Tears in the distal superficial medial collateral ligament: the wave sign and other associated MRI findings

Objective: To analyze the MRI characteristics of distal superficial medial collateral ligament (sMCL) tears and to identify features of tears displaced superficial to the pes anserinus (Stener-like lesion (SLL)).

Materials and methods: Knee MRI examinations at four institutions were selected which showed tears of the sMCL located distal to the joint line. MRIs were evaluated for a SLL, a wavy contour to the sMCL, and the location of the proximal sMCL stump. Additional coexistent knee injuries were recorded.

Results: The study included 51 patients (mean age, 28 years [sd, 12]). A SLL was identified in 20 of 51 cases. The proximal stump margin was located significantly (p < 0.01) more distal and more medial with a SLL (mean = 33 mm [sd = 11 mm] and mean = 6.5 mm [sd = 2.5 mm], respectively), than without a SLL (mean = 19 mm [sd = 16 mm] and mean = 4.8 mm [sd = 2.4 mm], respectively). Medial compartment osseous injury was significantly (p < 0.05) more common with a SLL (75%) than without a SLL (42%). The frequency of concomitant injuries in the group (ACL tear, 82%; PCL tear, 22%; deep MCL tear, 61%; lateral compartment osseous injury, 94%) did not differ significantly between patients with and without a SLL.

Conclusion: A distal sMCL tear should be considered when MRI depicts a wavy appearance of the sMCL. Distal sMCL tears have a frequent association with concomitant knee injuries, especially ACL tears and lateral femorotibial osseous injuries. A SLL is particularly important to recognize because of implications for treatment.