Human tendon cell response to 7 commercially available extracellular matrix materials: an in vitro study

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.

Rotator Cuff Repair with Graft Augmentation Improves Function, Decreases Revisions, and Is Cost-Effective

PURPOSE

The purpose of this study is to evaluate the cost effectiveness of the use of extracellular matrix (ECM) augment at the time of primary rotator cuff repair utilizing a decision tree analysis.

METHODS

A decision tree model was created utilizing the existing literature for retear rates with and without dermal graft augmentation. Costs for rotator cuff repair (hospital and surgeon fees) were based on published studies and the cost for graft augmentation was based on institutional data. Utility measures were based upon EQ-5D (European Quality of Life 5 Dimension) scores to assess for improvement in quality adjusted life years (QALY) over a 10-year postoperative period with and without graft augmentation. Cost effectiveness was assessed using the incremental cost effectiveness ratio (ICER), or the incremental cost for per QALY with graft augmentation. Cost effectiveness is based on previous literature whereby an intervention is considered cost effective if the ICER is less than $50,000/QALY.

RESULTS

On the basis of our decision tree analysis, total cost for rotator cuff tear without augmentation was $12,763, while the cost increased to $16,039 with ECM augmentation. With graft augmentation there was an improvement in 2.29 QALY, while there was an improvement of 2.05 without graft augmentation. The ICER of graft augmentation is $14,000/QALY, well below the cost effectiveness cut-off of $50,000/QALY. Sensitivity analysis showed the maximum cost of the ECM augment to be cost effective is $11,921.

CONCLUSION

Graft augmentation does come with a significant upfront cost; however, on the basis of our decision-tree analysis, it may represent a cost-effective procedure. There is evidence to potentially consider more routine use in rotator cuff repairs, while being cost effective.

LEVEL OF EVIDENCE

Economic: Level IV: computer simulation model (Monte Carlo simulation, Markov model) with inputs derived from Level IV studies.

Arthroscopic rotator cuff repair with biologically enhanced patch augmentation

OBJECTIVE

The purpose of this guide is to illustrate an arthroscopic rotator cuff repair (RCR) with two techniques for biologically enhanced patch augmentation.

INDICATIONS

Massive rotator cuff tears (> 5 cm) and revision RCR.

CONTRAINDICATIONS

Active joint or systemic infection; severe fatty muscle atrophy; severe glenohumeral arthropathy; American Society of Anesthesiologists Physical Status (ASA PS) IV.

SURGICAL TECHNIQUE

Dermal allograft patch augmented with concentrated bone marrow aspirate (cBMA), platelet-rich plasma (PRP) and platelet-poor plasma (PPP); or Regeneten patch augmented with bursa, PRP, PPP, and autologous thrombin.

POSTOPERATIVE MANAGEMENT

A 30° abduction sling for 6 weeks; unrestricted active-assisted external rotation and forward elevation after 12 weeks; focus on restoration of scapular stability and strength.

RESULTS

A total of 22 patients received revision massive RCR using a dermal allograft patch enhanced with cBMA and PRP with a mean follow-up of 2.5 years (1.0-5.8 years). There was a significant improvement in the preoperative Simple Shoulder Test (SST). There was also a trend towards improved pain and American Shoulder and Elbow Surgeons (ASES) Shoulder Score. In this cohort, 45% reached the minimal clinically important difference (MCID), 41% achieved substantial clinical benefit (SCB), and 32% had a patient-acceptable symptomatic state (PASS) for the ASES score. Preliminary data using the Regeneten patch technique with bursa, PRP, PPP, and autologous thrombin was prospectively collected in five patients between 05/2020 and 03/2021 at the author's institution. Mean follow-up was 6.5 ± 1.3 (6-8 months). There was an improvement from preop to postop in pain, ASES, SANE, Constant-Murley (CM) score and active range of motion.

Decellularized xenografts in regenerative medicine: From processing to clinical application

Decellularized xenografts are an inherent component of regenerative medicine. Their preserved structure, mechanical integrity and biofunctional composition have well established them in reparative medicine for a diverse range of clinical indications. Nonetheless, their performance is highly influenced by their source (ie species, age, tissue) and processing (ie decellularization, crosslinking, sterilization and preservation), which govern their final characteristics and determine their success or failure for a specific clinical target. In this review, we provide an overview of the different sources and processing methods used in decellularized xenografts fabrication and discuss their effect on the clinical performance of commercially available decellularized xenografts.

