Onlay Suture Anchor Fixation of Lateral Extra-articular Tenodesis Yields Superior Results to Staple Fixation and is Non-Inferior to Interference Screw Fixation: A Biomechanical Study
E.S. Mameri, R. Gilat, Z. Khan, D. Kaplan, P. Gelber, J. ChahlaObjective:
To compare the biomechanical performance and failure mechanisms of three femoral fixation techniques for lateral extra-articular tenodesis (LET): staple fixation, interference screw fixation, and onlay all-suture anchor fixation.
Methods:
Twenty-four fresh-frozen cadaveric knees were randomized to LET fixation with a cortical staple, interference screw, or all-suture anchor (n=8/group). A standardized iliotibial band graft was fixed at the distal Kaplan fibers with the knee at 30° of flexion. Specimens underwent cyclic loading from 10-60N for 500cycles, followed by load-to-failure testing. Primary outcomes included cyclic elongation, displacement at maximum load, stiffness, ultimate load to failure, and mode of failure. Between-group comparisons were performed using analysis of variance or Kruskal–Wallis testing with post-hoc analysis.
Results:
Three specimens in the staple group failed prematurely during cyclic loading, whereas no early failures occurred in the other groups. Cyclic elongation parameters did not differ significantly among fixation methods (P>.05). Ultimate load to failure differed significantly between groups (P=.02). Suture anchor fixation demonstrated load-to-failure values that were not statistically different from interference screw fixation, and both interference screw and anchor yielded significantly greater values than staple fixation. Displacement at maximum load was greater for the anchor group compared with staple fixation (P = .05), indicating a less rigid construct under high loads.
Conclusions:
Suture anchor fixation is a viable femoral fixation strategy for LET, offering strength that is superior to stable and comparable to interference screws, while potentially avoiding risks associated with rigid implants and femoral tunnel convergence.