Abstract

Background:The purpose of this study was to evaluate the mechanical, structural, and histologic quality of rotator cuff repairs augmented with an interposition electrospun nanofiber scaffold composed of polyglycolic acid (PGA) and poly-L-lactide-co-ε-caprolactone (PLCL) in an acute sheep model.Methods:Forty acute infraspinatus tendon detachment and repair procedures were performed in a sheep infraspinatus model using a double-row transosseous-equivalent anchor technique either with an interposition nanofiber scaffold composed of polyglycolic acid–poly-L-lactide-co-ε-caprolactone or with no scaffold. Animals were euthanized at the 6-week (20 samples) and 12-week (20 samples) postoperative time points to assess the biomechanical and histologic properties of the repairs and to compare differences within each group.Results:Within the scaffold-treated group, there was a significant increase in ultimate failure force (in newtons) from 6 to 12 weeks (P < .01), a significant increase in ultimate failure load from 6 to 12 weeks (P < .01), and a significant increase in ultimate failure stress (in megapascals) from 6 to 12 weeks (P < .01). At 6 weeks, the tendon-bone attachment was most consistent with an “indirect” type of insertion, whereas at 12 weeks, a visible difference in the progression and re-formation of the enthesis was observed. Compared with controls, animals in the scaffold-treated group displayed an insertion of the fibrous tendon with the humeral footprint that was beginning to be organized in a manner similar to the “native” direct/fibrocartilaginous insertion of the ovine infraspinatus tendon. In the majority of these animals treated with the scaffold, prominent perforating collagen fibers, similar to Sharpey fibers, were present and extending through a region of calcified fibrocartilage and attaching to the humeral footprint. No surgical complications occurred in any of the 40 sheep, including delayed wound healing or infection.Conclusions:In a sheep acute rotator cuff repair model, securing a nanofiber scaffold between the tendon and the bone using a double-row transosseous-equivalent anchor fixation technique resulted in greater failure strength. Additionally, at the enthesis, Sharpey fiber–like attachments (ie, collagen fibers extending from the tendon into the calcified fibrocartilage of the humerus) were observed, which were not seen in the control group.Level of evidence:Basic Science Study; Biomechanical/Histology

Highlights

  • The purpose of this study was to evaluate the mechanical, structural, and histologic quality of rotator cuff repairs augmented with an interposition electrospun nanofiber scaffold composed of polyglycolic acid (PGA) and poly-L-lactide-co-ε-caprolactone (PLCL) in an acute sheep model

  • The use of a welldeveloped animal model, such as the infraspinatus tendon in sheep, may provide further insight regarding best treatment practices including the repair of a torn rotator cuff as the biomechanical and histologic properties of the tendon can be assessed in a control untreated group, a control treatment group, and a group with a unique therapeutic intervention

  • This study evaluated the biomechanical and histologic effects on rotator cuff tendon healing when using a new, Food and Drug Administration–approved PGA-PLCL nanofiber scaffold between the surgically repaired infraspinatus tendon and its humeral footprint in a sheep model

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Summary

Introduction

The purpose of this study was to evaluate the mechanical, structural, and histologic quality of rotator cuff repairs augmented with an interposition electrospun nanofiber scaffold composed of polyglycolic acid (PGA) and poly-L-lactide-co-ε-caprolactone (PLCL) in an acute sheep model. Methods: Forty acute infraspinatus tendon detachment and repair procedures were performed in a sheep infraspinatus model using a double-row transosseous-equivalent anchor technique either with an interposition nanofiber scaffold composed of polyglycolic acid–poly-L-lactide-co-ε-caprolactone or with no scaffold. In the majority of these animals treated with the scaffold, prominent perforating collagen fibers, similar to Sharpey fibers, were present and extending through a region of calcified fibrocartilage and attaching to the humeral footprint. Conclusions: In a sheep acute rotator cuff repair model, securing a nanofiber scaffold between the tendon and the bone using a doublerow transosseous-equivalent anchor fixation technique resulted in greater failure strength. At the enthesis, Sharpey fiber–like attachments (ie, collagen fibers extending from the tendon into the calcified fibrocartilage of the humerus) were observed, which were not seen in the control group

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