Biomechanical and Clinical Evaluation of a Modified 3-Loop Pulley Suture Pattern for Reattachment of Canine Tendons to Bone

Reconstruction of the Quadriceps Extensor Mechanism with a Calcaneal Tendon-Bone Allograft in a Dog with a Resorbed Tibial Tuberosity Fracture

A non-reducible tibial tuberosity fracture is a rare complication of tibial tuberosity transposition performed during correcting of medial patella luxation (MPL) in dogs. This condition severely disrupts the quadriceps extensor mechanism, leading to significant pelvic limb lameness. An 11-year-old, 1.8 kg spayed female Yorkshire Terrier sustained a comminuted left tibial tuberosity fracture during surgical correction of an MPL. Six months after surgery, the dog was markedly lame and unable to extend the left stifle. Radiographs revealed patella alta and resorption of the fragmented tibial tuberosity. A composite frozen allogeneic calcaneal tendon-bone block was utilized to reconstruct the tibial tuberosity and reattach the patellar ligament. Initial postoperative radiographs confirmed restoration of a normal patellar ligament to patella length ratio (1.42). Both the allogeneic bone used for tibial tuberosity reconstruction and the tendon used to reattach the patellar ligament were successfully integrated. The dog regained satisfactory limb function without recurrence of patella luxation, as reported by the owners 29 months postoperatively. The use of a calcaneal tendon-bone allograft effectively restored the functional integrity of the quadriceps extensor mechanism, providing a viable option for addressing quadriceps insufficiency resulting from the loss of the osseous tibial insertion.

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.

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.

Retrospective multicentre evaluation of common calcaneal tendon injuries in 66 cats. Part 2: treatment, complications and outcomes

OBJECTIVES

The aims of the second part of this retrospective multicentre study were to describe the surgical techniques used in the treatment of common calcaneal tendon (CCT) injuries, and evaluate the short- and long-term outcomes and complications.

METHODS

The medical records of five different small animal referral centres and veterinary teaching hospitals between 2010 and 2020 were reviewed. Surgical vs conservative treatment was evaluated. Treatment type, type of postoperative immobilisation, and short- and long-term outcomes and complications were recorded. Minor complications were defined as not requiring surgical intervention. Long-term outcome was evaluated by an owner questionnaire.

RESULTS

Sixty-six cats met the inclusion criteria. Mean time to surgery was 9.6 days (range 0-185). Most cats (83.3%) were treated surgically. Regardless of treatment modality, all limbs were immobilised for a mean time of 48.2 days (range 2-98). For 63 cats that had the temporary tarsal joint immobilisation technique recorded, a transarticular external skeletal fixator (ESF; 57.1%) or a calcaneotibial screw (33.3%) were used most commonly. The method of immobilisation had a notable, although non-significant, influence on the occurrence of short-term complications, with most complications being reported for the transarticular ESF group. The total short-term complication rate was 41.3%, the minor complication rate was 33.3% and the major complication rate was 7.9%, with pin tract infections being the most commonly occurring minor complication. Three cats (6%) had a total of four major complications over the long term. Most cats (86%) were free of lameness at the long-term evaluation, with an overall successful clinical long-term outcome of 84.9%, according to the owner questionnaire. Cats with traumatic injuries and injuries treated surgically had higher questionnaire scores than those with atraumatic injuries and those treated conservatively.

CONCLUSIONS AND RELEVANCE

Outcome was generally good in cats with CCT injury, irrespective of the type of treatment. Complications included a high proportion of minor complications associated with the technique of tarsal joint immobilisation. ESF frames were more commonly involved in complications than other techniques. Surgically treated cats had a slightly better long-term outcomes.

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.

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.

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.

Calcaneotibial screws for immobilisation of the tarsocrural joint of dogs in extension: effect of the angle of screw placement on the force to failure in a canine cadaveric model

AIMS

To compare the force to failure under axial loading of a calcaneotibial screw placed approximately perpendicular to the tibia with that of a screw placed perpendicular to the calcaneus, when used to immobilise the tarsus in an ex vivo canine model.

