A Biomechanical Comparison of Different Tendon Repair Techniques

Previous studies have examined multiple suture techniques for the repair of ruptured tendons. In this study, we investigated how the two- and four-stranded Krackow suture weave techniques compared with a novel Krackow/Bunnell suture technique. Our hypothesis was that the Krackow/Bunnell suture would have greater strength compared with the two- and four-stranded Krackow suture in terms of resistance to pullout from the muscle tendon. Thirty fresh bovine Achilles tendons were assigned randomly to three groups: (1) two-stranded Krackow, (2) fourstranded Krackow, and (3) the Krackow/Bunnell combination. After suture placement, all specimens were subjected to initial cyclic loading (0-200 N for 200 cycles) and then the tension to failure force defined as the pullout through the muscle tendon was evaluated. Significantly greater deformation before suture failure was seen in the Krackow/Bunnell group compared with the four-stranded Krackow construct (36.2 vs. 28.7 mm, p = 0.009), as well as greater energy required to rupture the suture (4635 vs. 3346 N/mm; p = 0.016). There was no significant difference with regard to the force to failure between the two groups (four-stranded Krackow vs. Krackow/Bunnell). The two-stranded Krackow was found to be inferior to both the four-stranded Krakow and the Krakow/Bunnell techniques with regard to load to failure. We have found that the Krackow/Bunnell suture technique is at least comparable to, if not superior to, the four-stranded Krackow technique with regard to deformation before suture failure and energy required to rupture the tendon. Therefore, the Krackow/Bunnell technique may be an optimal construct if the surgeon is concerned about suture pullout through the tendon; however, future studies evaluating this technique in the clinical setting are required before making any final conclusions for patient use.