High Variability of Lateral Extra-articular Tenodesis Femoral Tunnel Position With Landmark-Based Techniques

Abstract

Background: The utilization of lateral extra-articular tenodesis (LET) augmentation for anterior cruciate ligament reconstruction has increased. Various fixation points have been recommended based on tactile and anatomic landmarks; however, there is limited reporting of the accuracy or precision of these techniques in clinical practice. Purpose/Hypothesis: The purpose of this study was to evaluate whether LET fixation points identified using anatomic landmarks and tactile techniques would fall within a predefined radiographic zone. It was hypothesized that the majority of LET fixation points would be inside the radiographic zone. Study Design: Cross-sectional study; Level of evidence, 4. Methods: Postoperative lateral knee radiographs of patients who underwent anterior cruciate ligament reconstruction with LET using a landmark-based technique without fluoroscopy between January 2018 and September 2023 were reviewed. Fixation points were measured by 2 raters based on their distance from an extension of the posterior femoral cortex line (PFCL) distally and a line perpendicular to the PFCL at the posterior condylar flare (PCF). Patients were excluded if the tunnel position could not be identified or if postoperative radiographs were malrotated. The mean LET position and percentage of points within the radiographic isometric zone, defined as 4 ± 4 mm posterior and 4 ± 3 mm anterior to the PFCL and 6 ± 4 mm distal and 20 ± 5 mm proximal to the PCF were calculated. Results: Complete data sets were obtained for 47 cases. The mean LET position was 6.4 ± 7.1 mm (range, –9 to 27.3 mm) anterior to the PFCL and 1.8 ± 7.6 mm (range, –16.7 to 12.6 mm) proximal to the PCF. Overall, 53% of LET fixation points were within the predefined radiographic zone. Of the malpositioned tunnels (n = 22), their locations relative to the radiographic zone were anterior (n = 18), posterior (n = 2), proximal (n = 1), and anterior and distal (n = 1). Conclusion: This study found large variation in the location of LET fixation points, and almost half of fixation points were outside the predefined radiographic zone. Accurate and precise tunnel placement is one of multiple factors that may be important to minimize the risk of lateral compartment overconstraint, anterior cruciate ligament graft failure, and anisometry leading to LET graft loosening.