Evidence of healing of partial-thickness rotator cuff tears following arthroscopic augmentation with a collagen implant: a 2-year MRI follow-up

Arthroscopic management of isolated partial-thickness rotator cuff tears

PURPOSE

The aim of the present study is to provide a comprehensive review on the surgical outcomes following arthroscopic treatments of partial-thickness rotator cuff tears (PT-RCTs) and to compare the postoperative American Shoulder and Elbow Surgeons (ASES) score following in situ transtendon repair and tear completion, followed by repair.

METHODS

Medline, EMBASE, Scopus, CINAHL and CENTRAL bibliographic databases were searched. Papers including patients with PT-RCTs of any grade who underwent treatment using debridement, in situ transtendon repair, tear completion and repair or bioinductive collagen implants were reviewed. Primary PT-RCTs were the sole indication for surgery. Primary postoperative outcomes assessed included the ASES score, the Absolute Constant-Murley score, the Simple Shoulder Test, the Visual Analogue Scale, the University of California-Los Angeles Shoulder Scale, the Western Ontario Rotator Cuff Score, range of motion, complications and revisions. A meta-analysis of comparative studies compared the postoperative ASES score between patients treated with in situ transtendon repair versus tear completion repair.

RESULTS

Twenty-eight studies were included. The ASES score was reported by four comparative studies with contrasting results. The heterogeneity was high (I2 = 86%), and effect sizes ranged from -0.49 in favour of the tear completion and repair technique to an effect size of +1.07 favouring in situ transtendon repair. The overall effect size of 0.02 suggests an equivalence between the two techniques in terms of the ASES score. Two studies with a total sample size of 111 patients reported on debridement, and four studies with a total sample size of 155 patients reported on bioinductive collagen implants.

CONCLUSION

Debridement alone is suitable for Ellman grades I-II PT-RCTs. In situ transtendon and tear completion repair techniques yield similar postoperative outcomes. Bioinductive collagen implants hold promise but lack long-term efficacy data. High-quality comparative studies are needed to determine the best treatment for PT-RCTs.

LEVEL OF EVIDENCE

Level IV.

Optimizing Tissue Engineering for Clinical Relevance in Rotator Cuff Repair

Rotator cuff tear (RCT) is the most common cause of disability in the upper extremity. It results in 4.5 million physician visits in the United States every year and is the most common etiology of shoulder conditions evaluated by orthopedic surgeons. Over 460,000 RCT repair surgeries are performed in the United States annually. Rotator cuff (RC) retear and failure to heal remain significant postoperative complications. Literature suggests that the retear rates can range from 29.5% to as high as 94%. Weakened and irregular enthesis regeneration is a crucial factor in postsurgical failure. Although commercially available RC repair grafts have been introduced to augment RC enthesis repair, they have been associated with mixed clinical outcomes. These grafts lack appropriate biological cues such as stem cells and signaling molecules at the bone-tendon interface. In addition, they do little to prevent fibrovascular scar tissue formation, which causes the RC to be susceptible to retear. Advances in tissue engineering have demonstrated that mesenchymal stem cells (MSCs) and growth factors (GFs) enhance RC enthesis regeneration in animal models. These models show that delivering MSCs and GFs to the site of RCT enhances native enthesis repair and leads to greater mechanical strength. In addition, these models demonstrate that MSCs and GFs may be delivered through a variety of methods including direct injection, saturation of repair materials, and loaded microspheres. Grafts that incorporate MSCs and GFs enhance anti-inflammation, osteogenesis, angiogenesis, and chondrogenesis in the RC repair process. It is crucial that the techniques that have shown success in animal models are incorporated into the clinical setting. A gap currently exists between the promising biological factors that have been investigated in animal models and the RC repair grafts that can be used in the clinical setting. Future RC repair grafts must allow for stable implantation and fixation, be compatible with current arthroscopic techniques, and have the capability to deliver MSCs and/or GFs.

Economic Evaluation of a Bioinductive Implant for the Repair of Rotator Cuff Tears Compared with Standard Surgery in Italy

INTRODUCTION

Rotator cuff tear (RCT) is a painful, progressive condition resulting from damage to the rotator cuff tendons and is the leading cause of shoulder-related disability. Surgical repair of rotator cuff is an established standard of care (SOC); however, failure of the procedure can occur. In this context, the use of collagen-based bioinductive implant REGENETEN showed long-term improvements in clinical scores. The aim of the study was to assess the cost-effectiveness of REGENETEN combined with SOC (SOC + REGENETEN) compared to SOC alone from both National Healthcare Service (NHS) and societal perspectives in Italy.

METHODS

A decision analytic model was developed to estimate the number of tears healed and costs for the two considered treatment strategies over 1 year. Clinical data were retrieved from the literature, and the clinical pathways for the management of patients with RCTs were retrieved from four key opinion leaders in Italy.

RESULTS

Over a 1-year time horizon, healed lesions were 90.70% and 72.90% for surgical repair of RCTs with and without REGENETEN, respectively. Considering the NHS perspective, mean costs per patient were €7828 and €4650 for the two strategies, respectively, leading to an incremental cost-effectiveness ratio (ICER) of €17,857 per healed tear. From the societal perspective, the mean costs per patient were €12,659 for SOC and €11,784 for REGENETEN, thus showing savings of €4918 per healed tear when the bioinductive implant is used. The sensitivity analyses confirmed the robustness of the model results.

CONCLUSION

In the context of paucity of cost-effectiveness studies, our findings provide additional evidence for clinicians and payers regarding the value of a new treatment option that supports a tailored approach for the management of patients with RCTs.

Augmentation of triceps tendon repair with a bio-inductive collagen scaffold

Two active, adult male patients, one with prior triceps rupture and direct repair, presented with traumatic rupture of the distal triceps tendon. MRI confirmed not only complete rupture with retraction in both, but also signal changes within the tendon, raising concern for healing potential and re-rupture. Surgical repair was performed using heavy, non-absorbable suture and suture anchors in the standard fashion, followed by augmentation with a bovine, bio-inductive collagen scaffold in order to increase tendon thickness and aid with healing capability. This technique is well described for rotator cuff repair augmentation but is a novel technique to the literature in the setting of triceps tendons repair. Both patients returned to full, preinjury activity without complication with sustained results at 3 and 3.5 years postoperatively.

Conservative Management of Partial Thickness Rotator Cuff Tears: A Systematic Review

BACKGROUND

Conservative management has emerged as an attractive option for partial thickness rotator cuff tears (PT-RCTs). A single algorithmic treatment strategy for patients with symptomatic PT-RCT has not yet been developed. This systematic review aims to ascertain whether a conservative approach to PT-RCTs yields positive results in terms of clinical outcomes and functional recovery.

