The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Santanu Chaudhury - One of the best experts on this subject based on the ideXlab platform.
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ARE THEY TOUGH ENOUGH? A COMPARISON OF HOW THE SHEAR MECHANICAL PROPERTIES OF ROTATOR CUFF REPAIR PATCHES MATCH NORMAL AND TORN ROTATOR CUFF TENDONS
2012Co-Authors: Santanu Chaudhury, Fritz Vollrath, C. Holland, D Porter, Andrew CarrAbstract:Background High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA). Methods The shear properties of four RCT repair grafts were measured (Restore, Graftjacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G9) as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations. A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn9s multiple comparison test. Results We report a significant difference in the shear moduli of all four rotator cuff repair grafts (P 0.05, Dunn9s multiple comparison test). The other repair grafts, Graftjacket and Restore, had a significantly lower storage modulus when compared to human rotator cuff tendons. Conclusions With increasing numbers of repairs of rotator cuff tears, and augmentation of these repairs, there is a need to understand the mechanical and biological properties of the both repair grafts and the tendons they are designed to augment. At present there is no clear definition of the ideal mechanobiological properties of rotator cuff repair patches. Current rotator cuff repair grafts display a wide variation in their shear mechanical properties, and how closely they are matched to the mechanical properties of human rotator cuff tendons. It is hoped that this study may help to guide surgeons in deciding on the most appropriate rotator cuff tendon repair graft.
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ARE THEY TOUGH ENOUGH? A COMPARISON OF HOW THE SHEAR MECHANICAL PROPERTIES OF ROTATOR CUFF REPAIR PATCHES MATCH NORMAL AND TORN ROTATOR CUFF TENDONS
Journal of Bone &amp; Joint Surgery British Volume, 2012Co-Authors: Santanu Chaudhury, C. Holland, Fritz Vollrath, D Porter, A J CarrAbstract:Background High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA). Methods The shear properties of four RCT repair grafts were measured (Restore, Graftjacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G') as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations. A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn's multiple comparison test. Results We report a significant difference in the shear moduli of all four rotator cuff repair grafts (P<0.0001, 1 way ANOVA, Kruskall-Wallis test). 2 of the grafts, Zimmer Collagen Repair and SportMesh, were not significantly different when compared to rotator cuff tendons and were found to have comparable shear mechanical properties (P > 0.05, Dunn's multiple comparison test). The other repair grafts, Graftjacket and Restore, had a significantly lower storage modulus when compared to human rotator cuff tendons. Conclusions With increasing numbers of repairs of rotator cuff tears, and augmentation of these repairs, there is a need to understand the mechanical and biological properties of the both repair grafts and the tendons they are designed to augment. At present there is no clear definition of the ideal mechanobiological properties of rotator cuff repair patches. Current rotator cuff repair grafts display a wide variation in their shear mechanical properties, and how closely they are matched to the mechanical properties of human rotator cuff tendons. It is hoped that this study may help to guide surgeons in deciding on the most appropriate rotator cuff tendon repair graft.
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Tensile and shear mechanical properties of rotator cuff repair patches.
Journal of Shoulder and Elbow Surgery, 2011Co-Authors: Santanu Chaudhury, Fritz Vollrath, C. Holland, Mark S. Thompson, Andrew CarrAbstract:Background Augmentation of rotator cuff tears aims to strengthen the repair and reduce rerupture, yet studies still report high failure rates. This study determines key mechanical properties of rotator cuff repair patches, including establishing values for toughness and measuring the shear properties of repair patches and human rotator cuff tendons. We hypothesized that different repair grafts would (1) have varying material parameters, and (2) not all have mechanical properties similar to human rotator cuff tendons. Materials and methods Eight specimens each from the Restore, Graftjacket, Zimmer Collagen Repair, and SportsMesh repair patches were tested to failure in tension and for suture pullout. We assessed ultimate tensile strength, tensile (Young’s) modulus, and failure strain. This study also established toughness values and shear data. Storage modulus was calculated using dynamic shear analysis for the patches and 18 samples of normal rotator cuff tendon. Results We report significant variability in important mechanical properties of repair patches, with the mechanical parameters of the patches diverting variously—and often significantly—from values for human rotator cuff tendon. Conclusions The repair grafts tested all displayed significant variation in their mechanical properties and had at least some reduced parameters compared with human rotator cuff tendons. This study offers experimentally derived information of value to surgeons when selecting rotator cuff repair grafts. A better understanding of the mechanical suitability of repair grafts for supporting human rotator cuffs is needed if repair patches are to provide a solution for the clinical problem of failure of rotator cuff repairs.
