Effect of a continuous epitendinous suture as adjunct to three-loop pulley and locking-loop patterns for flexor tendon repair in a canine model

Biomechanical evaluation of three adjunctive methods of orthopedic tension band-wire fixation to augment simulated patella tendon repairs in dogs

OBJECTIVE

To evaluate the effects of three adjunctive methods of tension band wire fixation (TBWF) on the biomechanical properties, gap formation, and failure mode in simulated canine patella tendon rupture (RPT).

STUDY DESIGN

Randomized, ex vivo.

SAMPLE POPULATION

Paired hindlimbs from 32 dog cadavers.

METHODS

Patellar tendons (PTs) and associated bone-muscle-tendon units were harvested. Each PT was transected then sutured using a core locking loop and simple continuous epitendinous pattern. Each hindlimb was randomly assigned to one of three groups (n = 18 hindlimbs/group) using 18 gauge 316 L wire, anchored to the tibial crest distally, to perform transpatellar, suprapatellar, or combined tension band-wire (TBW) augmentation. Ten hindlimbs were utilized as control specimens. Yield, peak, and failure loads, stiffness, loads to 1 and 3 mm gap formation, and failure mode were evaluated.

RESULTS

Combined transpatellar and suprapatellar TBW augmentation was superior to transpatellar or suprapatellar groups alone. Yield (p = .0008), peak (p = .004), and failure loads (p = .005) were greater for the combined group than for the transpatellar (p = .048) and suprapatellar groups (p = .01) respectively. There was no difference regarding the occurrence of 1 or 3 mm gap formation (1 mm, p = .05; 3 mm, p = .06); however, loads required to cause gap formation were greater in the combined group (p = .036). Mode of failure differed between techniques used for PT augmentation (p < .001).

CONCLUSION

Combined transpatellar and suprapatellar adjunctive TBW augmentation for simulated PT repairs was biomechanically superior to either transpatellar or suprapatellar TBWF alone.

CLINICAL SIGNIFICANCE

Combined suprapatellar and transpatellar TBWF may offer a viable surgical option for increased repair-site strength and greater loads to gap formation. Further studies investigating alternative techniques and materials for RPT repair augmentation are warranted.

Reoperation Following Zone II Flexor Tendon Repair

BACKGROUND

The goal of zone II flexor tendon surgery is to perform a repair with sufficient strength to withstand the forces encountered during rehabilitation. Postoperative rerupture and adhesion formation may lead to reoperation. This study aimed to determine the factors associated with reoperation after primary zone II flexor tendon repair.

METHODS

In this retrospective case series, a total of 252 fingers in 201 patients underwent zone II flexor tendon repair. A medical record review was performed to collect data regarding patient demographics, injury and treatment characteristics and postoperative complications including reoperation. Reoperation was defined as any unplanned surgical procedure performed after initial flexor tendon repair.

RESULTS

There were 49 fingers (19%) in 42 patients that underwent reoperation at a median of 5.5 (interquartile range: 2.8-7.9) months. Older age, workers' compensation, and a Kessler-type repair of the flexor digitorum profundus were independently associated with reoperation.

CONCLUSIONS

In vitro studies suggest that Kessler-type repairs are inferior compared with other suture configurations. Our study demonstrates a clinical correlation to these biomechanical studies. Our results suggest that Kessler-type repairs are inferior compared with non-Kessler-type repairs, due to postoperative complications requiring secondary surgeries.

Comparison of 4 Different 4-Strand Core Suturing Techniques for Flexor Tendon Laceration: An Ex Vivo Biomechanical Study

BACKGROUND

Forces applied to the repaired flexor tendon should not exceed its yield force during early postoperative rehabilitation to prevent gapping and rupture. We aimed to biomechanically compare the tensile strengths and the 2-mm gapping of 4 different 4-strand core suturing techniques for flexor tendon repair.

METHODS

Fifty-six goat deep digital flexor tendons were repaired with the 4-strand double-modified Kessler, the 4-strand augmented Becker, the 4-strand Savage, and the 4-strand modified Tang techniques. All tendons were repaired with 4-0 polyester for core suture and 5-0 polyester for continuous epitendinous running suture. The specimens were subjected to static linear tensile testing by applying a single linear load-to-failure pull. After the linear load testing, the yield load, the ultimate strength of the repaired tendons, and the force exerted to yield a 2-mm gap were measured.