METHODS

This is a systematic review of the literature on patients with PT-RCTs receiving conservative treatment with physiotherapy, platelet-rich plasma (PRP) injections, collagen injections, hyaluronic acid (HA) injections, or corticosteroids injections coupled with polydeoxyribonucleotide (PDRN). Outcomes such as the Visual Analog Scale (VAS) for pain, American Shoulder and Elbow Surgeons and Constant-Murley Score evaluations, as well as the Shoulder Pain and Disability Index and Euro Quality of Life-5D questionnaires were reported following a conservative approach.

RESULTS

Eleven studies were included. Six articles explored the outcomes of patients with PT-RCT treated with PRP injections. Significant improvements in VAS for pain were observed. Two studies examined collagen injections and reported variations in VAS for pain and Constant-Murley Score. Sodium hyaluronate and HA injections were studied in two other articles, showing notable improvements in American Shoulder and Elbow Surgeons scores. Corticosteroid and PDRN injections also displayed favorable outcomes. In addition, physical therapy protocols demonstrated improvements in VAS for pain and strength, particularly with eccentric rehabilitation.

CONCLUSIONS

Conservative management of PT-RCTs, involving physical therapy, PRP injections, collagen injections, corticosteroid injections, HA injections, and PDRN in jections, demonstrates favorable clinical outcomes. In addition, favorable results are observed in terms of decreased tear width and improved strength recovery, at least during a short-term follow-up. Unfortunately, long-term insight into the structural integrity of conservatively treated rotator cuff tendons following a partial injury has not been thoroughly evaluated yet.

STUDY DESIGN LEVELS OF EVIDENCE

Level IV-systematic review.

Biphasic Interpositional Allograft for Rotator Cuff Repair Augmentation Is Safe in an Ovine Model

PURPOSE

To perform a preclinical histologic assessment of a biphasic acellular interpositional cancellous allograft in an ovine model of rotator cuff repair (RCR) designed to better understand its safety profile and effects on tendon healing after RCR.

METHODS

Thirty skeletally mature sheep with clinically normal shoulders with an artificially created degenerative infraspinatus tendon tear were randomized to control and treatment groups. Animals were euthanized at 3 weeks, 6 weeks, and 12 weeks. After gross dissection, rotator cuff specimens were fixed with formalin and polymerized for sectioning and staining. Blinded histologic scores evaluated inflammatory cell infiltrates, signs of degradation, particulate debris, collagen arrangement, neovascularization, and enthesis qualitative measures.

RESULTS

There were no treatment specimens that exhibited histologic signs of a significant infection, inflammatory infiltrate, or foreign body reaction such as granuloma or fibrous capsule formation. Histologic scores in all categories were not significantly different at all time points, including the primary end point mean cumulative inflammatory score (control: 3.66 ± 1.21 vs treated: 4.33 ± 1.51, P = .42), when comparing the treatment and control RCR groups. In general, the degree of tendon healing and host tissue response was essentially equivalent between the 2 groups with observation of low overall levels of inflammation and progressive improvements in collagen organization, reduced tenocyte activity, and fibrocartilaginous enthesis reformation.

CONCLUSIONS

This histologic study demonstrated the use of a biphasic interpositional allograft for RCR augmentation in an ovine model does not generate an inflammatory response or foreign body reaction. Use of the biphasic interpositional allograft resulted in a histological profile that was essentially equivalent to that of a standard RCR at 3-, 6-, and 12-week postoperative timepoints. These findings suggest that a biphasic interpositional allograft is safe for further clinical investigation in humans before broader clinical application.

CLINICAL RELEVANCE

Patch augmentation of RCR is a popular technique that has shown clinical success in improving the likelihood of a successful repair in patients at elevated risk for retear. Newer augmentation technologies are being developed to address the biology at the interface between the bone and soft tissue where failure typically occurs.

Arthroscopic Autologous Coracoacromial Ligament Augment Technique for Particle Thickness of Rotator Cuff with at Least Two Years Follow-Up

OBJECTIVE

Patch technology has been the new technique in the treatment of partial thickness of the rotator cuff tear (PTRCTs) to address the limitation of traditional techniques. Compared with allogeneic patches and artificial materials, coracoacromial ligament is obviously closer to their own biology. The purpose of the study was to evaluate the functional and radiographic outcomes following arthroscopic autologous coracoacromial ligament augment technique for treatment of PTRCTs.

METHOD

This study included three female patients with PTRCTs who underwent arthroscopy operation in 2017 with an average age of 51 years (range from 50 to 52 years). The coracoacromial ligament implant was attached to the bursal side surface of the tendon. The clinical results were evaluated by American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST), acromiohumeral distance (AHD) and muscle strength before and 12 months after operation. Magnetic resonance imaging (MRI) was performed 24 months after operation to assess the integrity of the anatomical structure of the original tear site.

RESULT

The average ASES score improved significantly from 57.3 preoperatively to 95.0 at 1-year follow-up. The strength improved significantly from grade 3 preoperatively to grade 5 at 1 year. Two of three patients underwent the MRI at 2-year follow-up. Radiographic released the complete healing of rotator cuff tear. No implant-related serious adverse events were reported.

CONCLUSION

The new technique of using autogenous coracoacromial ligament patch augment provides good clinical results on patients with PTRCTs.

Revision Rotator Cuff Repair With Versus Without an Arthroscopically Inserted Onlay Bioinductive Implant in Workers' Compensation Patients

Background

The addition of onlay biological grafts to augment difficult rotator cuff repairs has shown encouraging results in a case series.

Purpose/Hypothesis

The purpose of this study was to determine whether the addition of an onlay bioinductive implant would improve repair integrity, shear wave elastographic appearance of the repaired tendon and patch, and patient-rated and/or surgeon-measured shoulder function when used in workers' compensation patients undergoing revision arthroscopic rotator cuff repair. We hypothesized that the addition of the bioinductive implant would enhance repair integrity and clinical outcomes compared with standard repair.

Study Design

Cohort study; Level of evidence, 3.

Methods

A post hoc matched-cohort study was conducted on prospectively recruited workers' compensation patients who received a bioinductive implant for revision rotator cuff repair (n = 19). The control group was selected from consecutive workers' compensation revision rotator cuff repair patients before the introduction of bioinductive implants. Then, they were matched for age and tear size (n = 32). Kaplan-Meier curves were generated to compare the primary outcome of repair integrity between groups. The secondary outcomes were to evaluate the elastographic appearance of the tendon and patch in the bioinductive implant group and to compare patient-rated and surgeon-measured shoulder function between groups preoperatively and at 1 week, 6 weeks, 3 months, and 6 months postoperatively.

