A new ligament was identified in controlling the anterolateral stability of the knee.
Recently the attention has been focused on the role of the anterolateral anatomic structures of the knee in the control of anterolateral stabilization. Several recent studies has suggested that the anterolateral ligament (ALL) plays an important role in controlling knee stability. However, other studies has shown that the ilio-tibial band could have a predominant action. Therefore there are still some controversies about the identification and the exact role of the different anatomic structures in the control of internal tibial rotation.
To identify an anatomic ligamentous structure located at the deep surface of the ilio-tibial band, which could have a role in tibial internal rotation control beside the anterolateral ligament.
Eleven fresh-frozen cadaveric knees underwent anatomical dissection using a standard dissection protocol. Dissection began with removing the skin on the lateral side of the knee, creating a large rectangular window. The ilio-tibial band was approached from posterior with progressive dissection of the inter-muscular septum and the lateral gastrocnemius muscle. After resection of the fat surrounding the distal septum and the posterior surface of the gastrocnemius tendon, a ligamentous structure was identified, inserted on the gastrocnemius tendon and the femur cortex proximally and the deep surface of the posterior longitudinal part of the ilio-tibial band distally. At this stage of the dissection, an internal rotational force was applied between 30 and 60 degrees of flexion, highlighting that this anatomic structure was coming under tension with the distal part of the ilio-tibial band. Then the distal insertion of the ilio-tibial band was detached from the Gerdy tubercle and progressively elevated proximally, with identification of the Kaplan fibers until the identification of the previous mentioned ligamentous structure which was dissected and measured.
In all the specimen cases, a clear ligament structure was identified between the femur and the deep surface of the ilio-tibial band. The identified ligament was measured. The proximal attachment of the ligament had an average width of 15.82 mm and the thickness was 0.88 mm. The proximal insertion was 8.1 mm distant from the distal intermuscular septum attachement, 20.3 mm from the lateral epicondyle and 63.2 mm from the center of the ilio-tibial distal Gerdy attachement. The length of the ligament was 21.7 mm on its proximal border and 26.9 mm on its distal border. The distal attachement of the ligament on the deep surface of the ilio-tibial band had an average width of 13.2 mm.
The anterolateral ligament is not the only anatomic structure controlling the anterolateral stabilization of the knee. Another well identified ligament attached from the gastrocnemius tendon and the immediate superior femoral cortex to the deep surface of the ilio-tibial band has been identified. This ligament makes a tenodesis effect on the distal part of the ilio-tibial band, controlling the internal rotation of the tibia. It should be considered when a reconstruction of the anterolateral structures is planned in addition to the intra-articular ACL reconstruction.