Comparison of channel-assisted minimally invasive repair and 3 common Achilles tendon restoration techniques

The present study aimed to investigate the biomechanical comparison of channel-assisted minimally invasive restoration and three common Achilles tendon restoration techniques in an in vitro model via a progressive rehabilitation program. The 42 porcine tendons were randomly assigned to the following six groups of tendons (n=7/group): Achillon, percutaneous Achilles repair system (PARS), Krackow, channel-assisted minimally invasive repair (CAMIR), CAMIR augmentation (CAMIR⁺), CAMIR-5 (repair with No. 5 Ethibond suture). There was no significant difference in elongation among groups following the first 10 loading cycles, which consisted of 20-100 N at 1 Hz. The elongation of the CAMIR group (7.51±1.77 mm) was significantly longer than the Achillon group (3.19±0.57 mm) and PARS group (3.73±0.66 mm; P<0.05) following 1,000 cycles. However, the CAMIR group exhibited no significant difference vs. the Krackow (7.32±1.09 mm) and CAMIR⁺ groups (7.11±1.50 mm) following 1,000 cycles. Following 2,000 cycles, there was no significant difference between the CAMIR-5 (7.99±1.68 mm) group, and the Achillon (3.19±0.57 mm) and PARS groups (3.73±0.66 mm). At the point of restoration construct failure, the total cycles of the CAMIR group (median, 1,000; range, 1,000-1,000) were significantly less than the Achillon group (median, 2,000; range, 2,000-2,013) and PARS group (median, 2,000; range, 2,000-2,010; P<0.05), but had no significant difference compared with the Krackow group (median, 1,000; range, 1,000-1,000) and CAMIR⁺ group 1,000 (median, 1,000; range, 1,000-1,004). There was also no significant difference between the CAMIR-5 group (median, 2,000; range, 2,000-2,000), and the Achillon group (median, 2,000; range, 2,000-2,013) and PARS group (median, 2,000; range, 2,000-2,010). Restricted by the strength of suture, the one-suture CAMIR restoration technique was weaker than the three-suture Achillon and PARS restoration techniques, but there was no significant difference with the open Krackow restoration technique, which provides a reliable mechanical strength for repairing. CAMIR has an advantage of reducing the risk of suture reactivity.