Results

No major complications associated with the bioinductive implants were identified. Six months after the revision rotator cuff repair, the retear rate in the bioinductive implant group was 16% (3/19), compared with 19% (6/32) in the age- and tear size-matched control group (P = .458). At the final follow-up, the retear rate in the bioinductive implant group was 47% (9/19) at a mean of 14 months compared with 38% (12/32) at a mean of 29 months in the control group (P = .489). The shear wave elastographic stiffness of repaired tendons augmented with the bioinductive implant remained unchanged at 6 m/s from 1 week to 6 months postoperatively, which is lower than the stiffness of 10 m/s in healthy tendons. There were no significant differences in patient-rated or surgeon-measured outcomes between groups 6 months postoperatively.

Conclusion

There were no differences in repair integrity or clinical outcomes between workers' compensation patients who underwent revision arthroscopic rotator cuff repair with an onlay bioinductive implant compared to those who underwent standard revision rotator cuff repair.

Bioinductive Collagen Implant Augmentation for Myotendinous Achilles Rupture in a Teenage Competitive Gymnast: A Case Report

CASE

A 16-year-old female competitive gymnast presented to our orthopaedic clinic with an acute Achilles tendon rupture at the myotendinous junction. Direct end-to-end repair was performed and augmented with a bioinductive collagen patch. The patient had increased tendon thickness at 6 months postoperatively, as well as significant improvements in strength and range of motion at 12 months.

CONCLUSION

Bioinductive collagen patch augmentation of Achilles tendon repair may be a useful adjunct for myotendinous junction Achilles ruptures, particularly in high-demand patients including competitive gymnasts.

Resorbable Bioinductive Collagen Implant Is Cost Effective in the Treatment of Rotator Cuff Tears

Purpose

This study was conducted to investigate whether the use of resorbable bioinductive collagen implant (RBI) in addition to conventional rotator cuff repair (conventional RCR) is cost-effective when compared to conventional RCR alone, in the treatment of full-thickness rotator cuff tears (FT RCT).

Methods

We developed a decision analytic model to compare the expected incremental cost and clinical consequences for a cohort of patients with FT RCT. The probabilities for healing or failure to heal (retear) were estimated from the published literature. Implant and healthcare costs were estimated from a payor's perspective in 2021 U.S. prices. An additional analysis included indirect cost estimations (e.g., productivity losses). Sensitivity analyses explored the effect of tear size, as well as the impact of risk factors.

Results

The base case analysis demonstrated that resorbable bioinductive collagen implant + conventional rotator cuff repair results in incremental costs of $232,468 and an additional 18 healed RCTs per 100 treated patients over 1 year. The estimated incremental cost-effectiveness ratio (ICER) is $13,061/healed RCT compared to conventional RCR alone. When return to work was included in the model, RBI + conventional RCR was found to be cost saving. Cost-effectiveness improved with tear size with the largest benefit seen in massive tears compared to large tears, as well as patients at higher risk of retearing.

Conclusions

This economic analysis demonstrated that RBI + conventional RCR delivered improved healing rates at a marginal increase in costs when compared to conventional RCR alone and is, therefore, cost-effective in this patient population. Considering indirect costs, RBI + conventional RCR resulted in lower costs compared to conventional RCR alone and is, therefore, deemed to be cost saving.

Level of Evidence

Level IV, economic analysis.

Subacromial-Subdeltoid Bursitis With Rice Bodies After Rotator Cuff Repair With a Collagen Scaffold Implant: A Case Report

CASE

We report the second-known case of subacromial-subdeltoid bursitis with rice bodies after rotator cuff repair with a Smith + Nephew REGENETEN bovine-derived bioinductive collagen scaffold implant. After the removal of rice bodies and a portion of implant that had not incorporated, the patient recovered well and made a full return to work and recreational activities.

CONCLUSION

This case demonstrates that persistent pain, swelling, or decreased range of motion for several months after rotator cuff repair with the use of a collagen implant may warrant a relatively early magnetic resonance imaging to evaluate for underlying pathology. It also provides a framework for physicians who may see similar patients in the future.

Intrasubstance Patellar Tendon Repair with the Addition of a Bio-inductive Implant

Intrasubstance patellar tendon ruptures are an uncommon injury that can have devastating long-term effects for patients. Operative intervention to repair the ruptured tendon is the gold standard treatment for these injuries and can be performed using a variety of techniques. Unlike the more common patellar tendon ruptures at the level of the patella, repairs of intrasubstance ruptures are often challenging because of the poor quality of the remaining tendon fibers. Tendon repair with augmentation via bio-inductive implants has gained popularity in upper extremity literature, as it has demonstrated improved tendon strength and patient outcomes. However, there remains a sparsity of reports regarding tendon augmentation in the lower extremity literature. Here, we describe repair of an intrasubstance patellar tendon rupture using a modified SpeedBridge repair and augmentation with a bio-inductive implant.

The use of long head biceps tendon autograft for massive rotator cuff tears: a PRISMA compliant systematic review

INTRODUCTION

Rotator cuff tears (RCT) are a common cause of shoulder pain and disability, with massive RCT accounting for 10-40% of all rotator cuff tears.

SOURCES OF DATA

A systematic search of PubMed and Scopus electronic databases was performed up to August 2022, and a total of 17 scientific articles were included in the present PRISMA compliant systematic review.

AREAS OF AGREEMENT

Understanding the geometric patterns in RCT is essential to achieve appropriate repositioning of the injured tendons in their anatomic location. The long head of the biceps tendon (LHBT) is usually exposed when defects of the anterolateral corner are present and can be easily used to augment rotator cuff repairs.

AREAS OF CONTROVERSY

There are no definite guideline regarding the management of massive rotator cuff tears.

GROWING POINTS

The use of LHBT graft is safe and effective, but technically demanding. All studies were level IV articles of medium to high quality.

AREAS TIMELY FOR DEVELOPING RESEARCH

Prospective long term follow-up studies and randomized controlled trials are needed, adding imaging evaluation and appropriate clinical outcome measures at follow-up.

