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1. General Principles & Basic Science MCQs

Practice Set 633 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 12641

Topic: 1. General Principles & Basic Science

Which of the following anatomical variations is LEAST likely to be a risk factor for patellar instability?

. Patella alta.
. Increased Q-angle.
. Deep trochlear groove.
. Generalized ligamentous laxity.
. Hypoplastic medial femoral condyle.

Correct Answer & Explanation

. Deep trochlear groove.

Explanation

A deep trochlear groove provides excellent bony constraint and is protective against patellar instability. A shallow or dysplastic trochlear groove is a significant risk factor. The other options (patella alta, increased Q-angle, generalized ligamentous laxity, hypoplastic medial femoral condyle) are all recognized risk factors for patellar instability.

Question 12642

Topic: 1. General Principles & Basic Science

What is the primary concern when performing a lateral retinacular release in an individual with no signs of medial patellar instability?

. Persistent lateral patellar subluxation.
. Increased risk of patella alta.
. Iatrogenic medial patellar instability.
. Damage to the saphenous nerve.
. Development of arthrofibrosis.

Correct Answer & Explanation

. Iatrogenic medial patellar instability.

Explanation

One of the most significant and well-documented complications of isolated lateral retinacular release, especially when performed in patients without severe lateral tightness or if over-released, is iatrogenic medial patellar instability. This can result in medial subluxation or even dislocation, which is often more challenging to treat than the initial lateral instability. Persistent lateral instability would suggest the release was insufficient. Patella alta is unrelated. Saphenous nerve damage is more associated with medial approaches or hamstring harvest. Arthrofibrosis can occur but isn't the primary concern unique to LRR.

Question 12643

Topic: 1. General Principles & Basic Science

Which type of trochleoplasty procedure involves lifting and advancing a block of cartilage and subchondral bone to create a new, deeper groove?

. Recession trochleoplasty (e.g., Albee type).
. Deepening trochleoplasty (e.g., Bereiter, Dejour type).
. Resection trochleoplasty.
. Medial patellofemoral ligament reconstruction.
. Tibial tubercle osteotomy.

Correct Answer & Explanation

. Deepening trochleoplasty (e.g., Bereiter, Dejour type).

Explanation

Deepening trochleoplasty (e.g., Bereiter, Dejour techniques) involves lifting a flap of articular cartilage and a thin layer of subchondral bone from the dysplastic trochlea, excising deeper cancellous bone, and then repositioning the cartilage-bone flap into the newly deepened groove. Recession trochleoplasty involves removing bone to make the trochlea deeper. Resection trochleoplasty removes only the spur. Therefore, deepening trochleoplasty accurately describes the technique of creating a new groove by manipulating the cartilage and subchondral bone.

Question 12644

Topic: 1. General Principles & Basic Science

In a patient undergoing surgery for recurrent patellar instability, the surgeon notes a significant deficiency of the vastus medialis obliquus (VMO) muscle. Which surgical adjunct could specifically target this deficiency?

. Lateral retinacular release.
. Trochleoplasty.
. Tibial tubercle medialization.
. VMO advancement or plication.
. Distalizing tibial tubercle osteotomy.

Correct Answer & Explanation

. VMO advancement or plication.

Explanation

VMO advancement or plication is a surgical technique aimed at improving the medializing pull of the VMO on the patella. This involves mobilizing the VMO muscle and suturing it more distally and laterally onto the patella or its tendon, or tightening the medial capsule. It is specifically used to augment the dynamic medial patellar stabilization, especially in cases of VMO insufficiency. The other procedures address bony alignment or static restraints.

Question 12645

Topic: 1. General Principles & Basic Science

What is the typical presentation of a patient with iatrogenic medial patellar instability following an inappropriate lateral retinacular release?

. Continued lateral patellar apprehension.
. Pain and crepitus with deep knee flexion.
. Medial patellar apprehension, often with a palpable clunk or subluxation medially.
. Fixed patella baja.
. Recurrent effusions without instability.

