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 2461
Topic: Knee Sports
A 22-year-old sustains a longitudinal tear in the red-white zone of the medial meniscus. Which vessel provides the primary vascular supply to the peripheral capillary plexus of the medial meniscus?
Correct Answer & Explanation
. Inferior medial genicular artery
Explanation
The menisci receive their primary blood supply from the medial and lateral genicular arteries. Specifically, the inferior and superior medial genicular arteries form the perimeniscal capillary plexus supplying the peripheral 10-30% (red zone) of the medial meniscus. The middle genicular artery supplies the cruciate ligaments (ACL/PCL).
Question 2462
Topic: Knee Sports
During a posterior cruciate ligament (PCL) reconstruction, the surgeon aims to anatomically reconstruct the anterolateral (AL) bundle. What is the primary biomechanical function of the AL bundle?
Correct Answer & Explanation
. Tightest in flexion; resists posterior translation
Explanation
The PCL consists of the larger anterolateral (AL) bundle and the smaller posteromedial (PM) bundle. The AL bundle is tightest in flexion and is the primary restraint to posterior tibial translation. The PM bundle is tightest in extension.
Question 2463
Topic: 5. Sports Medicine
Which of the following correctly describes the cellular mechanism and biological environment of Matrix-induced Autologous Chondrocyte Implantation (MACI) compared to traditional first-generation ACI?
Correct Answer & Explanation
. It uses a Type I/III collagen bilayer membrane seeded with cultured autologous chondrocytes to avoid a periosteal patch.
Explanation
MACI is a third-generation cartilage repair technique where autologous cultured chondrocytes are seeded onto a porcine-derived Type I/III collagen membrane. This eliminates the need for harvesting a periosteal flap (as used in 1st-generation ACI), thereby significantly reducing the risk of graft hypertrophy and allowing for less invasive or arthroscopic application.
Question 2464
Topic: Knee Sports
A patient demonstrates increased external rotation on the dial test at 30 degrees of knee flexion, but symmetrical external rotation at 90 degrees compared to the contralateral normal knee. Which structures are most likely injured?
Correct Answer & Explanation
. Isolated posterolateral corner (PLC)
Explanation
The dial test evaluates for posterolateral corner (PLC) and PCL injuries. Increased external rotation (>10 degrees compared to the normal side) only at 30 degrees of flexion indicates an isolated PLC injury (specifically the popliteus complex and fibular collateral ligament). If increased external rotation is present at both 30 and 90 degrees, it indicates a combined PLC and PCL injury.
Question 2465
Topic: Knee Sports
On MRI, which finding has the highest specificity for indicating instability of an osteochondritis dissecans (OCD) lesion in a skeletally mature patient?
Correct Answer & Explanation
. High T2 signal line surrounding the fragment
Explanation
A high T2-weighted signal line surrounding the OCD fragment indicates that synovial fluid has tracked behind the fragment into the subchondral bone, which strongly indicates lesion instability and a breach of the overlying articular cartilage. This is an indication for surgical stabilization in a skeletally mature patient.
Question 2466
Topic: Knee Sports
During reconstruction of the Medial Patellofemoral Ligament (MPFL) for recurrent patellar instability, non-anatomic femoral tunnel placement is a common cause of failure. If the femoral tunnel is placed too proximal to the anatomic footprint (Schöttle's point), what biomechanical consequence will occur during knee range of motion?
Correct Answer & Explanation
. The graft will be tight in flexion and loose in extension
Explanation
If the MPFL femoral tunnel is placed too proximally, the distance between the patellar attachment and the femoral attachment increases as the knee flexes. This results in an anisometry where the graft is excessively tight in flexion (causing increased medial patellofemoral contact pressures and loss of flexion) and loose in extension (failing to prevent lateral dislocation).
Question 2467
Topic: Knee Sports
Following a microfracture procedure for a 1.5 cm^2 symptomatic full-thickness chondral defect on the medial femoral condyle, what type of cartilage primarily fills the defect, and what is its major collagen component?
Correct Answer & Explanation
. Fibrocartilage; Type I collagen
Explanation
Marrow stimulation techniques, such as microfracture, result in the formation of a 'super clot' that organizes into fibrocartilage. Fibrocartilage is primarily composed of Type I collagen, which is biomechanically inferior to the Type II collagen found in native hyaline cartilage.
