Flexor tendon lacerations in horses are traumatic injuries that can be career ending and life threatening. In the horse, a tendon repair must withstand the strains placed on the tenorrhaphy by immediate weight bearing and locomotion post-operatively. Despite the use of external coaptation, such strains can lead to significant gap formation, construct failure, longer healing time and poor quality of the healed tendon. Similar to equine surgery, gap formation and construct failure are common concerns in human medicine, with early return to post-operative physiotherapy challenging the primary repair. Early return to exercise and decreased gap formation has been shown to reduce adhesion formation. Based on these concerns, the ideal tenorrhaphy suture pattern for equines would provide: 1) high ultimate failure load, 2) resistance to gap formation, 3) minimal alteration in blood supply, and 4) minimal adhesion formation. Historically, various suture patterns and materials have been evaluated for human and equine flexor tendon repair. Results of equine studies suggest the three-loop pulley pattern (3LP) compares favorably to other patterns and is recommended for primary tenorrhaphy. However, this pattern still experiences significant gap formation and can result in failure. As a result, a technique which decreases the problems inherent in the 3LP is warranted for tenorrhaphy of equine flexor tendons. A review of the human literature highlights certain characteristics of the tenorrhaphy that may improve results including core purchase length and suture loop characteristics. Optimization of these tenorrhaphy characteristics can increase tenorrhaphy performance and patient outcome. The six-strand Savage technique (SSS) is a pattern routinely used in human hand surgery for tendon repair, and possesses high ultimate failure load and resistance to gap formation that may be beneficial for application in equine tendon repair. This study compared a novel tenorrhaphy pattern for horses, the SSS, with the currently recommended pattern, the 3LP, in an in vitro model. We hypothesize the SSS will fail at a higher ultimate load, resist pull through, and resist gap formation better than the 3LP. All testing used cadaveric equine superficial digital flexor tendons from horses euthanized for reasons other than musculoskeletal injury. All testing was approved by the IACUC. The two techniques were applied to cadaveric equine superficial digital flexor tendons. The same investigator performed all repairs (EE). Biomechanical properties were determined in a blinded, randomized pair design. Ultimate failure load, mode of failure and load required to form a 3mm gap were recorded on an Instron Electropuls materials testing system. Gap formation was determined using synchronized high-speed video analysis. Results are reported as mean + standard deviation. Statistical comparisons were made using Student's T test, with significance set at p<0.05. The tenorrhaphies were tested for their ultimate failure load and failure mode. The mean failure load for the SSS construct (421.1 ± 47.6) was significantly greater than that for the 3LP repaired tendons (193.7 ± 43.0). Failure mode was suture breakage for the SSS constructs (13/13) and suture pull through for the 3LP constructs (13/13). The maximum load to create a 3mm gap in the SSS repair (102.0N ± 22.4) was not significantly different from the 3LP repair (109.9N ± 16.0). The results of the current study demonstrate that the SSS tenorrhaphy has a higher ultimate failure load and resistance to pull through than the 3LP. The biomechanical properties of the SSS technique show promise as a more desirable repair for equine flexor tendons. However, in vivo testing of the effects of the pattern on live tissue and in a cyclic loading environment is necessary before clinical application of the pattern is recommended. / Master of Science

As lesões traumáticas do membros que resultam em secções tendíneas são problemas comuns na clínica equina. Estas lesões podem ser tratadas de forma conservativa ou cirúrgica. Diversas complicações tem sido associadas às técnicas cirúrgicas, como ruptura do fio de sutura, ruptura do coto tendíneo suturado, infecções da ferida, entre outros. O objetivo do presente trabalho foi avaliar biomecanicamente a combinação entre os padrões de sutura locking loop duplo e locking loop simples com sutura de epitendão, com os fios de sutura polipropileno e poliglactina 910, ambos de número 2, visando estipular a melhor combinação entre as variáveis quando aplicadas ao tendão flexor digital profundo de equinos. Os corpos de prova foram submetidos a ensaios mecânicos de tração, onde determinaram-se valores de força mínima, força máxima e pico de força durante o afastamento de 3 milímetros entre os cotos suturados, além do afastamento observado entre os cotos durante o pico máximo de força. Quando avaliada a força máxima, observaram-se maiores valores (p0,05) nos grupos onde foi utilizado o padrão locking loop simples com sutura de epitendão, e também quando a sutura foi realizada com polipropileno. Para a força mínima, o padrão simples também se mostrou superior, não havendo diferença significativa quando variaram-se os fios de sutura. Quando avaliado o pico de força, as suturas duplas foram superiores, não havendo diferença estatística quando comparadas com a sutura simples realizada com polipropileno. Os padrões duplos permitiram maior afastamento que os padrões simples com sutura de epitendão. O padrão locking loop simples, com sutura de epitendão, atinge maiores valores de força enquanto o afastamento é de até 3 milímetros. Quando realizado com polipropileno, este padrão suporta maior carga do que quando realizado com poliglactina. / The traumatic lesions of the limbs that result in tendon sections are common problems in equine medicine. These lesions can be treated with clinical or surgical procedures. Several complications, as rupture of the suture material, rupture of the tendon extremity and wound infection have been associated with the technique. The objective of this study was evaluate biomechanically the locking loop suture and the locking loop with epitendon suture, when performed with polypropylene and polyglactin 910 suture material, number 2, looking for the best combination between the variables when applied to equine deep digital flexor tendon. The specimens was submitted to a strain test. Values of minimum strength, maximum strength and force peak were measured during 3 millimeters of separation between the tendon extremities, and the gap was observed between the tendon extremities during the maximum peak force. During maximum strength evaluation, the higher values (p0,05) were observed in groups which were used simple locking loop pattern associated with epitendon suture, and also when the suture was performed with polypropylene. For the minimum strength, the simple pattern was also better, showing no significant difference between the types of suture material. When the peak force was measured, the double sutures were better, and there was no statistic variation when compared with the suture performed with polypropilene in a simple pattern. The double patterns allowed higher separation than the simple patterns associated with epitendon suture. The simple locking loop pattern, with epitendon suture, reaches higher values of strength when there is 3 millimeters of separation. When performed with polypropylene, this pattern supports higher load than when performed with polyglactin.