METHODS

Twelve pairs of cadaveric hindlimbs from large breed dogs, without orthopaedic or soft tissue disease, were prepared by transecting the limb at the level of the stifle and stripping the limbs of all musculature from the stifle to mid-metatarsus, including removal of the common calcaneal tendon from all limbs. The limbs in each pair were randomly assigned to receive a calcaneotibial screw placed perpendicular to the long axis of either the calcaneus (C group) or the tibia (T group) with the tarsus in full extension. The distal limb was potted in resin and the proximal tibia was pinned to allow biomechanical testing in compressive loading. Testing was performed to apply an axial load using a material testing machine in a proximodistal direction through the tibia, advancing at a rate of 10 mm/second. The force to failure was recorded in kN and compared between groups.

RESULTS

The median force to failure of the C group was 0.86 (min 0.50; max 1.64) kN which was higher than the T group which had a median force to failure of 0.74 (min 0.26, max1.05) kN (p = 0.004). All modes of failure were by screw pull-out.

CONCLUSIONS

A calcaneotibial screw placed at an angle approximately perpendicular to the long axis of the calcaneus, has a higher force to failure under axial loading than a calcaneotibial screw that is placed at an angle approximately perpendicular to the tibia, in a canine cadaveric model.

CLINICAL RELEVANCE

A temporary calcaneotibial screw is a common method of immobilising the tarsus in extension to protect primary repair of a common calcaneal tendon injury. Placing a calcaneotibial screw perpendicular to the calcaneus may be a more reliable option for immobilisation of the tarsus to protect a common calcaneal tendon repair compared to screws placed perpendicular to the tibia. However extrapolation of these results into a clinical setting requires caution.

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.

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.

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.

Repair of Tendon Disruption Using a Novel Synthetic Fiber Implant in Dogs and Cats: The Surgical Procedure and Three Case Reports

Surgical management of tendon rupture is challenging. One concern is to provide adequate tensile strength to prevent distraction during weight-bearing and gap formation following repair, associated with an increased risk of repair failure. Additional challenges may arise from the nature or the chronicity of the lesion. In the event of avulsion, when the tendon is torn off at the bone insertion, its reinsertion on the bone is generally difficult and may even be impossible in the presence of an avulsion fracture, especially when the bone fragment is too small or fragmented. Repair management is also complicated in chronic cases, as degeneration of the tendon may lead to excessive scar tissue formation, tendon retraction, and muscle atrophy, resulting in a large gap and inadequate tissue for reconstruction. The authors describe the surgical procedure for implanting a novel implant, illustrated by three characteristic clinical cases: (1) an acute Achilles tendon avulsion; (2) a chronic patellar tendon rupture; and (3) a chronic avulsion fracture of the triceps tendon. In these three cases, complete recovery of the function was observed at the last clinical evaluation (6 or 8 months), and no complication was noted. A splinted dressing (6 to 8 weeks) was used successfully in two cases. A resin cast (8 weeks) was preferred in case 1, a very active dog. In conclusion, this novel implant represents a simple procedure for the effective repair of chronic tendon rupture, as well as an effective tendon reinsertion on the bone and adequate support for bone tendon healing in the treatment of tendon avulsion, even in cases of fragmented bone fracture. The thinness of the implant facilitates its insertion into the native tendon, while the bone-screw-implant interface provides immediate and lasting mechanical support. This may facilitate the healing process and potentially shorten the period of immobilization.

Biomechanical evaluation of an autologous flexor digitorum lateralis graft to augment the surgical repair of gastrocnemius tendon laceration in a canine ex vivo model

OBJECTIVE

To evaluate the effect of an autologous flexor digitorum lateralis (FDL) graft to augment a three-loop pulley (3LP) core repair in a canine cadaveric gastrocnemius tendon (GT) laceration model.

STUDY DESIGN

Ex vivo, biomechanical study.

SAMPLE POPULATION

Twenty-six canine cadaveric hind limbs.

METHODS

Tendons were divided into two groups (n = 13). After sharp transection, paired GT were repaired with 3LP or 3LP + FDL tendon augmentation. Yield, peak and failure loads, tensile loads required to create 1 and 3-mm gapping, and failure modes were analyzed. Significance was set at P < .05.