Nanofiber Scaffolds by Electrospinning for Rotator Cuff Tissue Engineering

Rotator cuff tears continue to be at risk of retear or failure to heal after surgical repair, despite the use of various surgical techniques, which stimulate development of novel scaffolding strategies. They should be able to address the known causes of failure after the conventional rotator cuff repair: (1) failure to reproduce the normal tendon healing process, (2) resultant failure to reproduce four zones of the enthesis, and (3) failure to attain sufficient mechanical strength after repair. Nanofiber scaffolds are suited for this application because they can be engineered to mimic the ultrastructure and properties of the native rotator cuff tendon. Among various methods for tissue-engineered nanofibers, electrospinning has recently been highlighted in the rotator cuff field. Electrospinning can create fibrous and porous structures that resemble natural tendon's extracellular matrix. Other advantages include the ability to create relatively large surface-to-volume ratios, the ability to control fiber size from the micro to the nano scale, and the flexibility of material choices. In this review, we will discuss the anatomical and mechanical features of the rotator cuff tendon, their potential impacts on improper healing after repair, and the current knowledge of the use of electrospinning for rotator cuff tissue engineering.

Use of implantable meshes for augmented rotator cuff repair: a systematic review and meta-analysis

OBJECTIVE

To appraise studies reporting on clinical effectiveness and safety of surgical meshes used to augment rotator cuff repairs (RCRs).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase and Cochrane databases were searched between April 2006 and April 2020.

ELIGIBILITY CRITERIA

All studies evaluating adults (≥18 years) undergoing RCR were considered. There were no language restrictions.

DATA EXTRACTION AND SYNTHESIS

Screening, data extraction and quality appraisal were conducted by two independent reviewers. Meta-analysis was conducted using a random-effects models if ≥2 comparative studies reported the same outcome measure. Risk of bias assessment was undertaken for randomised (RoB2, Cochrane) and comparative studies (ROBINS-I, Cochrane).

RESULTS

We included 60 studies, consisting of 7 randomised controlled trials, 13 observational comparative studies and 40 observational case series. All comparative studies reported on shoulder-specific functional outcome scores, 18 on the radiographic occurrence of re-tear and 14 on pain score metrics. All studies contained some risk of bias.Compared with non-augmented repair, a small improvement in shoulder-specific function or pain scores was observed for synthetic patches with a mean improvement of 6.7 points on the University of California Los Angles (UCLA) shoulder score (95% CI 0.1 to 13.4) and 0.46 point reduction on the Visual Analogue Scale (95% CI -0.74 to -0.17), respectively. A reduced likelihood of radiologically observed re-tear was observed for synthetic (risk ratio (RR) 0.41, 95% CI 0.27 to 0.61) and allograft (RR 0.34, 95% CI 0.18 to 0.65) patches. A total of 49 studies reported on the occurrence of complications. Slightly higher crude complication rates were observed following patch-augmented repair (2.1%) than standard repair (1.6%).

CONCLUSIONS

While several studies suggest a decreased failure rate and small improvements in shoulder function and pain following augmented RCR, a paucity of rigorous clinical evaluation, for both effectiveness and safety, prevents firm recommendations.

PROSPERO REGISTRATION NUMBER

CRD42017057908.

Scaffolds in the management of massive rotator cuff tears: current concepts and literature review

Injuries to the rotator cuff (RC) are common and could alter shoulder kinematics leading to arthritis. Synthetic and biological scaffolds are increasingly being used to bridge gaps, augment RC repair and enhance healing potential. Our review evaluates the clinical applications, safety and outcome following the use of scaffolds in massive RC repair.

A search was performed using EBSCO-Hosted Medline, CINAHL, Cochrane and PubMed using various combinations of the keywords ‘rotator cuff’, ‘scaffold’, ‘biological scaffold’, ‘massive rotator cuff tear’ ‘superior capsular reconstruction’ and ‘synthetic scaffold’ between 1966 and April 2018. The studies that were most relevant to the research question were selected. All articles relevant to the subject were retrieved, and their bibliographies hand searched.

Synthetic, biosynthetic and biological scaffolds are increasingly being used for the repair/reconstruction of the rotator cuff. Allografts and synthetic grafts have revealed more promising biomechanical and early clinical results than xenografts. The retear rates and local inflammatory reactions were alarmingly high in earlier xenografts. However, this trend has reduced considerably with newer versions. Synthetic patches have shown lower retear rates and better functional outcome than xenografts and control groups.

The use of scaffolds in the treatment of rotator cuff tear continues to progress. Analysis of the current literature supports the use of allografts and synthetic grafts in the repair of massive cuff tears in reducing the retear rate and to provide good functional outcome. Though earlier xenografts have been fraught with complications, results from newer ones are promising. Prospective randomized controlled trials from independent centres are needed before widespread use can be recommended.