RESULTS

All peripheral sutures ruptured near the yield point. All core suture techniques were similar regarding the yield force. The augmented Becker 4-strand technique had the greatest ultimate strength (98.7 [82-125.3] N). The modified double Kessler technique was the weakest in resisting a 2-mm gap formation. The 4-strand modified Tang repair had the shortest (11.3 [7-15] minutes), while the 4-strand augmented Becker had the longest operative time (29 [23-33] minutes).

CONCLUSIONS

All 4 techniques demonstrated similar yield force, with differences in operative time, ultimate strength, and resistance to gapping. Future clinical studies can further elucidate their appropriateness for early active motion protocols.

Ex Vivo Biomechanical Assessment of Various Repair Techniques in a Rabbit Calcaneal Tendon Avulsion Model: Application of Polycaprolactone Plate

This study was aimed at evaluating the biomechanical properties and gapping characteristics of tendon repair methods using a combination of a three-loop pulley (3LP) pattern, a titanium plate, and a polycaprolactone (PCL) plate in a rabbit gastrocnemius tendon (GT) model (n = 50). GTs were randomly assigned to five groups (n = 10/group). Transected GTs were repaired with a 3LP pattern alone or in conjunction with an epitendinous suture (ES), a 5-hole 1 mm PCL plate, a 5-hole 2 mm PCL plate, or a 5-hole 1.5 mm titanium plate. The yield, peak, and failure force, as well as the occurrence and force of 1-mm and 3-mm gapping were examined. The mean yield, peak, and failure force of the 3LP + titanium plate group were higher than that of other groups. The biomechanical properties of a 3LP + a 2 mm PCL plate were similar to 3LP + ES constructs in this model. In all specimens in all groups, 1 mm gap formation was observed. The frequency of 3 mm gap formation was 70% and 90% in the 3LP + 2 mm PCL plate group and the 3LP + 1.5 mm titanium plate group, respectively. Additional studies evaluating PCL plates to determine the effect on the healing and blood supply of tendon are needed.

Biomechanical Comparison of a 3-Loop Pulley and a 4-Loop Pulley Suture for Tenorrhaphy in the Canine Gastrocnemius Tendon

OBJECTIVE

 The aim of this study was to compare a 3-loop pulley (3LP) suture pattern with a 4-loop pulley (4LP) suture pattern for the tenorrhaphy of the canine gastrocnemius tendon STUDY DESIGN:  Randomized, cadaveric, biomechanical study of 30 canine gastrocnemius tendons. Tendons were transected and repaired with either 3LP or 4LP suture pattern with 2-0 polypropylene. A tensile load was applied at 25 mm/min until construct failure. The load required to form a 1 mm gap, 3 mm gap and maximum load at failure was recorded and compared between groups.

RESULTS

 The estimated mean load to form a 1 mm gap for the 3LP and 4LP was 28.4 N (95% confidence interval [CI]: 24.0-32.6N) and 45.5 N (95% CI: 40.7-50.1N) respectively. The 4LP mean load to form a 1 mm gap was 17.1 N (95% CI: 11.7-22.5N) greater than the 3LP. The estimated mean load to form a 3mm gap for the 3LP and 4LP was 39.7 N (95% CI: 34.1-45.4N) and 55.0 N (95% CI: 49.3-60.9N) respectively. The mean load to form a 3mm gap was 15.3 N (95% CI: 8.5-21.9N) greater in the 4LP than the 3LP. The estimated mean load for failure in the 3LP and 4LP was 41.2 N (95% CI: 35.6-46.9 N) and 54.3 N (95% CI: 48.7-60.3 N) respectively.

CONCLUSION

 A 4LP pattern was biomechanically superior to a 3LP pattern, as demonstrated by a greater load required to form both a 1 and 3 mm gap and a greater load for failure CLINICAL SIGNIFICANCE:  A 4LP suture pattern better resists gap formation and requires greater load prior to construct failure compared with a 3LP, in this canine gastrocnemius model.

Effect of calcanean bone-tunnel orientation for teno-osseous repair in a canine common calcanean tendon avulsion model

Objective

To determine the influence of bone‐tunnel anchoring technique on teno‐osseous repair of the common calcanean tendon (CCT) in dogs.

Study design

Randomized, ex vivo, biomechanical.

Population

Forty‐two skeletally mature canine hindlimbs.

Methods

Canine hindlimbs were dissected to produce a model simulating avulsion of the CCT and accessory tendons from the calcaneus. Hindlimbs were randomized to 1 of 3 anchoring techniques (n = 14/group): a single transverse tunnel (TT), vertical tunnels (VT), or modified bone tunnels (MT) for teno‐osseous repair in a 3‐loop‐pulley (3LP) pattern using 0 USP polypropylene. Yield, peak and failure loads, construct stiffness, loads to produce a 3 mm teno‐osseous gap, and failure modes were compared between groups.

