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5. Sports Medicine MCQs

Practice Set 339 of 360

This practice set contains high-yield board review questions covering key concepts in 5. Sports Medicine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 6761

Topic: 5. Sports Medicine

A 17-year-old female undergoes MPFL reconstruction. Postoperatively, she develops numbness and tingling along the medial aspect of her lower leg and foot. Which nerve is most likely involved?

. Common peroneal nerve.
. Saphenous nerve.
. Femoral nerve.
. Tibial nerve.
. Sural nerve.

Correct Answer & Explanation

. Saphenous nerve.

Explanation

The saphenous nerve is a branch of the femoral nerve that provides sensation to the medial aspect of the lower leg and foot. It runs in close proximity to the surgical field during MPFL reconstruction, particularly when harvesting hamstring autografts or during the dissection for femoral tunnel placement. Injury to the saphenous nerve or its infrapatellar branch is a known, though uncommon, complication of this procedure. The other nerves listed innervate different regions or have different primary functions.

Question 6762

Topic: Knee Sports

What is the typical age range at which trochlear dysplasia begins to clinically manifest as patellar instability?

. Infancy (0-2 years old).
. Early childhood (3-7 years old).
. Late childhood to adolescence (10-16 years old).
. Early adulthood (20-30 years old).
. Elderly (65+ years old).

Correct Answer & Explanation

. Late childhood to adolescence (10-16 years old).

Explanation

Patellar instability due to trochlear dysplasia most commonly manifests clinically during late childhood to adolescence (10-16 years old). This is often when activity levels increase, and the growth plates are still open, but the patellofemoral joint is undergoing significant remodeling. While the dysplasia is congenital, symptoms typically emerge during growth spurts and increased biomechanical stress on the knee.

Question 6763

Topic: Knee Sports

What is the primary mechanism by which the vastus medialis obliquus (VMO) muscle contributes to patellar stability?

. It acts as a primary flexor of the knee joint.
. It provides dynamic lateral restraint to the patella.
. It pulls the patella medially and superiorly, especially in terminal extension.
. It increases the leverage of the patellar tendon.
. It prevents internal rotation of the tibia.

Correct Answer & Explanation

. It pulls the patella medially and superiorly, especially in terminal extension.

Explanation

The VMO is the most distal and medial portion of the quadriceps femoris. Its unique fiber orientation (approximately 50-55 degrees to the femoral shaft) allows it to exert a significant medial and superior pull on the patella, particularly in the last 20-30 degrees of knee extension. This dynamic medializing force is crucial for centering the patella within the trochlear groove and preventing lateral subluxation or dislocation. It is a dynamic stabilizer, whereas the MPFL is a static stabilizer.

Question 6764

Topic: Knee Sports

A 19-year-old male presents with recurrent patellar instability. His MRI shows a TTPG distance of 25mm, severe trochlear dysplasia (Dejour Type D), and patella alta (Insall-Salvati ratio 1.5). He has failed extensive physical therapy. What is the MOST comprehensive surgical plan for this patient?

. MPFL reconstruction and lateral retinacular release.
. Isolated trochleoplasty.
. Tibial tubercle medialization and distalization osteotomy.
. Combined trochleoplasty, MPFL reconstruction, and tibial tubercle medialization/distalization osteotomy.
. VMO advancement and medial plication.

Correct Answer & Explanation

. Combined trochleoplasty, MPFL reconstruction, and tibial tubercle medialization/distalization osteotomy.

Explanation

This patient presents with severe patellar instability driven by multiple, significant bony risk factors: very high TT-TG, severe trochlear dysplasia, and patella alta. To achieve a stable outcome, all major contributors to instability should be addressed. Trochleoplasty will correct the severe trochlear dysplasia. MPFL reconstruction will restore the medial soft tissue restraint. Tibial tubercle osteotomy for medialization (to correct the TT-TG) and distalization (to correct patella alta) will address the extensor mechanism malalignment. A combined approach is necessary for such complex cases.

