Tissue‐engineered tendon constructs for rotator cuff repair in sheep

Abstract

Current rotator cuff repair commonly involves the use of single or double row suture techniques, and despite successful outcomes, failure rates continue to range from 20 to 95%. Failure to regenerate native biomechanical properties at the enthesis is thought to contribute to failure rates. Thus, the need for technologies that improve structural healing of the enthesis after rotator cuff repair is imperative. To address this issue, our lab has previously demonstrated enthesis regeneration using a tissue-engineered graft approach in a sheep anterior cruciate ligament (ACL) repair model. We hypothesized that our tissue-engineered graft designed for ACL repair also will be effective in rotator cuff repair. The goal of this study was to test the efficacy of our Engineered Tissue Graft for Rotator Cuff (ETG-RC) in a rotator cuff tear model in sheep and compare this novel graft technology to the commonly used double row suture repair technique. Following a 6-month recovery, the grafted and contralateral shoulders were removed, imaged using X-ray, and tested biomechanically. Additionally, the infraspinatus muscle, myotendinous junction, enthesis, and humeral head were preserved for histological analysis of muscle, tendon, and enthesis structure. Our results showed that our ETC-RCs reached 31% of the native tendon tangent modulus, which was a modest, non-significant, 11% increase over that of the suture-only repairs. However, the histological analysis showed the regeneration of a native-like enthesis in the ETG-RC-repaired animals. This advanced structural healing may improve over longer times and may diminish recurrence rates of rotator cuff tears and lead to better clinical outcomes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:289-299, 2018.

A prospective study comparing tendon-to-bone interface healing using an interposition bioresorbable scaffold with a vented anchor for primary rotator cuff repair in sheep

“…The sheep infraspinatus tendon acute transection/repair model was used as previous studies have demonstrated that it is a good analog for the human supraspinatus tendon. 14,17,18,[31][32][33][34][35]40,41 Using an open approach, the infraspinatus tendon was sharply detached from the humeral footprint followed by removal of any remaining soft tissue from the footprint by a bone burr. Repair or reattachment of the transected tendon was immediately performed using a total of two 2.7-mm suture anchors (BioWick SureLock W Suture Anchor; Zimmer-Biomet, Warsaw, IN, USA) with a PLGA scaffold (ie, Treatment group) ( Fig.…”

“…Various techniques have been employed to improve interface healing, including bone marrow venting; cellular therapies (mesenchymal stem cells); and xenograft, allograft, or acellular scaffolds. 27,29,32,36,41 Bone marrow vents have shown promise in improving the bone-tissue interface healing of many soft tissue injuries by allowing autologous marrow-derived cells to reach the repair site. 9,37 Bone marrow venting is a comparatively expeditious surgical procedure, has no issue of cellular incompatibility, and may be accomplished through vented tissue anchors or through separate bone puncture holes.…”

“…37 Scaffolds or ''patches'' have also shown value for augmenting torn tissue and promoting tissue thickening. 32,41 Tissue thickening has been demonstrated to have a beneficial effect on the inherent mechanical strength of the repair. 38,41 Most scaffolds are placed on top of the tendon (ie, onlay), not as an interposition between the tendon and the bone, and are primarily designed to add initial mechanical strength and surface area to the repair site, potentially reducing and preventing tendon retear and retraction from the footprint.…”

“…32,41 Tissue thickening has been demonstrated to have a beneficial effect on the inherent mechanical strength of the repair. 38,41 Most scaffolds are placed on top of the tendon (ie, onlay), not as an interposition between the tendon and the bone, and are primarily designed to add initial mechanical strength and surface area to the repair site, potentially reducing and preventing tendon retear and retraction from the footprint. 14,32 Recently, interest in interposition (ie, inlaydbetween the tendon and bone at the footprint) patches has increased as it is believed to not only improve the strength of the repair site, similar to onlay scaffolds but also lead to increased bone-tendon integration via increased cellular activity.…”

“…A previously investigated sheep rotator cuff model from our research group was used as the animal model. 14,17,18,[31][32][33][34][35]40,41…”