Results

The only difference detected consisted of TT constructs yielding at loads 25% higher than MT constructs (P = .027).

Conclusion

Although yield loads were lower in MT constructs than other groups, the bone‐tunnel anchoring techniques tested here did not appear to influence the biomechanical properties or gapping characteristics of teno‐osseous repairs in this canine CCT avulsion model.

Clinical significance

All drilling techniques and bone‐tunnel orientations tested in the study reported here offer viable options to reattach the CCT to the calcaneus. Surgeons should evaluate how bone‐tunnel orientation may affect placement of adjunctive fixation methods to stabilize the talocrural joint after primary CCT repair in dogs.

Zone II Flexor Pollicis Longus Repair: Thumb Flexion and Complications

Background: The aim of flexor pollicis longus (FPL) repair is to create a construct that is strong enough to withstand forces encountered during rehabilitation and to achieve an optimal active range of motion. The aim of this study was to: (1) assess factors influencing active thumb interphalangeal (IP) joint flexion; and (2) assess the factors associated with reoperation. Methods: Retrospectively, 104 patients with primary repair of a Zone II FPL laceration from 2000 to 2016 were identified. A medical chart review was performed to collect patient-, injury-, and surgery characteristics as well as the degree of postoperative active IP-flexion and occurrence of reoperation. Bivariate analyses were performed to identify factors influencing active IP-flexion and factors associated with reoperation. Results: The reoperation rate was 17% (n = 18) at a median of 3.4 months (range: 2.3-4.4). Indications for reoperation mainly included adhesion formation (n = 10, 56%) and re-rupture (n = 5, 28%). The median range of active IP-flexion was 30° (interquartile range [IQR]: 20-45) at a median of 12.4 weeks (IQR: 8.1-16.7). Solitary injury to the thumb (β = 17.9, P = .022) and the use of epitendinous suture (β = 10.0, P = .031) were associated with increased active IP-joint flexion. No factors were statistically associated with reoperation. Conclusions: About 1 in 5 patients undergo reoperation following primary repair of a Zone II FPL laceration, mostly within 6 months of initial surgery. The use of epitendinous suture is associated with greater active IP-flexion. Patients with multiple digits injured accompanying a Zone II FPL laceration have inferior IP-joint motion.

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.

Six-Strand Flexor Pollicis Longus Tendon Repairs With and Without Circumferential Sutures: A Multicenter Study

BACKGROUND

The purpose of this study is to assess outcomes in flexor pollicis longus tendon repairs with 6-strand core sutures with and without circumferential sutures.

METHODS

A 6-strand core suture technique with and without circumferential sutures was used. Thirty-three patients were summarized in the C group (circumferential group) and 16 patients in the NC group (non-circumferential group). After the surgery, the wrist was stabilized with a dorsal blocking splint and a controlled early active motion protocol was applied. At weeks 6, 13, and 26 data on demographics, type of injury, surgery, postoperative rehabilitation, complications such as re-rupture and the following outcome measurements were collected: range of motion and its recovery according to the Tang criteria, Kapandji score, thumb and hand strengths, Disabilities of the Arm, Shoulder and Hand score, and satisfaction.

RESULTS

There were no significant differences in range of motion and strength between the 2 treatment groups. In both groups, the outcome measurements increased over time and they expressed similar satisfaction with the surgical treatment. In 4 patients of the C group tendon repair ruptured and in 1 patient of the NC group.

CONCLUSIONS

Six-strand repair technique is an effective procedure to assure early active motion after flexor pollicis longus tendon injuries and good results can also be achieved by omitting the circumferential suture.

Effect of knot location on the biomechanical strength and gapping characteristics of ex vivo canine gastrocnemius tenorrhaphy constructs

OBJECTIVE

To evaluate the effect of knot location on the biomechanical strength and gapping characteristics of ex vivo canine gastrocnemius tenorrhaphy constructs.

SAMPLE

36 cadaveric gastrocnemius tendons from 18 adult dogs.

PROCEDURES

Tendons were randomly assigned to 3 groups (12 tendons/group) and sharply transected and repaired by means of a core locking-loop suture with the knot at 1 of 3 locations (exposed on the external surface of the tendon, buried just underneath the external surface of the tendon, or buried internally between the apposed tendon ends). All repairs were performed with size-0 polypropylene suture. All constructs underwent a single load-to-failure test. Yield, failure, and peak forces, mode of failure, and forces required for 1- and 3-mm gap formation were compared among the 3 knot-location groups.