Cite this article: EFORT Open Rev 2019;4:557-566. DOI: 10.1302/2058-5241.4.180040

Use of a Novel, Reinforced, Low Immunogenic, Porcine Small Intestine Submucosa Patch to Repair a Supraspinatus Tendon Defect in a Rabbit Model

Background

Repairs of large to massive rotator cuff tears have a high failure rate. We investigated the efficacy of a novel, reinforced, low immunogenic, porcine small intestine submucosa (SIS) patch to repair a supraspinatus tendon defect in a rabbit model. We hypothesized that the histological and biomechanical results of SIS patch repair would be comparable with those of autologous fascia lata (FL) repair.

Methods

The study mainly comprised two parts. First, the characteristics of the SIS patch were evaluated, including its micromorphology, mechanical properties, and immunogenic properties. Second, a supraspinatus tendon defect model was created in 36 rabbits (72 shoulders). The bilateral shoulders were randomly chosen to undergo repair using either a SIS patch (SIS group) or autologous FL (FL group). At 4, 8, and 12 weeks, histological analysis was performed using four shoulders from each group, and biomechanical tests were performed using eight shoulders from each group.

Results

The SIS patch was a three-dimensional construct mainly composed of collagen fibers. The mean single and double suture retention loads of the SIS patch were 48.6 ± 5.8 N and 117.9 ± 2.7 N, respectively. The DNA content in the SIS patch was 53.9 ± 10.9 ng/mg dry weight. Both the histological score and ultimate load to failure increased in a time-dependent manner in both groups, with no significant differences between the SIS and FL groups at 12 weeks.

Conclusion

Repair of a large supraspinatus tendon defect using a reinforced, low immunogenic, SIS patch achieves similar effects as autologous FL in a rabbit model. This novel patch might be useful to be employed as a structural tissue replacement in medical activities.

Patch-augmented rotator cuff surgery (PARCS) study-protocol for a feasibility study

BACKGROUND

A rotator cuff tear is a common disabling shoulder problem. Symptoms include pain, weakness, lack of shoulder mobility and sleep disturbance. Many patients require surgery to repair the tear; however, there is a high failure rate. There is a pressing need to improve the outcome of rotator cuff surgery and the use of patch augmentation to provide support to the healing process and improve patient outcomes holds new promise. Patches have been made using different materials (e.g. human/animal skin or intestine tissue, and completely synthetic materials) and processes (e.g. woven or a mesh). However, clinical evidence on their use is limited. The aim of the patch-augmented rotator cuff surgery (PARCS) feasibility study is to determine, using a mixed method approach, the design of a definitive randomised trial assessing the effectiveness and cost-effectiveness of a patch to augment surgical repair of the rotator cuff that is both acceptable to stakeholders and feasible.

METHODS

The objectives of this six-stage mixed methods feasibility study are to determine current practice, evidence and views about patch use; achieve consensus on the design of a randomised trial to evaluate patch-augmented rotator cuff surgery; and assess the acceptability and feasibility of the proposed design. The six stages will involve a systematic review of clinical evidence, two surveys of surgeons, focus groups and interviews with stakeholders, a Delphi study and a consensus meeting. The various stakeholders (including patients, surgeons, and representatives from industry, the NHS and regulatory bodies) will be involved across the six stages.

DISCUSSION

The PARCS feasibility study will inform the feasibility and acceptability of a randomised trial of the effectiveness and cost-effectiveness of a patch-augmented rotator cuff surgery. Consensus opinion on the basic design of a randomised trial will be sought.

TRIAL REGISTRATION

Not applicable.

Porcine Dermal Xenograft as Augmentation in the Treatment of Large Rotator Cuff Tears: Clinical and Magnetic Resonance Results at 2-Year Follow-Up

Purpose  The aim of the present retrospective study is to describe the results obtained at 2-year follow-up by using a porcine dermis-derived collagen membrane implanted as augmentation to treat large rotator cuff tears.

Methods  Thirty-five patients in total were included according to the following criteria: large or massive rotator cuff tear, confirmed during surgery, measuring between 3 and 5 cm in width and stage 1 to 2 fatty infiltration documented at magnetic resonance imaging (MRI). Patients underwent arthroscopic repair of the cuff augmented by the implantation of a porcine dermal collagen membrane. Patients were evaluated up to 24 months after surgery by the Constant score and MRI imaging to assess functional outcomes and re-tear rate. The results obtained were compared to those of a matched cohort of 35 patients operated by arthroscopic repair alone by the same surgical team.

Results  The application of the porcine membrane proved to be safe without scaffold-related adverse events documented. A statistically significant difference in the Constant score in favor of the treatment group was documented at the final evaluation ( p  = 0.036 ). Furthermore, a subgroup analysis revealed that patients treated by augmentation and presenting re-tear at MRI showed a significantly higher functional outcome compared with control patients with MRI evidence of re-tear ( p  = 0.0136).

Conclusion  Arthroscopic repair augmented by porcine dermal xenograft for the treatment of chronic and retracted rotator cuff tears with low-grade fatty degeneration proved to be safe and also effective, with higher functional score compared with the arthroscopic repair alone.

