American Board of Internal Medicine (ABIM) Certification Practice Exam

How is a medial collateral ligament tear typically characterized on examination?

1. Pain with passive range of motion

2. Medial joint line tenderness and increased laxity

3. Posterior knee pain with swelling

4. Stable joint with no tenderness

The correct answer is: Medial joint line tenderness and increased laxity

A medial collateral ligament (MCL) tear is typically characterized by specific examination findings, among which medial joint line tenderness and increased laxity are notable. When assessing a suspected MCL injury, a clinician will often palpate the medial joint line and may elicit tenderness, indicating inflammation or injury to the ligament itself. Additionally, an increased laxity upon testing the ligament, often assessed with various stress tests such as the valgus stress test at both 0 and 30 degrees of knee flexion, can indicate a compromise of the MCL's integrity. This increased laxity occurs because the ligament's primary role is to stabilize the medial aspect of the knee, and when it is torn or stretched, the knee may demonstrate abnormal movement compared to the healthy side. In contrast, pain with passive range of motion might be present but is not specific to MCL tears, as it can occur in various knee pathologies. Posterior knee pain with swelling is more commonly associated with ligaments in the posterior compartment, like the posterior cruciate ligament. A stable joint with no tenderness would generally indicate that a significant injury such as an MCL tear is less likely, as MCL tears typically present with some degree of instability and tenderness to palpation.