RESULTS

Mean yield, failure, and peak forces and mean forces required for 1- and 3-mm gap formation did not differ significantly among the 3 groups. The mode of failure also did not differ significantly among the 3 groups, and the majority (33/36 [92%]) of constructs failed owing to the suture pulling through the tendinous substance.

CONCLUSIONS AND CLINICAL RELEVANCE

Final knot location did not significantly affect the biomechanical strength and gapping characteristics of canine gastrocnemius tenorrhaphy constructs. Therefore, all 3 evaluated knot locations may be acceptable for tendon repair in dogs. In vivo studies are necessary to further elucidate the effect of knot location in suture patterns commonly used for tenorrhaphy on tendinous healing and collagenous remodeling at the repair site.

Investigation of the effects of two-, four-, six- and eight-strand suture repairs on the biomechanical properties of canine gastrocnemius tenorrhaphy constructs

OBJECTIVE

To determine the effects of 2-, 4-, 6- and 8-strand suture repairs on the biomechanical properties of canine gastrocnemius tenorrhaphy constructs in an ex vivo model.

SAMPLE

56 cadaveric gastrocnemius musculotendinous units from 28 adult large-breed dogs.

PROCEDURES

Tendons were randomly assigned to 4 repair groups (2-, 4-, 6- or 8-strand suture technique; n = 14/group). Following tenotomy, repairs were performed with the assigned number of strands of 2-0 polypropylene suture in a simple interrupted pattern. Biomechanical testing was performed. Yield, peak, and failure loads, the incidence of 1- and 3-mm gap formation, forces associated with gap formation, and failure modes were compared among groups.

RESULTS

Yield, peak, and failure forces differed significantly among groups, with significantly greater force required as the number of suture strands used for tendon repair increased. The force required to create a 1- or 3-mm gap between tendon ends also differed among groups and increased significantly with number of strands used. All constructs failed by mode of suture pull-through.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that increasing the number of suture strands crossing the repair site significantly increases the tensile strength of canine gastrocnemius tendon repair constructs and their resistance to gap formation. Future studies are needed to assess the effects of multistrand suture patterns on tendon glide function, blood supply, healing, and long-term clinical function in dogs to inform clinical decision-making.

Ex vivo evaluation of novel core tenorrhaphy patterns in dogs

OBJECTIVE

To compare the biomechanical properties and gapping characteristics of four novel tenorrhaphy patterns in a canine flexor tendon model.

STUDY DESIGN

Ex vivo, randomized, biomechanical study.

SAMPLE POPULATION

Superficial digital flexor tendons of 60 forelimbs (30 dogs).

METHODS

Each tendon was transected 25 mm distal to its musculotendinous junction prior to tenorrhaphy with 2-0 polypropylene. Repair patterns included the three-loop pulley (3LP, control), exposed double-cross-lock (ExDCrL), embedded double-cross-lock (EmDCrL), triple-circle-lock (TCiL), and Modified-Tang patterns (MTang) were randomly assigned to each experimental group (n = 12/group). Yield, peak, and failure loads, gap formation and failure modes were compared.

RESULTS

Tendons repaired with ExDCrL (p < .0001), EmDCrL (p < .0001), and MTang (p < .0001) sustained yield, peak, and failure loads ~2.2x, ~2.0x, and ~1.9x, respectively, greater than those repaired with 3LP. Loads to 1 and 3 mm gapping were also higher for ExDCrL (p < .0001), EmDCrL (p < .0004), and MTang constructs (p < .0017) compared to 3LP. Although TCiL constructs sustained higher loads, their resistance to gap formation did not differ from that of 3LP repairs. Failure mode differed between groups (p < .0001), EmDCrL, ExDCrL, MTang, and TCiL constructs failing predominantly by suture breakage compared to 3LP repairs that failed by suture pull-through.

CONCLUSION

Use of novel patterns ExDCrL, EmDCrL, and MTang improved resistance to loads and gap formation and were biomechanically superior compared to 3LP in healthy canine tendon repairs.

CLINICAL SIGNIFICANCE

These results justify in vivo evaluation of ExDCrL, EmDCrL, or MTang pattern for tenorrhaphy in dogs.

Use of a Transarticular Calcaneo-Tibial Locking Plate for Temporary Immobilization of the Tarsocrural Joint following Surgical Repair of Common Calcaneal Tendon Rupture in Eight Dogs

OBJECTIVE

 The purpose of this clinical communication is to report the management of common calcaneal tendon rupture in dogs using a transarticular calcaneo-tibial locking plate as a method of temporary immobilization of the tarsocrural joint to support primary repair of the common calcaneal tendon.

