Porcine tibia is a poor substitute for human cadaver tibia for evaluating interference screw fixation.
BACKGROUND: Animal tissues are commonly used in anterior cruciate ligament graft fixation studies. HYPOTHESIS: Porcine bones and tendons provide good surrogates for human cadaver tissues in the biomechanical evaluation of anterior cruciate ligament reconstruction. STUDY DESIGN: Randomized experimental study. METHOD: Three different tissue models-pure porcine (porcine graft fixed in porcine tibia, group 1), combination (human hamstring graft and porcine tibia, group 2), and pure human (human graft and tibia, group 3)-were compared using both cyclic-loading and subsequent single-cycle load-to-failure tests to assess the effect of graft and bone tissue source (porcine vs human) on the fixation strength of anterior cruciate ligament reconstruction. RESULTS: In the cyclic-loading test, the displacement (slippage) after 1500 cycles was 2.0 mm +/- 0.7 mm, 1.6 mm +/- 0.4 mm, and 4.4 mm +/- 1.9 mm for groups 1, 2, and 3, respectively (P <.001 between 1 and 2 vs 3). In the subsequent single-cycle load-to-failure test, the corresponding average yield loads were 668 N +/- 157 N, 962 N +/- 238 N, and 448 N +/- 98 N, all differences being statistically significant. CONCLUSIONS: In comparison to young human cadaver tibia, porcine tibia underestimate graft slippage and overestimate the failure load of the soft tissue graft in anterior cruciate ligament reconstruction. CLINICAL RELEVANCE: Porcine tibia does not provide a reasonable surrogate for human cadaver tibia for evaluating ACL reconstructions.