Level of Evidence  This is a Level III, retrospective cohort study.

Systematic review of the surgical management of rotator cuff repair with an augmentative patch: a feasibility study protocol

BACKGROUND

Shoulder pain is a common problem in the general population and is responsible for prolonged periods of disability, loss of productivity, absence from work and inability to carry out household activities. Rotator cuff problems account for up to 70% of shoulder pain problems and are the third most prevalent musculoskeletal disorder after those occurring in the lower back and neck. Rotator cuff surgery has high failure rates (25-50% within 12 months), and as a result, there is a pressing need to improve the outcome of rotator cuff surgery. Patch augmented surgery for rotator cuff repairs has recently been developed and is increasingly being used within the UK National Health Service. Patch augmented surgery could lead to a dramatic improvement in patient and surgical outcomes, but its clinical and cost effectiveness needs rigorous evaluation. The existing evidence on the use of patches may be at risk of bias as currently only a small number of single-centre comparative studies appear to have been carried out. Additionally, it is unclear for which patches a clinical study (comparative and non-comparative) has been conducted. This paper outlines the protocol for a systematic review intended to summarise the best available clinical evidence and will indicate what further research is required.

METHODS

Electronic databases (Medline, Embase and Cochrane) will be systematically searched between April 2006 and the present day for relevant publications using a specified search strategy, which can be adapted for the use in multiple electronic databases, and inclusion criteria. Screening of both titles and abstracts will be done by two independent reviewers with any discrepancies resolved by a third independent reviewer. Data extraction will include information regarding the type of participants, type of intervention and outcomes including but not limited to shoulder-specific function and pain scores, patch-related adverse events and type of study. The results will be summarised in a narrative review where qualitative analysis is not possible.

DISCUSSION

This review aims to collate the current evidence base regarding the use of patches to augment rotator cuff repair. The results of this review will help to develop, using consensus methods, the design of a definitive randomised trial assessing the clinical and cost-effectiveness of a patch to augment surgical repair of the rotator cuff that is both acceptable to stakeholders and is feasible.

SYSTEMATIC REVIEW REGISTRATION

CRD42017057908.

Orthopaedic regenerative tissue engineering en route to the holy grail: disequilibrium between the demand and the supply in the operating room

Orthopaedic disorders are very frequent, globally found and often partially unresolved despite the substantial advances in science and medicine. Their surgical intervention is multifarious and the most favourable treatment is chosen by the orthopaedic surgeon on a case-by-case basis depending on a number of factors related with the patient and the lesion. Numerous regenerative tissue engineering strategies have been developed and studied extensively in laboratory through in vitro experiments and preclinical in vivo trials with various established animal models, while a small proportion of them reached the operating room. However, based on the available literature, the current strategies have not yet achieved to fully solve the clinical problems. Thus, the gold standards, if existing, remain unchanged in the clinics, notwithstanding the known limitations and drawbacks. Herein, the involvement of regenerative tissue engineering in the clinical orthopaedics is reviewed. The current challenges are indicated and discussed in order to describe the current disequilibrium between the needs and solutions made available in the operating room. Regenerative tissue engineering is a very dynamic field that has a high growth rate and a great openness and ability to incorporate new technologies with passion to edge towards the Holy Grail that is functional tissue regeneration. Thus, the future of clinical solutions making use of regenerative tissue engineering principles for the management of orthopaedic disorders is firmly supported by the clinical need.

Porcine Dermis Patch Augmentation of Supraspinatus Tendon Repairs: A Pilot Study Assessing Tendon Integrity and Shoulder Function 2 Years After Arthroscopic Repair in Patients Aged 60 Years or Older

PURPOSE

To investigate the 2-year postoperative clinical and subjective outcomes after arthroscopic rotator cuff repair (ARCR) with xenologous porcine dermal patch augmentation compared with ARCR alone.

METHODS

Patients aged 60 years or older with a complete supraspinatus (SSP) tendon tear underwent primary ARCR with a transosseous-equivalent technique. By use of a matched-pair comparative trial design, a consecutive series of 20 patients receiving additional xenologous porcine dermal patch augmentation (patch group) was matched by tear location with 20 patients who received ARCR only (control group). Prior conservative treatment failed in all patients. Patients with concomitant pathologies precluding accurate repair assessment, partial or open reconstruction, or a latissimus dorsi and/or pectoralis major muscle transfer were excluded. Patients reported daily pain levels for 10 days after surgery. Clinical parameters and various patient-reported outcome scores were documented preoperatively and at 3, 6, and 24 months after surgery. Repair integrity was determined by magnetic resonance imaging or ultrasound at 24 months. Adverse events were recorded. Group outcome differences were analyzed with t tests, Fisher exact tests, and mixed models.