Correct Answer & Explanation

. Medial patellar apprehension, often with a palpable clunk or subluxation medially.

Explanation

Iatrogenic medial patellar instability, a known complication of excessive or unwarranted lateral retinacular release, presents as apprehension or actual subluxation/dislocation of the patella medially. Patients often describe a feeling of the patella 'falling off' to the medial side, which can be elicited with a specific medial apprehension test. Continued lateral apprehension would suggest the LRR was insufficient. Pain with deep flexion can be general patellofemoral pain, not specific to medial instability. Fixed patella baja is not related. Recurrent effusions are non-specific.

Question 12646

Topic: 1. General Principles & Basic Science

Which physical examination finding is most suggestive of patellofemoral hypermobility rather than true instability?

. A positive J-sign.
. A positive patellar apprehension test.
. A Beighton score of 7/9.
. Gross effusion with hemarthrosis.
. Audible clunk with active knee extension.

Correct Answer & Explanation

. A Beighton score of 7/9.

Explanation

A Beighton score of 7/9 indicates generalized ligamentous laxity or hypermobility. While hypermobility is a risk factor for instability, a high Beighton score itself suggests a more generalized condition and can manifest as patellofemoral hypermobility without necessarily progressing to overt instability (dislocation). A positive J-sign or apprehension test, and audible clunk, are direct signs of instability or impending instability. Hemarthrosis suggests acute traumatic dislocation. Therefore, a high Beighton score is most indicative of generalized hypermobility.

Question 12647

Topic: 1. General Principles & Basic Science

Compared to the medial meniscus, the lateral meniscus is characterized by:

. Greater attachment to the joint capsule.
. A more C-shaped morphology.
. Less mobility during knee flexion and extension.
. Stronger attachments to the collateral ligament.
. A more circular shape and greater mobility.

Correct Answer & Explanation

. A more circular shape and greater mobility.

Explanation

The lateral meniscus is more circular (O-shaped) than the medial meniscus (C-shaped). Crucially, it has significantly fewer attachments to the joint capsule and no direct attachment to the lateral collateral ligament, allowing it greater mobility during knee motion compared to the medial meniscus. This increased mobility helps it adapt to changes in femorotibial contact during rotation and flexion/extension.

Question 12648

Topic: 1. General Principles & Basic Science
What is the primary collagen type found in the meniscal fibrocartilage?
. Type II collagen.
. Type X collagen.
. Type I collagen.
. Type III collagen.
. Type IX collagen.

Correct Answer & Explanation

. Type I collagen.

Explanation

The meniscus is primarily composed of type I collagen, accounting for approximately 90-95% of its total collagen content. This is characteristic of fibrocartilage. Type II collagen is more abundant in hyaline cartilage, though small amounts of type II are found in the meniscus, particularly near the articular surfaces.

Question 12649

Topic: Biomechanics & Biomaterials

Which of the following contributes most significantly to the viscoelastic properties of the meniscus?

. Predominant type II collagen content.
. High concentration of elastin fibers.
. Interaction between water and proteoglycans within the extracellular matrix.
. The specific orientation of radial collagen fibers.
. Dense innervation by Pacinian corpuscles.

Correct Answer & Explanation

. Interaction between water and proteoglycans within the extracellular matrix.

Explanation

The viscoelastic properties of the meniscus, which allow it to absorb energy and deform under load while slowly recovering, are largely attributed to the interaction between its high water content (70-80%) and the negatively charged proteoglycan aggregates (primarily aggrecan). These proteoglycans attract and retain water, creating a fluid-filled matrix that resists compression and dissipates energy.

Question 12650

Topic: Biology, Genetics & Bone Healing

Which of the following best describes the cellular composition of the adult meniscus?

. Chondrocytes predominantly, similar to hyaline cartilage.
. Fibroblasts in the outer regions and chondrocytes in the inner regions.
. Predominantly osteocytes, with some chondroblasts.
. Synoviocytes throughout the substance.
. Avascular tenocytes for tensile strength.

