Biomechanical comparison of double grasping repair versus cross-locked cruciate flexor tendon repair

Abstract

Purpose: This study was conducted to compare the in vitro biomechanical properties of tensile strength and gap resistance of a double grasping loop (DGL) flexor tendon repair with the established four-strand cross-locked cruciate (CLC) flexor tendon repair, both with an interlocking horizontal mattress (IHM) epitendinous suture. The hypothesis is that the DGL-IHM method which utilizes two looped core sutures, grasping and locking loops, and a single intralesional knot will have greater strength and increased gap resistance than the CLC-IHM method.

Methods: Forty porcine tendons were evenly assigned to either the DGL-IHM or CLC-IHM group. The tendon repair strength, 2-mm gap force and load to failure, was measured under a constant rate of distraction. The stiffness of tendon repair was calculated and the method of repair failure was analyzed.

Results: The CLC-IHM group exhibited a statistically significant greater resistance to gapping, a statistically significant higher load to 2-mm gapping (62.0 N), and load to failure (99.7 N) than the DGL-IHM group (37.1 N and 75.1 N, respectively). Ninety percent of CLC-IHM failures were a result of knot failure whereas 30 % of the DGL-IHM group exhibited knot failure.

Conclusions: This study demonstrates that the CLC-IHM flexor tendon repair method better resists gapping and has a greater tensile strength compared to the experimental DGL-IHM method. The authors believe that while the DGL-IHM provides double the number of sutures at the repair site per needle pass, this configuration does not adequately secure the loop suture to the tendon, resulting in a high percentage of suture pullout and inability to tolerate loads as high as those of the CLC-IHM group.

Keywords: Biomechanical study; Flexor tendon repair.

Fig. 1

Schematic representation of CLC core suture (a), double grasping loop core suture (b), and IHM circumferential suture (c)

Fig. 2

Double grasping loop flexor tendon repair method: looped suture is initiated (a); passed through suture, looped, and tightened (b); advanced through grasped tendon portion to laceration site (c), attaining 10-mm purchase length of opposite segment (d); passed from lateral wall to central point (e); locked as inserted centrally returning to laceration site (f); and knotted within repair site with mirrored suture of opposite segment (g)

Fig. 3

Mean loads with 95 % confidence intervals at 0.5-, 1.0-, 2.0-, and 4.0-mm gapping levels and at loads to failure for both CLC-IHM and DGL-IHM repair methods (p ≤ 0.025)

Fig. 4

Stiffness measurements as resistance to gapping with p value of the CLC-IHM and DGL-IHM repair methods

Fig. 5

Methods of failure for core suture of the CLC-IHM and DGL-IHM repair methods (p < 0.01)

Fig. 6

Methods of failure for epitendinous suture of the CLC-IHM and DGL-IHM repair methods