Biomechanical comparisons of suture and wedding tendon techniques

Objective: To examine the adequacy of surgical knots, including the modified Kessler and Bunnell suture techniques, and the Weston and Duncan knot techniques, which have not yet been examined in the literature but have only been used for arthroscopic surgery, were applied to the flexor tendons of sheeps. Suture adequacy was evaluated on the criteria of biomechanical stability and knot failure rate.Materials and Methods: The flexor digitorum profundus was isolated from both front limbs of 100 sheeps. A total of twenty-five groups were established. For each group, distraction was applied to eight tendons. Group K was set as our control group and all other groups underwent tenography. In the tenography groups, modified Kessler and Bunnell suture techniques were combined with Prolene 3.0 and 4.0 polypropylene suture, Ethibond 3.0 and 4.0 polyester suture, and Weston and Duncan surgical knots. Following the suturing of fresh cadaver sheep, the sheep tendons were subjected to continued elongation using an Instron instrument at a constant rate of 20 mm/min, until suture failure. Maximum tensile strength, elastic modulus values, and failure strains were recorded.Results: Amongst all of the groups subjected to tenography, the MKD3E group exhibited the highest maximum tensile strength, while the MKSL4P group exhibited the lowest tensile strength. The difference between the groups was statistically significant in terms of maximum tensile strength. Regarding the lowest values, BSL4E group was the closest group to MKSL4P group. The difference was statistically significant between all three groups. Within the tenography applied groups, the MKD3E group displayed the highest elastic modulus value, while the MKSL4P group exhibited the lowest value. Our control group, Group K, which was composed of healthy tendons, displayed the highest value of maximum tensile strength compared to the tenography applied groups; however, the elastic modulus value of this group was significantly lower than in all tenography applied groups. When failure strains were compared amongst the tenography applied groups, there was no failure of the knots in either the MKD3E or MKD3P groups. Overall, seventy-five percent of tenography-applied groups resulted in failure and twenty-five percent resulted in stripping.Conclusion: The maximum tensile strength and elastic modulus values of the group, in which modified Kessler suture technique was applied together with Duncan knot technique, were found to be significantly high when compared with the tenography applied groups. In addition, when assessed for failure strain, no snapping of the tendons was observed.Key words: Biomechanical stress; Duncan knot technique; Flexor tendon; Modified Kessler suture technique