Biological augmentation of rotator cuff tendon repair.
ABSTRACT: A histologically normal insertion site does not regenerate following rotator cuff tendon-to-bone repair, which is likely due to abnormal or insufficient gene expression and/or cell differentiation at the repair site. Techniques to manipulate the biologic events following tendon repair may improve healing. We used a sheep infraspinatus repair model to evaluate the effect of osteoinductive growth factors and BMP-12 on tendon-to-bone healing. Magnetic resonance imaging and histology showed increased formation of new bone and fibrocartilage at the healing tendon attachment site in the treated animals, and biomechanical testing showed improved load-to-failure. Other techniques with potential to augment repair site biology include use of platelets isolated from autologous blood to deliver growth factors to a tendon repair site. Modalities that improve local vascularity, such as pulsed ultrasound, have the potential to augment rotator cuff healing. Important information about the biology of tendon healing can also be gained from studies of substances that inhibit healing, such as nicotine and antiinflammatory medications. Future approaches may include the use of stem cells and transcription factors to induce formation of the native tendon-bone insertion site after rotator cuff repair surgery.
Project description:<h4>Introduction</h4>An increased bone mineral density (BMD) in the proximity to tendon insertion can improve rotator cuff repair and healing. However, how a decrease of BMD in the humeral head affects the biomechanical properties of the rotator cuff tendon is still unclear. Previous studies have demonstrated ovariectomy in animals to lead to osteoporosis and decreased BMD, and Teriparatide (PTH) administration to improve BMD and strength of bone. This study aimed to explore the correlation between humeral head BMD and infraspinatus (ISP) tendon insertion strength, and if an increase in bone quantity of the humeral head can improve the strength of the rotator cuff.<h4>Materials and methods</h4>Eighteen New England white rabbits were divided into the 3 groups: Control, Ovariectomy-Saline (OVX-Saline), and Ovariectomy-PTH (OVX-PTH). The OVX-Saline group and the OVX-PTH were administered daily saline and Teriparatide injections for 8 weeks starting at 17 weeks of OVX. BMD of the humeral head was measured, the ISP tendon failure load was tested and the failure stress was calculated. One specimen from each group was used for histological analysis. Linear regression analysis was used to derive equations for the BMD and failure stress.<h4>Results</h4>Significant differences were observed in the measured humeral head BMD of the Control and OVX-PTH groups compared to the OVX-Saline group (P = 0.0004 and P = 0.0024, respectively). No significant difference was found in failure stress among the three groups, but an expected trend with the control group and OVX-PTH group presenting higher failure strength compared to the OVX-Saline group. BMD at the humeral head showed a positive linear correlation with stress (r2 = 0.54). Histology results showed the superiority in OVX-PTH group ISP enthesis compared to the OVX-Saline group.<h4>Conclusion</h4>Bone loss of the humeral head leads to decreased tendon/bone insertion strength of the infraspinatus tendon enthesis. Teriparatide administration can increase bone density of the humeral head and may improve the mechanical properties of the infraspinatus tendon enthesis.
Project description:The objective of this study was to understand the effect of pre-repair rotator cuff chronicity on post-repair healing outcomes using a chronic and acute multi-tendon rat rotator cuff injury model. Full-thickness dual tendon injuries (supra- and infraspinatus) were created unilaterally in adult male Sprague Dawley rats, and left chronically detached for 8 or 16 weeks. After chronic detachment, tears were repaired and acute dual tendon injuries were created and immediately repaired on contralateral shoulders. Tissue level outcomes for bone, tendon, and muscle were assessed 4 or 8 weeks after repair using histology, microcomputed tomography, biomechanical testing, and biochemical assays. Substantial gap formation was seen in 35% of acute repairs and 44% of chronic repairs. Gap formation negatively correlated with mechanical and structural outcomes for both healing time points regardless of injury duration. Bone and histomorphometry, as well as biomechanics, were similar between acute and chronic injury and repair regardless of chronicity and duration of healing. This study was the first to implement a multi-tendon rotator cuff injury with surgical repair following both chronic and acute injuries. Massive tear in a rodent model resulted in gap formation regardless of injury duration which had detrimental effects on repair outcomes.
