[Distal femoral fixation of the iliotibial tract].

Two femoral fixation areas were defined in the distal iliotibial tract (ITT) system. They were named supracondylar insertion and insertion near the septum. Biomechanical studies on these insertions revealed tension peaks in the insertion near the septum with anterior translation of the knee, with varus stress and rotational movements. We conclude that the fibers inserting here are secondary restraints against anterior and lateral knee instability. 5 lateral extraarticular procedures were investigated to evaluate their biomechanical effect on knee instability. A standardized cadaver knee model was used with two basic experiments: an excentric quadriceps contraction from 0 to 90 degrees of flexion and an anterior translation with 100 N in 30 degrees of flexion. 5 knees were investigated for each procedure. Results from the excentric quadriceps contraction study imply reduced ACL strain with all extraarticular procedures except the Andrews tenodesis. The quantitative effect was related to the mechanical strength of the fixation of the ITT. All lateral procedures reduced ACL strain with anterior translation of the knee. The last part of the study included simultaneous registration of rotation and translation of the knee. We demonstrated a close relation of decreased ACL strain due to a lateral procedure and pathological external rotation of the knee. The knee no longer reached the physiological neutral rotation angle after an effective lateral tenodesis procedure. The significance of this effect is not clear at the present time.