Two-year outcomes with a bioinductive collagen implant used in augmentation of arthroscopic repair of full-thickness rotator cuff tears: final results of a prospective multicenter study

BACKGROUND

Full-thickness rotator cuff tears (FTRCTs) represent a common shoulder injury that, if untreated, can progress in size, become increasingly painful, and inhibit function. These lesions are often surgically repaired, with double-row arthroscopic repair often preferred for larger tears. Biological augmentation technologies have been developed to improve rates of postoperative radiographic retear and enhance patient-reported outcomes after surgical FTRCT repair. This study sought to confirm that augmented repair with a bioinductive bovine collagen implant results in favorable retear rates and patient outcomes with follow-up to 2 years.

METHODS

A prospective multicenter cohort study was undertaken to determine the efficacy and safety of augmenting single- or double-row arthroscopic repair of FTRCTs with a bioinductive bovine collagen implant. Of 115 adult patients participating, 66 (57.4%) had medium (1-3-cm) tears and 49 (42.6%) had large (3-5-cm) tears. Magnetic resonance imaging and patient-reported outcomes (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES] and Constant-Murley Score [CMS]) were performed and recorded at baseline, 3 months, 1 year, and 2 years.

RESULTS

Mean duration of follow-up was 2.1 years (range, 1.5-2.9 years). Between baseline and 2-year follow-up, mean total thickness of the supraspinatus tendon increased by 12.5% for medium tears and by 17.1% for large tears. Radiographic retear was noted in 7 of 61 available patients (11.5%) with medium tears, and in 14 of 40 patients (35.0%) with large tears. In both groups, these tears primarily occurred before the 3-month follow-up visit (13 of 21 [61.9%]). Radiographic retear with the supplemented double-row (DR) repair technique was 13.2% overall (12 of 91 DR patients; 11.3% for medium tears and 15.8% for large tears). The minimal clinically important difference was achieved by >90% of patients with both medium and large tears for both ASES and CMS. There were 2 serious adverse events classified by the treating surgeon as being possibly related to the device and/or procedure (1 case of swelling/drainage and 1 case of intermittent pain). Nine patients (7.8%; 4 medium tears and 5 large tears) required reoperation of the index rotator cuff surgery.

CONCLUSION

Final 2-year data from this study confirm that using this implant in augmentation of arthroscopic double-row repair of FTRCTs provides favorable rates of radiographic retear and substantial functional recovery. The relative safety of the device is also further supported.

Bioinductive collagen implants facilitate tendon regeneration in rotator cuff tears

Purpose

To evaluate the clinical outcomes, MRI imaging and histological characteristics of biopsy samples of the tendon from patients in whom rotator cuff repair was previously performed with a bioinductive type I bovine collagen implants.

Methods

Prospective study of 30 patients with partial or complete rotator cuff tears who underwent arthroscopic repair and augmentation with a resorbable type I bovine collagen implant. Preoperatively and at 6 and 12 months after surgery, the VAS, ASES and Constant-Murley scores were evaluated and an MRI study was performed. At 6 months, biopsies of the resulting tissue were obtained and examined histologically.

Results

Patients experienced statistically significant and sustained improvement from baseline for all scores and the mean tendon thickness increased by 1.84 mm. Magnetic resonance imaging evidence of complete healing was found in 27 patients and a considerable reduction in defect size, greater than 50%, was shown in 3. In all samples obtained, the new tissue generated had the histological appearance of a tendon, and was indistinguishable from the native tendon. There was no evidence of any remaining collagen implant.

Conclusions

Biopsies of tissue formed from bioinductive type I bovine collagen implants showed, six months after surgery, the generation of a neotendon indistinguishable from the native one. Histology and MRI imaging, revealed complete integration of the implant and absence of inflammatory or foreign body reactions. The clinical parameters, thickness and MRI signal of the tendon improved significantly at 6 months, regardless of the type and size of the tear, and remained unchanged until 12 months.

Level of evidence

Level IV, case series.

Optimal Management of Partial Thickness Rotator Cuff Tears: Clinical Considerations and Practical Management

Partial thickness rotator cuff tears have been diagnosed with increased frequency due to heightened awareness and an improvement in diagnostic modalities. When >50% of the tendon thickness has ruptured, intra-tendinous strain of the residual tendon increases. Surgery is generally confined to patients who have failed non-operative measures and have persistent symptoms. The rationale for repairing partial thickness tears lies in their limited self-healing capacity, and propensity to enlarge over time and progress to a full thickness defect. Although tear debridement and acromioplasty can improve pain and function, tear progression can occur, in addition to worse results being noted in bursal-sided defects. Several surgical strategies have been recommended but there is a lack of evidence to advocate one form of treatment over another. The aim of this narrative review is to discuss the treatment options for partial thickness tears of the rotator cuff.

A bio-inductive collagen scaffold that supports human primary tendon-derived cell growth for rotator cuff repair

Background

Rotator Cuff (RC) tendon tearing is a common clinical problem and there is a high incidence of revision surgery due to re-tearing. In an effort to improve patient outcome and reduce surgical revision, scaffolds have been widely used for augmentation of RC repairs. However, little is known about how scaffolds support tendon stem cell growth or facilitate tendon regeneration. The purpose of this study is to evaluate the structural and biological properties of a bioactive collagen scaffold (BCS) with the potential to promote tendon repair. Additionally, we conducted a pilot clinical study to assess the safety and feasibility of using the BCS for repair of RC tears.

Methods

A series of physical, ultrastructural, molecular and in vitro tests determined the biocompatibility and teno-inductive properties of this BCS. In addition, a prospective case study of 18 patients with RC tendon tears (>20 ​mm in diameter) was performed in an open-label, single-arm study, involving either mini-open or arthroscopic surgical RC repair with the BCS. Clinical assessment of RC repair status was undertaken by MRI-imaging at baseline, 6 and 12 months and patient evaluated questionnaires were taken at baseline as well as 3, 6 & 12 months.

Results

The BCS consists of highly purified type-I collagen, in bundles of varying diameter, arranged in a higher order tri-laminar structure. BCS have minimal immunogenicity, being cell and essentially DNA-free as well as uniformly negative for the porcine α-Gal protein. BCS seeded with human primary tendon-derived cells and exposed to 6% uniaxial loading conditions in vitro, supported increased levels of growth and proliferation as well as up-regulating expression of tenocyte differentiation marker genes including TNMD, Ten-C, Mohawk and Collagen-1α1. To test the safety and feasibility of using the BCS for augmentation of RC repairs, we followed the IDEAL framework and conducted a first, open-label single arm prospective case series study of 18 patients. One patient was withdrawn from the study at 3 months due to wound infection unrelated to the BCS. The remaining 17 cases showed that the BCS is safe to be implanted. The patients reported encouraging improvements in functional outcomes (ASES, OSS and Constant-Murley scores), as well as quality of life assessments (AQoL) and a reduction in VAS pain scores. MRI assessment at 12 months revealed complete healing in 64.8% patients (11/17), 3 partial thickness re-tears (17.6%) and 3 full thickness re-tears (17.6%).