RESULTS

Patients in both groups were aged 67 years on average (range, 60-74 years), and 70% of patients were men. Patients in the patch group had slightly more SSP fatty infiltration preoperatively. Patch surgical procedures were on average 22 minutes longer than control interventions (P = .003). At 24 months, 4 patients and 9 patients were diagnosed with a recurrent SSP tendon defect in the control group (n = 20) and patch group (n = 19), respectively (relative risk, 2.4; P = .096). Of 11 defects (85%) identified as medial cuff failure, 8 occurred in the patch group. Pain rated by all patients decreased from postoperative day 1 to day 10 without any significant group difference (P = .348). No significant group differences were noted for other outcome parameters, and recurrent defects had no relevant effect on functional outcomes. Local complications (including recurrent defects) occurred in 8 patients in the control group and 12 in the patch group (P = .343).

CONCLUSIONS

Our pilot study supports the view that an SSP tear repair with porcine dermal xenograft augmentation does not benefit patients in terms of reducing the risk of a recurrent tendon defect or improving shoulder function up to 24 months after surgical repair.

LEVEL OF EVIDENCE

Level III, therapeutic study, retrospective comparative trial.

[Patch augmentation of the rotator cuff. A reasonable choice or a waste of money?]

BACKGROUND

Although reconstruction methods have improved, tendon retears remain a major complication associated with rotator cuff repair. With the application of patches, either by interposition or by augmentation, surgeons can attempt to close an irreparable cuff defect or improve the mechanical and biological properties of tendons respectively.

OBJECTIVES

Which factors need to be considered when using a patch and what outcome can be expected?

MATERIALS AND METHODS

Based on the current literature, an overview of the techniques and materials in use and biomechanical and clinical experience is provided.

RESULTS

The literature shows clear improvements in the biomechanical properties of a repair with patch augmentation; in particular, weakened tendons of the anterior supraspinatus and superior infraspinatus benefit most. It is important to keep in mind that each patch material has its own individual properties, which makes comparison of the various patch types difficult. The current scientific evidence is promising, although larger level 1 studies are still required.

CONCLUSIONS

The general use of patches cannot be recommended at this time. Nevertheless, the use of a patch should be considered in patients who are at a high risk of recurrent retears. In future, patches will probably be applied mainly as part of a combined effort, together with biological measures to further reduce retear rates.

Nutritional research may be useful in treating tendon injuries

Tendon injures cause a great deal of disability and pain, and increase medical costs. However, relatively little is known about tendon biology and healing. Many tendon-related surgical procedures are not very successful and leave the patient with essentially a chronic injury. New therapeutic approaches for tendon injury are needed. Preliminary evidence suggests that various nutrients such as proteins, amino acids (leucine, arginine, glutamine), vitamins C and D, manganese, copper, zinc, and phytochemicals may be useful in improving tendon growth and healing. More research on nutrition and tendon health is needed. Because many nutrients are required for tendon health, nutritional interventions involving multiple nutrients may be more effective than single-nutrient strategies. In the future, ideal treatment regimens for tendon injuries may include a multifaceted "bundle" of nutrition, drugs, biologic products, extracellular matrix therapies, exercise/physical therapy, and possibly surgery.

Aligned multilayered electrospun scaffolds for rotator cuff tendon tissue engineering

The rotator cuff consists of several tendons and muscles that provide stability and force transmission in the shoulder joint. Whereas most rotator cuff tears are amenable to suture repair, the overall success rate of repair is low, and massive tears are prone to re-tear. Extracellular matrix (ECM) patches are used to augment suture repair, but they have limitations. Tissue-engineered approaches provide a promising solution for massive rotator cuff tears. Previous studies have shown that, compared to nonaligned scaffolds, aligned electrospun polymer scaffolds exhibit greater anisotropy and exert a greater tenogenic effect. Nevertheless, achieving rapid cell infiltration through the full thickness of the scaffold is challenging, and scaling to a translationally relevant size may be difficult. Our goal was to evaluate whether a novel method of alignment, combining a multilayered electrospinning technique with a hybrid of several electrospinning alignment techniques, would permit cell infiltration and collagen deposition through the thickness of poly(ε-caprolactone) scaffolds following seeding with human adipose-derived stem cells. Furthermore, we evaluated whether multilayered aligned scaffolds enhanced collagen alignment, tendon-related gene expression, and mechanical properties compared to multilayered nonaligned scaffolds. Both aligned and nonaligned multilayered scaffolds demonstrated cell infiltration and ECM deposition through the full thickness of the scaffold after only 28days of culture. Aligned scaffolds displayed significantly increased expression of tenomodulin compared to nonaligned scaffolds and exhibited aligned collagen fibrils throughout the full thickness, the presence of which may account for the increased yield stress and Young's modulus of cell-seeded aligned scaffolds along the axis of fiber alignment.