Question 2468
Topic: Knee Sports
Six months following a bone-patellar tendon-bone anterior cruciate ligament (ACL) reconstruction, a patient complains of a palpable clunk and pain at the anterior knee, along with a 15-degree lack of full terminal extension. MRI reveals a nodular mass in the intercondylar notch anterior to the ACL graft. What is the most likely diagnosis?
A Cyclops lesion is a form of localized anterior arthrofibrosis consisting of a fibrovascular nodule that forms anterior to the ACL graft in the intercondylar notch. It acts as a mechanical block, classically causing an anterior clunk, pain, and loss of terminal extension.
Question 2469
Topic: Knee Sports
A 24-year-old athlete sustains a direct blow to the anteromedial tibia. Physical examination reveals an abnormal Dial test with 15 degrees of increased external tibial rotation at 30 degrees of knee flexion, but symmetric rotation at 90 degrees compared to the uninjured side. This finding is highly specific for an isolated injury to which of the following structures?
Correct Answer & Explanation
. Posterolateral corner (PLC)
Explanation
The Dial test evaluates for external rotation asymmetry. The posterolateral corner (PLC) is the primary restraint to external rotation at 30 degrees of flexion. At 90 degrees of flexion, the posterior cruciate ligament (PCL) becomes the primary restraint. Therefore, an increase of >10 degrees of external rotation at 30 degrees but not at 90 degrees indicates an isolated PLC injury. If rotation is increased at both 30 and 90 degrees, it indicates a combined PCL and PLC injury.
Question 2470
Topic: 5. Sports Medicine
Matrix-induced Autologous Chondrocyte Implantation (MACI) has largely replaced first-generation ACI in many centers. Which of the following describes the primary procedural advantage of MACI over first-generation ACI?
Correct Answer & Explanation
. It eliminates the need for a periosteal patch harvest
Explanation
First-generation ACI required the harvesting and suturing of a periosteal patch over the defect to contain the liquid chondrocyte suspension, which was associated with prolonged operative time and a high rate of patch hypertrophy. MACI uses a porcine-derived collagen membrane seeded with cultured autologous chondrocytes, eliminating the need for a periosteal patch. It remains a two-stage procedure requiring in-vitro expansion.
Question 2471
Topic: Knee Sports
When drilling the femoral tunnel during a medial patellofemoral ligament (MPFL) reconstruction, identifying Schöttle's point is critical to ensure near-isometric graft behavior. On a strict lateral radiograph, where is this point located?
Correct Answer & Explanation
. 1 mm posterior to the posterior femoral cortex extension line, 2.5 mm proximal to the posterior origin of the medial femoral condyle, and distal to Blumensaat's line
Explanation
Schöttle's point marks the radiographic femoral origin of the MPFL. It is located 1 mm anterior to a line extending the posterior femoral cortex, 2.5 mm distal to the posterior origin of the medial femoral condyle, and distinctly proximal to the level of the posterior aspect of Blumensaat's line. Placing the graft here avoids anisometry and abnormal patellofemoral tracking.
Question 2472
Topic: Knee Sports
Histological evaluation of the repair tissue one year following marrow stimulation (microfracture) for a full-thickness chondral defect of the medial femoral condyle will demonstrate a matrix composed predominantly of which type of collagen?
Correct Answer & Explanation
. Type I
Explanation
Marrow stimulation techniques like microfracture rely on releasing marrow elements to form a 'superclot' over the cartilage defect. The resulting repair tissue differentiates into fibrocartilage, which is predominantly composed of Type I collagen. This tissue is mechanically inferior and less durable than native hyaline cartilage, which is predominantly Type II collagen.
Question 2473
Topic: Knee Sports
The anterior cruciate ligament (ACL) is composed of distinct anteromedial (AM) and posterolateral (PL) bundles. Which of the following statements regarding their biomechanical behavior is most accurate?
Correct Answer & Explanation
. The AM bundle is tightest in flexion and serves as the primary restraint to anterior tibial translation at 90 degrees
Explanation
The anteromedial (AM) bundle of the ACL is tight in flexion and is the primary restraint to anterior tibial translation at 90 degrees of knee flexion. Conversely, the posterolateral (PL) bundle is tight in extension and is primarily responsible for providing rotatory stability to the knee.
Question 2474
Topic: Knee Sports
A 10-year-old skeletally immature male presents with lateral knee pain. Radiographs show a 15 mm osteochondritis dissecans (OCD) lesion on the lateral aspect of the medial femoral condyle. The physes are widely open. MRI reveals intact overlying cartilage with no high T2 signal fluid behind the lesion. What is the most appropriate initial management?