RESULTS

Yield and failure force (mean ± SD) for 3LP + FDL were 134.9 ± 44.1 N and 205.4 ± 46.4 N, respectively, which were greater than for 3LP alone (67.9 ± 12.2 N and 91.8 ± 9.9 N, respectively, P < .0001). No constructs (0%) formed 1 or 3-mm gaps in the 3LP + FDL graft group compared with 84% and 39% for 3LP, respectively (P < .0001). Failure modes were different between groups (P < .001), with 85% of 3LP + FDL constructs failing by tissue rupture at the myotendinous junction, distant to the repair site.

CONCLUSION

Addition of an autologous FDL graft to a core 3LP tendon repair increased yield, peak, and failure forces by twofold, 2.3-fold, and 2.2-fold, respectively, compared with core 3LP alone while preventing the occurrence of gap formation.

CLINICAL SIGNIFICANCE

Use of FDL tendon augmentation for GT laceration may increase repair site strength and resist gap formation better than 3LP core suture use alone. Additional studies are required in vivo to determine the effect of FDL graft augmentation on clinical function.

Suturing Achilles tendon and mesh simultaneously in augmented repair resists gap formation foremost: an experimental study

Background

The common calcanean tendon (Achilles tendon) is the strongest and largest tendon and is one of the most commonly affected by spontaneous rupture. Different suture techniques are used to repair the tendon rupture. We compare the biomechanical properties of three different modalities of suture pattern in a mechanical experiment in rabbits with the purpose of evaluating the use of polypropylene mesh augmentation for Achilles tendon repair to find out the best surgical option.

Methods

The study tests single cycle to failure tensile strength characteristics of three different combinations of the 3-loop pulley (3-LP) suture technique with polypropylene mesh, and statistically compares the biomechanical properties as the maximum load at failure for all 3-LP repair.

Results

The normal Achilles tendon—control group—failed at a mean load of 25.5 + 13.6; the experimental groups failed at a significantly lower load (p < 0.001), with the group of 3-LP suture with polypropylene mesh included in the suture being the more similar to controls, but all the groups exhibited statistically significant differences with regard to normal tendons (p < 0.001). The distance at which each group failed was also significant between control and experimental groups (p < 0.001) with the exception of the suture-only group and the group with the mesh over the suture (p = 0.15).

Conclusion

Results from this study suggest that incorporating the mesh within the suture provides benefit to the Achilles tendon repair by improving strength and resistance to pull through. However, further in vivo studies will be necessary to confirm these results and incorporate this technique to the routine human and veterinary surgery.

The use of bidirectional barbed suture in the treatment of a complete common calcanean tendon rupture in a dog: Long-term clinical and ultrasonographic evaluation

The canine common calcanean tendon can be repaired successfully using a modified Kessler knotless barbed technique. A long-term ultrasound follow-up showed improved and increased normal tendon fibrillar echotexture and homogeneity.

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

OBJECTIVE

To evaluate the effect of combining a continuous epitendinous suture with three-loop pulley (3LP) and locking-loop (LL) core patterns for flexor tendon repair.

STUDY DESIGN

Ex vivo biomechanical study.

SAMPLE POPULATION

Seventy-two cadaveric superficial digital flexor musculotendon (SDFT) units.

METHODS

Tendons were divided into four groups (n = 18/group). After sharp transection, SDFT were repaired with 3LP, LL, 3LP + epitendinous (E), or LL + E suture patterns. After preloading, repaired constructs were tested to failure. Video data acquisition allowed evaluation of failure mode and quantitation of gap formation. Yield, peak, and failure force were measured from force-displacement data. Significance was set at P < .05.

RESULTS

Mode of failure did not differ between repairs with or without an epitendinous suture (P = .255). Gap formation was best prevented with 3LP compared with LL when used alone (P = .001). Mean yield force for 3LP, LL, 3LP + E, and LL + E were 91.4 N ± 25.4, 61.3 N ± 18.4, 195.2 N ± 66.0, 165.3 N ± 46.8, respectively. Tenorrhaphies combined with an epitendinous suture achieved higher yield (P < .0001), peak (P < .0001), and failure forces (P < .0001), without gapping between tendon ends.

