Biologic augmentation of rotator cuff repair

Is cellular therapy beneficial in management of rotator cuff tears? Meta-analysis of comparative clinical studies

BACKGROUND

Mesenchymal stromal cell (MSC)-based cellular therapy promotes type I collagen production, enhance mechanical strength of tissues, and enhance biology at the bone-tendon interface, which primarily explains their potential clinical utility in rotator cuff (RC) tears.

AIM

To analyze the efficacy and safety of cellular therapy utilizing MSCs in the management of RC tears from clinical studies available in the literature.

METHODS

We conducted independent and duplicate electronic database searches including PubMed, Embase, Reference Citation Anallysis, Web of Science, and Cochrane Library in August 2021 for studies analyzing the efficacy and safety of cellular therapy (CT) utilizing MSCs in the management of RC tears. Visual Analog Score (VAS) score for pain, American Shoulder and Elbow Surgeons (ASES) score, Disability of the Arm, Shoulder, and Hand score, Constant score, radiological assessment of healing, and complications such as retear rate and adverse events were the outcomes analyzed. Analysis was performed in R-platform using OpenMeta [Analyst] software.

RESULTS

Six studies involving 238 patients were included for analysis. We noted a significant reduction in VAS score for pain at 3 mo (weighed mean difference [WMD] = -2.234, P < 0.001) and 6 mo (WMD = -3.078, P < 0.001) with the use of CT, which was not maintained at long-term follow-up (WMD = -0.749, P = 0.544). Concerning functional outcomes, utilization of CT produced a significant short-term improvement in the ASES score (WMD = 17.090, P < 0.001) and significant benefit in functional scores such as Constant score (WMD = 0.833, P = 0.760) at long-term follow-up. Moreover, we also observed significantly improved radiological tendon healing during the long-term follow-up (odds ratio [OR] = 3.252, P = 0.059). We also noted a significant reduction in the retear rate upon utilization of CT in RC tears both at short- (OR = 0.079, P = 0.032) and long-term (OR = 0.434, P = 0.027) follow-ups. We did not observe any significant increase in the adverse events directly related to cellular therapy, as compared with the control group (OR = 0.876, P = 0.869).

CONCLUSION

Based on our comprehensive and critical review, we could observe that the utilization of CT in RC tear significantly reduced pain severity at 3 and 6 mo, improved short-term functional outcome, enhanced radiological tendon healing, and mitigated retear rates at both short- and long-term follow-ups. The literature also confirmed the relative safety of using MSC therapy in patients presenting with RC tears.

Functional and radiologic results of the crimson duvet procedure in rotator cuff treatment: a randomized controlled clinical trial

BACKGROUND

Rotator cuff tears are one of the more frequent pathologies of the shoulder. Arthroscopic techniques and biologic augmentation have been developed to improve the rate and quality of healing. The crimson duvet procedure (CDP) theoretically provides mesenchymal stem cells through microfracture treatment of the footprint. The aim of this research was to evaluate the effect of CDP in patients who had undergone arthroscopic surgery for complete rotator cuff repair.

METHODS

A prospective randomized clinical trial was performed in a total of 123 patients, consisting of 59 women and 64 men, with a mean age of 58 years. We included patients with a clinical and radiologic diagnosis of a complete rotator cuff tear. All patients were treated with arthroscopic rotator cuff repair. In group 1, the surface of the footprint was débrided; in group 2, the footprint underwent microfracture. The primary outcome was the nonhealing rate, which was detected by magnetic resonance imaging (MRI) or ultrasonography, and the secondary outcome was the functional result. A Sugaya classification of I to III was considered to indicate healing. For clinical evaluation, the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) and Constant scores were evaluated, along with the range of motion. The functional evaluation was performed preoperatively and at 6 months and 1 year postoperatively. The radiologic (MRI or ultrasonography) evaluation was performed at 6 months. Neither the patients nor the radiologists and physical therapists who performed the postoperative evaluations were informed of the random selection.