STATEMENT OF SIGNIFICANCE

Rotator cuff tears are an important clinical problem in the shoulder, with over 300,000 surgical repairs performed annually. Re-tear rates may be high, and current methods used to augment surgical repair have limited evidence to support their clinical use due to inadequate initial mechanical properties and slow cellular infiltration. Tissue engineering approaches such as electrospinning have shown similar challenges in previous studies. In this study, a novel technique to align electrospun fibers while using a multilayered approach demonstrated increased mechanical properties and development of aligned collagen through the full thickness of the scaffolds compared to nonaligned multilayered scaffolds, and both types of scaffolds demonstrated rapid cell infiltration through the full thickness of the scaffold.

Platelet-rich plasma and other cellular strategies in orthopedic surgery

The use of biologics in the treatment of musculoskeletal disease has become increasingly more common as research studies continue to provide further elucidation of their mechanisms in healing. Platelet-rich plasma, patches, growth factors, and stem cells are among the many biologics under active investigation and have varying levels of success in augmenting surgical or nonoperative interventions. However, the limitations of these treatments exist, and clear guidelines for their indications and application have yet to be established. Well-designed clinical trials will help determine the appropriate future use of biologics to ensure consistent outcomes.

Properties of biologic scaffolds and their response to mesenchymal stem cells

PURPOSE

The purpose of this study was to examine, in vitro, the cellular response of human mesenchymal stem cells (MSCs) to sample types of commercially available scaffolds in comparison with control, native tendon tissue (fresh-frozen rotator cuff tendon allograft).

METHODS

MSCs were defined by (1) colony-forming potential; (2) ability to differentiate into tendon, cartilage, bone, and fat tissue; and (3) fluorescence-activated cell sorting analysis (CD73, CD90, CD45). Samples were taken from fresh-frozen human rotator cuff tendon (allograft), human highly cross-linked collagen membrane (Arthroflex; LifeNet Health, Virginia Beach, VA), porcine non-cross-linked collagen membrane (Mucograft; Geistlich Pharma, Lucerne, Switzerland), a human platelet-rich fibrin matrix (PRF-M), and a fibrin matrix based on platelet-rich plasma (ViscoGel; Arthrex, Naples, FL). Cells were counted for adhesion (24 hours), thymidine assay for cell proliferation (96 hours), and live/dead stain for viability (168 hours). Histologic analysis was performed after 21 days, and the unloaded scaffolds were scanned with electron microscopy.

RESULTS

MSCs were successfully differentiated into all cell lines. A significantly greater number of cells adhered to both the non-cross-linked porcine collagen scaffold and PRF-M. Cell activity (proliferation) was significantly higher in the non-cross-linked porcine collagen scaffold compared with PRF-M and fibrin matrix based on platelet-rich plasma. There were no significant differences found in the results of the live/dead assay.

CONCLUSIONS

Significant differences in the response of human MSCs to biologic scaffolds existed. MSC adhesion, proliferation, and scaffold morphology evaluated by histologic analysis and electron microscopy varied throughout the evaluated types of scaffolds. Non-cross-linked porcine collagen scaffolds showed superior results for cell adhesion and proliferation, as well as on histologic evaluation.

CLINICAL RELEVANCE

This study enables the clinician and scientist to choose scaffold materials according to their specific interaction with MSCs.

Management of disorders of the rotator cuff: proceedings of the ISAKOS upper extremity committee consensus meeting

The goal of this article is to consolidate the International Society of Arthroscopy, Knee Surgery & Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee's (UEC's) current knowledge on rotator cuff disease and management, as well as highlight key unresolved issues. The rotator cuff is an anatomically complex structure important for providing glenohumeral function and stability as part of a closed chain system. Current consensus suggests rotator cuff injuries are most accurately diagnosed, at levels similar to diagnosis by magnetic resonance imaging, with a combination of cuff- and impingement-specific clinical tests. Updates in the understanding of acromion morphology, the insertional anatomy of the rotator cuff, and the role of suprascapular nerve release may require changes to current classification systems and surgical strategies. Although initial management focuses on nonoperative protocols, discussion continues on whether surgery for isolated impingement is clinically more beneficial than rehabilitation. However, clear indications have yet to be established for the use of single- versus double-row repair because evidence confirms neither is clinically efficacious than the other. Biceps tenodesis, however, in non-isolated cuff tears has proven more successful in addressing the etiology of shoulder pain and yields improved outcomes over tenotomy. Data reviewing the benefits of tendon transfers, shoulder prostheses, and mechanical scaffolds, as well as new research on the potential benefit of platelet-rich plasma, pluripotential stem cells, and gene therapies, will also be presented.

