Rotator cuff repair using a bioresorbable nanofiber interposition scaffold: a biomechanical and histologic analysis in sheep

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 doublerow 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.Institutional review board approval was not required for this basic science study. This study was conducted under Institutional Animal Care and Use Committee approval by board-certified veterinary surgeons (Colorado State University no. 17-7154).

Use of a Nanofiber Resorbable Scaffold During Rotator Cuff Repair: Surgical Technique and Results After Repair of Small- to Medium-Sized Tears

“…Also, the tendon-bone attachment at 12 weeks histologically appeared more like native fibrocartilaginous insertion with prominent perforating collagen fibers. 28 …”

“…The scaffold has a microporous nature, which, combined with the structure of the nanofibers, is the likely mechanism through which the scaffold promotes a healing response similar to that of native tissue. 1 , 22 In a recent sheep study, Romeo et al 28 demonstrated that the inclusion of the nanofiber scaffold significantly increased the strength of rotator cuff repair and produced more Sharpey fiber–like attachments at the enthesis at 3 months compared with repairs without scaffold augmentation. Specifically, incorporation of the scaffold into rotator cuff repair increased the ultimate failure force by 47% at 12 weeks compared with suture anchors alone.…”

Functional biomaterials for tendon/ligament repair and regeneration

“…They have greater mechanical strength, better mechanical properties and better degradation rates in vivo than natural polymer materials [ 65–68 ]. Among these commonly used polymers, PCL has the slowest degradation rate, followed by PLA [ 69 ] and polyglycolide acid (PGA) [ 70 ]. In contrast, Poly (lactic-co-glycolic acid) (PLGA) has the fastest degradation rate [ 71 ].…”

Evolution of functional tissue engineering for tendon and ligament repair

“…The FTE field has seen exciting research in: (1) developmental biology to learn how tissues form and grow (e.g., Brown et al, 2015;Glass et al, 2014); (2) novel biomaterials as carriers of autologous and allogeneic cells (Marturano et al, 2016;Ratcliffe et al, 2015;Romeo et al, 2022); and (3) sophisticated bioreactors to mature TECs (e.g., Butler et al, 2009). These publications over the past decade are too F I G U R E 1 0 A functional tissue engineering (FTE) "road-map" to describe steps in the in vitro tissue engineering (above the line) as well as in vivo surgery and evaluation phases (below the line).…”