Question 6765

Topic: Knee Sports

What is the role of patellofemoral bracing in the conservative management of patellar instability?

. To prevent all future dislocations.
. To limit knee flexion and extension to promote healing.
. To provide proprioceptive feedback and some mechanical support, especially during activity.
. To solely replace the function of the MPFL.
. To significantly reduce the TT-TG distance.

Correct Answer & Explanation

. To provide proprioceptive feedback and some mechanical support, especially during activity.

Explanation

Patellofemoral braces, especially those with a J-shaped buttress or similar design, are used in conservative management to provide mechanical support, help guide the patella medially, and offer proprioceptive feedback. They are not foolproof in preventing all dislocations but can reduce the risk during activity and provide confidence. They limit motion to a controlled degree for protection, but their main role is dynamic support. They do not replace the MPFL or alter bony alignment like TT-TG.

Question 6766

Topic: 5. Sports Medicine

A patient with Ehlers-Danlos Syndrome presents with chronic, recurrent patellar dislocations. Surgical stabilization is being considered. What is a key consideration unique to this patient population?

. Higher likelihood of patella alta requiring distalization.
. Increased risk of wound healing complications and graft failure due to poor tissue quality.
. Lower risk of recurrent instability due to generalized ligamentous laxity.
. Standard MPFL reconstruction with autograft is contraindicated.
. They typically respond better to isolated lateral retinacular release.

Correct Answer & Explanation

. Increased risk of wound healing complications and graft failure due to poor tissue quality.

Explanation

Patients with Ehlers-Danlos Syndrome or other connective tissue disorders often have generalized ligamentous laxity, which leads to poor tissue quality. This poor tissue quality can compromise the integrity and strength of autografts used in procedures like MPFL reconstruction, increasing the risk of graft failure and recurrent instability. They also have an increased risk of wound healing complications. While patella alta can occur, poor tissue quality and graft failure are the most critical unique surgical considerations. Isolated LRR is rarely effective, and autograft is not necessarily contraindicated but has a higher failure rate, leading some to consider allografts or specialized techniques.

Question 6767

Topic: Knee Sports

Which finding on a true lateral knee radiograph is indicative of patella alta?

. A crossover sign.
. Insall-Salvati ratio > 1.2.
. Increased sulcus angle.
. Decreased patellar tilt angle.
. Reduced medial patellar facet height.

Correct Answer & Explanation

. Insall-Salvati ratio > 1.2.

Explanation

Patella alta is diagnosed radiographically by an elevated patellar position relative to the femoral trochlea. Using the Insall-Salvati ratio (patellar tendon length / patellar articular length), a ratio greater than 1.2 is generally indicative of patella alta. A crossover sign and increased sulcus angle are related to trochlear dysplasia. Decreased patellar tilt means the patella is flatter, not higher. Reduced medial patellar facet height is not a standard measure for patellar height.

Question 6768

Topic: Knee Sports

During MPFL reconstruction, the surgeon places the femoral tunnel at Schottle's point. What is the anatomical landmark that is consistently used to identify Schottle's point?

. Midpoint of the lateral femoral epicondyle.
. Anterior border of the adductor tubercle.
. Proximal-most aspect of the medial epicondyle.
. Intersection of a line tangential to the posterior femoral cortex and a line anterior to Blumensaat's line.
. The most prominent point of the medial femoral condyle.

Correct Answer & Explanation

. Intersection of a line tangential to the posterior femoral cortex and a line anterior to Blumensaat's line.

Explanation

Schottle's point, a commonly used landmark for the isometric femoral attachment of the MPFL, is identified by specific radiographic or anatomical relationships: it is distal and posterior to the adductor tubercle, anterior to the posterior femoral cortex, and proximal to the level of the posterior femoral condylar cartilage. Specifically, on a lateral radiograph, it's typically described as the intersection of a line extending proximally from the posterior femoral cortex and a line drawn perpendicular to Blumensaat's line, passing through the posterior aspect of the trochlear groove. The option describes a specific radiographic method. The most consistent anatomical reference is its position relative to the adductor tubercle, but the description given in option 3 more accurately reflects a precise radiographic identification often used.