Synthetic and degradable patches: an emerging solution for rotator cuff repair

The use of rotator cuff augmentation has increased dramatically over the last 10 years in response to the high rate of failure observed after non-augmented surgery. However, although augmentations have been shown to reduce shoulder pain, there is no consensus or clear guideline as to what is the safest or most efficacious material. Current augmentations, either available commercially or in development, can be classified into three categories: non-degradable structures, extra cellular matrix (ECM)-based patches and degradable synthetic scaffolds. Non-degradable structures have excellent mechanical properties, but can cause problems of infection and loss of integrity in the long-term. ECM-based patches usually demonstrate excellent biological properties in vitro, but studies have highlighted complications in vivo due to poor mechanical support and to infection or inflammation. Degradable synthetic scaffolds represent the new generation of implants. It is proposed that a combination of good mechanical properties, active promotion of biological healing, low infection risk and bio-absorption are the ideal characteristics of an augmentation material. Among the materials with these features, those processed by electrospinning have shown great promis. However, their clinical effectiveness has yet to be proven and well conducted clinical trials are urgently required.

Multilayered electrospun scaffolds for tendon tissue engineering

Full-thickness rotator cuff tears are one of the most common causes of shoulder pain in people over the age of 65. High retear rates and poor functional outcomes are common after surgical repair, and currently available extracellular matrix scaffold patches have limited abilities to enhance new tendon formation. In this regard, tissue-engineered scaffolds may provide a means to improve repair of rotator cuff tears. Electrospinning provides a versatile method for creating nanofibrous scaffolds with controlled architectures, but several challenges remain in its application to tissue engineering, such as cell infiltration through the full thickness of the scaffold as well as control of cell growth and differentiation. Previous studies have shown that ligament-derived extracellular matrix may enhance differentiation toward a tendon or ligament phenotype by human adipose stem cells (hASCs). In this study, we investigated the use of tendon-derived extracellular matrix (TDM)-coated electrospun multilayered scaffolds compared to fibronectin (FN) or phosphate-buffered saline (PBS) coating for use in rotator cuff tendon tissue engineering. Multilayered poly(ɛ-caprolactone) scaffolds were prepared by sequentially collecting electrospun layers onto the surface of a grounded saline solution into a single scaffold. Scaffolds were then coated with TDM, FN, or PBS and seeded with hASCs. Scaffolds were maintained without exogenous growth factors for 28 days in culture and evaluated for protein content (by immunofluorescence and biochemical assay), markers of tendon differentiation, and tensile mechanical properties. The collagen content was greatest by day 28 in TDM-scaffolds. Gene expression of type I collagen, decorin, and tenascin C increased over time, with no effect of scaffold coating. Sulfated glycosaminoglycan and dsDNA contents increased over time in culture, but there was no effect of scaffold coating. The Young's modulus did not change over time, but yield strain increased with time in culture. Histology demonstrated cell infiltration through the full thickness of all scaffolds and immunofluorescence demonstrated greater expression of type I, but not type III collagen through the full thickness of the scaffold in TDM-scaffolds compared to other treatment groups. Together, these data suggest that nonaligned multilayered electrospun scaffolds permit tenogenic differentiation by hASCs and that TDM may promote some aspects of this differentiation.

Biologically based strategies to augment rotator cuff tears

Lesions of the rotator cuff (RC) are among the most frequent tendon injuries. In spite of the developments in both open and arthroscopic surgery, RC repair still very often fails. In order to reduce the failure rate after surgery, several experimental in vitro and in vivo therapy methods have been developed for biological improvement of the reinsertion. This article provides an overview of the current evidence for augmentation of RC reconstruction with growth factors. Furthermore, potential future therapeutic approaches are discussed. We performed a comprehensive search of the PubMed database using various combinations of the keywords “tendon,” “rotator cuff,” “augmentation,” “growth factor,” “platelet-rich fibrin,” and “platelet-rich plasma” for publications up to 2011. Given the linguistic capabilities of the research team, we considered publications in English, German, French, and Spanish. We excluded literature reviews, case reports, and letters to the editor.

A biomechanical analysis of gap formation and failure mechanics of a xenograft-reinforced rotator cuff repair in a cadaveric model

HYPOTHESIS

Failure rates of rotator cuff repairs are reported to be as high as 90%, in part because of gap formation at the repair site that occurs before healing. The purpose of this study was to evaluate whether the application of an extracellular matrix (ECM) graft (Conexa; Tornier, Edina, MN, USA) to a rotator cuff repair will decrease the gap formation at the tendon-bone interface and increase the ultimate load to failure over control specimens by mechanically sharing load with the repair in a cadaveric model.

METHODS

Six pairs of human cadaveric shoulders were used to test ECM-reinforced and unreinforced rotator cuff repairs for repair-site gapping, ultimate load, failure mode, and load-sharing capabilities of the ECM patch under both cyclic and monotonic loading.

