The anterolateral ligament of the knee: unwrapping the enigma. Anatomical study and comparison to previous reports

BACKGROUND: It has been suggested that the anterolateral ligament (ALL) of the knee may have importance in limiting rotational instability, and reconstruction may prevent a continued pivot-shift following anterior cruciate ligament surgery. However, the anatomy of this ligament has not been consistently reported in recent publications. We describe our experience of cadaveric dissection with reference to other published work. MATERIALS AND METHODS: Eleven fresh-frozen cadaveric knees were dissected using a standard technique. The ALL tissue was identified with internal rotation of the tibia and varus stress. Measurements were made using a digital caliper and details of the origin and insertion were recorded. RESULTS: The ALL was identified in ten of the 11 cadavers. The only specimen in which it was not identified was found to also have an anterior cruciate ligament deficiency. The mean dimensions were: length 40.1 (± 5.53) mm, width 4.63 (± 1.39) mm, thickness 0.87 (± 0.18) mm. The femoral origin was posterior and proximal to the lateral collateral ligament attachment in six knees, anterior and distal in three knees, and at the same site in one knee. The tibial insertion was a mean 17.7 (± 2.95) mm from Gerdy’s tubercle (GT) and 12.3 (± 3.55) mm from the fibula head (FH). This was 59.5 (± 5.44) % from GT to FH. CONCLUSIONS: This anatomical data adds to previous information about the ALL. Our results support the finding that the ALL is a capsular thickening with meniscal attachment. The findings will help to guide the further work required to define the indications for reconstruction and appropriate grafts.