Project description:Successful rotator cuff repair requires biological anchoring of the repaired tendon to the bone. However, the histological structure of the repaired tendon-bone interface differs from that of a normal tendon insertion. We analysed differences between the normal tendon insertion and the repaired tendon-bone interface after surgery in the mechanical properties, histomorphometric analysis, and 3-dimensional ultrastructure of the cells using a rat rotator cuff repair model. Twenty-four adult Sprague-Dawley (SD) rats underwent complete cuff tear and subsequent repair of the supraspinatus tendon. The repaired tendon-bone interface was evaluated at 4, 8, and 12 weeks after surgery. At each time point, shoulders underwent micro-computed tomography scanning and biomechanical testing (N?=?6), conventional histology and histomorphometric analysis (N?=?6), and ultrastructural analysis with focused ion beam/scanning electron microscope (FIB/SEM) tomography (N?=?4). We demonstrated that the cellular distribution between the repaired tendon and bone at 12 weeks after surgery bore similarities to the normal tendon insertion. However, the ultrastructure of the cells at any time point had a different morphology than those of the normal tendon insertion. These morphological differences affect the healing process, partly contributing to re-tearing at the repair site. These results may facilitate future studies of the regeneration of a normal tendon insertion.
Project description:<h4>Background</h4>Despite advances in surgical treatment options, failure rates of rotator cuff repair have continued to range from 20% to 90%. Hence, there is a need for new repair strategies that provide effective mechanical reinforcement of rotator cuff repair as well as stimulate and enhance the intrinsic healing potential of the patient. The purpose of this study was to evaluate the extent to which augmentation of acute repair of rotator cuff tendons with a newly designed poly-L-lactide repair device would improve functional and biomechanical outcomes in a canine model.<h4>Methods</h4>Eight adult, male mongrel dogs (25 to 30 kg) underwent bilateral shoulder surgery. One shoulder underwent tendon release and repair only, and the other was subjected to release and repair followed by augmentation with the repair device. At twelve weeks, tendon retraction, cross-sectional area, stiffness, and ultimate load of the repair site were measured. Augmented repairs underwent histologic assessment of biocompatibility. In addition, eight pairs of canine cadaver shoulders underwent infraspinatus injury and repair with and without device augmentation with use of identical surgical procedures and served as time-zero biomechanical controls. Eight unpaired, canine cadaver shoulders were included as normal biomechanical controls.<h4>Results</h4>At time zero, repair augmentation significantly increased the ultimate load (23%) (p = 0.034) but not the stiffness of the canine infraspinatus tendon repair. At twelve weeks, the poly-L-lactide scaffold was observed to be histologically biocompatible, and augmented repairs demonstrated significantly less tendon retraction (p = 0.008) and significantly greater cross-sectional area (137%), stiffness (26%), and ultimate load (35%) than did repairs that had not been augmented (p < 0.001, p = 0.002, and p = 0.009, respectively).<h4>Conclusions</h4>While limiting but not eliminating tendon repair retraction, the augmentation device provided a tendon-bone bridge and scaffold for host tissue deposition and ingrowth, resulting in improved biomechanical function of the repair at twelve weeks.
Project description:Surgical management of massive rotator cuff tears remains challenging, with failure rates ranging from 20% to 90%. Multiple different arthroscopic and open techniques have been described, but there is no current gold standard. Failure after rotator cuff repair is typically multifactorial; however, failure of tendon-footprint healing is often implicated. Patch augmentation has been described as a possible technique to augment the biology of rotator cuff repair in situations of compromised tendon quality and has shown promising short-term results. The purpose of this article is to describe our preferred surgical technique for arthroscopic rotator cuff repair with patch augmentation.
Project description:The treatment of massive and irreparable rotator cuff tears remains a challenge for shoulder surgeons. When treating patients with chronic rotator cuff tears, especially those with severe fatty degeneration, severe tendon retraction, or muscle atrophy, the risk of re-tear and persistent severe pain persists. Therefore, surgeons can choose from numerous options. Superior capsular reconstruction (SCR) was introduced as a technique to maintain the stability of the upper shoulder and stabilize the muscles without repairing the supraspinatus and infraspinatus. Various autograft and allograft techniques have been developed. SCR performed using an autograft has the disadvantage of requiring harvesting the tensor fascia lata. Although allografts reduce harvest time, they also increase donor-site morbidity and the time required for healing. To solve the healing problem, we have introduced an SCR technique through grafting with the Achilles tendon-bone. Although this is an unproven technique for patients with chronic irreparable rotator cuff tears, our short-term outcomes seem promising. Further studies and follow-ups are needed to determine the success of this technique.
