Variations in meniscofemoral ligaments at anatomical study and MR imaging

Purpose To demonstrate variations in the meniscofemoral ligaments (ligament s of Wrisberg and Humphrey) at anatomical study and magnetic resonance (MR) imaging. Design Twenty-eight cadaveric knees were partially dissected for the examin ation of the meniscofemoral ligaments. One hundred knee MR examinations wer e reviewed by two experienced musculoskeletal radiologists. Proximal variat ions in the meniscofemoral ligaments at MR imaging were classified into thr ee types according to the attachment site: type I, medial femoral condyle; type II, proximal half of the posterior cruciate ligament (PCL); type III, distal half of the PCL. Distal variations were classified into vertical or oblique types according to the orientation of the intermediate signal at th e interface of the ligament and lateral meniscus. Results At anatomical study, six cases showed variations in the proximal in sertion site of the meniscofemoral ligaments. At MR imaging 93 cases had on e or more meniscofemoral ligaments, giving a total of 107 ligaments: 90 lig aments of Wrisberg and 17 ligaments of Humphrey. Forty-one ligaments of Wri sberg were type I, 28 type II, 19 type III, and with two indeterminate type , while 6 ligaments of Humphrey were type I and the remaining 11 were indet erminate. Seven cases showed no meniscofemoral ligament. Of the 107 menisco femoral ligaments, the distal insertion orientation was of vertical type in 10 ligaments, oblique type in 70 and unidentified in 27. Conclusion An understanding of the high incidence of meniscofemoral ligamen t variations may help in the interpretation of knee MR studies.