STUDY DESIGN

 Dogs presented with partial or complete common calcaneal tendon rupture treated with primary tendon repair supported by the transarticular calcaneo-tibial locking plate technique from July 2016 to December 2019 were included. The tarsus was placed at a standing angle of 150 degrees and the pre-contoured Fixin locking 'L' or 'T' plate was medially applied with two locking screws inserted in the calcaneus and two screws inserted in the distal tibia. Tendon healing judgement was mostly based on clinical palpation and ultrasound examination was not performed in all the cases. Plates were removed in all dogs 6 weeks postoperatively.

RESULTS

 All tendons healed and no complications at the level of the tenorrhaphy were noted in the postoperative period. All dogs returned to hunting activity with full function of the affected limb. No major complications requiring revision surgery were observed. Minor complications occurred in two cases; osteomyelitis and screw pull-out.

CONCLUSION

 The use of a transarticular calcaneo-tibial locking plate for temporary immobilization of the tarsocrural joint after surgical repair of common calcaneal tendon rupture appears to be an effective technique with comparable results to other reported techniques.

Ex vivo mechanical testing of various suture patterns for use in tendon plating

OBJECTIVE

To determine the influence of suture patterns on resistance to gap formation after tendon plating STUDY DESIGN: Ex vivo study SAMPLE POPULATION: Suspensory ligament and superficial and deep digital flexor tendons harvested from 16 neonatal cadaver foal limbs.

METHODS

Each tendon/ligament from a given limb was randomly assigned to one of three treatment groups consisting of a 7-hole veterinary cuttable plate fixed with alternating simple interrupted, figure-8, or hybrid suture patterns. The constructs were distracted at a rate of 1.0 mm/s to failure, as determined by the formation of a 1 mm gap for initial failure and a 3 mm gap for ultimate failure. The mode of failure was also recorded.

RESULTS

Constructs prepared with hybrid and figure-8 patterns sustained over 2× higher (p < .01) forces before gap formation compared to those prepared with a simple interrupted pattern. No difference was identified between tendons whose plate was secured with hybrid or figure-8 suture patterns. Mode of failure between groups did not differ.

CONCLUSION

The figure-8 and hybrid patterns described herein improved the resistance to gap formation of plated tendons compared to an alternating simple interrupted pattern described previously.

CLINICAL SIGNIFICANCE

Figure-8 and hybrid patterns should be considered over simple interrupted patterns to improve resistance to gap formation in horses undergoing tendon plating.

Effect of epitendinous suture caliber on the tensile strength of repaired canine flexor tendons

OBJECTIVE

To determine the effect of epitendinous suture (ES) caliber on the tensile strength of flexor tendon repairs in cadaveric specimens from dogs.

SAMPLE

60 cadaveric superficial digital flexor tendons (SDFTs) from 30 skeletally mature dogs.

PROCEDURES

Specimens were randomly assigned to 5 suture caliber groups (n = 12 SDFTs/group). After sharp transection, SDFTs were repaired by placement of a simple continuous circumferential ES created with size-0, 2-0, 3-0, 4-0, or 5-0 polypropylene suture. Constructs were preloaded to 2 N and load tested to failure. Loads at yield, peak, and failure and mode of failure were compared among groups by statistical methods.

RESULTS

Yield, peak, and failure loads for SDFT repair constructs were positively correlated with ES caliber and did not differ between the size-0 and 2-0 groups on pairwise comparisons. Yield load was significantly greater for size-0, 2-0, and 3-0 groups than for the 4-0 and 5-0 groups. Peak and failure loads were significantly greater for the size-0 and 2-0 groups than for the remaining groups. Most size-0 (12/12), 2-0 (12/12), and 3-0 (10/12) group constructs failed because of ES pull-through; several constructs in the 4-0 group (5/12) and most in the 5-0 group (11/12) failed because of ES breakage.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested size-0 and 2-0 sutures should be considered when placing an ES for flexor tendon repairs in dogs. However, in vivo studies are needed determine the effects of increasing ES caliber on clinical outcomes for dogs undergoing these procedures.

Biomechanical evaluation of a novel barbed suture pattern with epitendinous suture augmentation in a canine flexor tendon model

OBJECTIVE

To determine the effect of a novel barbed suture pattern (NBSP) compared to a three-loop-pulley (3LP) with and without epitendinous suture (ES) augmentation on the biomechanical strength and gap formation of repaired canine tendons.