CONCLUSION

Addition of an epitendinous suture eliminated gapping between tendon ends until failure and increased resistance to loads tolerated at the repair site.

CLINICAL SIGNIFICANCE

The addition of an epitendinous suture may increase the strength of tendon repairs and resistance to gap formation over core suture use alone. The influence of epitendinous suture placement on tendinous healing and blood supply warrants in-vivo testing.

Biomechanical comparison of three epitendinous suture patterns as adjuncts to a core locking loop suture for repair of canine flexor tendon injuries

OBJECTIVE

To determine the effects of different epitendinous sutures (ES) in addition to core locking-loop (LL) sutures on the mechanical properties and gap formation in a canine cadaveric tendon model.

STUDY DESIGN

Experimental, ex vivo, biomechanical study.

SAMPLE POPULATION

Seventy-two cadaveric superficial digital flexor tendon specimens.

METHODS

Superficial digital flexor tendon specimens were divided into four groups (n = 18): sharply transected and repaired with LL, LL + simple continuous ES, LL + Silfverskiöld cross-stitch ES, and LL + interlocking horizontal mattress ES. Constructs were loaded to monotonic failure. Failure modes, gapping, yield, peak, and failure forces were analyzed. Significance was set at P < .05.

RESULTS

Yield, peak, and failure forces increased by 2.5-fold, two-fold, and twofold, respectively when ES groups were compared with core LL suture patterns alone (P < .0001). Resistance to 1- and 3-mm gap formation was greater in ES groups compared with core LL constructs alone (P < .0001). No differences in yield, peak, failure force, or gapping were observed among ES patterns (P > .827).

CONCLUSION

Adding an ES reduced gap formation and increased yield, peak, and failure forces of tenorrhaphies. No difference was detected between the epitendinous patterns tested in this study.

CLINICAL SIGNIFICANCE

The addition of an ES seems more relevant than the specific type of pattern to improve the biomechanical properties of flexor tendon repairs. In vivo studies are warranted to determine the biological implications of the patterns tested here.

Biomechanical comparison of a modified three-loop pulley technique and a three-level self-locking technique for repair of patellar tendon rupture in dogs

OBJECTIVE

To compare use of a 3-level self-locking suture (3LSLS) technique with use of a previously described modified 3-loop pulley (M3LP) technique to repair rupture of the proximal aspect of patellar tendons in limbs from canine cadavers.

SAMPLE

Paired hind limbs of 6 adult mixed-breed dogs.

PROCEDURES

A limb from each pair was randomly assigned to be repaired by the 3LSLS technique or M3LP technique with size-2 ultrahigh-molecular-weight polyethylene and size-0 monofilament polypropylene suture, respectively. Limbs were prepared, and each patellar tendon was transected at a site chosen to simulate rupture at the proximal aspect. Tendons were repaired with the assigned techniques and mechanically tested with a biaxial servohydraulic test system; the clamp was distracted until the repair failed. Force at 1 -mm gap formation, 3-mm gap formation, and repair failure and gap size at failure were measured and compared between methods. Mode of failure was recorded.

RESULTS

There was no significant difference between methods for the force required to produce a 1 - or 3-mm gap in the repair. The 3LSLS technique required a significantly higher load for complete failure; gap formation immediately before failure was significantly greater for this method than for the M3LP technique. Four of 6 repairs with the M3LP technique and 0 of 6 repairs with the 3LSLS technique failed by suture breakage.

CONCLUSIONS AND CLINICAL RELEVANCE

The 3LSLS technique with size-2 ultrahigh-molecular-weight polyethylene suture was as effective at resistance to 1 - and 3-mm gap formation as the M3LP with size-0 monofilament polypropylene suture.

Clinical outcomes after common calcanean tendon rupture repair in dogs with a loop-suture tenorrhaphy technique and autogenous leukoreduced platelet-rich plasma

OBJECTIVE

To report outcomes of dogs with common calcanean tendon (CCT) ruptures treated with a platelet-rich plasma (PRP) enhanced nonabsorbable loop-suture technique.

STUDY DESIGN

Retrospective case series.

ANIMALS

Client-owned dogs (n = 12).

