The anterolateral ligament of the human knee: an anatomic and histologic study.

PURPOSE: The functional anatomy of the knee is frequently studied but remains incompletely understood. Numerous authors have described a structure in the lateral knee connecting the lateral femoral condyle with the lateral meniscus and tibial plateau. The goal of this study is to define the incidence, anatomy, and histology of this structure, the anterolateral ligament.

METHODS: The incidence of the ligament was determined in 30 consecutive patients undergoing total knee arthroplasty (TKA) for medial compartment osteoarthritis. The anatomy and histology were evaluated using 10 cadaveric knees.

RESULTS: The anterolateral ligament was noted to be present in all 40 knees. In all cases, it was noted to take origin near or on the popliteus tendon insertion and insert into the lateral meniscus and tibial plateau 5 mm distal to the articular surface and posterior to Gerdy's Tubercle. The average width of the relatively flat structure was 8.2 ± 1.5 mm, and the average length was 34.1 ± 3.4 mm. Histologic analysis revealed a discreet structure with a fibrous core surrounded by synovium. Fibers blended with the popliteus at its origin and with the lateral meniscus as it passed distally.

CONCLUSIONS: The anterolateral ligament may play a role in preventing anterior tibial translation. The role, if any, of this structure in meniscal stability and the pathology of meniscal tears remain unclear.

LEVEL OF EVIDENCE: Not applicable-Descriptive Anatomic Study.