Project description:PURPOSE:To develop a clinically relevant, robust murine model of rotator cuff tendon repair to examine cellular and molecular mechanisms of healing. METHODS:Sixty C57BL/6 male mice underwent rotator cuff transection and repair using microsurgical techniques. A modified Kessler suturing technique was used prior to tendon detachment. Sutures were passed through 2 intersecting bone tunnels that were made at the tendon attachment site. Mice were sacrificed at 2 and 4 weeks with subsequent biomechanical, histologic, micro-CT, and gene expression evaluations. RESULTS:Failure forces in the 2- and 4-week groups were 36% and 75% of the intact tendon, respectively. Histologic evaluation revealed complete reattachment of the tendon with no observable gap. Healing occurred by formation of fibrovascular tissue at the tendon-bone interface, similar to larger animal models. Molecular analysis revealed gene expression consistent with gradual healing of the reattached tendon over a period of 4 weeks. Comparisons were made using 1-way analysis of variance. CONCLUSIONS:This model is distinguished by use of microsurgical suturing techniques, which provides a robust, reproducible, and economic animal model to study various aspects of rotator cuff pathology. CLINICAL RELEVANCE:Improvement of clinical outcomes of rotator cuff pathology requires in-depth understanding of the underlying cellular and molecular mechanisms of healing. This study presents a robust murine model of supraspinatus repair to serve as a standard research tool for basic and translational investigations into signaling pathways, gene expression, and the effect of biologic augmentation approaches.
Project description:Despite advances in surgical technology, as well as generally good outcomes, repairs of full-thickness rotator cuff tears show a retear rate of 25% to 57% and may fail to provide full return of function. The repairs tend to fail at the suture-tendon junction, which is due to several factors, including tension at the repair site, quality of the tendon, and defective tissue repair. One strategy to augment repair of large to massive rotator cuff tears is the development of biological scaffold materials, composed of extracellular matrix (ECM). The goal is to strengthen and evenly distribute the mechanical load across the repair site, thus minimizing the rupture risk of the native tendon while providing the biological elements needed for healing. The promising results of ECM-derived materials and their commercial availability have increased their popularity among shoulder surgeons. In contrast to a traditional open or arthroscopically assisted mini-open approach, this completely arthroscopic technique offers the full advantages warranted by the use of a minimally invasive approach. This technical guide describes arthroscopic rotator cuff repair using an ECM graft technique.
Project description:Rotator cuff tears can be associated with significant shoulder dysfunction and pain. Despite improved surgical techniques and new materials for rotator cuff reconstruction, there is no significant reduction in the re-rupture rate. Innovative approaches for enhanced tendon healing are required. The potential of biologically optimized tendon integration has probably been insufficiently explored so far. The existing practice of debridement might eliminate repair tissue and a major source of cells and blood vessels necessary for tendon healing. Biological augmentation may be an option to improve the healing process. The subacromial bursa is a highly proliferative tissue with mesenchymal stem cells capable of differentiating into various cell lines and is easily accessible during rotator cuff repair. We describe the technique of bursal augmentation in arthroscopic double-row SutureBridge repair of a posterosuperior rotator cuff tear with the aim of improving tendon-to-bone healing.
Project description:Tendon-to-bone healing after rotator cuff repair surgery has a failure rate of 20%-94%. There has been a recent interest to determine the factors that act as determinants between successful and unsuccessful rotator cuff repair. Vitamin D level in patients is one of the factors that have been linked to bone and muscle proliferation and healing, and it may have an effect on tendon-to-bone healing. The purpose of this article is to critically review relevant published research that relates to the effect of vitamin D on rotator cuff tears and subsequent healing. A review of the literature was conducted to identify all studies that investigate the relationship between vitamin D and tendon healing, in addition to its mechanism of action. The data were then analyzed in order to summarize what is currently known about vitamin D, rotator cuff pathology, and tendon-to-bone healing. The activated metabolite of vitamin D, 1?,25-dihydroxyvitamin D3, affects osteoblast proliferation and differentiation. Likewise, vitamin D plays a significant role in the tendon-to-bone healing process by increasing the bone mineral density and strengthening the skeletal muscles. The 1?,25-dihydroxyvitamin D3 binds to vitamin D receptors on myocytes to stimulate growth and proliferation. The form of vitamin D produced by the liver, calcifediol, is a key initiator of the myocyte healing process by moving phosphate into myocytes, which improves function and metabolism. Investigation into the effect of vitamin D on tendons has been sparse, but limited studies have been promising. Matrix metalloproteinases play an active role in remodeling the extracellular matrix (ECM) of tendons, particularly deleterious remodeling of the collagen fibers. Also, the levels of transforming growth factor-?3 positively influence the success of the surgery for rotator cuff repair. In the tendon-to-bone healing process, vitamin D has been shown to successfully influence bone and muscle healing, but more research is needed to delve into the mechanisms of vitamin D as a factor in skeletal tendon health and healing.