Evaluation of suture strength of asymmetric six-strands pennington suture in finger flexor tendon suture

Abstract

For the medical treatment of damage or ruptures in the flexor digital tendon, finger flexor tendon suture surgery is utilized. In previous studies, various core suture methods have indicated that important factors affect biomechanical properties, including the number of suture strands. In many suture methods, Fore-strands core suture and Six-strands core suture are used. Recently, asymmetric sutures have been reported to be effective in the gap formation. However, what has not been studied is the optimal asymmetry or required degree of asymmetry. Therefore, this study was aimed to evaluate the strength in asymmetric core sutures under cyclic load testing. Porcine flexor tendons were used in this study. We sutured porcine flexor tendons using combinations of six-strands Pennington suture and interlocking cross-stitch peripheral suture. This study looked at one symmetrical and five types of asymmetrical six-strands Pennington suture. In reference to the suture standard suture length (10 mm) from the end of the porcine flexor tendon, an asymmetric suture was shifted 1 mm, 2 mm, 3 mm, 4 mm and 5 mm from the reference position, respectively. This experiment was performed under cyclic load testing using an evaluation simulator our research group developed. A 2 N preload was applied to each of the sutured tendons. Tendons were tested with an initial load of 10 N for 500 cycles. If no evidence of failure was noted after the 500 cycles, the force was increased by 5 N for each additional 500 cycles. This procedure was continued until rupture. The sutured tendons were pulled at a constant distraction rate of 300 mm/min. As a result, tendons with 2 mm or more asymmetry had significantly greater the number of cycles to rupture than tendons with symmetry and with 3 mm or more asymmetry had significantly greater the number of cycles to rupture than tendons with asymmetry 1 mm. Tendons with 3 mm or more asymmetry had significantly less gap formation than tendons with symmetry. Furthermore, tendons with asymmetry 3 mm and 4 mm had significantly less gap formation than tendons with asymmetry 1 mm. Asymmetry 3 mm was the highest in both number of cycles to rupture and fatigue strength. Furthermore, it had the smallest value in the gap formation. Therefore, our results support that asymmetry 3 mm produces better beneficial had results compared to the others.

Keywords

• flexor tendon repair
• core suture
• number of cycles
• fatigue strength
• cyclic loading