Conclusion

The BCS is composed of type-I collagen that is free of immunogenic proteins and supports tendon-derived cell growth under mechanical loading in vitro. This pilot study shows that it is safe and feasible to use BCS for RC argumentation and further controlled prospective studies are required to demonstrate its efficacy.

The Translational potential of this article

The results of this study indicate that this bioactive collagen scaffold has unique properties for supporting tendon growth and that it is non-immunogenic. The clinical study further confirms that the scaffold is a promising biological device for augment of human rotator cuff repairs.

Biceps Augmentation Outperforms Tear Completion Repair or In Situ Repair for Bursal-Sided Partial-Thickness Rotator Cuff Tears in a Rabbit Model

BACKGROUND

There is an ongoing debate on the treatment of bursal-sided partial-thickness rotator cuff tears (PTRCTs), including ideal repair techniques. Augmentation using a collagen patch has been introduced as a new surgical approach to treat PTRCTs, while the effect of autogenous biceps augmentation (BA) has not been investigated.

PURPOSE

To analyze the effects of BA on bursal-sided PTRCTs and compare its histological and biomechanical results with those of tear completion followed by repair and in situ repair (ISR).

STUDY DESIGN

Controlled laboratory study.

METHODS

Unilateral chronic PTRCTs were created in 96 mature New Zealand White rabbits, which were randomly divided into 4 groups: no repair, tear completion repair (TCR), ISR, and BA. A new bicipital groove was fabricated in BA for the biceps tendon that was transferred to augment the bursal-sided PTRCT repair. In each group, we sacrificed 6 rabbits for biomechanical testing of the whole tendon-to-bone complex (WTBC) and 6 for histological evaluation of bursal- and articular-sided layers at 6 and 12 weeks postoperatively. Healing responses between the biceps and new bicipital groove in the BA group were determined using histological analysis, and final groove morphologies were evaluated using micro-computed tomography.

RESULTS

The remaining tendon and enthesis in bursal-sided PTRCTs progressively degenerated over time. WTBCs of ISR exhibited a larger failure load than those of TCR, although better healing properties in the bursal-sided repaired site were achieved using TCR based on histological scores and superior articular-sided histological scores were observed using ISR. However, WTBCs of BA displayed the best biomechanical results and superior histological scores for bursal- and articular-sided regions. The new bicipital groove in BA remodeled over time and formed similar morphologies to a native groove, which provided a mature bone bed for transferred biceps tendon healing to augment bursal-sided PTRCTs.

CONCLUSION

BA achieved better biomechanical and histological results for repairing bursal-sided PTRCTs as compared with TCR and ISR. When compared with that of TCR, the WTBC of ISR exhibited a higher failure load, showing histological superiority in the articular-sided repair and inferiority in the bursal-sided repair.

CLINICAL RELEVANCE

BA may be an approach to improve bursal-sided PTRCT repair in humans, which warrants further clinical investigation.

The Evolution of Arthroscopic Rotator Cuff Repair

Over the past 30 years, arthroscopic rotator cuff repair (ARCR) has evolved to become the gold standard in treating rotator cuff pathology. As procedural concepts of ARCR continue to improve, it is also continually compared with the open rotator cuff repair as the historical standard of care. This review highlights the evolution of ARCR, including a historical perspective; the anatomic, clinical, and surgical implications of the development of an arthroscopic approach; how arthroscopy improved some of the problems of the open approach; adaptations in techniques and technologies associated with ARCR; future perspectives in orthobiologics as they pertain to ARCR; and lastly, the clinical improvements, or lack of improvements, with all of these adaptations.

Full-Thickness Rotator Cuff Tears Can Be Safely Treated With a Resorbable Bioinductive Bovine Collagen Implant: One-Year Results of a Prospective, Multicenter Registry

Purpose

The purpose of this study was to prospectively collect safety and efficacy data in a large group of patients undergoing arthroscopic repair of full-thickness rotator cuff tears augmented with a resorbable bioinductive bovine collagen implant designed to promote healing.

Methods

Seventeen centers across the United States enrolled patients in an institutional review board-approved registry to collect outcomes data on the implant. Patients undergoing surgical management of full-thickness rotator cuff tears augmented with the implant were enrolled. Inclusion criteria were age of ≥21 years, willingness to participate and the ability to read and speak English. Exclusion criteria included hypersensitivity to bovine-derived products. Patients were assessed before and after surgery at up to 1 year with outcomes including the single-assessment numeric evaluation (SANE), Veterans RAND 12-Item (VR-12) mental components and physical components (VR-12 PCS), American Shoulder and Elbow Surgeons (ASES), and Western Ontario Rotator Cuff (WORC) outcome measures. Ad hoc analyses were performed to compare these outcomes at all time points depending on tear size (small/medium vs large/massive). Serious complications were collected.

Results

Of 210 patients enrolled, 192 had 1-year follow-up data available. The patients experienced statistically significant improvement between baseline and 1 year for mean SANE, VR-12 PCS, ASES, and WORC scores (40.0-82.0, 33.5-47.3, 46.2-87.8, and 36.2-81.0, respectively; P < .001 for all results). Ad-hoc analysis demonstrated that similar results were obtained at 1 year regardless of tear size. Twenty patients (10.4%) experienced serious complications (10.4%), including revision surgery (n = 18), proximal humerus fracture/partial subscapularis tear resulting from multiple falls (n = 1), and adhesive capsulitis (n = 1).

Conclusions

The safety and efficacy of a bioinductive implant in the surgical management of full-thickness rotator cuff tears at 1 year was shown in this study. Implant efficacy appears to be comparable regardless of the underlying tear size.

Level of Evidence

Level IV, therapeutic case series.

Treatment of Partial-Thickness Rotator Cuff Tears With a Resorbable Bioinductive Bovine Collagen Implant: 1-Year Results From a Prospective Multicenter Registry

Background:

Surgical treatment of partial-thickness rotator cuff tears remains challenging and controversial, with several traditional options including debridement with acromioplasty, transtendon or in situ repair, and take-down and repair. A resorbable bioinductive bovine collagen implant has shown promise as an alternative treatment option for partial-thickness tears.