STUDY DESIGN

Ex vivo, cadaveric, randomized, experimental study.

SAMPLE POPULATION

Forty, adult superficial digital flexor tendons (SDFT).

METHODS

SDFT were randomly assigned to one of four groups (n = 10/group). Sharp tenotomy was performed and repaired with 3LP, NBSP, 3LP + ES, and NBSP + ES. Constructs were tested to failure while evaluating yield, peak, and failure loads, loads at 1 and 3 mm gap formation, and failure mode.

RESULTS

Constructs augmented with ES sustained 80% greater yield (p < .001), peak (p < .001), and failure (p < .001) loads, with no difference between 3LP + ES and NBSP + ES constructs regarding peak (p = .614), and failure forces (p = .865). Loads resulting in 1 and 3 mm gap formation were greater when constructs were augmented with an ES (p ≤ .003). Failure mode differed between groups (p < .001), occurring predominantly due to suture pull-through in 3LP and NBSP groups compared to tissue failure distant to the repair site in ES augmented constructs.

CONCLUSION

Tendons repaired with the NBSP used in this study resisted similar forces as those repaired with 3LP. Augmentation with an ES improved the biomechanical properties of repaired constructs, including resistance to gap formation.

CLINICAL RELEVANCE

The NBSP repair tested here may be advantageous over monofilament suture repair as it uses a similar-sized barbed core suture but eliminates the requirement for knot tying.

Biomechanical analysis of accessory tendon graft augmentation for primary gastrocnemius tendon reconstruction in dogs

OBJECTIVE

To evaluate the effect of accessory tendon graft (ATG) augmentation as an adjunct to a core locking-loop (LL) and epitendinous suture (ES) repair in a gastrocnemius tendon (GT) model.

STUDY DESIGN

Randomized, ex vivo, biomechanical.

POPULATION

Twenty-two canine GT musculotendinous constructs.

METHODS

GT repair constructs were randomly divided into two groups (n = 10/group). After transection, paired GT were repaired with LL + ES alone or with concurrent ATG augmentation. Yield, peak and failure loads, tensile loads required to create 1 and 3 mm gapping, and failure modes were evaluated. Four GT were used as intact controls for validation of testing methodology. ATG constructs were compared to LL + ES and control specimens.

RESULTS

Yield (p < .0001), peak (p = .0001) and failure loads (p = .0003) were greater when ATG was used for repair. Greater force was required to cause 1 mm (p = .0001) and 3 mm (p = .0002) gap formation in the ATG group, however, the frequency of gap formation did not differ between groups. All repaired constructs failed exclusively by suture pull-through.

CONCLUSION

Autologous ATG augmentation as an adjunct to primary GT repair increased yield, peak and failure forces by approximately 1.6×, 1.9×, 1.8× respectively and required 2.1× greater force to cause 1 and 3 mm formation respectively compared to LL + ES repairs alone.

CLINICAL SIGNIFICANCE

ATG augmentation should be considered as an autologous method to support and strengthen the primary GT repair. These results justify studies to determine the effect of ATG on clinical function following graft harvest in dogs.

Ex Vivo Biomechanical Assessment of a Novel Multi-Strand Repair of Canine Tendon Lacerations

OBJECTIVE

 This study aimed to evaluate the effect of increasing the number of suture strands traversing the transection site, level of suture purchase and depth of suture penetrance on the biomechanical properties of repaired gastrocnemius tendons.

STUDY DESIGN

 Thirty-eight adult cadaveric gastrocnemius tendons were randomized, transected and repaired with either two-, four- or six-strand locking multi-level repair. Tensile loads required to create a 1 and 3 mm gap, yield, peak and failure loads and failure mode were analysed. Significance was set at p < 0.05.

RESULTS

 Mean ± standard deviation yield, peak and failure force for six-strand repairs was 90.6 ± 22.1 N, 111.4 ± 15.2 N and 110.3 ± 15.1 N respectively. This was significantly greater compared with both four-strand (55.0 ± 8.9 N, 72.9 ± 7.8 N and 72.1 ± 8.2 N) and two-strand repairs (24.7 ± 8.3 N, 36.5 ± 6.0 N and 36.1 ± 6.3 N) respectively (p < 0.001). Occurrence of 3 mm gap formation was significantly less using six-strand repairs (p < 0.001). Mode of failure did not differ between groups with all repairs (36/36; 100%) failing by suture pull-through.

