Reconstruction of the medial patellofemoral ligament with double curved semi-patellar tunnels: A biomechanical study.

BACKGROUND

Multiple fixation techniques are available for securing the graft on the patellar side during medial patellofemoral ligament reconstruction. The double curved semi-patellar tunnels (DCST) method is a novel fixation technology, but its biomechanical properties have not yet been investigated.

METHODS

72 porcine patellae and bovine tendons were used to establish MPFL reconstruction models employing the three fixation methods: suture anchor (SA), single semi-patellar tunnel (SST), DCST. Load to failure and cyclic loading testing were performed to compare biomechanical performance among the groups.

FINDINGS: In the Load to failure testing, the DCST group demonstrated a higher ultimate failure load than both SST and SA (P = 0.006, P = 0.016). The DCST group showed lower maximum load elongation compared to SST group (P = 0.048), but not significantly different from SA (P = 0.147). Stiffness was greater with the DCST group than with SST and SA (P = 0.002, P = 0.003). Under cyclic loading, both SA and SST exhibited higher elongation compared to the DCST group (P = 0.007, P = 0.019). Failures of the DCST group were predominantly due to graft tear.

INTERPRETATION: All three fixation techniques provided stable graft fixation under the tested experimental conditions. The DCST technique provides higher initial fixation strength and stability in vitro. These results appear worthy of further clinical investigation.