Purpose:

Data from a registry were analyzed to further establish that the implant contributes to improved patient-reported outcome (PRO) scores across a large number of patients treated for partial-thickness rotator cuff tears.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 19 centers in the United States enrolled patients >21 years old with partial-thickness tears of the rotator cuff in a comprehensive prospective multicenter registry. PRO scores were recorded preoperatively and postoperatively at 2 and 6 weeks, 3 and 6 months, and 1 year: American Shoulder and Elbow Surgeons, Single Assessment Numeric Evaluation, Veterans RAND 12-Item Health Survey (physical and mental component scores), and Western Ontario Rotator Cuff scores. Revisions were reported throughout the study.

Results:

The registry included 272 patients with partial-thickness tears (49 grade 1 tears, 101 grade 2 tears, and 122 grade 3 tears), 241 who underwent isolated bioinductive repair (IBR; collagen implant placed after bursectomy without a traditional rotator cuff repair), and 31 who had take-down and repair with bioinductive augmentation. Patients experienced statistically significant and sustained improvement from baseline for all PRO scores beginning at 3 months. Among patients with grade ≥2 tears, those with take-down and repair had significantly inferior scores at 2 and 6 weeks for most PRO scores as compared with those who underwent IBR, but the difference was no longer significant at 1 year for all but the physical component score of the Veterans RAND 12-Item Health Survey. There were 11 revisions, which occurred at a mean ± SD of 188.7 ± 88.0 days after the index surgery. There were no infections.

Conclusion:

This registry analysis further establishes across a large data set that this resorbable bioinductive bovine collagen implant improves PROs in all grades of partial-thickness tears, whether used as IBR or in conjunction with take-down and repair. IBR may offer improved early clinical outcomes (≤6 weeks) and comparable outcomes at 1 year when compared with a more invasive “take-down and repair” approach.

Isolated bioinductive repair of partial-thickness rotator cuff tears using a resorbable bovine collagen implant: two-year radiologic and clinical outcomes from a prospective multicenter study

BACKGROUND

Current surgical treatment options for partial-thickness tears (eg, takedown and repair, in situ repair) are limited by the degenerative nature of the underlying tendon and may require extensive intervention that can alter the anatomic footprint. The complexity of available techniques to address these issues led to the development of a resorbable collagen implant, which can be used to create a bioinductive repair of partial-thickness tears.

METHODS

We prospectively enrolled 33 patients with chronic, degenerative, intermediate-grade (n = 12), or high-grade (n = 21) partial-thickness tears (11 articular, 10 bursal, 4 intrasubstance, and 8 hybrid) of the supraspinatus tendon in a multicenter study. After arthroscopic subacromial decompression without a traditional rotator cuff repair, a bioinductive implant was secured over the bursal surface of the tendon. Clinical outcomes were assessed using American Shoulder and Elbow Surgeons (ASES) and Constant-Murley scores (CMS) preoperatively and at 3 months, 1 year, and 2 years postoperatively. Magnetic resonance imaging was performed to assess postoperative tendon healing and thickness at the original tear site.

RESULTS

At 2-year follow-up, mean ASES and CMS scores improved both clinically and statistically at 1 and 2 years, compared with baseline, for intermediate- and high-grade tears. There was magnetic resonance imaging evidence of new tissue fill-in within the original baseline tear in 100% of the intermediate-grade tears and 95% of the high-grade tears. In 90.9% of the intermediate-grade tears and 84.2% of the high-grade tears, this new tissue fill-in represented at least an additional 50% of the volume of the initial lesion. From baseline to 2-year follow-up, the mean tendon thickness increased by 1.2 mm (standard deviation, 1.3; P = .012) and 1.8 mm (standard deviation, 2.2; P = .003) in the intermediate- and high-grade tears, respectively. The analysis of tear grade and location revealed no statistically significant difference in the change in mean tendon thickness at any time point. One patient with a high-grade articular lesion demonstrated progression to a full-thickness tear; however, the patient was noncompliant and the injury occurred while shoveling snow 1 month after surgery. Neither tear location nor treatment of bicep pathology affected the ASES or CMS scores at any follow-up point. No serious adverse events related to the implant were reported.

CONCLUSION

Final results from this 2-year prospective study indicate that the use of this resorbable bovine collagen implant for isolated bioinductive repair of intermediate- and high-grade partial-thickness rotator cuff tears of the supraspinatus is safe and effective, regardless of tear grade and location.

Revision Rotator Cuff Repair: A Comprehensive Approach and Stepwise Technique

The indications for and techniques to accomplish revision rotator cuff repair continue to be challenging problems that surgeons face. Complexity of tears, poor tissue quality, retained hardware, and adhesions are routinely encountered during surgical intervention for failed rotator cuff repairs. A successful outcome for any revision rotator cuff repair is determined, in part, by the surgeon's ability to address these intraoperative issues in an optimum manner. The surgical technique described in this article outlines a comprehensive and stepwise approach that can aid the surgeon in developing an effective strategy to accomplish revision rotator cuff repair.

Endoscopic Implantation of Bioinductive Patch for Chronic Partial Retearing After Hamstring Repair

Proximal hamstring tendon avulsions are a relatively rare type of hamstring injury associated with persistent morbidity, including pain, weakness, and functional limitations. Open or endoscopic surgical repair is the standard treatment for complete tendon avulsions or partial tears that remain symptomatic despite conservative management in relatively young, healthy, and active patients. However, complications known to occur include retearing of the hamstring, infection, nerve injury, inability to return to work or sport, subjective persistent weakness, and subjective persistent pain. In the case of persistent pain where the repair is partially retorn, a careful history, physical examination, and scrutiny of radiologic studies can help guide management. We describe a technique for using revision endoscopy and augmentation with a bovine bioinductive patch in a case of chronic persistently painful partial retear after a proximal hamstring repair.

Retear rates and clinical outcomes at 1 year after repair of full-thickness rotator cuff tears augmented with a bioinductive collagen implant: a prospective multicenter study

Background

Biologic technologies can potentially augment existing arthroscopic rotator cuff repair to improve retear rates and postoperative outcomes. The purpose of this study was to evaluate healing rates and clinical outcomes of full-thickness rotator cuff repairs augmented with a bioinductive bovine collagen implant.

