Positioning of the cross-stitch on the modified Kessler core tendon suture

Biomechanical Evaluation of a Tubular Braided Construct for Primary Deep Flexor Tendon Surgery

PURPOSE

Immediate postoperative mobilization has been shown to avoid adhesion formation and improve range of motion after flexor tendon repair. A tubular braided construct was designed to allow for these rehabilitation protocols.

METHODS

In this ex vivo study, 92 ovine flexor tendons were divided randomly into 2 equal groups. After creating a transection, the tendons of the first group were repaired using a tubular braided construct. This construct, consisting of a tubular braid of polypropylene and polyethylene terephthalate fibers, exerts a grasping effect on the tendon ends. The control group received a multistrand modified Kessler repair with a looped polydioxanone suture (PDS) 4-0 suture and a Silfverskiöld epitendinous repair using an Ethilon 6-0 suture. After the repair, a static and an incremental cyclic tensile test was performed until failure.

RESULTS

During the static test, the tubular braid resulted in a significantly higher load at 3 mm gap formation (86.3 N ± 6.0 vs 50.1 N ± 11.6), a higher ultimate load at failure (98.3 N ± 12.7 vs 63 N ± 11.1), higher stress at ultimate load (11.8 MPa ± 1.2 vs 8.1 MPa ± 3.1), and higher stiffness (7.1 N/mm ± 2.9 vs 8.7 N/mm ± 2.2). For the cyclic tests, survival analyses for 1-, 2- and 3-mm gap formation and failure demonstrated significant differences in favor of the tubular braided construct.

CONCLUSION

The tubular braided construct withstands the required loads for immediate rehabilitation not only in static tests, but also during cyclic tests. This is in contrast with the control group, where sufficient strength is reached during static tests, but failures occur below the required loads during cyclic testing.

CLINICAL RELEVANCE

The tubular braided construct provides a larger safety margin for immediate intensive rehabilitation protocols.

Ex vivo biomechanical characteristics and effects on gap formation of using an internal fixation plate to augment primary three-loop pulley repair of canine gastrocnemius tendons

OBJECTIVE

To evaluate the effects of using an internal fixation plate to augment primary 3-loop pulley (3LP) repair of canine gastrocnemius tendons (GTs).

SAMPLE

48 cadaveric GTs from 24 adult dogs.

PROCEDURES

GTs were dissected free from other tissues, transected, and randomly assigned to 4 groups (n = 12/group). GTs were repaired with 2-0 polypropylene with a 3LP repair alone or a 3LP repair augmented with a 3-hole veterinary cuttable plate (3VCP), a 5-hole veterinary cuttable plate (5VCP), or a 7-hole veterinary cuttable plate (7VC P). Biomechanical loads, construct stiffness, gap formation, and failure modes were compared between groups.

RESULTS

Yield, peak, and failure loads were all significantly increased for the 5VCP and 7VCP groups, compared with the 3LP alone group. Increasing plate length from 3VCP to 5VCP and from 3VCP to 7VCP increased yield, peak, and failure loads. No differences were found between the 3LP and 3VCP groups with regard to yield and peak loads, but failure load was increased in the 3VCP group. Loads to create 1-mm and 3-mm gaps were significantly greater for the 5VCP and 7VCP groups, compared with the 3LP alone and 3VCP groups. Mode of plate attachment failure differed among groups.

CLINICAL RELEVANCE

Tendon plate augmentation may be a viable surgical option to increase the strength of the tenorrhaphy in dogs. However, in vivo studies evaluating the effects of plate augmentation on the tendon blood supply and progression of healing are needed prior to clinical application.

Effect of bite distance of an epitendinous suture from the repair site on the tensile strength of canine tendon constructs

OBJECTIVE

To evaluate effects of bite distance of an interlocking horizontal mattress epitendinous suture (IHMES) from the repair site on tensile strength of canine tendon repairs.

SAMPLE

72 canine cadaveric superficial digital flexor tendons (SDFTs).

PROCEDURES

Transverse tenotomy was performed, and SDFTs were repaired with a locking-loop construct (LL construct) or 3 LL constructs with IHMES suture bites placed 5 (LL + 5ES construct), 10 (LL + 10ES construct), or 15 (LL + 15ES construct) mm from the transection site (18 SDFTs/group). Constructs were loaded to failure. Load at 1- and 3-mm gapping, yield force, failure load, and failure mode were evaluated.

RESULTS

Mean ± SD yield force and failure load for LL constructs were significantly lower than for IHMES constructs. Load at 1- and 3-mm gapping was significantly higher for IHMES constructs. Increasing the bite distance significantly increased construct strength (134.4 ± 26.1 N, 151.0 ± 16.8 N, and 182.1 ± 23.6 N for LL + 5ES, LL + 10ES, and LL + 15ES constructs, respectively), compared with strength for the LL construct. Failure mode differed significantly among constructs when an IHMES was used.

CONCLUSIONS AND CLINICAL RELEVANCE

Addition of an IHMES to an LL construct led to increased ultimate tensile strength by 2.5 times and significantly reduced gap formation. Increasing the IHMES bite distance increased yield force by 2.1, 2.3, and 2.7 times for bites placed 5, 10, and 15 mm from the tenotomy, respectively. Positioning an IHMES at a greater distance from the repair site provided superior biomechanical strength for tendon repairs in dogs.

Effect of bite depth of an epitendinous suture on the biomechanical strength of repaired canine flexor tendons

OBJECTIVE

To determine effects of bite depth for placement of an epitendinous suture on the biomechanical strength and gap formation of repaired canine tendons.

SAMPLE

48 superficial digital flexor tendons (SDFTs) obtained from 24 canine cadavers.

PROCEDURES

Tendons were assigned to 3 groups (16 tendons/group). Each SDFT was transected and then repaired with a continuous epitendinous suture placed with a bite depth of 1, 2, or 3 mm for groups 1, 2, and 3, respectively. Specimens were loaded to failure. Failure mode, gap formation, yield force, peak force, and failure force were analyzed.

RESULTS

Yield, peak, and failure forces differed significantly between groups 1 and 3 and groups 2 and 3 but not between groups 1 and 2. Comparison of the force resisted at 1 and 3 mm of gapping revealed a significant difference between groups 1 and 3 and groups 2 and 3 but not between groups 1 and 2. Failure mode did not differ among groups; suture pull-through occurred in 43 of 48 (89.6%) specimens.

CONCLUSIONS AND CLINICAL RELEVANCE

Increasing bite depth of an epitendinous suture toward the center of the tendon substance increased repair site strength and decreased the incidence of gap formation. Repair of tendon injuries in dogs by use of an epitendinous suture with bites made deep into the tendon should result in a stronger repair, which potentially would allow loading and rehabilitation to begin sooner after surgery. Suture techniques should be investigated in vivo to determine effects on tendinous healing and blood supply before clinical implementation.