As lesões traumáticas do membros que resultam em secções tendíneas são problemas comuns na clínica equina. Estas lesões podem ser tratadas de forma conservativa ou cirúrgica. Diversas complicações tem sido associadas às técnicas cirúrgicas, como ruptura do fio de sutura, ruptura do coto tendíneo suturado, infecções da ferida, entre outros. O objetivo do presente trabalho foi avaliar biomecanicamente a combinação entre os padrões de sutura locking loop duplo e locking loop simples com sutura de epitendão, com os fios de sutura polipropileno e poliglactina 910, ambos de número 2, visando estipular a melhor combinação entre as variáveis quando aplicadas ao tendão flexor digital profundo de equinos. Os corpos de prova foram submetidos a ensaios mecânicos de tração, onde determinaram-se valores de força mínima, força máxima e pico de força durante o afastamento de 3 milímetros entre os cotos suturados, além do afastamento observado entre os cotos durante o pico máximo de força. Quando avaliada a força máxima, observaram-se maiores valores (p0,05) nos grupos onde foi utilizado o padrão locking loop simples com sutura de epitendão, e também quando a sutura foi realizada com polipropileno. Para a força mínima, o padrão simples também se mostrou superior, não havendo diferença significativa quando variaram-se os fios de sutura. Quando avaliado o pico de força, as suturas duplas foram superiores, não havendo diferença estatística quando comparadas com a sutura simples realizada com polipropileno. Os padrões duplos permitiram maior afastamento que os padrões simples com sutura de epitendão. O padrão locking loop simples, com sutura de epitendão, atinge maiores valores de força enquanto o afastamento é de até 3 milímetros. Quando realizado com polipropileno, este padrão suporta maior carga do que quando realizado com poliglactina. / The traumatic lesions of the limbs that result in tendon sections are common problems in equine medicine. These lesions can be treated with clinical or surgical procedures. Several complications, as rupture of the suture material, rupture of the tendon extremity and wound infection have been associated with the technique. The objective of this study was evaluate biomechanically the locking loop suture and the locking loop with epitendon suture, when performed with polypropylene and polyglactin 910 suture material, number 2, looking for the best combination between the variables when applied to equine deep digital flexor tendon. The specimens was submitted to a strain test. Values of minimum strength, maximum strength and force peak were measured during 3 millimeters of separation between the tendon extremities, and the gap was observed between the tendon extremities during the maximum peak force. During maximum strength evaluation, the higher values (p0,05) were observed in groups which were used simple locking loop pattern associated with epitendon suture, and also when the suture was performed with polypropylene. For the minimum strength, the simple pattern was also better, showing no significant difference between the types of suture material. When the peak force was measured, the double sutures were better, and there was no statistic variation when compared with the suture performed with polypropilene in a simple pattern. The double patterns allowed higher separation than the simple patterns associated with epitendon suture. The simple locking loop pattern, with epitendon suture, reaches higher values of strength when there is 3 millimeters of separation. When performed with polypropylene, this pattern supports higher load than when performed with polyglactin.

Tensile strength of flexor tendon repair using barbed suture material in a dynamic ex vivo model. The purpose of this study was to compare two sutures; a knotted polydioxane with a knotless barbed in a 4-strand Kirchmayr-Kessler suture technique. Human flexor digitorum tendons were separated into four groups. Group 1 - polydioxane; Group 2 - barbed suture; Group 3 and 4 - same as group 1 and 2 with an additional peripheral running suture. In each group the repaired tendons were subjected to linear and cyclical loads. No difference in maximum tensile strength after linear and cyclical force could be detected between the knotted polydioxane suture and the knotless barbed suture. On linear force tests an additional circumferential repair increased the maximum tensile strength of both sutures. Cyclical force loading did not lead to a reduction of maximum strength. Following linear and cyclical loading the 4-strand barbed suture achieved maximum tensile strengths comparable to the 4-strand repair using the polydioxane suture. Barbed suture repair may offer the advantage of knotless suture techniques. / In einem ex vivo Modell wurde die Stabilität verschiedener Beugesehnennähte mit unterschiedlichen Nahtmaterialien und -methoden verglichen. Darunter eine knotenlose Technik mit Nahtmaterial mit Widerhaken. Des weiteren wurde der Stabilitätsvorteil durch eine zusätzliche Feinadaptionsnaht getestet. Angelehnt an eine frühe postoperative aktive Nachbehandlung wurde auch ein dynamisches Testmodell mit zyklischer Vorbelastung angewendet.

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