Scientific article
Influence of Locking Stitch Size in a Four-Strand Cross-Locked Cruciate Flexor Tendon Repair

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Purpose

The 4-strand cross-locked cruciate technique (Adelaide technique) for repairing flexor tendons in zone II is a favorable method in terms of strength and simplicity. The purpose of this study was to investigate the effects of varying the cross-lock stitch size in this repair technique. Outcomes measured were load to failure and gap formation.

Methods

We harvested 22 deep flexor tendons from adult pig forelimbs and randomly allocated them into 2 groups. After cutting the tendons at a standard point, we performed a 4-strand cross-locked cruciate repair using 3-0 braided polyester with either 2-mm cross-locks (n = 11) or 4-mm cross-locks (n = 11). All repairs were completed with a simple running peripheral suture using 6-0 polypropylene. Repaired tendons were loaded to failure and the mechanism of failure, load to failure, stiffness, and load to 2-mm gap formation were determined.

Results

All repairs failed by suture breakage; we noted no suture pullout. There was no difference in load to failure (71.7–71.1 N; p = .89) or stiffness (4.1–4.6 N/mm; p = .23) between the 2-mm cross-lock and the 4-mm cross-lock groups. There was a trend toward higher resistance to 2-mm gap formation with the 4-mm cross-locks (55–62.2 N; p = .07).

Conclusions

Four-strand cross-locked cruciate repairs with cross-lock sizes of 2 and 4 mm provide high tensile strength and are resistant to pullout. Repairs with 4-mm cross-locks tend to provide a more central load distribution and better gapping resistance than repairs with 2-mm cross-locks.

Section snippets

Materials and Methods

Many ex vivo animal models use porcine deep flexor tendons to investigate tendon repair constructs.2, 7, 16, 17, 18, 19, 20, 21, 22 Although previous investigators confirmed the resemblance of diameters and arrangement of flexor tendons in pig toes with those of human digits,23, 24 we felt the need to define an exact point of dissection to reliably mimic a zone II laceration in humans. Therefore, we dissected 6 forelimbs from adult pigs and re-examined the anatomy of the deep flexor apparatus.

Results

There was no pullout of the core suture. Of 22 repairs, 21 failed by breakage of the core suture at the knot; one failed by breakage of the thread 1 mm adjacent to the knot.

The load to failure was 71.7 N (±11.0 N) for group 1 (2-mm cross-locks) compared with 71.1 N (±11.8 N) for group 2 (4-mm cross-locks). Therefore, we noted no significant difference in load to failure (p = .89) (Fig. 4).

The load to 2-mm gap formation was 55 N (±8.7 N) for group 1 (2-mm cross-locks) compared with 62.2 N (±9.4

Discussion

According to Strickland,27 a well-constructed 4-strand repair in conjunction with a peripheral suture is capable of tolerating light composite grip during the healing period. However, modern early-active rehabilitation regimens may require high repair loads of up to 50 N17, 28 and a trend toward reduced splint usage is recognizable.29 Taking this into consideration and bearing in mind that unavoidable mishaps during the rehabilitation process might require additional repair strength, stronger

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