Limited-Open Achilles Tendon Repair Using Locking Sutures Versus Nonlocking Sutures: An In Vitro Model.

BACKGROUND: Several limited-open Achilles tendon repair techniques that use locking or nonlocking sutures have been developed, but direct comparisons of in vitro mechanical properties have not yet been reported in the literature. It was our hypothesis that loads applied to the repaired Achilles tendon would be better resisted by limited-open techniques that use locking stitches compared with limited-open repairs that use nonlocking stitches. METHODS: The Achilles tendons of 31 fresh-frozen cadaver lower limbs were incised 4 cm proximal to the calcaneal insertion. Tendons were then repaired using 1 of 2 limited-open Achilles tendon repair tools, one using 3 nonlocking sutures and the other using a combination of locking and nonlocking sutures. Repaired specimens were cycled to 1000 cycles from 20 to 100 N and from 20 to 190 N followed by a single load to failure test. Nonparametric analyses were performed to compare the number of cycles to gapping and total load to failure between the 2 repair techniques. RESULTS: During cyclic loading, more cycles occurred prior to detection of 2-mm and 9.5-mm gaps in the locking suture construct compared with the nonlocking suture construct ( P = .012 and P = .005, respectively). There was no difference in the number of cycles to a gap of 5 mm ( P = .053). The locking suture construct also resisted a significantly greater load to failure compared with the nonlocking suture construct ( P < .001; median 385.0 and 299.6 N, respectively). CONCLUSION: Limited-open repair techniques using locking sutures provided greater construct strength under both cyclic and ultimate loads compared with a repair technique that used only nonlocking sutures. CLINICAL RELEVANCE: Limited-open Achilles tendon repairs using locking sutures are better able to resist forces simulating early accelerated rehabilitation than repairs using nonlocking sutures.