Biomechanical Results of Lateral Extra-articular Tenodesis Procedures of the Knee: A Systematic Review.

PURPOSE To systematically review and compare biomechanical results of lateral extra-articular tenodesis (LET) procedures. METHODS A systematic review was performed using the PubMed, Medline, Embase, and Cochrane databases. The search terms included the following: extraarticular, anterolateral, iliotibial, tenodesis, plasty, augmentation, procedure, reconstruction, technique, biomechanics, kinematic, robot, cadaver, knee, lateral tenodesis, ACL, Marcacci, Lemaire, Losee, Macintosh, Ellison, Andrews, Hughston, and Muller. The inclusion criteria were nonanatomic, in vitro biomechanical studies, defined as in vitro investigations of joint motion resulting from controlled, applied forces. RESULTS Of the 10 included studies, 7 analyzed anterior tibial translation and reported that isolated LET procedures did not restore normal anterior stability to the anterior cruciate ligament (ACL)-deficient knee. Seven of the 8 studies analyzing tibial rotation reported a reduction in internal tibial rotation across various flexion angles in the ACL-deficient knee when compared with the native state. Five studies reported a reduction in intra-articular graft force with the addition of an LET. Two studies evaluated length change patterns, graft course, and total strain range and found that reconstruction techniques in which the graft attached proximal to the lateral epicondyle and coursed deep to the fibular collateral ligament were most isometric. CONCLUSIONS In the ACL-deficient knee, LET procedures overconstrained the knee and restricted internal tibial rotation when compared with the native state. In addition, isolated LET procedures did not return normal anterior stability to the ACL-deficient knee but did significantly reduce anterior tibial translation and intra-articular graft forces during anteriorly directed loading. CLINICAL RELEVANCE Combined injury to the ACL and anterolateral structures has been reported to exhibit greater anterolateral rotatory instability when compared with isolated ACL injuries. Despite the reported risk of joint over-constraint, consideration should be given to reconstructing the anterolateral structures and the ACL concurrently to maximally restore both anterior tibial translation and rotatory stability.