Correct Answer & Explanation
. Activity modification and restricted weight-bearing
Explanation
Juvenile Osteochondritis Dissecans (JOCD) in a patient with widely open physes and a stable lesion (no fluid behind the lesion on T2 MRI, intact cartilage) has a very high rate of spontaneous healing. The standard initial treatment is conservative management, which consists of activity modification, protected weight-bearing, and potential immobilization. Surgery is reserved for unstable lesions or failure of prolonged conservative treatment.
Question 2475
Topic: Knee Sports
A 24-year-old male presents with an acute knee dislocation (KD III-M) with complete tears of the ACL, PCL, and MCL. Vascular status is intact. When considering reconstruction versus repair of the MCL in this multi-ligament setting, what does the current evidence suggest regarding surgical management?
Correct Answer & Explanation
. Acute/subacute reconstruction of the MCL provides superior stability compared to direct repair in the setting of multiligamentous injury
Explanation
In multiligament knee injuries, recent literature (e.g., Stannard et al.) demonstrates that MCL reconstruction has significantly lower failure rates and provides superior stability compared to direct primary repair, especially for severe grade III tears in the setting of a multi-ligament injured knee.
Question 2476
Topic: 5. Sports Medicine
In fresh osteochondral allograft (OCA) transplantation for large full-thickness cartilage defects of the femoral condyle, what is the maximum recommended storage time at 4 degrees Celsius to maintain acceptable chondrocyte viability before implantation?
Correct Answer & Explanation
. 14-28 days
Explanation
Prolonged storage of fresh osteochondral allografts at 4 degrees Celsius results in decreased chondrocyte viability. Current tissue bank protocols using specialized media typically allow storage up to 28 days, balancing disease testing requirements with chondrocyte viability, which drops significantly after 28 days.
Question 2477
Topic: Knee Sports
During clinical examination of a knee, the dial test is performed at both 30 degrees and 90 degrees of flexion. An increase in external rotation of 15 degrees at 30 degrees of flexion, but NO increase in external rotation at 90 degrees of flexion, indicates injury to which of the following structures?
Correct Answer & Explanation
. Posterolateral corner only
Explanation
The dial test measures external rotation. Asymmetry of >10-15 degrees compared to the contralateral side is considered positive. A positive test at 30 degrees but normal at 90 degrees indicates an isolated posterolateral corner (PLC) injury. If the test is positive at both 30 and 90 degrees, it indicates a combined PCL and PLC injury.
Question 2478
Topic: Knee Sports
The Medial Patellofemoral Ligament (MPFL) is the primary restraint to lateral patellar translation. At what degree of knee flexion does the MPFL provide the greatest relative contribution to preventing lateral patellar displacement?
Correct Answer & Explanation
. 0 to 30 degrees
Explanation
The MPFL is the primary soft tissue restraint to lateral patellar displacement, contributing 50-60% of the restraining force at 0-30 degrees of knee flexion. As the knee flexes past 30 degrees, the patella engages the trochlear groove, and bony architecture becomes the primary stabilizer.
Question 2479
Topic: Knee Sports
Matrix-induced autologous chondrocyte implantation (MACI) involves harvesting chondrocytes, expanding them in vitro, and seeding them onto a membrane prior to implantation. Which type of collagen primarily constitutes the membrane used in current FDA-approved MACI implants?
Correct Answer & Explanation
. Type I and III collagen (porcine derived)
Explanation
The MACI implant utilizes a resorbable, porcine-derived type I and III collagen membrane. Autologous human chondrocytes are cultured and seeded onto this membrane before it is implanted into the cartilage defect.
Question 2480
Topic: Knee Sports
When drilling the femoral tunnel during Anterior Cruciate Ligament (ACL) reconstruction, positioning the tunnel too vertically (at the 12 o'clock position in the intercondylar notch) rather than lower (at the 10 o'clock or 2 o'clock position) results in which of the following biomechanical outcomes?
Correct Answer & Explanation
. Restores anterior-posterior stability but fails to restore rotational stability
Explanation
A vertical femoral tunnel (e.g., 12 o'clock position) poorly controls rotational instability. While it acts strictly in the sagittal plane and may correct the Lachman test (AP stability), it fails to control the pivot shift (rotational stability). A more anatomic, lower position on the lateral notch wall is necessary to restore both.
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