Evaluation of an Autologous Tendon Graft Repair Method for Gap Healing of the Deep Digital Flexor Tendon in Horses

Abstract

A sutured tenorrhaphy technique that incorporated an autologous tendon graft was compared mechanically and histologically with a sutured tenorrhaphy at 6, 12, and 24 weeks after repair. Tenorrhaphy was performed in the forelimb tendon of the deep digital flexor muscle and the graft was taken from the hindlimb tendon of the lateral digital extensor muscle; one forelimb site included the graft, whereas the other forelimb site was not grafted. Tenotomies were made immediately proximal to the insertion of the accessory ligament into the tendon of the deep digital flexor muscle. Grafted and nongrafted tenorrhaphies were sutured with 2 polydioxanone in a modified double locking-loop pattern. Limbs were supported with a bandage and an extended elevated heel shoe that maintained the dorsal hoof wall angle at 70 degrees to 75 degrees; this support was removed at 12 weeks and dorsal hoof wall angle was maintained at 40 degrees to 45 degrees for the remainder of the study. Gap formation (2.5 +/- .3 cm) was evident at all tenorrhaphy sites at 3 days on ultrasound examination. In grafted repairs, the breaking stress was increased (P < .001) between 6 weeks (2.56 +/- .44 MPa) and 12 weeks (17.69 +/- 7.68 MPa), with grafted tendon having a greater breaking stress than nongrafted tendon (8.77 +/- 2.5 MPa; P < .05). No differences in breaking stress were evident at 24 weeks. At 12 weeks, repair tissue in grafted tendon was histologically more mature, had less cellularity, better fibroblast orientation and more homogeneous collagen matrix than nongrafted tendon. Polydioxanone suture was still evident histologically at 24 weeks and was associated with minimal cellular reaction. Incorporation of an autologous tendon graft improved the mechanical properties and histological quality of the repair tissue in equine flexor tenorrhaphies at 12 weeks but not at 24 weeks after repair.

Plasma rico em plaquetas autólogas na cicatrização do tendão do músculo gastrocnêmio de coelhos

“…As rupturas do tendão músculo gastrocnêmio podem ocasionar alteração postural grave de difícil correção (VAUGHAN, 1980). Na perda expressiva de parte do tecido tendíneo, a substituição torna-se necessária por meio de enxerto ou com o emprego de próteses, que fornecem suporte e orientação para a migração de células e formação de fibras (VALDÉS-VAZQUEZ;McCLURE;OLIVER, 1996). Entretanto, apesar de serem disponíveis vários métodos de tratamento de lesões tendíneas, ainda é necessário o desenvolvimento e aprimoramento de métodos que permitam o retorno morfológico e funcional do tendão (GOODSHIP, 1993).…”

Estudo experimental do poliuretano de óleo de mamona (Ricinus communis) como substituto parcial do tendão calcâneo comum em coelhos (Oryctolagus cuniculus)

“…A secção do tendão calcâneo comum ou dos flexores digitais leva a alteração postural grave que poderá ser de difícil correção, não sendo incomum nas espécies canina (Vaughan, 1980;Bonneau et al, 1983), eqüina (Goodship, 1993) e humana (Nystrom & Holmlund, 1983). A substituição do tendão torna-se necessária especialmente quando há perda de parte do tecido e, nesses casos, o enxerto ou a prótese fornecem suporte e orientação para a migração de células e formação de fibras (Valdés-Vásquez et al, 1996). Ocasionalmente tendões devem ser alongados ou encurtados devido a defeito de conformação, desenvolvimento inadequado ou por complicações de tratamentos de feridas que envolvem essas estruturas (Clark, 1993).…”

Assessment of digital flexors tenorrhaphy in equine: a review

“…The repaired tendons during the early stages of healing must be protected from full weight bearing through some form of external cooptation, regardless of the method and material used to reconstruct the damaged tendon until the collagenous scar has developed adequate tensile strength to support weight bearing function (Lin et al 2004;Dehghani & Varzandian 2007). Valdez-Vazquez et al (1996) found that in vitro data for healing of SDFT revealed load failure ranged from less than 150 kg at 6th week to 600 kg at 9-12th weeks and up to 700 kg at 24th week. However, load failure of the DDFT at 6th week is slightly more than 100 kg, by 12th week it is about 260 kg and by 24th week, it is 575 kg.…”

“…The use of allografts appeared as successful as that of autograft, but if fresh allografts are used a donor animal is required each time (Valdez-Vazquez et al 1996;Soliman et al 1999). The efficacy of carbon fibres and plasma preserved tendon allograft for gap repair in the SDFT in 12 crossbred calves.…”

“…The ideal implant should have mechanical and fibrogenic properties similar to those of normal tendon and serves as a scaffold for the migration of fibroblasts derived from normal tenocytes (Valdez-Vazquez et al 1996).…”