A biomechanical study of different techniques in medial patellofemoral ligament reconstruction

Purpose: The purpose of this study was to compare the ultimate failure load, stiffness and elongation of 3 different MPFL patellar fixation techniques: suture anchor, sutured tendon (a semi-tunnel technique, the free ends were sutured) and folio tendon (a semi-tunnel technique, the folio ends were passed through by suture). Materials and methods: We used six fresh-frozen cadaveric knees, each of them was performed MPFL reconstruction by the three techniques orderly. We named them suture anchor group, sutured tendon group and folio tendon group. Suture anchor reconstruction was completed with 2 parallel 3.0-mm biocomposite suture anchors. Sutured tendon group: The free ends of the sutured tendon were pulled into patellar semi-tunnels. Folio tendon group: The two folded ends were pulled separately into the patellar semi-tunnels. After preconditioned each graft, we recorded maximum load, stiffness, and elongation. Results: The suture anchor group had lower mean failure load (222.17±5.19 N) than the sutured tendon (364.50±2.42 N) and folio tendon (367.83±5.00 N) group. Compared with the folio tendon (43.73±2.62 N/mm) group, the sutured tendon group (28.68±6.92 N/mm) had lower stiffness values. There was no significant difference in the ultimate load between the sutured tendon group (364.5±2.42 N) and the folio tendon group (367.83±5.00 N). But the most important finding was that the sutured tendon group’s elongation was longer than the folio tendon group in the initial phase of the test. Conclusions: The suture anchor group was found to be weaker than the sutured tendon and folio tendon group when compared the ultimate failure load. The overlength of the sutured tendon group in the initial phase of the test verified that the tendon slide relatively to the suture. Clinical relevance: This study compared the biomechanical properties of 3 methods for patellar graft fixation in MPFL reconstruction surgery. It supported the use of sutured tendon group would occurs the tendon slide relatively to the suture. The folio tendon method provided the strongest strength and could avoid tendon slide relatively to suture.