Question 6769

Topic: 5. Sports Medicine

A 16-year-old active female undergoes MPFL reconstruction with a hamstring autograft. Which of the following is the most appropriate post-operative rehabilitation guideline for the initial 6 weeks?

. Full weight-bearing immediately, no brace, and immediate aggressive quadriceps strengthening.
. Non-weight-bearing, full range of motion allowed, and no specific strengthening.
. Protected weight-bearing (crutches), knee brace locked in extension, and passive ROM from 0-30 degrees.
. Protected weight-bearing, knee brace allowing 0-90 degrees flexion, and gentle quad sets/ROM exercises.
. Non-weight-bearing, CPM machine for 24 hours, and immobilization in 45 degrees flexion.

Correct Answer & Explanation

. Protected weight-bearing, knee brace allowing 0-90 degrees flexion, and gentle quad sets/ROM exercises.

Explanation

Post-MPFL reconstruction rehabilitation typically involves a period of protected weight-bearing (crutches) to protect the healing graft and fixation, along with a knee brace to control motion. Early, controlled range of motion (e.g., 0-90 degrees) is initiated to prevent stiffness while protecting the graft. Immediate full weight-bearing or aggressive strengthening is too early. Non-weight-bearing without controlled motion is also not ideal. Immobilization in 45 degrees flexion is detrimental. The goal is controlled progression to restore function without jeopardizing the repair. So, protected weight-bearing, a brace allowing controlled flexion, and gentle exercises are appropriate.

Question 6770

Topic: Knee Sports

Which of the following describes the 'crossover sign' on an axial MRI of the patellofemoral joint?

. The medial facet of the patella is significantly smaller than the lateral facet.
. The deepest point of the trochlear groove is lateral to the most anterior point of the medial condyle.
. The lateral trochlear facet is flat or convex.
. The patella is positioned entirely lateral to the trochlear groove.
. The lateral aspect of the patella articulates with the intercondylar notch.

Correct Answer & Explanation

. The deepest point of the trochlear groove is lateral to the most anterior point of the medial condyle.

Explanation

The 'crossover sign' is a key feature of trochlear dysplasia, particularly Dejour Types C and D. It is present when the line representing the lateral facet of the trochlea appears to cross over the line representing the medial facet, meaning the deepest part of the trochlear groove is lateral to the most anterior aspect of the medial condyle. This indicates a flattened or even convex trochlear shape, leading to inadequate patellar containment.

Question 6771

Topic: Knee Sports

What is the primary anatomical structure that guides patellar tracking into the trochlear groove as the knee flexes?

. The quadriceps tendon.
. The medial patellofemoral ligament (MPFL).
. The lateral patellar retinaculum.
. The vastus medialis obliquus (VMO) muscle.
. The bony morphology of the trochlear groove.

Correct Answer & Explanation

. The bony morphology of the trochlear groove.

Explanation

While the VMO and MPFL play crucial roles in dynamic and static medial patellar stability, respectively, the primary anatomical structure thatguidesthe patellaintothe trochlear groove and contains it during flexion is the bony morphology of the trochlear groove itself. A well-formed, deep trochlear groove provides the primary constraint, especially beyond 20-30 degrees of flexion where the MPFL becomes relatively less important. Dysplasia of this groove is a major cause of instability.

Question 6772

Topic: Knee Sports

In evaluating a patient for patellar instability, what information obtained from an axial CT scan is most critical for surgical planning?

. Insall-Salvati ratio.
. Q-angle.
. TT-TG distance.
. Size of osteochondral fragments.
. Presence of effusion.

Correct Answer & Explanation

. TT-TG distance.

Explanation

An axial CT scan is the gold standard for accurately measuring the Tibial Tubercle-Trochlear Groove (TT-TG) distance. This measurement quantifies the lateralization of the extensor mechanism relative to the trochlear groove and is a crucial parameter for determining the need for and extent of tibial tubercle medialization osteotomy. The Insall-Salvati ratio is for patellar height (lateral X-ray). Q-angle is clinical or plain X-ray. Osteochondral fragments and effusion are better assessed by MRI or plain X-rays respectively. Thus, TT-TG is the most critical information derived from an axial CT.