RESULTS

We observed a healing rate of 85.11% in the control group and 93.7% in the CDP group, which was not significant (P = .19). However, a significant improvement in function was observed in all patients. The ASES score improved from 68.9 (SD 13.8) preoperatively to 92.2 at 6 months and to 96.4 (SD 6.2) at 12 months (P < .05), but no difference was observed between the groups. A similar level of improvement was observed in the Constant score.

CONCLUSION

The arthroscopic repair of complete rotator cuff tears presents good and excellent clinical results in most patients. Nevertheless, nonhealing occurs at a rate that depends mainly on the age of the patient and the size of the tear. The addition of CDP did not improve the functional results or the healing rate.

Systematic Review of Platelet-Rich Plasma for Rotator Cuff Repair: Are We Adhering to the Minimum Information for Studies Evaluating Biologics in Orthopaedics?

Background

The therapeutic efficacy of orthobiologic therapies for rotator cuff repair is difficult to evaluate owing to reporting inconsistences. In response, the Minimum Information for Studies Evaluating Biologics in Orthopaedics (MIBO) guidelines were developed to ensure standard reporting on orthobiologic therapies.

Purpose

To systematically review clinical studies evaluating platelet-rich plasma (PRP) for full-thickness rotator cuff repair and adherence to MIBO guidelines.

Study Design

Scoping review; Level of evidence, 4.

Methods

A search was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using PubMed, EMBASE, and the Cochrane Library databases. Inclusion criteria were clinical studies reporting on rotator cuff tears (≥1 cm) surgically repaired with PRP. Patient demographics, biologic intervention, and adherence to the MIBO guidelines were systematically reviewed.

Results

A total of 19 studies (1005 patients) were included in this review. Across all studies, 58.5% of the MIBO checklist items for PRP were reported. Out of 47 checklist items, 19 were reported in over 85% of studies, whereas 22 were reported in less than half of studies. Details of whole-blood processing and characteristics, as well as PRP processing and characteristics, were reported inconsistently, and no study provided adequate information to enable the precise replication of preparation protocols for PRP.

Conclusion

This systematic review highlights the current reporting deficiencies within the scientific literature of important variables for evaluating PRP for full-thickness rotator cuff repair. There was widespread variability among published studies that evaluate PRP for this application and, more specifically, studies were limited by inconsistent universal reporting of whole-blood and PRP processing and postprocessing characteristics. To improve our understanding of biologic efficacy and to promote repeatability, stricter adherence to the MIBO guidelines is necessary. We propose that the checklist limitations be addressed and that modification of the MIBO guidelines be considered to improve the reporting of individual components within certain categories.

Metal-based nanoparticles for bone tissue engineering

Tissue is vital to the organization of multicellular organisms, because it creates the different organs and provides the main scaffold for body shape. The quest for effective methods to allow tissue regeneration and create scaffolds for new tissue growth has intensified in recent years. Tissue engineering has recently used some promising alternatives to existing conventional scaffold materials, many of which have been derived from nanotechnology. One important example of these is metal nanoparticles. The purpose of this review is to cover novel tissue engineering methods, paying special attention to those based on the use of metal-based nanoparticles. The unique physiochemical properties of metal nanoparticles, such as antibacterial effects, shape memory phenomenon, low cytotoxicity, stimulation of the proliferation process, good mechanical and tensile strength, acceptable biocompatibility, significant osteogenic potential, and ability to regulate cell growth pathways, suggest that they can perform as novel types of scaffolds for bone tissue engineering. The basic principles of various nanoparticle-based composites and scaffolds are discussed in this review. The merits and demerits of these particles are critically discussed, and their importance in bone tissue engineering is highlighted.

Bone marrow-stimulating techniques in arthroscopic rotator cuff repair: a systematic review protocol

INTRODUCTION

Bone marrow-stimulating (BMS) techniques during arthroscopic rotator cuff repair surgery theoretically enhance the biological component for healing and hence improve tendon healing, but their efficacy remains unproven. The purpose of this review is to determine the effects and associated harms of BMS in arthroscopic rotator cuff repair surgery.

