Linear Frictional Properties of a Barbed Suture in the Tendon Tissue

Abstract

Objective: The barbed suture has been around for some time with some important theoretical advantages for tendon repairs such as resistance to suture slippage and knotless application. However, these theoretical advantages are not yet proven to be practically important. The literature on the barbed suture for tendon repair has a focus on in-vivo or ex-vivo preclinical investigations of established tenorrhaphy methods. Current literature is poor in knowledge on its fundamental properties thus basic research. Our study attracts attention on the lack of basic research on barbed suture for tendon repair and investigates a barbed suture's linear frictional performance in the tendon. Methods: Thirty-two fresh frozen porcine forefoot digital flexor tendons were separated into four groups of eight tendons. In group 1 a barbed suture was introduced to the tendons 1 cm proximal to the distal cut-end and was advanced through the core of the tendon tissue leaving the distal cut-end at the core. In group 2 the suture was introduced in the same way purchasing 2 cm of tendon tissue, in group 3 and 4 the suture purchase length was 3 and 4 cm respectively. Ultimate tensile strength generated by anchorage of the barbs of the suture in the tendon tissue was assessed with a mechanical testing machine and the results were statistically compared between groups. Results: Mean ultimate tensile strength was found to be 5.4N for group 1, 7.45N in group 2, 4.87N in group 3 and 5.76N for group 4. Intergroup comparison was made with a data set corrected for suture purchase length which was obtained by dividing each sample's ultimate tensile value by the distance of suture purchase length accordingly. Statistical analysis with corrected data set revealed that group 1 versus 2 showed no difference whereas comparison of group 1 vs 3 and group 1 vs 4 showed a significant difference. Discussion: Our results showed that the frictional forces generated by the barbed suture were directly proportional to the suture purchase length only to some extent. Statistical analysis confirmed the direct linear relation between pullout strength and suture purchase length up to 2 centimeters of suture purchase. Pullout strength in samples with 3 and 4 centimeters of suture purchase showed deterioration. Conclusion: The tissue grasping strength of the barbed suture we tested in our study is not directly proportional to the suture purchase length. More basic research on barbed suture for tendon repair is needed to better understand how its theoretical advantages can be appreciated practically. Suture producing companies should investigate and produce barbed sutures specially tailored for tendon repair.