignment. Patellar clunk syndrome is due to suprapatellar scarring.

Question 12630

Topic: 1. General Principles & Basic Science

Which of the following describes the potential consequence of placing the femoral component in an overly extended position (e.g., too much anterior femoral cut)?

. Flexion contracture
. Hyperextension and posterior instability
. Anterior impingement in flexion
. Patellar clunk syndrome
. Excessive femoral external rotation

Correct Answer & Explanation

. Flexion contracture

Explanation

Placing the femoral component in an overly extended position (or insufficient resection of the posterior femoral condyles) makes the extension gap excessively tight. This can lead to a flexion contracture as the knee cannot achieve full extension. Hyperextension is often linked to excessive tibial posterior slope. Anterior impingement in flexion is more associated with an anteriorized or oversized femoral component. Patellar clunk is a specific syndrome.

Question 12631

Topic: 1. General Principles & Basic Science

What is the consequence of placing the tibial component in an excessively external rotation position?

. Medial patellar subluxation
. Lateral patellar subluxation
. Increased tension on the medial collateral ligament in flexion
. Increased tension on the lateral collateral ligament in flexion
. Flexion contracture

Correct Answer & Explanation

. Medial patellar subluxation

Explanation

Excessive external rotation of the tibial component can cause the tibial tubercle to be too far laterally, potentially leading to medial patellar subluxation as the patella is drawn medially relative to the trochlear groove. It can also lead to an asymmetrical flexion gap, with tightening of the lateral compartment and loosening of the medial compartment, but medial patellar subluxation is a direct patellofemoral consequence.

Question 12632

Topic: Infection, Pharmacology & VTE

A patient with a severe fixed valgus deformity undergoes TKA. During surgery, significant tightness of the lateral compartment in both flexion and extension is noted. What is the most appropriate initial soft tissue release to address this?

. Superficial MCL release
. Pes anserinus release
. Posterior cruciate ligament release
. Lateral collateral ligament (LCL) release and popliteus tenotomy
. Posteromedial capsular release

Correct Answer & Explanation

. Lateral collateral ligament (LCL) release and popliteus tenotomy

Explanation

For a severe fixed valgus deformity with tightness of the lateral compartment in both flexion and extension, the primary structures causing this tightness are the lateral collateral ligament (LCL) and the popliteus tendon. Releasing these structures, along with the posterolateral capsule, is typically required to balance the lateral side. MCL and pes anserinus releases are for medial tightness. PCL release is for a tight flexion gap.

Question 12633

Topic: 1. General Principles & Basic Science

What is the typical post-operative rehabilitation protocol after a first MTP joint arthrodesis?

. Immediate full weight-bearing in regular shoes
. Non-weight-bearing in a cast for 6 weeks, then a walking boot
. Weight-bearing as tolerated in a post-op shoe or walking boot for 6-8 weeks, followed by rigid-soled shoe
. Partial weight-bearing with crutches for 2 weeks, then regular shoes
. Continuous passive motion (CPM) machine for the first MTP joint for 4 weeks

Correct Answer & Explanation

. Weight-bearing as tolerated in a post-op shoe or walking boot for 6-8 weeks, followed by rigid-soled shoe

Explanation

Following a first MTP joint arthrodesis, the typical protocol involves weight-bearing as tolerated in a stiff-soled post-operative shoe or walking boot for approximately 6-8 weeks to protect the fusion site and allow for bone healing. After radiographic evidence of early fusion, patients transition to rigid-soled regular shoes. Immediate full weight-bearing without protection is too aggressive. Non-weight-bearing for 6 weeks is often overly cautious for a stable fixation, though it might be used in specific cases. CPM is contraindicated for fusion surgery as it aims to prevent motion. Partial weight-bearing for only 2 weeks before regular shoes is usually insufficient for bone healing.

Question 12634

Topic: 1. General Principles & Basic Science

What is the typical range of motion (dorsiflexion) considered sufficient at the first MTP joint for normal gait mechanics during push-off?

. 5-10 degrees
. 15-20 degrees
. 30-40 degrees
. 45-50 degrees
. More than 60 degrees

Correct Answer & Explanation

. 30-40 degrees

Explanation

For normal gait mechanics, particularly during the push-off phase, approximately 30-40 degrees of dorsiflexion at the first MTP joint is generally considered necessary. Less than this range contributes to hallux limitus/rigidus symptoms and altered gait. While the full physiological range can be higher, 30-40 degrees is the functional threshold for unimpeded propulsion. Options like 5-10 or 15-20 degrees indicate significant restriction, consistent with hallux limitus.

Question 12635

Topic: 1. General Principles & Basic Science

What is the typical range of valgus alignment recommended for a first MTP joint arthrodesis to ensure comfortable shoe wear and avoid impingement?

. 0-5 degrees varus
. 0-5 degrees valgus
. 10-15 degrees valgus
. 20-25 degrees valgus
. Greater than 30 degrees valgus

Correct Answer & Explanation

. 10-15 degrees valgus

Explanation

For first MTP joint arthrodesis, the optimal position generally includes 10-15 degrees of dorsiflexion and 10-15 degrees of valgus. This degree of valgus alignment prevents impingement with the second toe, provides a good cosmetic appearance, and allows for comfortable fitting in most standard footwear. Excessive valgus or varus can lead to rubbing, transfer lesions, or cosmetic dissatisfaction.

