The Three-Loop Pulley Suture Versus Two Locking-Loop Sutures for the Repair of Canine Achilles Tendons


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Address correspondence to Andy P. Moores, BVSc, Department of Clinical Veterinary Science, University of Bristol, Langford House, Langford, Bristol BS40 5DU, UK. E-mail:


Objective— To compare a 3-loop pulley suture pattern with 2 locking-loop sutures for the repair of components of the canine Achilles mechanism.

Study Design— In vitro biomechanical study.

Animals— Forty-eight paired tendons collected from 9 canine cadavers.

Methods— Paired tendons were repaired with either a 3-loop pulley suture or 2 locking-loop sutures and tensile tested to failure. To ensure accurate anastomosis gap measurement a direct, non-contact, method of gap measurement, using digital video, was devised. Load initiating gap formation (defined as load at a 1 mm gap) and load producing a 3 mm gap were evaluated in addition to maximum load, gap at failure, mode of failure, and time spent placing the sutures.

Results— Maximum load values were similar for both repairs. The mean 1 mm gap loads were 44.0 and 18.4 N, and the mean 3 mm gap loads were 56.3 and 34.7 N, for the 3-loop pulley pattern and the 2 locking-loops, respectively; these differences were statistically significant. The 3-loop pulley pattern was faster to place and resulted in a smaller gap at failure. All but 2 repairs failed by suture pull out.

Conclusions— The 3-loop pulley pattern is more resistant to gap formation during tensile loading, and is quicker to place, than 2 locking-loop sutures.

Clinical Relevance— Gap formation can significantly delay tendon healing. Tendon repairs with a gap >3 mm are reported to be at increased risk of rupture during the first 6 weeks postoperatively.