A J Carr - One of the best experts on this subject based on the ideXlab platform.
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ARE THEY TOUGH ENOUGH? A COMPARISON OF HOW THE SHEAR MECHANICAL PROPERTIES OF ROTATOR CUFF REPAIR PATCHES MATCH NORMAL AND TORN ROTATOR CUFF TENDONS
Journal of Bone &amp; Joint Surgery British Volume, 2012Co-Authors: Santanu Chaudhury, C. Holland, Fritz Vollrath, D Porter, A J CarrAbstract:Background High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA). Methods The shear properties of four RCT repair grafts were measured (Restore, Graftjacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G') as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations. A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn's multiple comparison test. Results We report a significant difference in the shear moduli of all four rotator cuff repair grafts (P<0.0001, 1 way ANOVA, Kruskall-Wallis test). 2 of the grafts, Zimmer Collagen Repair and SportMesh, were not significantly different when compared to rotator cuff tendons and were found to have comparable shear mechanical properties (P > 0.05, Dunn's multiple comparison test). The other repair grafts, Graftjacket and Restore, had a significantly lower storage modulus when compared to human rotator cuff tendons. Conclusions With increasing numbers of repairs of rotator cuff tears, and augmentation of these repairs, there is a need to understand the mechanical and biological properties of the both repair grafts and the tendons they are designed to augment. At present there is no clear definition of the ideal mechanobiological properties of rotator cuff repair patches. Current rotator cuff repair grafts display a wide variation in their shear mechanical properties, and how closely they are matched to the mechanical properties of human rotator cuff tendons. It is hoped that this study may help to guide surgeons in deciding on the most appropriate rotator cuff tendon repair graft.
Stephen J Snyder - One of the best experts on this subject based on the ideXlab platform.
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arthroscopic Graftjacket reconstruction of rotator cuff tears technique and outcome
Orthopaedic Proceedings, 2012Co-Authors: Ivan Wong, Joseph P Burns, Stephen J SnyderAbstract:Purpose Management of massive, degenerative, and irreparable rotator cuff tears is challenging. Excessive re-tear rates and poor clinical outcome after standard repair have led to alternative methods of treatment. Tendon transfers and shoulder arthroplasty have had mixed results; both are invasive procedures with high potential morbidity. We began performing rotator cuff augmentation and replacement using Graftjacket allograft acellular human dermal matrix as a biologic minimally invasive alternative in this difficult population almost 6 years ago. This article highlights our preferred arthroscopic technique and early results. Method From January 2004 to June 2007, 45 patients (36 men, 9 women) with massive rotator cuff tears were treated arthroscopically with the Graftjacket allograft. All patients completed a preoperative University of California, Los Angeles (UCLA) score. Follow-up was a minimum of 2 years (range, 24–68 months) and patients completed UCLA, Western Ontario Rotator Cuff (WORC), and American Shoulder and Elbow Surgeons (ASES) scores. Results Analysis was performed using the 3 validated outcomes measurement scores. The mean UCLA score increased from 18.4 preoperatively to 27.5 postoperatively (P Conclusion Evidence-based data to outline an algorithm for management of irreparable rotator cuff tears is being developed. We documented significant clinical improvement with arthroscopic rotator cuff reconstruction using the Graftjacket allograft acellular human dermal matrix. The procedure is safe and associated with high patient satisfaction, without the morbidity of tendon transfer or arthroplasty. For those few cases where further surgery is required, no bridges are burned. The early success of this procedure warrants further study with more patients, longer follow-up, and higher levels of evidence-based investigation.