METHODS

Medical records (2015-2017) of dogs with CCT ruptures repaired with a loop-suture tenorrhaphy and autogenous leukoreduced PRP were reviewed for signalment, history, type of injury, treatment, and clinical follow-up. Outcomes were assessed by functional anatomic measurements and Canine Orthopedic Index (COI) scores transformed to percentages, with 100% representing no problems.

RESULTS

Twelve tendons were treated. Two dogs had major complications that were successfully revised. Follow-up was available in 11 of 12 dogs, with a median time of 12 months (range, 4-36), including COI for 11 dogs and anatomic measurements for 6 dogs. Anatomic measurements did not differ between treated and normal contralateral limbs (midthigh muscle mass P > .99, cranial tibial muscle mass P = .37, CCT diameter P = .08, tibiotarsal joint angle P > .99). Owners scored function (COI) as 96.4% (range, 93.3%-97.8%) and quality of life as 94.6% (range, 92%-98.2%).

CONCLUSION

Loop-suture tenorrhaphy with application of autogenous leukoreduced PRP at the repair site resulted in restoration of functional anatomic measurements, high COI, and client satisfaction.

CLINICAL SIGNIFICANCE

Loop-suture tenorrhaphy with local application of autogenous leukoreduced PRP appears to offer an acceptable option to treat CCT injuries in dogs.

Triceps brachii tendon injury in four Pomeranians

The cases of 4 Pomeranians with injury of the triceps brachii tendon that underwent surgical treatment were retrospectively reviewed to evaluate some clinical findings including signalment, cause of injury, clinical signs, pattern of injury, surgical technique, external coaptation after operation, complications, and outcomes. While all of the dogs showed non-weight bearing posture of the affected limbs and severe pain shortly after injury onset, the pain level decreased over time. A characteristic finding of the 4 cases was an absence of tension in the triceps brachii tendon when the elbow joint was flexed. The pattern of triceps brachii tendon injury was either laceration of the central part of the tendon (n=1) or tendon rupture at its insertion to the olecranon (n=3). Although there were no major complications after surgery in 3 cases, the remaining case required a revision surgery. Long lateral splint was effective method for external coaptation after operation. Diagnosis of triceps brachii tendon injury was not difficult if we even recognize this trauma. This form of injury can have a good prognosis with adequate surgery and postoperative coaptation.

Repair of chronic rupture of the insertion of the gastrocnemius tendon in the dog using a polyethylene terephthalate implant

Objectives: Chronic degeneration of the gastrocnemius tendon results in scar tissue formation at the insertion of the tendon, and detachment from the calcaneus. In severe cases, excision of this tissue makes repositioning of the tendon to the calcaneus extremely difficult. A polyethylene terephtha-late implant, used to aide repair by bridging gaps and allowing tissue ingrowth, was evaluated.

Methods: In this retrospective study, clinical records were evaluated to assess long-term outcomes and complications. The surgical technique is also described. The implant was sutured proximally into the gastrocnemius at the myotendinous junction, and secured into the calcaneus using an interference screw.

Results: The implant was used in 10 patients; of which seven returned to full function. Major complications, due to infection, were identified in two of the 10 patients. Minor complications occurred in five of the 10 patients. These were associated with external coaptation in three of the patients in the immediate postoperative period. One minor infection was reported. These all resolved without further complication. Long-term outcome was available in eight patients, with six of these eight dogs returning to normal exercise.

Clinical significance: This implant may be suitable for use in canine patients with severe gastrocnemius tendon degeneration. Ongoing evaluation is warranted.

Ex vivo biomechanical comparison of barbed suture and standard polypropylene suture for acute tendon laceration in a canine model

Objectives: Evaluate performance and resistance to gap formation of a non-absorbable, barbed, monofilament suture, in comparison with a non-absorbable, smooth, monofilament polypropylene suture, in two different suture patterns: three-loop pulley (3LP) and modified Bunnell-Mayer (BM).

Sample size: Seventy-two medium-sized cadaveric superficial digital flexor muscle tendon units.

Methods: After manual transection and suture repair, individual specimens were placed in an electromechanical tensile testing machine and tested to monotonic failure using tensile ramp loading. Video data acquisition allowed evaluation of failure mode and quantification of gap formation.