Correct Answer & Explanation

. Fibroblasts in the outer regions and chondrocytes in the inner regions.

Explanation

The adult meniscus is primarily composed of specialized fibrochondrocytes, which have characteristics of both fibroblasts and chondrocytes. In the vascularized outer regions, the cells are more fibroblast-like, while in the avascular inner regions, they tend to be more chondrocyte-like. These cells are sparsely distributed within the extensive extracellular matrix.

Question 12651

Topic: Physiology & Rehabilitation

The 'red-red zone' of the meniscus refers to the region that is:

. Innervated by pain receptors and highly vascularized.
. Vascularized and capable of intrinsic healing.
. Predominantly composed of type I collagen and avascular.
. Where the meniscus attaches directly to the tibial plateau.
. Responsible for proprioception but lacks direct blood supply.

Correct Answer & Explanation

. Vascularized and capable of intrinsic healing.

Explanation

The 'red-red zone' is the outermost peripheral region of the meniscus (approximately 10-30% of its width) that receives a direct blood supply from the perimeniscal capillary plexus. Tears in this zone have the best potential for biological healing due to the presence of blood-borne healing factors and cells.

Question 12652

Topic: 1. General Principles & Basic Science

Which of the following proteoglycans is most abundant in the meniscal extracellular matrix and contributes to its compressive stiffness?

. Decorin.
. Biglycan.
. Aggrecan.
. Fibromodulin.
. Luminecan.

Correct Answer & Explanation

. Aggrecan.

Explanation

Aggrecan is the most abundant proteoglycan in the meniscus, similar to hyaline cartilage. It forms large aggregates with hyaluronan and other proteins. Its numerous negatively charged chondroitin sulfate and keratan sulfate chains attract and bind water, creating a high osmotic pressure that gives the tissue its turgor and resistance to compressive forces.

Question 12653

Topic: 1. General Principles & Basic Science

In an ACL-deficient knee, which structure exhibits increased strain under anterior tibial load, and its integrity becomes even more critical?

. Patellar tendon.
. Posterior horn of the medial meniscus.
. Lateral collateral ligament.
. Anterior horn of the lateral meniscus.
. Quadriceps tendon.

Correct Answer & Explanation

. Posterior horn of the medial meniscus.

Explanation

In an ACL-deficient knee, the menisci, particularly the posterior horn of the medial meniscus, become critical secondary restraints to anterior tibial translation. Studies have shown increased strain in the posterior horn of the medial meniscus when the ACL is deficient, highlighting its compensatory role in stability. Tears in this region, especially root tears, in an ACL-deficient knee can lead to profound instability and rapid degenerative changes.

Question 12654

Topic: 1. General Principles & Basic Science

What is the primary role of the transverse meniscal ligament (also known as the intermeniscal ligament)?

. To prevent anterior translation of the medial meniscus.
. To provide the main blood supply to the anterior horns.
. To connect the anterior horns of the medial and lateral menisci.
. To stabilize the lateral meniscus against excessive posterior translation.
. To reinforce the posterior cruciate ligament.

Correct Answer & Explanation

. To connect the anterior horns of the medial and lateral menisci.

Explanation

The transverse meniscal ligament connects the anterior horns of the medial and lateral menisci. Its exact biomechanical significance is debated, but it is thought to help synchronize the movement of the anterior horns during knee motion and may contribute to preventing excessive anterior displacement of either meniscus.

Question 12655

Topic: Physiology & Rehabilitation

Which aspect of meniscal function is most impaired by a total meniscectomy?

. Proprioception.
. Joint lubrication.
. Load distribution and shock absorption.
. Ligamentous stability.
. Synovial fluid production.

Correct Answer & Explanation

. Load distribution and shock absorption.

