Comparative experimental study of biomechanical features of suture materials in tendon repair

Introduction Many different suture configurations and pathomorphology of tendon repair have been described for tendon repair over the past 20 years. However, the biomechanical properties of suture material at primary flexor tendon repair have not been sufficiently explored. A cyclic loading test is performed to evaluate the performance of the different sutures under repeated loading conditions simulating dynamic conditions in postoperative rehabilitation procedures. The objective was to compare the strength of suture materials under cyclic loading on a biological model of a tendon. Material and methods Eighty porcine digital flexor tendons were examined in a pilot study. The sutured tendons were tested with a universal testing machine. Tendon repair was produced using polypropylene in group I, braided polyamide suture in group II, complex polytetrafluoroethylene thread in group III and a thread of superelastic titanium nickelide in group IV. The standard Chang protocol was used for cyclic loading. Results The percentage of intact sutures was 25 % in group I and in group II, 80 % in group III and 85 % in group IV after completing the entire load cycle. A pairwise comparison showed suture disruption being more common for group I and group II as compared to group III and group IV. Irreversible gap was more common for group 1 as compared to group IV. Neither knot ruptures nor tissue cutting were seen in the groups. Discussion The topic of biomechanical properties of suture material remains poorly understood. Although static load testing is commonly used in current experimental studies and cyclic testing is suitable for simulating postoperative conditions. The search continues for the “ideal” suture material for flexor tendon repair to prevent tears and retain tensile properties until the repair reaches strength. Conclusion The threads of polytetrafluoroethylene and nickelide-titanium showed the best biomechanical properties for tendon repair in the form of linear strength, good elasticity and low plasticity of the suture material. There were no significant differences between polypropylene and braided polyamide threads.