Question 6773

Topic: Knee Sports

A 22-year-old female presents with recurrent patellar dislocations. MRI shows an intact MPFL but a markedly increased TT-TG distance (24mm) and patellar tilt. There is no significant trochlear dysplasia or patella alta. Which procedure is most appropriate?

. Isolated MPFL reconstruction.
. Isolated lateral retinacular release.
. Tibial tubercle medialization osteotomy (e.g., Elmslie-Trillat or modified Fulkerson).
. Trochleoplasty.
. VMO advancement.

Correct Answer & Explanation

. Tibial tubercle medialization osteotomy (e.g., Elmslie-Trillat or modified Fulkerson).

Explanation

Given an intact MPFL and the primary issue being a markedly increased TT-TG distance and patellar tilt, a tibial tubercle medialization osteotomy is the most appropriate procedure. This addresses the lateralization of the extensor mechanism and realigns the patella. Isolated MPFL reconstruction is not indicated if the MPFL is intact. Isolated LRR is rarely indicated for instability. Trochleoplasty is for trochlear dysplasia, which is not significant here. VMO advancement is less potent for significant bony malalignment.

Question 6774

Topic: 5. Sports Medicine

What is the typical mechanism of injury for an acute, primary lateral patellar dislocation?

. Direct blow to the anterior knee with the knee in flexion.
. Twisting injury on an extended knee with a valgus force and internal rotation of the femur on the tibia.
. Hyperextension injury during sports activity.
. Fall onto the patella with the knee in deep flexion.
. Direct blow to the lateral aspect of the patella with the knee in slight flexion and valgus.

Correct Answer & Explanation

. Twisting injury on an extended knee with a valgus force and internal rotation of the femur on the tibia.

Explanation

Acute, primary lateral patellar dislocations most commonly occur with a combination of knee flexion (often 20-30 degrees), valgus stress, and external rotation of the tibia on the femur (or internal rotation of the femur on the tibia). This creates a powerful lateralizing force on the patella, especially when the trochlear groove is shallowest. A direct blow to the lateral aspect of the patella is a less common but possible mechanism.

Question 6775

Topic: Knee Sports

Which of the following is considered a primary static stabilizer of the patella against lateral displacement?

. Vastus medialis obliquus (VMO).
. Rectus femoris.
. Medial patellofemoral ligament (MPFL).
. Lateral retinaculum.
. Patellar tendon.

Correct Answer & Explanation

. Medial patellofemoral ligament (MPFL).

Explanation

The MPFL is widely recognized as the primary static (passive) stabilizer of the patella, resisting lateral translation, especially in the initial 0-30 degrees of knee flexion. The VMO is a dynamic stabilizer. The rectus femoris and patellar tendon are components of the extensor mechanism, primarily involved in knee extension. The lateral retinaculum provides lateral soft tissue constraint.

Question 6776

Topic: 5. Sports Medicine

A patient undergoing MPFL reconstruction has a history of knee effusions. Which type of graft would be least likely to cause post-operative knee effusions and pain?

. Semitendinosus autograft harvested through an open incision.
. Gracilis autograft harvested through an open incision.
. Quadriceps tendon autograft.
. Adductor magnus tendon graft (proximal part of MPFL).
. Allograft (e.g., tibialis anterior).

Correct Answer & Explanation

. Adductor magnus tendon graft (proximal part of MPFL).

Explanation

While any graft can potentially cause post-operative effusions, harvesting autografts (semitendinosus, gracilis, quadriceps tendon) can lead to donor site morbidity, pain, and sometimes increased inflammation or effusion. Allografts avoid donor site morbidity. The adductor magnus tendon, specifically the aponeurotic extension of the adductor magnus that forms the proximal part of the native MPFL, can be used for reconstruction. This technique is 'quadriceps-sparing' and often associated with less anterior knee pain and potentially fewer effusions compared to hamstring or quad tendon autografts as it avoids injury to the extensor mechanism and a separate graft harvest site.

