MILD TO MODERATE MEDIAL COLLATERAL LIGAMENT (MCL) INJURIES OF THE KNEE: SONOGRAPHIC FINDINGS AND SONOGRAPHIC VALGUS STRESS TEST

Abstract

The purposes of this study are to describe the sonographic findings of the injured medial collateral ligament (MCL) of the knee, to perform a sonographic valgus stress test, and to correlate these findings in order to advance the proper treatment for these patients. We examined 23 patients with clinical diagnosis of MCL injury. We evaluated proximal and distal MCL thickness, free fluid, and avulsion fractures. In addition, we performed a sonographic valgus stress test in the stress and rest positions. We also examined the knee joint on the same side in 18 sex- and age-matched patients with no history of knee injury as a control. The average thickness of proximal MCL was 6.4 mm (range, 4.2–8.1 mm) in injured MCL and 4.3 mm (range, 3.2–6.2 mm) in normal MCL. The average thickness of distal MCL was 4.4 mm (range, 2.4–6.1 mm) in injured MCL and 3.1 mm (range, 2.1–4.1 mm) in normal MCL. The average joint space width of the injured knee at rest was 6.1 mm (range, 4.0–8.5 mm) and increased to 10.5 mm (range, 7.6–14.0 mm) after stress. The average joint space width of the normal knee at rest was 6.7 mm (range, 5.0–7.7 mm) and increased to 9.6 mm (range, 7.7–10.4 mm) after stress. In conclusion, the combination of the sonographic findings in MCL injury and the real-time sonography valgus stress test can support the clinical diagnosis and pinpoint the exact location of isolated MCL injury, thus advancing the proper treatment of the patient.