METHODS AND ANALYSIS

We will perform a systematic review and meta-analysis of randomised-controlled trials (RCTs) and retrospective cohort studies (RCS) that compare outcomes following BMS use against no use of BMS during arthroscopic rotator cuff repair surgery. We will search the databases including the Cochrane Central Register of Controlled Trials, Medline and Embase, and clinical trial registries for relevant studies. We will include studies published from start of indexing until 23 August 2018. Two reviewers will independently assess the eligibility for studies. For each included trial, we will conduct duplicate independent data extraction and risk of bias assessment. We will use the Cochrane Collaboration tool to assess the risk of bias of included RCTs, while we will use the Risk Of Bias In Non-randomised Studies - of Interventions tool to evaluate the risk of bias of RCS. We will perform a random-effects meta-analysis in calculating the pooled risk estimates when appropriate. We will assess the overall quality of the data for each individual outcome using the Grading of Recommendations, Assessments, Development and Evaluation approach. The primary outcomes are tendon healing rate, overall pain and shoulder functions. The secondary outcomes are the proportion of participants with adverse events related to interventions, the range of motion and the proportion of participants with return to previous activities.

ETHICS AND DISSEMINATION

We will report this review according to the guidance of the PRISMA statement. The results of this review will be disseminated through conference presentations and publications in peer-reviewed journals.

PROSPERO REGISTRATION NUMBER

CRD42018087161.

Platelet-Rich Plasma Derived Growth Factors Contribute to Stem Cell Differentiation in Musculoskeletal Regeneration

Stem cell treatment and platelet-rich plasma (PRP) therapy are two significant issues in regenerative medicine. Stem cells such as bone marrow mesenchymal stem cells, adipose-derived stem cells and periodontal ligament stem cells can be successfully applied in the field of tissue regeneration. PRP, a natural product isolated from whole blood, can secrete multiple growth factors (GFs) for regulating physiological activities. These GFs can stimulate proliferation and differentiation of different stem cells in injury models. Therefore, combination of both agents receives wide expectations in regenerative medicine, especially in bone, cartilage and tendon repair. In this review, we thoroughly discussed the interaction and underlying mechanisms of PRP derived GFs with stem cells, and assessed their functions in cell differentiation for musculoskeletal regeneration.

Efficacy of bone marrow-stimulating technique in rotator cuff repair

BACKGROUND

This study used a chronic rotator cuff (RC) tear model to investigate the effect of microfracture as a bone marrow-stimulating (BMS) technique for RC healing.

METHODS

A chronic retracted RC tendon tear model was created bilaterally in the subscapularis tendons of 20 New Zealand rabbits. The tendons were repaired after 8 weeks using a single-row configuration. Tendons in the right shoulder were repaired in standard fashion (control group). Microfractures were performed in the left shoulders before repair (microfracture group). The animals were euthanized 8 and 16 weeks after repair. The repaired tendons were tested biomechanically for their ultimate failure load, linear stiffness, and elongation at failure. Gross and histologic evaluations of the tendon-to-bone healing were evaluated.

RESULTS

Macroscopically, subscapularis tendons were attached on the lesser tuberosity. In the microfracture group, collagen fibers were organized in relatively thicker bundles. The mean ultimate failure load of the microfracture group was significantly greater at 8 weeks (148.4 ± 31 N vs. 101.4 ± 26 N, respectively; P = .011) and 16 weeks (155 ± 30 N vs. 114.9 ± 25 N, respectively; P = .017) after repair. There were no significant differences between the groups for linear stiffness at 8 weeks (15.9 ± 2.7 N/mm vs. 15.8 ± 1.3 N/mm, respectively; P = .798) and 16 weeks (16.9 ± 4.3 N/mm vs. 17.1 ± 3.6 N/mm, respectively, P = .848) and elongation at failure at 8 weeks (4.7 ± 1.1 mm vs. 4.7 ± 1.3 mm, respectively; P = .848) and 16 weels (4.8 ± 1.5 mm vs. 4.9 ± 0.9 mm, respectively; P = .749).

