Biomechanical evaluation of varying the number of loops in a repair of a physiological model of Achilles tendon rupture.

BACKGROUND

Numerous suturing techniques have been described to treat Achilles tendon ruptures. No prior studies have evaluated frayed tendon ends on construct strength and whether this allows for less extensile exposure.

METHODS

Forty bovine Achilles tendons were divided into groups: 1 control and 4 experimental. Experimental groups were sectioned with ends frayed longitudinally in 2 mm intervals for 2 cm with no fraying for the control group. Four-stand Krackow sutures were used for repairs with 3 loops in the control group, 2 loops in frayed section for experimental groups, and varying numbers of loops (1-4) in healthy tendon. Samples were tested in loading cells at 100 N and 190 N for 1000 cycles. Gap width and maximum load failure were measured.

RESULTS

Gapping was <5 mm in controls at 100 N-190 N, significantly lower than experimentals. Greatest gapping occurred in groups with 1-2 loops in healthy tendon (10.9-13.9 mm). Most early catastrophic failures (5/8) occurred in groups with 1-2 loops in healthy tendon. Two failures at 100 N occurred in 1-loop healthy tendons. The least failures occurred in controls (2/8), at 190 N.

CONCLUSION

Suture loops incorporated into frayed tendon portions predisposed repairs to significantly greater gapping and lower maximal failure forces than 4-strand Krackow repairs in unfrayed tendons.

CLINICAL RELEVANCE: We cannot recommend attempting more limited exposures with sutures in frayed tendon as this may lead to early repair failure. We provided a physiologic model utilizing frayed tendon ends that resembles in vivo Achilles tendon rupture.