Methods

In this prospective multicenter study, investigators enrolled 115 patients (mean age, 60.4 years) with full-thickness rotator cuff tears. There were 66 (57.4%) medium (1-3 cm) tears and 49 (42.6%) large (3-5 cm) tears. Eligible patients consisted of those ≥21 years of age with chronic shoulder pain lasting longer than 3 months and unresponsive to conservative therapy. Patients underwent single- or double-row repair augmented with a bioinductive bovine collagen implant. At the baseline, 3 months, and 1 year, magnetic resonance imaging was performed and patients were assessed for American Shoulder and Elbow Surgeons (ASES) Shoulder Score and Constant-Murley Score (CMS). The primary failure end point was retear, classified as any new full-thickness defect observed on magnetic resonance imaging.

Results

There were 13 retears (11.3%) at 3 months, with an additional 6 (19 total [16.5%]) found at 1 year. In large tears, double-row repair had a significantly lower rate of retear at 3 months (P = .0004) and 1 year (P = .0001) compared with single-row repair. ASES and CMS scores significantly improved between the baseline and 1 year for medium and large tears. At 1 year, the minimally clinically important difference for ASES and CMS was met by 91.7% (95% CI: 84.9-96.1) and 86.4% (95% CI: 78.2-92.4) of patients, respectively. Patients without retear and those <65 years of age had significantly better CMS scores at 1 year when compared with those with retear and those ≥65 years (P < .05). There was no statistically significant difference in outcomes based on treatment of the biceps tendon. Of 9 reported reoperations in the operative shoulder, only 2 were considered potentially related to the collagen implant.

Conclusion

Interim results from this prospective study indicate a favorable rate of retear relative to the literature and improvement in clinical function at 1 year after adjunctive treatment with the study implant augmenting standard arthroscopic repair techniques.

Revision Hip Capsular Repair and Augmentation With a Bioinductive Implant After a Post-arthroscopy Hip Subluxation Event

In the past decade, the number of hip arthroscopy procedures has exponentially increased, primarily for the treatment of femoroacetabular impingement syndrome and labral lesions. As the techniques have evolved, so has the acknowledgment of the potential complications, including iatrogenic instability that may result from soft-tissue laxity, subtle dysplastic morphologies, or residual defects from capsulotomies in which the capsular closure is insufficient. In most cases, direct capsular repair or plication can be performed at the conclusion of the procedure; however, larger defects, poor-quality tissue, or cases of gross ligamentous laxity may require reconstruction or augmentation. In such instances, several options exist. The purpose of this technical note is to describe a capsular repair augmentation with a bioinductive implant during revision hip arthroscopy.

The role of biologic agents in the management of common shoulder pathologies: current state and future directions

The field of orthopedic surgery has seen a rapid increase in the use of various biologic agents for the treatment of common musculoskeletal injuries. Most biologic agents attempt to harness or mimic naturally occurring growth factors, cytokines, and anti-inflammatory mediators to improve tissue healing and recovery. The most commonly used biologic agents are platelet-rich plasma and cells derived from bone marrow aspirate and adipose tissue. These agents have become increasingly popular despite a relative dearth of clinical data to support their use. Much confusion exists among patients and physicians in determining the role of these agents in treating common shoulder pathologies, such as glenohumeral osteoarthritis, rotator cuff tears, and tendinopathy. This article reviews the basic science and clinical evidence for the most commonly used biologic agents in the management of common shoulder pathology.

Patient-Reported Outcomes After Use of a Bioabsorbable Collagen Implant to Treat Partial and Full-Thickness Rotator Cuff Tears

PURPOSE

To collect outcomes data on patients treated with a bioinductive collagen implant designed to induce rotator cuff healing in partial- and full-thickness cuff tears and to assess the safety and efficacy of the device.

METHODS

Fifteen surgeons in 15 centers in the United States enrolled patients between April 2016 and August 2017 and collected standardized outcomes data. Patients 21 years of age and older, able to read and speak English, and with partial- or full-thickness tears of the rotator cuff documented by magnetic resonance imaging were included in the study. Patients were assessed preoperatively with visual analogue scale (VAS), single-assessment numeric evaluation (SANE), Veterans RAND 12-Item (VR-12), American Shoulder and Elbow Surgeons (ASES), and Western Ontario Rotator Cuff (WORC) outcomes measures. Postoperative assessment was made at 2, 6, and 12 weeks, 6 months, and 1 year. Patients underwent a standardized operative procedure with the implant. Patient demographics, comorbidities, tear types, and concomitant operative procedures were recorded.

RESULTS

Patients in both groups experienced statistically significant improvement in VAS, SANE, VR-12 PCS, ASES, and WORC scores (mean values 1.1, P < .001; 86.0, P < .001; 49.7, P < .001; 85.6, P < .001; and 84.4, P < .001 for partial tears and 1.2, P < .001; 80.7, P < .001; 45.7, P < .001; 83.8, P < .0001; and 80.1, P < .001 for full-thickness tears, respectively). For the partial tear group, average times for return to driving, work, and nonoverhead athletic activity were 14.6, 37.3, and 65.6 days, and for the full-thickness group, 24.5, 50.7, and 119.2 days, respectively. In the partial-thickness group, 84% and 83% of patients reported improvement in their VAS pain and ASES scores, respectively, that met or exceeded each measure's minimal clinically important difference. In the full-thickness group, 72% and 77% of the patients met or exceeded the minimal clinically important differences for VAS pain and ASES, respectively.

CONCLUSION

Outcomes after repair of partial- and full-thickness rotator cuff tears using a bioinductive implant show safety and efficacy at 1-year follow-up.

LEVEL OF EVIDENCE

Retrospective case series, level IV evidence.

Evaluation of Healing Rates and Safety With a Bioinductive Collagen Patch for Large and Massive Rotator Cuff Tears: 2-Year Safety and Clinical Outcomes

BACKGROUND

Failure of repair of large and massive rotator cuff tears is a challenging problem within orthopaedics. Poor tendon tissue and vascularity are known causes for failure of rotator cuff repairs.

PURPOSE

To assess the safety, outcomes, and healing rates when large and massive rotator cuff repairs are augmented with a bioinductive collagen scaffold patch in a proof-of-principle design.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-three patients undergoing repair of full-thickness large (2-tendon) or massive (3-tendon) rotator cuff tears augmented with a bioinductive collagen patch were enrolled in a prospective single-arm proof-of-principle study. No partial repairs were performed, and a complete rotator cuff repair was successfully achieved in each case. Sixteen patients underwent revision rotator cuff repairs versus 7 primary repairs. Safety was determined by any implant-related adverse event. A single magnetic resonance imaging (MRI) scan was utilized to confirm tendon healing and thickness at a minimum of 6 months postoperatively. Postoperative ultrasound (US) was used in office by the treating surgeon to assess tendon thickness at 3-, 6-, 12-, and 24-month intervals. American Shoulder and Elbow Surgeons (ASES) scores were collected at final follow-up.