CONCLUSION

The microfracture on the tuberosity of the repaired chronic rotator cuff tear promoted dynamic tendon healing with significantly increased ultimate force to failure and with thicker collagen bundles and more fibrocartilage histologically at 8 weeks.

Tissue-Engineered Tendon for Enthesis Regeneration in a Rat Rotator Cuff Model

Healing of rotator cuff (RC) injuries with current suture or augmented scaffold techniques fails to regenerate the enthesis and instead forms a weaker fibrovascular scar that is prone to subsequent failure. Regeneration of the enthesis is the key to improving clinical outcomes for RC injuries. We hypothesized that the utilization of our tissue-engineered tendon to repair either an acute or a chronic full-thickness supraspinatus tear would regenerate a functional enthesis and return the biomechanics of the tendon back to that found in native tissue. Engineered tendons were fabricated from bone marrow-derived mesenchymal stem cells utilizing our well-described fabrication technology. Forty-three rats underwent unilateral detachment of the supraspinatus tendon followed by acute (immediate) or chronic (4 weeks retracted) repair by using either our engineered tendon or a trans-osseous suture technique. Animals were sacrificed at 8 weeks. Biomechanical and histological analyses of the regenerated enthesis and tendon were performed. Statistical analysis was performed by using a one-way analysis of variance with significance set at p < 0.05. Acute repairs using engineered tendon had improved enthesis structure and lower biomechanical failures compared with suture repairs. Chronic repairs with engineered tendon had a more native-like enthesis with increased fibrocartilage formation, reduced scar formation, and lower biomechanical failure compared with suture repair. Thus, the utilization of our tissue-engineered tendon showed improve enthesis regeneration and improved function in chronic RC repairs compared with suture repair. Clinical Significance: Our engineered tendon construct shows promise as a clinically relevant method for repair of RC injuries.

The influence of different footprint preparation techniques on tissue regeneration in rotator cuff repair in an animal model

INTRODUCTION

Rotator cuff tears are common diseases of the upper extremity. There are no recommendations to the surgeon on how to prepare the footprint to ensure optimal tendon-to-bone healing. However, biologic augmentation using stem cells and growth factors is considered to encourage the healing process of the tendon. The aim of the study was to investigate the biomechanical and histological outcome of different footprint preparations in rotator cuff repair.

MATERIAL AND METHODS

One hundred and eighty-nine Sprague-Dawley rats were randomly assigned to either spongialization, radiofrequency ablation or an untreated control group. Rats were killed after 1 or 7 weeks for histological evaluation or after 7 weeks for biomechanical testing.

RESULTS

Histological evaluation showed better tissue organization in the control and spongialization group compared to the radiofrequency ablation group. The highest collagen I to collagen III quotient was found in the control group, followed closely by the spongialization group. Measured quotients showed a decrease in the values after 1 week compared to the values after 7 weeks, except in the radiofrequency ablation group, where an increase was detected. A significant difference was found in the load to failure test comparing the radiofrequency ablation group to the spongialization group (p = 0.0409) and control group (p = 0.014), but not comparing the spongialization group to the control group (p = 0.2456).

CONCLUSIONS

The results of this study suggest that spongialization of the footprint before attaching the torn supraspinatus tendon can lead to better structural properties and higher quality of tendon-to-bone restoration at the insertion area when compared with radiofrequency ablation.

