A biomechanical comparison of Achilles tendon suture repair techniques: Locking Block Modified Krackow, Kessler, and Percutaneous Achilles Repair System with the early rehabilitation program in vitro bovine model

Abstract

The Krackow technique has the advantage of high strength, though it is not minimally invasive. The "Locking Block Modified Krackow" (LBMK) peri-tendon fixation technique was designed for minimally invasive surgery. This study aimed to compare the biomechanics of LBMK with Kessler and Percutaneous Achilles Repair System (PARS) techniques using a simulated early rehabilitation program. Thirty-fresh bovine Achilles tendon specimens were randomly assigned to the LBMK, Kessler, and PARS groups (n = 10). In LBMK group, the main suture configuration was the LBMK technique, and the transverse suture was used as the secondary suture configuration. The Kessler group employed three suture configurations, two sagittal, one coronal plane. In the PARS group, two transverse and one locking sutures were placed at either end of the tendon. Each repaired specimen underwent two cyclic loading protocols (20-100N, 20-190N), 500 cycles, followed by measurement of the gap between the tendon ends. All specimens underwent a load-to-failure test at a 25mm/s stretching rate. After the first loading cycle, the average gaps of the LBMK, Kessler and PARS groups were 0.76 ± 0.44mm, 1.80 ± 0.82mm, and 2.66 ± 1.04mm, respectively. The LBMK group had a significantly reduced gap than the other groups (p < 0.01). The LBMK group gaps were all within 2mm. The Kessler and PARS groups had six, and two specimens within 2mm, respectively. After the second loading cycle, the average end gaps of the LBMK, Kessler, and PARS groups were 3.68 ± 1.08mm, 5.70 ± 0.89mm and 7.59 ± 1.26mm, respectively. The LBMK group had a significantly reduced average gap than the other groups (p < 0.01). The maximum load-to-failure was highest 732.8 ± 138N in the LBMK than the other groups (p < 0.01). The biomechanical strength of the LBMK suture was significantly greater than Kessler and PARS. The reduced gap in the LBMK group suggests superior resistance to gap formation, which may occur during early postoperative rehabilitation.