RESULTS

The gap formation under cyclic loading was reduced by 40% for the reinforced specimens compared with the control group (1.3 ± 0.6 mm vs 2.1 ± 0.5 mm, P < .05) The load at 5-mm gap formation was significantly higher for the reinforced group (389 ± 71 N) compared with the control group (307 ± 33 N) (P < .05). The ultimate load to failure was significantly higher for the ECM-reinforced group compared with the control group: 429 ± 69 N versus 335 ± 57 N (P < .05). The ECM graft was estimated to share 35% of the load applied to the tendon repair.

CONCLUSIONS

Application of an ECM graft to a rotator cuff repair decreased tendon gapping and increased load to failure by load sharing in a human rotator cuff repair model.

Tenocyte proliferation on collagen scaffolds protects against degradation and improves scaffold properties

Tissue engineering scaffolds encourage cell proliferation whilst degrading to facilitate tissue regeneration. Their mechanical properties therefore change, decreasing due to scaffold degradation and increasing due to extracellular matrix deposition. This work compares the changing properties of collagen scaffolds incubated in culture medium, with and without human tenocytes, in order to investigate the relationship between degradation and tenocyte proliferation. The material properties of scaffolds are compared over 26 days using mechanical testing, differential scanning calorimetry, infra-red spectroscopy, and histology and biochemical assays. For medium-only scaffolds, the mechanical properties decrease rapidly, while culture medium sulfhydryl content increases significantly, with no significant changes in the denaturation temperature of scaffold collagen content. Conversely, the mechanical properties and collagen content of tenocyte-seeded scaffolds increase significantly while culture medium sulfhydryl content decreases and denaturation temperature remains the same. These results indicate that tenocytes proliferation both reduces the degradation of collagen scaffolds incubated in culture medium and produces scaffolds with improved properties.

Cell- and gene-based approaches to tendon regeneration

Repair of rotator cuff tears in experimental models has been significantly improved by the use of enhanced biologic approaches, including platelet-rich plasma, bone marrow aspirate, growth factor supplements, and cell- and gene-modified cell therapy. Despite added complexity, cell-based therapies form an important part of enhanced repair, and combinations of carrier vehicles, growth factors, and implanted cells provide the best opportunity for robust repair. Bone marrow-derived mesenchymal stem cells provide a stimulus for repair in flexor tendons, but application in rotator cuff repair has not shown universally positive results. The use of scaffolds such as platelet-rich plasma, fibrin, and synthetic vehicles and the use of gene priming for stem cell differentiation and local anabolic and anti-inflammatory impact have both provided essential components for enhanced tendon and tendon-to-bone repair in rotator cuff disruption. Application of these research techniques in human rotator cuff injury has generally been limited to autologous platelet-rich plasma, bone marrow concentrate, or bone marrow aspirates combined with scaffold materials. Cultured mesenchymal progenitor therapy and gene-enhanced function have not yet reached clinical trials in humans. Research in several animal species indicates that the concept of gene-primed stem cells, particularly embryonic stem cells, combined with effective culture conditions, transduction with long-term integrating vectors carrying anabolic growth factors, and development of cells conditioned by use of RNA interference gene therapy to resist matrix metalloproteinase degradation, may constitute potential advances in rotator cuff repair. This review summarizes cell- and gene-enhanced cell research for tendon repair and provides future directions for rotator cuff repair using biologic composites.

Decellularized human dermis to treat massive rotator cuff tears: in vitro evaluations

Interest is increasing in biological scaffolds for tissue regeneration such as extracellular matrix membranes, developed through soft tissue decellularization. Extracellular matrix membranes were developed to heal different tendon and soft tissue lesions that are very frequent in the general population with high health-care costs and patient morbidity. The aim of this research was to evaluate a human dermal matrix (HDM) decellularized by a chemico-physical method. A primary culture of rat tenocytes was performed: tenocytes were seeded on HDM samples and on polystyrene wells as controls (CTR). Cell viability and synthetic activity were evaluated at 3 and 7 days. An in vitro microwound model was used to evaluate HDM bioactivity: after tenocyte expansion, artificial wounds were created, HDM extracts were added, and closure time and decorin synthesis were monitored histomorphometrically at 1, 4, 24, and 72 hr. A significant higher amount of collagen I was observed when cells were cultured on HDM in comparison with that on CTR (3 days: p < 0.0001; 7 days: p < 0.05). In HDM group, fibronectin synthesis was significantly higher at both experimental times (p < 0.0001). At 3 days, proteoglycans and transforming growth factor-β1 releases were significantly higher on HDM (p < 0.0001 and p < 0.005, respectively). The artificial microwound closure time and decorin expression were significantly enhanced by the addition of 50% HDM extract (p < 0.05). In vitro data showed that the decellularization technique enabled the development of a matrix with adequate biological and biomechanical properties.