Current Status of Tissue-Engineered Scaffolds for Rotator Cuff Repair

Rotator cuff tears continue to be at significant risk for re-tear or for failure to heal after surgical repair despite the use of a variety of surgical techniques and augmentation devices. Therefore, there is a need for functionalized scaffold strategies to provide sustained mechanical augmentation during the critical first 12-weeks following repair, and to enhance the healing potential of the repaired tendon and tendon-bone interface. Tissue engineered approaches that combine the use of scaffolds, cells, and bioactive molecules towards promising new solutions for rotator cuff repair are reviewed. The ideal scaffold should have adequate initial mechanical properties, be slowly degrading or non-degradable, have non-toxic degradation products, enhance cell growth, infiltration and differentiation, promote regeneration of the tendon-bone interface, be biocompatible and have excellent suture retention and handling properties. Scaffolds that closely match the inhomogeneity and non-linearity of the native rotator cuff may significantly advance the field. While substantial pre-clinical work remains to be done, continued progress in overcoming current tissue engineering challenges should allow for successful clinical translation.

Immunobiological factors aggravating the fatty infiltration on tendons and muscles in rotator cuff lesions

Rotator cuff lesions (RCLs) are a common cause of shoulder pain and dysfunction. The rotator cuff tendons can degenerate and/or tear from the greater tuberosity of the humerus, which is associated with several anatomical, physiological, biochemical, and molecular changes in tendon and muscle. In this article, these pathways are critically reviewed and discussed with various management strategies of RCLs. The article also highlights the immunobiological responses following the RCL and the inherent repair mechanisms elicited by the body. The greatest difficulty in treating this pathology is that the muscle can undergo irreversible fatty infiltration in the setting of chronic tears that is associated with poor surgical outcomes. The article also investigates the key molecular pathways of the muscle homeostasis (mTOR, Rho kinase, AMPK, and Ca(2+)) with the energy metabolism to propose a possible mechanism for fatty infiltration. Future research is warranted to target the key players of these pathways in the management of fatty infiltration and thus RCL.

[Clinical management of rotator cuff tears. Current concepts in cell-based therapy strategies]

Due to the increasing demand for functionality in an aging yet physically active society, the treatment of rotator cuff tears is of ever-growing importance. Despite intensive research efforts, the treatment of degenerative rotator cuff tears, in particular their long-term outcome, is still a challenge. While in recent years the focus was on biomechanics and the technical aspects of rotator cuff reconstruction, attention has now turned to the biological considerations of tendon regeneration. This article highlights the current state of biological rotator cuff augmentation in a clinical setting and provides an insight into and an outlook on the experimental procedures.

Augmentation of Rotator Cuff Repair With Soft Tissue Scaffolds

Background

Tears of the rotator cuff are one of the most common tendon disorders. Treatment often includes surgical repair, but the rate of failure to gain or maintain healing has been reported to be as high as 94%. This has been substantially attributed to the inadequate capacity of tendon to heal once damaged, particularly to bone at the enthesis. A number of strategies have been developed to improve tendon-bone healing, tendon-tendon healing, and tendon regeneration. Scaffolds have received considerable attention for replacement, reconstruction, or reinforcement of tendon defects but may not possess situation-specific or durable mechanical and biological characteristics.

Purpose

To provide an overview of the biology of tendon-bone healing and the current scaffolds used to augment rotator cuff repairs.

Study Design

Systematic review; Level of evidence, 4.

Methods

A preliminary literature search of MEDLINE and Embase databases was performed using the terms rotator cuff scaffolds, rotator cuff augmentation, allografts for rotator cuff repair, xenografts for rotator cuff repair, and synthetic grafts for rotator cuff repair.

Results

The search identified 438 unique articles. Of these, 214 articles were irrelevant to the topic and were therefore excluded. This left a total of 224 studies that were suitable for analysis.

Conclusion

A number of novel biomaterials have been developed into biologically and mechanically favorable scaffolds. Few clinical trials have examined their effect on tendon-bone healing in well-designed, long-term follow-up studies with appropriate control groups. While there is still considerable work to be done before scaffolds are introduced into routine clinical practice, there does appear to be a clear indication for their use as an interpositional graft for large and massive retracted rotator cuff tears and when repairing a poor-quality degenerative tendon.