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arthroscopic Graftjacket repair of rotator cuff tears
Journal of Shoulder and Elbow Surgery, 2010Co-Authors: Ivan Wong, Joseph P Burns, Stephen J SnyderAbstract:Hypothesis Management of massive, degenerative, and irreparable rotator cuff tears is challenging. Excessive re-tear rates and poor clinical outcome after standard repair have led to alternative methods of treatment. Tendon transfers and shoulder arthroplasty have had mixed results; both are invasive procedures with high potential morbidity. We began performing rotator cuff augmentation and replacement using Graftjacket allograft acellular human dermal matrix as a biologic minimally invasive alternative in this difficult population almost 6 years ago. This article highlights our preferred arthroscopic technique and early results. Materials and methods From January 2004 to June 2007, 45 patients (36 men, 9 women) with massive rotator cuff tears were treated arthroscopically with the Graftjacket allograft. All patients completed a preoperative University of California, Los Angeles (UCLA) score. Follow-up was a minimum of 2 years (range, 24-68 months) and patients completed UCLA, Western Ontario Rotator Cuff (WORC), and American Shoulder and Elbow Surgeons (ASES) scores. Results Analysis was performed using the 3 validated outcomes measurement scores. The mean UCLA score increased from 18.4 preoperatively to 27.5 postoperatively ( P Discussion Evidence-based data to outline an algorithm for management of irreparable rotator cuff tears is being developed. We documented significant clinical improvement with arthroscopic rotator cuff reconstruction using the Graftjacket allograft acellular human dermal matrix. The procedure is safe and associated with high patient satisfaction, without the morbidity of tendon transfer or arthroplasty. For those few cases where further surgery is required, no bridges are burned. The early success of this procedure warrants further study with more patients, longer follow-up, and higher levels of evidence-based investigation.
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histologic evaluation of a biopsy specimen obtained 3 months after rotator cuff augmentation with Graftjacket matrix
Arthroscopy, 2009Co-Authors: Stephen J Snyder, James L Bond, Steven P Arnoczky, Ryan M DopirakAbstract:Understanding the cellular response to a biologic graft used in rotator cuff applications is important because foreign-body reactions and inflammation complications have historically been seen with xenograft-derived grafts. The purpose of this study was to histologically evaluate a biopsy specimen taken from a rotator cuff of a 62-year-old man 3 months after augmentation with an acellular human dermal graft, Graftjacket Matrix-MaxForce Extreme (Wright Medical Technology, Arlington, TN). The graft material was intact and filled with numerous elastic fibers and blood vessels. Extensive host cellular infiltration was evident along the margins of the graft, whereas the more central regions were more sparsely populated. Calcification and infection were not evident. There was little to no inflammatory response. The orientation of the collagen fibers indicated early organization of new tissue. The incorporation of the Graftjacket Matrix-MaxForce Extreme evidenced by cellular infiltration, alignment of collagen fibers, and blood vessel ingrowth shows that this graft exhibits key biologic factors of the remodeling process when used as an augmentation device in rotator cuff repair.
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arthroscopic replacement of massive irreparable rotator cuff tears using a Graftjacket allograft technique and preliminary results
Arthroscopy, 2008Co-Authors: James L Bond, Ryan M Dopirak, Jason Higgins, Joseph P Burns, Stephen J SnyderAbstract:Purpose: Our purpose was to assess the short-term results and describe the technique of arthroscopic repair of irreparable rotator cuff tears by use of a Graftjacket allograft (Wright Medical Technology, Arlington, TN). Methods: Between March 2003 and February 2004, 16 patients with massive, contracted, immobile rotator cuff tears were treated with arthroscopic placement of a Graftjacket allograft by a single surgeon. Patients were followed up for 1 to 2 years. All were evaluated preoperatively and postoperatively by use of the modified University of California, Los Angeles scoring system, Constant score, and Simple Shoulder Test. Magnetic resonance imaging was performed postoperatively at 3 months and 1 year. Results: At a mean follow-up of 26.8 months (range, 12 to 38 months), 15 of 16 patients were satisfied with the procedure. The mean University of California, Los Angeles score increased from 18.4 preoperatively to 30.4 postoperatively ( P = .0001). The Constant score increased from 53.8 to 84.0 ( P = .0001). Statistically significant improvements were seen in pain, forward flexion, and external rotation strength. Thirteen patients had full incorporation of the graft into the native tissue as documented on magnetic resonance imaging. There were no complications in this cohort of patients. Conclusions: Our study supports Graftjacket allograft as a viable solution for surgical salvage in select cases of massive, irreparable rotator cuff pathology. This treatment option may provide patients with decreased pain and increased function despite a previously irreparable rotator cuff tear. Level of Evidence: Level IV, therapeutic case series.
