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- Author or Editor: Daniel J. Duffy x
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Abstract
OBJECTIVE
To evaluate effects of loop diameter of a modified Kessler locking-loop (LL) suture on in vitro tensile strength and gapping characteristics of canine flexor tendon repairs.
SAMPLE
48 cadaveric superficial digital flexor tendons from 24 adult medium- to large-breed dogs.
PROCEDURES
Flexor tendons were randomly assigned to 4 groups (n = 12/group) and repaired with 2-0 polypropylene in a LL pattern with loops measuring 1, 2, 3, or 4 mm in diameter. Biomechanical loads, gap formation between tendon ends, and failure modes were evaluated and compared between groups.
RESULTS
Increasing loop diameter from 1 to 4 mm significantly increased yield (P = .048), peak (P < .001), and failure (P < .001) loads. There were no significant differences in yield, peak, and failure loads between 1- and 2-mm loops. Load to 3-mm gap formation was significantly (P < .001) greater for 4-mm loops, compared with 1-, 2-, and 3-mm loops. Failure mode did not differ significantly among experimental groups, with 46 of 48 (96%) of constructs failing because of suture breakage.
CLINICAL RELEVANCE
Loop diameter of a LL suture pattern is an important biomechanical variable that influences construct biomechanics of canine tendon suture repairs. Loop diameters > 3 mm are recommended when the size of the tendon allows. Further studies are necessary to determine the in vivo effect of these findings, particularly the effects on tendon blood supply.
Abstract
OBJECTIVE
To evaluate the effect of a double Krackow suture pattern (DK), with and without epitendinous suture augmentation (ES), in a canine gastrocnemius tendon (GT) model.
SAMPLE
Paired GTs from 12 adult dog cadavers and 4 control GT.
PROCEDURES
GTs were assigned to 2 groups (n = 12/group). Transverse tenotomy was performed and repaired with a DK or DK + ES. Yield, peak, and failure force, stiffness, occurrence of 1-and 3-mm gapping, and failure mode were examined.
RESULTS
Yield, peak, and failure loads were greater for DK + ES. Yield force was 48% greater for DK + ES (mean ± SD, 149.56 ± 53.26 N) versus DK (101.27 ± 37.17 N; P = 0.017). Peak force was 45% greater for DK + ES P < 0.001). Failure force was 47% greater for DK + ES (193.752 ± 31.43 N) versus DK (131.54 ± 22.28 N; P < 0.001). Construct stiffness was 36% greater for DK + ES (P = 0.04). All 12 DK and 10 of 12 DK + ES repairs produced a 1-mm gap, with all DK and 4 DK + ES repairs producing a 3-mm gap (P < 0.001). Loads required to create a 3-mm gap were significantly greater for DK + ES (P < 0.013). Suture breakage occurred in all DK repairs, which differed from DK + ES, where suture breakage (7/12) and tissue failure (5/12; P = 0.037) predominated.
CLINICAL RELEVANCE
Augmentation of a primary DK repair with an ES significantly improved construct strength in canine GT constructs while increasing loads required to cause 1- and 3-mm gap formation, respectively. ES augmentation is a simple technique modification that can be used to significantly increase construct strength, compared with DK alone.
Abstract
OBJECTIVE
To compare the biomechanical properties and gapping characteristics following loop modification of a 3-loop-pulley (3LP) pattern in an ex vivo canine common calcaneal tendon (CCT) avulsion repair model.
SAMPLE
56 skeletally mature hindlimbs from 28 canine cadavers.
PROCEDURES
The CCTs were randomized to 1 of 4 experimental groups (n = 14/group) then sharply transected at the teno-osseous junction. Groups consisted of a 3LP, 4-loop-pulley (4LP), 5-loop-pulley (5LP), or 6-loop-pulley (6LP) pattern with loops placed 60° apart using size-0 polypropylene. Yield, peak, and failure loads, construct stiffness, loads to produce a 3-mm teno-osseous gap, and failure mode were evaluated and compared between groups.
RESULTS
Yield (P = 0.001), peak (P < 0.001), and failure loads (P < 0.001), construct stiffness (P < 0.001), and loads to 3-mm gap formation (P = 0.005) were all significantly greater for 6LP compared to all other groups. Mode of failure did not differ among groups (P = 0.733) with 75% (42/56) of repairs failing by mechanism of core sutures pulling through the tendinous tissue. Pattern modification by increasing the number of loops increased the repair site strength by 1.4, 1.6, and 1.8 times for 4LP, 5LP, and 6LP compared to 3LP, respectively.
CLINICAL RELEVANCE
Increasing the number of suture loops compared to a traditional 3LP repair is a relatively simple technique modification that significantly increases teno-osseous repair site strength and loads required to cause 3-mm gap formation. The results of this study justify further focused investigation of increasing the number of suture loops in vivo for teno-osseous CCT repair in dogs.
Abstract
OBJECTIVE
To evaluate the influence of superficial digital flexor tendon (SDFT) graft augmentation on the biomechanical properties and resistance to gap formation in a canine gastrocnemius tendon repair model.
SAMPLE POPULATION
28 canine cadaveric hind limbs.
PROCEDURES
Respective hindlimbs from each dog were randomized to one of two groups (n = 14/group) using a 3-loop–pulley (3LP) pattern alone or 3LP + SDFT graft augmentation. Biomechanical parameters evaluated included yield, peak, and failure loads; tensile loads required to create 1- and 3-mm gap formations; and mode of construct failure.
RESULTS
Mean yield and failure loads for the 3LP + SDFT graft group were 483.6 ± 148.0 N and 478.3 ± 147.9 N, respectively, and were greater compared to the 3LP group (34.2 ± 6.7 N and 34.0 ± 8.0 N, P < .0001). Loads to both 1- and 3-mm gap formations for the 3LP + SDFT graft group were greater compared to 3LP alone (P < .001). Failure modes did not differ between groups (P = .120), with constructs failing most commonly by suture pulling through opposed tendinous tissues whereas SDFT grafts remained intact.
CLINICAL RELEVANCE
SDFT graft augmentation increased yield, peak, and failure forces 14-fold across all examined biomechanical variables compared to the 3LP group. The 3LP + SDFT graft group required 3.6X and 6.5X greater loads to cause a 1- and 3-mm gap, respectively, between tendon ends. These data support the biomechanical advantages of SDFT graft augmentation to increase repair-site strength and to promote resistance to gap formation of the tenorrhaphy. Additional in vivo studies are required to determine the effect of SDFT augmentation on clinical function and active limb use after graft harvest in dogs.
