Iliotibial Band Tenodesis: A New Strategy for Attachment

Abstract

We investigated the changes in distance between Gerdy's tubercle on the tibia and points on the posterior two thirds of the lateral surface of the lateral femoral condyle and adjacent lateral femoral shaft in 15 cadav eric knees. A three-dimensional digitizer was used to quantify motion of the knee during flexion ranging from full extension to 120° of flexion. Four load states were applied: internal, external, and neutral rotation, and quadriceps muscles loads based on one third of values in the literature for maximal isometric quadriceps muscles moments. The femoral location most isometric to Gerdy's tubercle was found to be strongly influenced by the load state. A 1.0 cm wide iliotibial band tenodesis was mod elled by five straight lines arising from Gerdy's tu bercle and attaching to a simulated washer at the junction of the lateral femoral condyle and shaft. Using this model and the motion data obtained from the cadavers, we investigated the effects of quadri ceps muscles loading and external rotation of the knee on changes in the distances between these tibial and femoral attachments for each of the five lines. A 180° twist modelled into the tenodesis sig nificantly reduced the range of changes in distance (difference between the largest and smallest changes in distance among the lines for a given angle of flex ion) for both of these load states. Therefore, a 180° twist in the tenodesis can enhance isometry among the fibers of the tenodesis. This implies that a 180° twist can enhance load sharing among the fibers of the tenodesis and, therefore, enhance the overall strength of the tenodesis.