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technique for arthroscopic replacement of severely damaged rotator cuff using Graftjacket allograft
Operative Techniques in Sports Medicine, 2007Co-Authors: Stephen J Snyder, James L BondAbstract:Massive non-repairable injuries to the rotator cuff are a difficult problem to treat. Current methods include tendon transfers and reverse total joint replacement, both procedures have many drawbacks especially in the young patient. The use of a reliable acellular allograft scaffold material derived from freeze-dried human dermis called Graftjacket (Wright Medical Technology, Arlington, TN) has demonstrated promise in a small consecutive group of patients when inserted under arthroscopic control in our prospective study. The pre-clinical work in both the animal and laboratory settings, as well as human biopsies, demonstrates that this unique scaffold will attract host stem cell, offers binding sites for them, and supports their re-growth into a viable tendon-like tissue. The Graftjacket is also rapidly revascularized and attached to the surrounding host tissue including bone, tendon, and muscle. All study patients were evaluated with pre and post op MRI scans and followed clinically for at least a year. The arthroscopic technique for insertion of the Graftjacket allograft has been refined and is now performed in a reasonable surgical time using standard equipment. This paper reviews the SCOI technique and post op care and suggests further areas of study to define the role of this promising material in the future.
G. Russell Huffman - One of the best experts on this subject based on the ideXlab platform.
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Foreign Body Reaction to Acellular Dermal Matrix Allograft in Biologic Glenoid Resurfacing
Clinical Orthopaedics and Related Research®, 2013Co-Authors: Surena Namdari, Christopher Melnic, G. Russell HuffmanAbstract:Background Biologic glenoid resurfacing is a treatment option for young patients with glenohumeral arthritis. An optimal synthetic graft for glenoid resurfacing should allow repopulation with host cells, be durable enough to tolerate suture fixation and forces across the joint, and present no host inflammatory response. We report two cases of giant cell reaction to Graftjacket^® after biologic glenoid resurfacing. Case Description Two patients who underwent hemiarthroplasty and biologic glenoid resurfacing using Graftjacket^® had a foreign body giant cell reaction that required revision surgery. Intraoperatively, both patients were observed to have a well-fixed humeral component and a dense, erythematous, synovitic membrane overlying the glenoid. Pathology specimens showed a benign reactive synovium, chronic inflammation, and foreign body giant cell reaction. After débridement and conversion to total shoulder arthroplasty, both patients continued to be pain-free at greater than 1-year followup. Literature Review Multinucleated giant cell and mononuclear cell responses have been observed in an animal model after use of Graftjacket^®. Although the use of acellular matrix-based scaffold for biologic glenoid resurfacing is not new, the possibility of foreign body reaction as a source of persistent symptoms has not been described. Clinical Relevance Given the lack of data to indicate an advantage to biologic resurfacing of the glenoid over hemiarthroplasty alone, resurfacing should not introduce significant additional surgical complications. We suggest foreign body reaction be considered in the differential diagnosis for a persistently painful shoulder after biologic glenoid resurfacing using an acellular allograft patch.
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Foreign Body Reaction to Acellular Dermal Matrix Allograft in Biologic Glenoid Resurfacing
Clinical Orthopaedics and Related Research, 2013Co-Authors: Surena Namdari, Christopher Melnic, G. Russell HuffmanAbstract:Background Biologic glenoid resurfacing is a treatment option for young patients with glenohumeral arthritis. An optimal synthetic graft for glenoid resurfacing should allow repopulation with host cells, be durable enough to tolerate suture fixation and forces across the joint, and present no host inflammatory response. We report two cases of giant cell reaction to Graftjacket® after biologic glenoid resurfacing.
Andrew Carr - One of the best experts on this subject based on the ideXlab platform.
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Characterizing the macro and micro mechanical properties of scaffolds for rotator cuff repair.
