Adequate Failure Loads for Modified Lemaire Lateral Extra-articular Tenodesis Are Achieved With an Interference Screw, Staple, and Suture Anchor: A Biomechanical Study of Structural Properties

Background: A lateral extra-articular tenodesis (LET) is increasingly being utilized to augment an anterior cruciate ligament reconstruction because it has been shown to reduce the risk of postreconstruction graft failure or recurrent rotatory instability. Various femoral fixation techniques are available, including the use of an interference screw, staple, or suture anchor.

Purpose: To determine and compare the biomechanical properties of an LET graft when using an interference screw, staple, or suture anchor for the femoral fixation for a modified Lemaire LET.

Study design: Controlled laboratory study.

Methods: Eighteen fresh-frozen cadaveric knees were obtained and randomly assigned via a random group generator to undergo a modified Lemaire LET using either an interference screw, a staple, or a suture anchor for femoral fixation. The specimen underwent load-to-failure testing at 20 mm/min until graft failure. The maximum failure load, stiffness, and failure mode for each specimen were recorded.

Results: The mean failure load was highest for the interference screw (252.7 ± 131.2 N), followed by the staple (151.8 ± 34.1 N) and the suture anchor (105.7 ± 16.4 N). There was a significant difference in failure load between the interference screw and the suture anchor (P = .015). There was no significant difference between the staple and the interference screw (P = .101) or the suture anchor (P = .577). There was no significant difference in graft stiffness across all fixation methods (P = .089).

Conclusion: All 3 femoral fixation methods achieved adequate failure loads, although the interference screw had a greater failure load than the suture anchor and there was no significant difference between these implants and the staple. There were no significant differences in stiffness between the fixation methods.

Clinical relevance: The maximum failure load occurred with an interference screw for femoral fixation of a modified Lemaire LET; however, because of socket size, this implant may be at greater risk of anterior cruciate ligament reconstruction tunnel collision compared to a smaller-diameter suture anchor drill hole. The failure load of the suture anchor was the lowest; however, it appears sufficient for stable fixation based on the force experienced by an LET graft reported in the literature.