Question 12636

Topic: 1. General Principles & Basic Science

In a patient undergoing first MTP joint arthrodesis, what is the critical consideration regarding the interphalangeal (IP) joint of the great toe?

. It should always be fused concomitantly.
. Its motion will be significantly reduced, requiring stretching exercises.
. It must be mobile and healthy to compensate for the fused MTP joint.
. Its function is irrelevant after MTP fusion.
. It should be immobilized post-operatively to protect the MTP fusion.

Correct Answer & Explanation

. It must be mobile and healthy to compensate for the fused MTP joint.

Explanation

After a first MTP joint arthrodesis, the interphalangeal (IP) joint of the great toe becomes critically important. It must be mobile, healthy, and pain-free to compensate for the loss of motion at the MTP joint, allowing for some toe flexion during gait and adapting to uneven surfaces. If the IP joint also has significant degenerative changes or stiffness, an MTP fusion can lead to persistent pain and functional limitations. Therefore, its health and mobility are paramount. It is not typically fused concomitantly unless it is also severely arthritic.

Question 12637

Topic: 1. General Principles & Basic Science

Post-operative stiffness is a known complication following patellar stabilization surgery. Which factor is most strongly associated with an increased risk of post-operative arthrofibrosis?

. Early weight-bearing.
. Aggressive rehabilitation protocol.
. Delayed initiation of range of motion exercises.
. Use of absorbable suture anchors.
. Concomitant articular cartilage repair.

Correct Answer & Explanation

. Delayed initiation of range of motion exercises.

Explanation

Delayed initiation of range of motion (ROM) exercises post-operatively is a significant risk factor for arthrofibrosis and stiffness following knee surgery, including patellar stabilization. Early, controlled ROM is crucial to prevent adhesions and maintain joint mobility. While aggressive rehabilitation without proper protection can cause other issues, it's delayed ROM that directly leads to stiffness. Early weight-bearing (if allowed) can be beneficial for healing. The type of anchor is less relevant than rehabilitation. Concomitant articular repair might necessitate a slower rehab but the core issue for stiffness is ROM.

Question 12638

Topic: 1. General Principles & Basic Science

In a patient presenting with an acute patellar dislocation, what is the most important initial radiographic view to obtain?

. AP view of the knee.
. Lateral view of the knee.
. Axial (Merchant or Laurin) view of the patella.
. Standing long leg alignment view.
. Stress views of the patellofemoral joint.

Correct Answer & Explanation

. Lateral view of the knee.

Explanation

Following an acute patellar dislocation, after reduction, it is crucial to obtain a lateral view of the knee. This view is essential to assess for any osteochondral fragments (which can avulse from the medial patella or lateral femoral condyle), patellar height (patella alta), and gross alignment. An AP view is also standard but less informative for patellar stability-specific injuries. Axial views are important for patellar tilt/subluxation but usually obtained later. Long leg alignment views and stress views are not for acute dislocations.

Question 12639

Topic: 1. General Principles & Basic Science

What is the primary rationale for distalizing a patellar tendon insertion during a tibial tubercle osteotomy for patellar instability?

. To correct an increased Q-angle.
. To address patella baja.
. To decrease patellofemoral contact pressures in cases of patella alta.
. To improve vastus medialis obliquus (VMO) function.
. To prevent lateral patellar subluxation.

Correct Answer & Explanation

. To decrease patellofemoral contact pressures in cases of patella alta.

Explanation

Tibial tubercle distalization (e.g., part of a Fulkerson osteotomy) is performed to address patella alta, which is a risk factor for instability and can also lead to increased patellofemoral contact pressures. By moving the patellar tendon insertion distally, the patella is lowered, improving its engagement in the trochlear groove and reducing stress. Correcting an increased Q-angle involves medialization, not distalization. Patella baja is the opposite and would be exacerbated by distalization. While VMO function might indirectly improve with better tracking, it's not the primary aim. Preventing lateral subluxation is a general goal of instability surgery, but distalization specifically targets patellar height.

Question 12640

Topic: 1. General Principles & Basic Science

Which of the following surgical procedures is specifically designed to address patella alta?

. Lateral retinacular release.
. Medial patellofemoral ligament reconstruction.
. Tibial tubercle distalization osteotomy.
. Trochleoplasty.
. Vastus medialis obliquus advancement.

Correct Answer & Explanation

. Tibial tubercle distalization osteotomy.

Explanation

Tibial tubercle distalization osteotomy is a bony procedure specifically aimed at lowering the patellar position. By moving the tibial tubercle (the insertion of the patellar tendon) distally on the tibia, the patella is brought down into a more appropriate height relative to the femoral trochlea, thus correcting patella alta. The other procedures address lateral tightness, medial soft tissue restraint, trochlear morphology, or VMO function, but not patellar height directly.

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