Question 6777

Topic: Knee Sports

Following an acute patellar dislocation, what is the most common site of injury to the medial patellofemoral ligament (MPFL)?

. Mid-substance tear.
. Patellar avulsion.
. Femoral avulsion.
. Tear at the retinacular attachment.
. Complete MPFL avulsion from both patellar and femoral insertions.

Correct Answer & Explanation

. Femoral avulsion.

Explanation

While MPFL injuries can occur at any point, femoral avulsions are the most common site of MPFL rupture in acute patellar dislocations. This typically occurs through an avulsion of a small bone fragment from the medial femoral condyle (often called a 'sleeve avulsion' or 'avulsion fracture'). Patellar avulsions are less common than femoral avulsions but can also occur. Mid-substance tears are less frequent.

Question 6778

Topic: Knee Sports

A patient presents with a 'double contour' sign on an axial patellofemoral CT scan. This finding is indicative of:

. Patella baja.
. Generalized ligamentous laxity.
. Trochlear dysplasia with a flat or convex trochlea.
. Increased Q-angle.
. Isolated lateral retinacular tightness.

Correct Answer & Explanation

. Trochlear dysplasia with a flat or convex trochlea.

Explanation

The 'double contour' sign on an axial patellofemoral CT scan is a radiological indicator of trochlear dysplasia. It refers to the appearance where the posterior aspect of the lateral trochlear facet is more anterior than the anterior border of the medial trochlear facet, suggesting a flat or even convex trochlear groove rather than a concave one. This is a characteristic feature of more severe forms of trochlear dysplasia (e.g., Dejour Types C and D).

Question 6779

Topic: 5. Sports Medicine

Which of the following statements regarding patellofemoral contact pressures after MPFL reconstruction is most accurate?

. Over-tensioning the MPFL graft always leads to patella alta.
. Excessive tensioning of the MPFL graft can increase patellofemoral contact pressures, leading to anterior knee pain and potential chondral damage.
. MPFL reconstruction uniformly decreases patellofemoral contact pressures.
. The choice of graft type (autograft vs. allograft) significantly impacts post-operative contact pressures.
. Patellofemoral contact pressures are primarily affected by the patellar tendon length, not MPFL tension.

Correct Answer & Explanation

. Excessive tensioning of the MPFL graft can increase patellofemoral contact pressures, leading to anterior knee pain and potential chondral damage.

Explanation

Excessive tensioning of the MPFL graft during reconstruction is a well-recognized cause of iatrogenic patellofemoral pain and increased patellofemoral contact pressures. This can lead to anterior knee pain, stiffness, and accelerate patellofemoral arthritis. The optimal tension is crucial, and typically, the graft is tensioned with the knee in 30 degrees of flexion to achieve stability without over-constraining. Over-tensioning does not cause patella alta; that is a matter of patellar height. While graft type can affect other outcomes, it does not directly determine contact pressures as much as graft tension and placement.

Question 6780

Topic: Knee Sports

Which imaging modality is considered the most comprehensive for evaluating the full spectrum of risk factors for patellar instability, including trochlear morphology, patellar height, TT-TG distance, and MPFL integrity?

. Plain radiographs (AP, lateral, axial).
. Dynamic ultrasound.
. Computed Tomography (CT) scan.
. Magnetic Resonance Imaging (MRI).
. SPECT-CT.

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI).

Explanation

Magnetic Resonance Imaging (MRI) is the most comprehensive imaging modality for evaluating patellar instability. It can assess soft tissues (MPFL integrity, chondral damage, effusion, bone bruising) as well as provide information on bony morphology (trochlear dysplasia, patellar height, TT-TG distance with sequences that mimic CT measurements). While plain radiographs are initial, and CT is excellent for bony measurements like TT-TG, MRI offers the best overall picture including all relevant soft tissue and bony components simultaneously.

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