RESULTS

Overall, a 96% (22 of 23) healing rate was confirmed on US and MRI. However, incidence of treatment clinical failure was 9% (2 of 23), as 1 patient's tendon healed but eventually underwent additional surgery. There were no adverse events attributed to the implant reported. Final US rotator cuff thickness was 7.28 ± 0.85 mm (mean ± SD), and final MRI rotator cuff thickness was 5.13 ± 1.06 mm. The mean ASES score at final follow-up was 82.87 ± 16.68 (range, 53.33-100).

CONCLUSION

No complications attributed to the implant were reported, and new tendon formation was apparent on US and MRI, with relatively high healing rates at 2-year follow-up. Arthroscopic application of this bioinductive collagen scaffold when combined with rotator cuff repair is a safe and effective treatment for healing of large and massive rotator cuff repairs.

Arthroscopic Rotator Cuff Repair With Allograft Augmentation: Making It Simple

Rotator cuff tears are increasing in frequency in the aging population and are a common issue seen by orthopaedic surgeons. In patients with large, multi-tendon rotator cuff tears or retears, treatment can be challenging. Failure rates of up to 90% have been reported for rotator cuff repair (RCR) of large, multi-tendon tears. Biological augmentation has been an area of interest because of the distinctly different biology of the repaired tendon compared with the native tendon. These biological differences affect the ultimate tensile properties of the repair and may contribute to gap formation and the high failure rate of repairs. RCR with allograft augmentation is a technique that shows potential benefit to healing and preventing retears. Arthroscopic augmentation of RCRs can be challenging. The technique described in this Technical Note illustrates a simple and easily reproducible method for augmenting RCRs with human acellular dermal allograft.

Open Gluteus Medius and Minimus Repair With Double-Row Technique and Bioinductive Implant Augmentation

Lateral hip pain in patients without significant osteoarthritis may be due to a number of different etiologies. Recent attention has been placed on the role of abductor tendon (gluteus medius and minimus) deficiency in these patients. These tears, analogous to rotator cuff tears in the shoulder, may cause pain, weakness, limp, and dysfunction. Mainstays of treatment include nonoperative treatment and, in select patients, operative fixation. This article presents an overview of management of patients with symptomatic, large, retracted, chronic tears of the abductor tendons. The highlighted repair is a "double-row" repair with biological patch augmentation.

Editorial Commentary: Is Arthroscopic In Situ Repair Effective for Long-Term Functional Recovery and Pain Relief in Symptomatic Partial Rotator Cuff Tears?

Currently, although most evidence suggests that surgery is effective in treating symptomatic partial-thickness rotator cuff tears in patients with failure of nonoperative management and with a tear of more than 50% of the tendon thickness, there is little consensus on the best method of repair. Some surgeons would advocate completing the tear and repairing it, whereas others would advocate performing in situ repair. In our opinion, it is important to also consider treating the long head of the biceps tendon, which is frequently a source of pain at the time of or after surgery.

Radiologic and clinical evaluation of a bioabsorbable collagen implant to treat partial-thickness tears: a prospective multicenter study

BACKGROUND

Treatment of partial-thickness cuff tears remains controversial. Although conservative therapy may treat symptoms, these defects do not spontaneously heal and conversion to a full-thickness lesion with subsequent repair may alter the tendon footprint. The ability to induce new tissue formation and limit tear progression in intermediate- and high-grade partial-thickness tears without surgical repair may represent a significant advancement in the treatment paradigm for these lesions.

METHODS

We prospectively enrolled 33 patients with chronic, degenerative, intermediate-grade (n = 12) or high-grade (n = 21) partial-thickness tears (11 articular, 10 bursal, 4 intrasubstance, and 8 hybrid) of the supraspinatus tendon in a multicenter study. Following arthroscopic subacromial decompression without repair, a bioinductive implant was attached over the bursal surface of the tendon. Clinical outcomes were assessed using American Shoulder and Elbow Surgeons and Constant-Murley scores preoperatively and at 3 and 12 months postoperatively. Magnetic resonance imaging was performed to assess postoperative tendon healing and thickness at the original tear site.

RESULTS

At 1-year follow-up, clinical scores improved significantly (P <.0001) and the mean tendon thickness increased by 2.0 mm (P <.0001). Magnetic resonance imaging evidence of complete healing was found in 8 patients and a considerable reduction in defect size was shown in 23, whereas 1 lesion remained stable. In 1 noncompliant patient with a high-grade articular lesion, progression to a full-thickness tear occurred while shoveling snow 1 month after surgery. No serious adverse events related to the implant were reported.

CONCLUSIONS

Arthroscopic implantation of a bioinductive collagen scaffold is a safe and effective treatment for intermediate- to high-grade partial-thickness rotator cuff tears of the supraspinatus tendon.

Histologic Evaluation of Biopsy Specimens Obtained After Rotator Cuff Repair Augmented With a Highly Porous Collagen Implant

PURPOSE

To histologically evaluate biopsy specimens from patients who previously underwent rotator cuff repair augmented with a highly porous collagen implant.

METHODS

Biopsies of collagen implant/host-tissue constructs were obtained from 7 patients undergoing a second arthroscopic procedure at various time periods (5 weeks to 6 months) after arthroscopic rotator cuff repair augmented with a collagen implant overlay. The biopsy specimens were examined histologically for host-tissue ingrowth, host-tissue maturation, and host-implant biocompatibility.

RESULTS

At the earliest time period (5 weeks), the biopsy revealed the presence of host cells (fibroblasts) within the interstices of the porous collagen implant. Cells were aligned along the linear orientation of the collagen implant structure, and there was evidence of early collagen formation. The 3-month biopsies showed increased collagen formation, maturation, and organization over the surface of the implant and evidence of the collagen implant. At 6 months, the newly generated tissue had the histologic appearance of a tendon, suggesting functional loading of the new generated host tissue. There was no evidence of any remnants of the collagen implant in the 6-month biopsy. There was no evidence of any inflammatory or foreign body reaction within any of the tissue samples.

CONCLUSIONS

Biopsies of collagen implants retrieved from human rotator cuff repair subjects revealed cellular incorporation, tissue formation and maturation, implant resorption, and biocompatibility.

CLINICAL RELEVANCE

The histologic observations from these clinical biopsies support the biocompatibility of this implant and its ability to promote new connective tissue with the histological appearance of tendon over the surface of the native cuff tendon.