Explanation

A total meniscectomy profoundly impairs the meniscus's primary biomechanical functions: load distribution and shock absorption. By removing the menisci, the contact area between the femoral and tibial condyles is significantly reduced, leading to a marked increase in peak contact stresses and accelerated articular cartilage degeneration. While proprioception and lubrication also suffer, the load-bearing deficit is the most critical factor for long-term joint health.

Question 12656

Topic: 1. General Principles & Basic Science

In which zone of the meniscus would a complex, degenerative tear have the least intrinsic healing potential?

. The outermost red-red zone.
. The mid-body red-white zone.
. The innermost white-white zone.
. The anterior horn, near its attachment.
. The posterior horn, near its attachment.

Correct Answer & Explanation

. The innermost white-white zone.

Explanation

The white-white zone, being entirely avascular, has virtually no intrinsic healing potential. Complex degenerative tears in this region, which often extend into the avascular portion, are unlikely to heal even with biological stimulation, making partial meniscectomy the standard treatment.

Question 12657

Topic: 1. General Principles & Basic Science

Which type of meniscal tear is most frequently associated with instability of the knee, particularly ACL deficiency, and is a significant contributor to meniscal extrusion and early osteoarthritis?

. Horizontal cleavage tear.
. Radial tear in the white-white zone.
. Bucket-handle tear of the lateral meniscus.
. Posterior horn root tear (avulsion).
. Flap tear of the medial meniscus.

Correct Answer & Explanation

. Posterior horn root tear (avulsion).

Explanation

Posterior horn root tears, particularly of the medial meniscus, are increasingly recognized as functionally equivalent to a total meniscectomy. By disrupting the circumferential integrity of the meniscus, they lead to significant meniscal extrusion, loss of load-bearing function, and dramatically increased tibiofemoral contact pressures, predisposing to rapid cartilage degeneration and osteoarthritis. They are also strongly associated with ACL deficiency.

Question 12658

Topic: 1. General Principles & Basic Science

What is the approximate anterior-posterior excursion of the medial meniscus during full knee flexion and extension?

. 1-2 mm.
. 3-5 mm.
. 6-8 mm.
. 9-11 mm.
. 12-14 mm.

Correct Answer & Explanation

. 6-8 mm.

Explanation

The medial meniscus is relatively less mobile than the lateral meniscus due to its firm attachments. It typically moves about 6-8 mm anteriorly and posteriorly during a full range of knee motion. The lateral meniscus, with its fewer attachments, can move up to 10-12 mm.

Question 12659

Topic: 1. General Principles & Basic Science
Which growth factor is commonly studied for its potential role in enhancing meniscal healing and repair?
. Epidermal Growth Factor (EGF).
. Insulin-like Growth Factor-1 (IGF-1).
. Fibroblast Growth Factor (FGF).
. Transforming Growth Factor-beta (TGF-β).
. Nerve Growth Factor (NGF).

Correct Answer & Explanation

. Transforming Growth Factor-beta (TGF-β).

Explanation

Transforming Growth Factor-beta (TGF-β) is a crucial growth factor involved in cartilage and fibrocartilage repair. It stimulates meniscal fibrochondrocytes to produce extracellular matrix components like collagen and proteoglycans, and it can promote cell proliferation and differentiation, making it a target for enhancing meniscal healing.

Question 12660

Topic: 1. General Principles & Basic Science

In knee flexion, how does the load transmission through the menisci change compared to extension?

. It decreases significantly.
. It remains constant.
. It shifts primarily to the patellofemoral joint.
. It increases, with a higher percentage of load borne by the menisci.
. It becomes negligible beyond 90 degrees of flexion.

Correct Answer & Explanation

. It increases, with a higher percentage of load borne by the menisci.

Explanation

As the knee flexes, the contact area between the femur and tibia decreases, and the percentage of compressive load transmitted through the menisci increases. While it's 50-70% in extension, it can increase to 85% or more in deeper flexion, highlighting the menisci's critical role in protecting articular cartilage throughout the range of motion.

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