The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site.

BACKGROUND: Tibial fixation is more problematic than femoral fixation in anterior cruciate ligament reconstruction.

HYPOTHESIS: There is no difference in initial fixation strength among hamstring tendon graft tibial fixation devices.

STUDY DESIGN: Randomized experimental study.

METHODS: Each of six devices used to fix 120 quadrupled human semitendinosus-gracilis tendon grafts into porcine tibiae was tested 10 times with a single-cycle load-to-failure test and 10 times with a 1500-cycle loading test. Specimens surviving cyclic loading were subjected to a single-cycle load-to-failure test.

RESULTS: Intrafix (1332 N) was the strongest in the single-cycle load-to-failure test, followed by WasherLoc (975 N), tandem spiked washer (769 N), SmartScrew ACL (665 N), BioScrew (612 N), and SoftSilk (471 N). After cyclic-loading tests, Intrafix showed the lowest residual displacement (1.5 mm) and was also strongest (1309 N) in the single-cycle load-to-failure test after the cyclic-loading test, followed by WasherLoc (3.2 mm; 917 N).

CONCLUSION: The Intrafix provided clearly superior strength in the fixation of hamstring tendon grafts to the tibial drill hole.

CLINICAL RELEVANCE: Some caution may be warranted when using the implants that showed increased residual displacement, especially if aggressive rehabilitation is to be used. Preconditioning of the hamstring tendon graft-implant complex before tibial fixation is needed.