Journal of Shoulder and Elbow Surgery, 2017Co-Authors: Nasim Zargar, Stephanie G. Dakin, Osnat Hakimi, Cameron P. Brown, Navraj S. Nagra, Andrew CarrAbstract:Background Retearing after rotator cuff surgery is a major clinical problem. Numerous scaffolds are being used to try to reduce retear rates. However, few have demonstrated clinical efficacy. We hypothesize that this lack of efficacy is due to insufficient mechanical properties. Therefore, we compared the macro and nano/micro mechanical properties of 7 commercially available scaffolds to those of the human supraspinatus tendons, whose function they seek to restore. Methods The clinically approved scaffolds tested were X-Repair, LARS ligament, Poly-Tape, BioFiber, Graftjacket, Permacol, and Conexa. Fresh frozen cadaveric human supraspinatus tendon samples were used. Macro mechanical properties were determined through tensile testing and rheometry. Scanning probe microscopy and scanning electron microscopy were performed to assess properties of materials at the nano/microscale (morphology, Young modulus, loss tangent). Results None of the scaffolds tested adequately approximated both the macro and micro mechanical properties of human supraspinatus tendon. Macroscale mechanical properties were insufficient to restore load-bearing function. The best-performing scaffolds on the macroscale (X-Repair, LARS ligament) had poor nano/microscale properties. Scaffolds approximating tendon properties on the nano/microscale (BioFiber, biologic scaffolds) had poor macroscale properties. Conclusion Existing scaffolds failed to adequately approximate the mechanical properties of human supraspinatus tendons. Combining the macroscopic mechanical properties of a synthetic scaffold with the micro mechanical properties of biologic scaffold could better achieve this goal. Future work should focus on advancing techniques to create new scaffolds with more desirable mechanical properties. This may help improve outcomes for rotator cuff surgery patients.
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The response of tenocytes to commercial scaffolds used for rotator cuff repair.
European Cells & Materials, 2016Co-Authors: R D Smith, Andrew Carr, Stephanie G. Dakin, Sarah J. B. Snelling, Clarence Yapp, Osnat HakimiAbstract:Surgical repairs of rotator cuff tears have high re-tear rates and many scaffolds have been developed to augment the repair. Understanding the interaction between patients' cells and scaffolds is important for improving scaffold performance and tendon healing. In this in vitro study, we investigated the response of patient-derived tenocytes to eight different scaffolds. Tested scaffolds included X-Repair, Poly-Tape, LARS Ligament, BioFiber (synthetic scaffolds), BioFiber-CM (biosynthetic scaffold), Graftjacket, Permacol, and Conexa (biological scaffolds). Cell attachment, proliferation, gene expression, and morphology were assessed. After one day, more cells attached to synthetic scaffolds with dense, fine and aligned fibres (X-Repair and Poly-Tape). Despite low initial cell attachment, the human dermal scaffold (Graftjacket) promoted the greatest proliferation of cells over 13 days. Expression of collagen types I and III were upregulated in cells grown on non-cross-linked porcine dermis (Conexa). Interestingly, the ratio of collagen I to collagen III mRNA was lower on all dermal scaffolds compared to synthetic and biosynthetic scaffolds. These findings demonstrate significant differences in the response of patient-derived tendon cells to scaffolds that are routinely used for rotator cuff surgery. Synthetic scaffolds promoted increased cell adhesion and a tendon-like cellular phenotype, while biological scaffolds promoted cell proliferation and expression of collagen genes. However, no single scaffold was superior. Our results may help understand the way that patients' cells interact with scaffolds and guide the development of new scaffolds in the future.
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95 An in vitro comparative analysis of scaffolds for the augmentation of rotator cuff repair
British Journal of Sports Medicine, 2014Co-Authors: Richard J. Smith, Andrew Carr, Sarah J. B. Snelling, Osnat HakimiAbstract:Introduction Rotator cuff tears are one of the most common musculoskeletal problems affecting the adult population and can cause significant pain and disability. Large tears often require surgical repair but repair failure remains a significant clinical problem with failure rates reported as high as 94%. 4 Hence, there is a growing need for an effective clinical solution. Implanted scaffolds are an increasingly popular option to improve the biomechanical properties and native repair process. Over 20 scaffolds are commercially available and these are derived from mammalian tissue, synthetic polymers or a combination thereof. Despite increasing scaffold use, several concerns regarding their efficacy, safety, biocompatibility and mechanism of action remain. In this in vitro study we have assessed the interactions of human tenocytes from rotator cuff tear patients with 8 commercially available scaffolds. We hypothesise that there will be a difference in cell adhesion and proliferation between the 8 scaffolds. By using diseased human tenocytes, we hypothesise that this in vitro model will more accurately represent human rotator cuff cell response in vivo . In the absence of comparative clinical studies, this model may provide surgeons with information to help them select the most appropriate scaffold for their