Biomechanical properties of femoral posterior cruciate ligament fixations

The success of reconstructions of the posterior cruciate ligament (PCL) mainly depends on the fixation strength of the tendon-bone interface. Reliable data about the mechanical characteristics of PCL fixation techniques are sparse. The aim of this study was to investigate the biomechanical properties of different femoral PCL fixation techniques. Fresh human cadaver quadriceps (Q) and hamstring (H) tendons were harvested and fixed into porcine femora with a press-fit fixation suturing the tendon over a bone bridge (group A), a novel implant post-fixation (group B) or an interference screw fixation (group C). Each group consisted of 10 specimens. The constructs were cyclically stretched and eventually loaded until failure. Elongation during cyclic loading, stiffness, failure mode and maximum failure load was evaluated. Elongation during cyclical loading was significantly larger between the 1st and the 20th cycle than between the 20th and the 500th cycle in all groups (p < 0.05). Maximum failure load was 409 +/- A 71 (336-517) N in group QA, 456 +/- A 58 (347-510) N in group QB, 548 +/- A 116 (400-798) N in group QC, 472 +/- A 114 N (316-676 N) in group HA, 494 +/- A 98 N (371-668 N) in group HB and 498 +/- A 87 N (391-687 N) in group HC (significantly higher for QB compared to QA, p < 0.05). This is the first study investigating the biomechanical properties of femoral PCL fixations. Implant-free fixation techniques like press-fit or post-fixations are able to withstand equal biomechanical forces compared to interference screw fixation. The novel fixations described in this study can be considered as a reliable alternative for the reconstruction of PCL using either hamstring or quadriceps tendons.