Integra Application On Denuded Tendon in An Animal Model

BACKGROUND: Denuded tendon presents the reconstructive surgeon with a tissue-coverage challenge. It has been shown clinically that Integra placed over denuded tendon can provide a stable, vascularized bed for skin grafting. Although clinically described we were unable to identify a histologic examination. We undertook the current study to histologically evaluate Integra applied to avascular tendon and whether revascularization occurs from the denuded tendon or surrounding tissue.

METHODS: Eight female New Zealand white rabbits were anesthetized. An incision measuring 4cm x 6cm was made over the Achilles tendon of a randomly selected hindlimb. Paratenon was debrided and Integra was placed over the avascular tendon. Acticoat was placed over the Integra and the limbs splinted. Two animals were euthanized at each timepoint (weeks 1, 2, 3, and 4) and hematoxylin and eosin (H&E) stains of tissue were made.

RESULTS: At week 1 H&E slides demonstrated limited adherence between the Integra and the tendon while myofibroblasts were found encircling the tendon. At week 2 a substantial number of eosinophils and multinucleated giant cells were present within the Integra. These cells were most concentrated at the dermal edges but were absent at the center of the repair. Similarly, adherence between the Integra and tendon and the presence of blood vessels was greatest near the native skin edge, lessening towards the repair's center. By week 3 the Integra was completely revascularized with good adherence to a myofibroblastic layer surrounding the tendon. At week 4 the Integra was showed a histological appearance of normal dermis.

CONCLUSION: This data supports a neovascularization of Integra from the peripheral tissue as hypothesized. Ingrowth occurs from the dermal/Integra interface toward the center of the graft. Further studies are warranted to evaluate tendon glide and determine the maximum defect size for which Integra may be used to cover bare tendon.