Results: Incidence of gap formation between tendon ends was significantly greater in tenorrhaphies repaired with barbed suture compared to those repaired with smooth polypropylene. Use of a 3LP suture pattern caused significantly less gapping between tendon ends when compared to the BM pattern.

Conclusion: Smooth polypropylene suture was consistently superior in load performance than a unidirectional barbed suture. The 3LP pattern was more resistant than a BM pattern at preventing gap formation.

Clinical significance: Smooth polypropylene should be recommended over barbed unidirectional suture for use in canine tendinous repair to provide increased resistance to gap formation. The 3LP is superior to the BM suture pattern, requiring significantly more force to cause tenorrhaphy gap formation and failure, which may translate to increased accrual of repair site strength and tendinous healing in clinical situations.

Barbed versus smooth poly- propylene three-loop pulley sutures for repair of canine gastrocnemius tendon

Objective: To compare the ultimate tensile strength (UTS) and load to 1 and 3 mm gap formation of smooth (3-metric) and knotless barbed (4-metric) polypropylene sutures placed in a three-loop pulley pattern for canine gastrocnemius tendon repair.

Study design: In vitro.

Sample size: Thirty-three paired bonetendon units with one of each pair assigned to each suture type. Barbed suture size was based on previously published materials testing results.

Methods: Each unit was placed in a servohydraulic testing machine and tested under single cycle tensile loading until repair failure.

Results: There was a significantly higher UTS for smooth polypropylene compared to the barbed polypropylene repairs. The loads resulting in 1 and 3 mm gaps for the barbed repairs were consistently significantly less than the corresponding smooth polypropylene repair values.

Conclusion: The knotted smooth polypropylene repair was consistently stronger than the knotless barbed polypropylene repair when placed in a three-loop pulley pattern for gastrocnemius repair.

Clinical significance: Knotless barbed polypropylene suture should not be considered equivalent to knotted smooth polypropylene of comparable tensile strength when placed in a three-loop pulley pattern for canine gastrocnemius tendon repair. The low failure loads of the barbed repair are probably due to failure of the barbs to anchor consistently throughout the tendon in the knotless configuration.

Surgical management and follow-up of triceps tendon avulsion after repeated local infiltration of steroids: two cases

Disruption of the triceps tendon insertion is an uncommon injury, with only a few reports of traumatic triceps tendon avulsion in dogs or cats present in the veterinary literature. Although this injury has been previously described in two dogs that had received a local injection of corticosteroids for the treatment of soft tissue injuries, reports with long term clinical follow-up and outcome in working dogs are lacking.

This report describes two surgically treated cases of complete triceps tendon avulsion rupture in Malinois police dogs. These two dogs had a history of repeated local infiltration of a corticosteroid preparation used to treat adventitial bursitis. The clinical features, surgical treatment, long-term management and outcome are reported. A modified triple locking loop pattern was used to suture the tendons. The long-term outcome was considered excellent with both dogs resuming work. Although it is an uncommon condition in small animals, avulsion of the triceps tendon should remain on the differential diagnosis list for acute onset forelimb lameness, particularly if there is a history of local infiltration with corticosteroids. The diagnosis should be based on clinical, radiographic and ultrasonographic examination.

Biomechanical evaluation of a non-locking pre-manufactured loop suture technique compared to a three-loop pulley suture in a canine calcaneus tendon avulsion model

Objective: The purpose of this cadaveric study was to compare the strength of a non-locking pre-manufactured loop (Speed -Whip™ [SW]) suture pattern using Fiber-wire® with the three-loop pulley (TLP) suture pattern using polypropylene for the surgical repair of canine calcaneal tendon avulsion injuries.

Methods: In vitro biomechanical study using 22 paired tendons collected from 11 canine cadavers. Paired tendons were repaired with either a SW suture pattern using Fiberloop® suture or a TLP suture pattern using polypropylene suture. Tensile loads required to create a 1 mm gap, 3 mm gap, and construct failure were measured.