CONCLUSION

 Pattern modification by increasing the number of suture strands crossing the repair site, increasing points of suture purchase from the transection site and depth of suture penetrance is positively correlated with repair site strength while significantly reducing the occurrence of gap formation in a canine cadaveric model. Additional studies in vivo are recommended to evaluate their effect on tendinous healing, blood supply and glide resistance prior to clinical implementation.

Evaluation of a continuous locking novel epitendinous suture pattern with and without a core locking-loop suture on the biomechanical properties of tenorrhaphy constructs in an ex vivo model of canine superficial digital flexor tendon laceration

OBJECTIVE

To evaluate the effect of a continuous locking novel epitendinous suture (nES) pattern with and without a core locking-loop (LL) suture on the biomechanical properties of ex vivo canine superficial digital flexor tendon (SDFT) tenorrhaphy constructs.

SAMPLE

54 cadaveric forelimb SDFTs from 27 musculoskeletally normal adult dogs.

PROCEDURES

Tendons were assigned to 3 groups (18 SDFTs/group): sharply transected and repaired with a core LL suture alone (group 1), an nES pattern alone (group 2), or a combination of a core LL suture and nES pattern (group 3). All constructs underwent a single load-to-failure test. Yield, peak, and failure loads; gap formation incidence; and mode of failure were compared among the 3 groups.

RESULTS

Mean yield, peak, and failure loads differed significantly among the 3 groups and were greatest for group 3 and lowest for group 1. Mean yield, peak, and failure loads for group 3 constructs were greater than those for group 1 constructs by 50%, 47%, and 44%, respectively. None of the group 3 constructs developed 3-mm gaps. The most common mode of failure was suture pulling through the tendon for groups 1 (12/18) and 2 (12/18) and suture breakage for group 3 (13/18).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested augmentation of a core LL suture with an nES pattern significantly increased the strength of and prevented 3-mm gap formation at the tenorrhaphy site in ex vivo canine SDFTs. In vivo studies are necessary to assess the effectiveness and practicality of the nES pattern for SDFT repair in dogs.

Effect of suture caliber on the tensile strength of tenorrhaphies in cadaveric canine tendons

OBJECTIVE

To evaluate the effect of suture caliber on the tensile strength of tenorrhaphies performed with a locking-loop technique in cadaveric canine tendons.

SAMPLE

60 superficial digital flexor tendons (SDFTs) from 30 cadaveric adult dogs.

PROCEDURES

Transverse tenotomy was performed, and SDFTs were repaired with a locking-loop technique and polypropylene suture of 5 randomly assigned calibers: size-0, 2-0, 3-0, 4-0, or 5-0 (n = 12 SDFTs/suture caliber). Tendon constructs were tested to failure. Yield, peak, and failure forces and causes of failure were compared between groups.

RESULTS

Mean ± SD failure force for the constructs was significantly greater with large-caliber suture (size-0: 73.5 ± 3.1 N; size 2-0: 54.4 ± 7.1 N; size 3-0: 28.7 ± 4.9 N; size 4-0: 18.7 ± 3.4 N; and size 5-0: 8.8 ± 2.8 N). The likelihood of construct failure by suture pullout through the tendon substance increased with large-caliber suture (size-0: 12/12), whereas the likelihood of construct failure by suture breakage increased with small-caliber suture (2-0: 10/12; 3-0, 4-0, and 5-0: 12/12 each).

CONCLUSIONS AND CLINICAL RELEVANCE

Large-caliber suture had greater tensile strength for tenorrhaphies performed with a locking-loop technique in cadaveric canine tendons. Prior to the use of large-caliber suture in patients requiring tenorrhaphy, however, in vivo studies are required to confirm the results obtained here.

Influence of barbed epitendinous sutures combined with a core locking-loop suture to repair experimental flexor tendon lacerations

OBJECTIVE

To determine the influence of barbed epitendinous sutures (ES) on the biomechanical properties and gap formation of repaired canine tendons.

STUDY DESIGN

Ex vivo, experimental study.

SAMPLE POPULATION

Eighty (n = 16/group) canine superficial digital flexor tendons (SDFT).

METHODS

After transection, SDFT were repaired with a locking-loop (LL) pattern alone (group 1), an LL + smooth ES with monofilament suture (group 2), an LL + V-loc-ES (group 3), an LL + Quill-ES (group 4), or an LL + Stratafix-ES (group 5). All core LL repairs were performed with 0 USP polypropylene, and all ES were placed with 2-0 USP equivalent. Constructs were preloaded and tested to failure. Yield, peak, and failure loads; occurrence of gap formation; and failure modes were compared.

