Biomechanical and clinical evaluation of a modified 3-loop pulley suture pattern for reattachment of canine tendons to bone

Abstract

Objective: To describe a modified 3-loop pulley suture pattern for the reattachment of canine tendons to bone along with a biomechanical comparison with the locking-loop suture.

Study design: In vitro biomechanical study and clinical case report.

Animals or sample population: Biomechanical study: 10 paired gastrocnemius tendons and calcaneii harvested from 5 canine cadavers.

Case report: a Doberman with avulsion of the gastrocnemius tendon of insertion.

Methods: Biomechanical study: paired tendons were reattached to the calcaneus with either a modified 3-loop pulley pattern or a locking-loop pattern. Tensile loading to failure was performed. A direct, non-contact, method of gap measurement, using digital video, was used to measure gap formation. Load required to initiate gap formation (defined as load at a 1 mm gap) and to produce a 3 mm gap was evaluated in addition to maximum load and gap at failure.

Results: Mean (+/-SEM) 1 mm gap loads were 31.0+/-4.2 and 17.2+/-2.5 N, mean 3 mm gap loads were 49.1+/-2.4 and 28.9+/-3.2 N, and mean maximum loads were 72.9+/-4.3 and 55.8+/-2.2 N for the modified 3-loop pulley suture and the locking-loop suture, respectively. These differences were statistically significant (P<.05). The gap at failure was similar for both repairs. The clinical case remained sound 7 months postoperatively.

Conclusions: A modified 3-loop pulley pattern is biomechanically superior to a locking-loop pattern for reattachment of the canine gastrocnemius tendon to bone and may be suitable for clinical use.

Clinical relevance: Tendon repairs with a gap >3 mm are reported to be at increased risk of rupture during the first 6 weeks postoperatively. A modified 3-loop pulley pattern resists gap formation better than a locking-loop pattern.