patients. Methods Tenocytes were extracted from tissue biopsies taken from 2 patients with large-massive rotator cuff tears who were undergoing subacromial decompression surgery. Tenocytes were seeded onto the prepared scaffolds and incubated in supplemented growth media for 28 days. 3 Initial cell attachment was assessed using AlamarBlue ® assay on day 1. Cell proliferation was measured using AlamarBlue ® assay every 3 days over the 28-day period. Results Finely meshed X-Repair and Poly-Tape scaffolds demonstrated the greatest cell attachment at day 1 (p Graftjacket demonstrated statistically increased rate of cell proliferation, particularly during the first 2 weeks. Cell proliferation on all scaffolds was similar after 28 days. Discussion Initial cell attachment was greatest on synthetic scaffolds with straight, regularly oriented, and densely packed fibres. The parallel orientation and dimensions of these synthetic fibres mimic those of native collagen tendon fibres and may account for increased initial cell attachment. Cell proliferation during the first 2 weeks was greatest on non-crosslinked, non-irradiated, human-derived dermis, Graftjacket. These results confirm favourable outcomes from several clinical studies that used Graftjacket to augment rotator cuff repair. 1,2,5 Cell proliferation appeared to be similar on all scaffolds after 28 days, most likely due to cell confluence on the substratum. In terms of biological versus synthetic materials, no clear trend was observed in terms of cell proliferation, but factors such as scaffold structure, collagen source, polymer type and industrial processing techniques could be suggested as possible modulators of cell attachment and growth. References 1 Barber, et al . Arthroscopy . 2012;28:8–15 2 Bond, et al . Arthroscopy . 2008;24:403–409 3 Chard, et al . Ann Rheum Dis . 1987;46:385–390 4 Galatz, et al . J Bone Joint Surg Am . 2004;86:219–224 5 Wong, et al . J Shouler Elbow Surg . 2010;19:104–9
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ARE THEY TOUGH ENOUGH? A COMPARISON OF HOW THE SHEAR MECHANICAL PROPERTIES OF ROTATOR CUFF REPAIR PATCHES MATCH NORMAL AND TORN ROTATOR CUFF TENDONS
2012Co-Authors: Santanu Chaudhury, Fritz Vollrath, C. Holland, D Porter, Andrew CarrAbstract:Background High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA). Methods The shear properties of four RCT repair grafts were measured (Restore, Graftjacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G9) as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations. A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn9s multiple comparison test. Results We report a significant difference in the shear moduli of all four rotator cuff repair grafts (P 0.05, Dunn9s multiple comparison test). The other repair grafts, Graftjacket and Restore, had a significantly lower storage modulus when compared to human rotator cuff tendons. Conclusions With increasing numbers of repairs of rotator cuff tears, and augmentation of these repairs, there is a need to understand the mechanical and biological properties of the both repair grafts and the tendons they are designed to augment. At present there is no clear definition of the ideal mechanobiological properties of rotator cuff repair patches. Current rotator cuff repair grafts display a wide variation in their shear mechanical properties, and how closely they are matched to the mechanical properties of human rotator cuff tendons. It is hoped that this study may help to guide surgeons in deciding on the most appropriate rotator cuff tendon repair graft.
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Tensile and shear mechanical properties of rotator cuff repair patches.
Journal of Shoulder and Elbow Surgery, 2011Co-Authors: Santanu Chaudhury, Fritz Vollrath, C. Holland, Mark S. Thompson, Andrew CarrAbstract:Background Augmentation of rotator cuff tears aims to strengthen the repair and reduce rerupture, yet studies still report high failure rates. This study determines key mechanical properties of rotator cuff repair patches, including establishing values for toughness and measuring the shear properties of repair patches and human rotator cuff tendons. We hypothesized that different repair grafts would (1) have varying material parameters, and (2) not all have mechanical properties similar to human rotator cuff tendons. Materials and methods Eight specimens each from the Restore, Graftjacket, Zimmer Collagen Repair, and SportsMesh repair patches were tested to failure in tension and for suture pullout. We assessed ultimate tensile strength, tensile (Young’s) modulus, and failure strain. This study also established toughness values and shear data. Storage modulus was calculated using dynamic shear analysis for the patches and 18 samples of normal rotator cuff tendon. Results We report significant variability in important mechanical properties of repair patches, with the mechanical parameters of the patches diverting variously—and often significantly—from values for human rotator cuff tendon. Conclusions The repair grafts tested all displayed significant variation in their mechanical properties and had at least some reduced parameters compared with human rotator cuff tendons. This study offers experimentally derived information of value to surgeons when selecting rotator cuff repair grafts. A better understanding of the mechanical suitability of repair grafts for supporting human rotator cuffs is needed if repair patches are to provide a solution for the clinical problem of failure of rotator cuff repairs.