Results: The mean loads to achieve a 1 mm gap in the TLP and SW constructs were not significantly different. Gap formation at 3 mm occurred at significantly lower loads for the SW (106.4 ± 21.5N) than for the TLP (127.2 ± 27.5N) (p = 0.05). The mean loads to construct failure for the TLP (172.8 ± 39.4N) and SW (131.3 ± 34.3N) were significantly different (p = 0.001).

Clinical significance: The TLP with polypropylene suture is superior to the SW using Fiberloop® at resistance to 3 mm gap formation.

Traumatic triceps tendon avulsion in a dog: magnetic resonance imaging and surgical management evaluation

We report here the clinical presentation, magnetic resonance imaging (MRI) findings and successful surgical management associated with triceps tendon avulsion in a dog. A definitive diagnosis of triceps tendon avulsion was made based on MRI with evidence of displacement of the triceps tendon. Surgical correction of triceps tendon avulsion was performed with two horizontal mattress sutures using polyester and two tunnels drilled in the olecranon to reattach the tendon to the proximal olecranon. At 9 months, there was no evidence of lameness on the left thoracic limb. This is the first case report to describe MRI evaluation for the diagnosis of the triceps tendon avulsion.

The use of a stifle flexion device to manage avulsion of the lateral head of the gastrocnemius muscle in a cat

This report describes the diagnosis and treatment of a traumatic avulsion of the lateral head of the gastrocnemius muscle in a three-and-a-half-year-old male neutered Domestic Shorthaired cat. Surgical repair was achieved using a modified three-loop pulley suture pattern passed through a suture anchor inserted at the point of origin of the tendon and around the fabella. A stifle flexion device was utilised during the postoperative period to protect the repair. Follow-up at five months showed a return to normal function. This is the first report of avulsion of the lateral head of the gastrocnemius in a cat.

Biceps brachii and brachialis tendon of insertion injuries in eleven racing greyhounds

OBJECTIVE

To report injuries of the biceps brachii (BTI) or brachialis (BrTI) tendons of insertion in 11 racing Greyhounds.

STUDY DESIGN

Case series.

ANIMALS

Greyhounds (n=11).

METHODS

Medical records (1990-2006) of racing Greyhound dogs with BTI injuries were reviewed. Preinjury, injury, and posttreatment information was obtained via trainer telephone questionnaire and individual greyhound race data. Outcomes between surgical and conservative management were compared.

RESULTS

Dogs had elbow hyperextension, positive biceps test, and forelimb circumduction and 82% were male, whereas Queensland's male to female ratio of racing Greyhounds was almost equal. Eight dogs had right BTI injuries. Nine dogs had surgically confirmed tendon injuries: 5 combined BTI and BrTI, 2 mid-body BTI, 1 musculotendinous BTI, and 1 ulnar tuberosity avulsion fracture. Seven dogs were treated surgically (3 loop pulley sutures, single radial screw and washer, suture screws or fracture fixation in lag fashion), 2 dogs were euthanatized at surgery, 2 were rehomed and hence managed conservatively. All surgically treated dogs returned to near preinjury performance; 6 returned to racing and at least 4 won races in the same or higher grade. One conservatively managed dog returned to "pet" function. No dog reinjured its BTI or BrTI.

CONCLUSION

BTI and BrTI avulsions are rare acute traumatic performance injuries of racing Greyhounds.

CLINICAL RELEVANCE

Preinjury racing performance can be achieved with early surgical repair of BTI and BrTI and optimal postoperative management.

Traumatic triceps tendon avulsion in a cat

Traumatic avulsion of the triceps tendon was diagnosed in a 15-month-old, male, neutered European shorthair cat. Diagnosis was established clinically by palpation of a transverse groove proximal to the olecranon and by radiography. The avulsed end of the tendon was surgically reapposed using a modified three-loop pulley suture and horizontal mattress sutures. Postoperatively, elbow flexion was limited for three weeks with the aid of a spica splint and by exercise restriction for six weeks. The cat showed no lameness after bandage removal up to the time of writing (seven months). Although rare, triceps tendon injuries can occur after a blunt trauma and should be included in the differential diagnosis of foreleg lameness in the cat. The modified three-loop pulley suture in combination with subsequent immobilisation of the limb with a splinted bandage resulted in a successful outcome in this cat with a triceps tendon avulsion.