RESULTS

Yield loads were greater for groups 2 and 5 (P < .0001). Peak and failure loads were greater when an ES was used (P < .005), especially for groups 2 and 5 (P < .0001). Groups with an ES required higher loads to generate 1- and 3-mm gaps compared with specimens without an ES (P < .002). Force to create 1- and 3-mm gaps was greater for group 5 (P < .0001) and groups 2 and 5 (P < .0001), respectively. Failure mechanism did not differ (P = .092) between ES groups, consisting of suture breakage in 51 of 64 constructs compared with pull-through in seven of 16 group 1 constructs.

CONCLUSION

Epitendinous suture placement improved the biomechanical properties of repaired tendons. Stratafix barbed suture performed better as an ES compared with other barbed sutures and similarly to monofilament suture.

CLINICAL SIGNIFICANCE

Stratafix barbed suture eliminates the requirement for knot tying and seems to be equivalent to smooth monofilament suture when used as an ES in this pattern.

Effect of partial vs complete circumferential epitendinous suture placement on the biomechanical properties and gap formation of canine cadaveric tendons

OBJECTIVE

To determine the effect of partial vs complete circumferential epitendinous suture (ES) placement in addition to a core suture on the biomechanical strength and gapping characteristics of repaired canine tendinous constructs.

STUDY DESIGN

Ex vivo, biomechanical study.

SAMPLE POPULATION

Thirty-six canine superficial digital flexor tendons.

METHODS

Superficial digital flexor tendons were randomly assigned to three groups (n = 12), sharply transected and repaired with a core locking-loop suture with Group 1 a partial circumferential ES, 180° on the palmar side; Group 2 a complete circumferential ES, 360° and double knotting technique; or Group 3 a complete circumferential ES, 360° and single knotting technique. After preloading, constructs were distracted to monotonic failure. Failure mode, gap formation, yield, peak, and failure forces were analyzed.

RESULTS

Mean yield (group 1 = 68.6 N, group 2 = 106.5 N, group 3 = 114 N, P < .013), peak (group 1 = 92.8 N, group 2 = 134.6 N, group 3 = 147.3 N; P < .001), and failure (group 1 = 88.7 N, group 2 = 133.0 N, group 3 = 145.5 N, P < .001) loads differed between groups. No difference in yield (P = .874), peak (P = .434), or failure load (P = .434) was detected between complete circumferential ES groups. Force to create 1-mm (P < .001) and 3-mm (P < .038) gap formation was greater in specimens with complete vs partial circumferential ES placement. Complete circumferential ES repairs failed primarily by suture pull-through compared with suture breakage in most partial circumferential ES constructs.

CONCLUSION

Addition of a complete circumferential ES with a single or double knotting technique increased the biomechanical strength of normal tendon repairs while reducing gap formation compared with partial ES placement alone.

CLINICAL SIGNIFICANCE

Complete circumferential ES is recommended over partial ES placement.

Assessment of skin staples for augmentation of core tenorrhaphy in an ex vivo model of canine superficial digital flexor tendon laceration

OBJECTIVE

To compare the biomechanical strength and incidence of gap formation among canine superficial digital flexor tendon (SDFT) constructs that underwent core tenorrhaphy only and those in which the core tenorrhaphy was augmented with skin staples or a continuous Silfverskiold cross-stitch (SXS) suture pattern.

SAMPLE

42 cadaveric forelimb SDFTs from 21 musculoskeletally normal dogs.

PROCEDURES

Tendons were randomly assigned to 3 groups (14 SDTFs/group), sharply transected, and repaired with a core locking-loop suture alone (group 1) or augmented with circumferential placement of skin staples (group 2) or a continuous SXS suture pattern (group 3) in the epitenon. All constructs underwent a single load-to-failure test. Yield, peak, and failure loads, incidence of gap formation, and mode of failure were compared among the 3 groups.

RESULTS

Mean yield, peak, and failure loads differed significantly among experimental groups and were greatest for group 3 and lowest for group 1 constructs. The incidence of gap formation differed among the tested groups and was lowest for group 3 and highest for group 1. The most common mode of construct failure was the suture pulling through the tendon for group 1, staple deformation for group 2, and epitendinous suture breakage for group 3.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated epitendinous placement of skin staples around a core SDFT tenorrhaphy site improved the biomechanical strength and resistance to gap formation for the repair but was inferior to epitendinous placement of SXS sutures. Further research is necessary before skin staples are used for tenorrhaphy augmentation in clinical patients.