Growth factor release by vesicular phospholipid gels: in-vitro results and application for rotator cuff repair in a rat model

Background

Biological augmentation of rotator cuff repair is of growing interest to improve biomechanical properties and prevent re-tearing. But intraoperative single shot growth factor application appears not sufficient to provide healing support in the physiologic growth factor expression peaks. The purpose of this study was to establish a sustained release of granulocyte-colony stimulating factor (G-CSF) from injectable vesicular phospholipid gels (VPGs) in vitro and to examine biocompatibility and influence on histology and biomechanical behavior of G-CSF loaded VPGs in a chronic supraspinatus tear rat model.

Methods

G-CSF loaded VPGs were produced by dual asymmetric centrifugation. In vitro the integrity, stability and release rate were analyzed. In vivo supraspinatus tendons of 60 rats were detached and after 3 weeks a transosseous refixation with G-CSF loaded VPGs augmentation (n = 15; control, placebo, 1 and 10 μg G-CSF/d) was performed. 6 weeks postoperatively the healing site was analyzed histologically (n = 9; H&E by modified MOVIN score/Collagen I/III) and biomechanically (n = 6).

Results

In vitro testing revealed stable proteins after centrifugation and a continuous G-CSF release of up to 4 weeks. Placebo VPGs showed histologically no negative side effects on the healing process. Histologically in vivo testing demonstrated significant advantages for G-CSF 1 μg/d but not for G-CSF 10 μg/d in Collagen III content (p = 0.035) and a higher Collagen I/III ratio compared to the other groups. Biomechanically G-CSF 1 μg/d revealed a significant higher load to failure ratio (p = 0.020) compared to control but no significant differences in stiffness.

Conclusions

By use of VPGs a continuous growth factor release could be obtained in vitro. The in vivo results demonstrate an improvement of immunohistology and biomechanical properties with a low dose G-CSF application via VPG. The VPG itself was well tolerated and had no negative influence on the healing behavior. Due to the favorable properties (highly adhesive, injectable, biocompatible) VPGs are a very interesting option for biologic augmentation. The study may serve as basis for further research in growth factor application models.

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.

Arthroscopic double row cuff repair with suture-bridging and autologous conditioned plasma injection: Functional and structural results

Purpose:

The double row cuff repair with suture bridging is commonly used for arthroscopic rotator cuff repair (RCR). Despite its biomechanical qualities, the rate of iterative tears with this technique is important. The aim of our study was to evaluate the effect of autologous conditioned plasma (ACP) on functional results and on the rate of iterative tears after RCR by suture bridging.

Materials and Methods:

A consecutive series of 65 patients who underwent arthroscopic double-row suture bridge (Speed-Bridge, Arthrex) primary cuff repair of symptomatic full-thickness supraspinatus tear (retraction <3 in the Patte classification) were evaluated. Mean patient age was 60 (+/-8). The supraspinatus was repaired by knot-less bridging (SwiveLock, Arthrex) with suture tape material. 2 homogenous groups were created (A: 33 patients, B: 32 patients). In group A, all patients received, besides the cuff repair, an intra-tendinous ACP injection. Constant scores and Simple Shoulder Tests (SST) were measured pre-operatively and after a minimum follow-up period of 12 months post-operatively. Structural integrity of the repairs was evaluated by MRI according to the Sugaya classification. Sugaya >4 were considered as iterative tears.

Results:

Mean follow-up was 19 months (+/−42) in the 2 groups. The mean quantity of ACP injected was 6ml. (+/−1.5) and no specific complication of the injection was found. Mean preoperative Constant-Murley scores were 41,2 (±7,7) and 38 (±11)in group B. Mean normalized Constant-Murley score increased from 41 points (±7) pre-operatively to 70 points (±8) post-operatively in group A and from 38 points (±11) to 73 points (±11) in group B. There were no significative differences between the two groups (P > 0.05). In group A, 31 repairs were Sugaya 1-3 (94%), vs. 30 in group B (93%), and 1 was type 4 in group A (5%) vs. 2 in group B (8%).

Conclusion:

In both groups, RCR with suture bridging gave successful functional outcomes, with a low rate of iterative tear. In this preliminary study, the adjuvant effect of ACP injections could not be showed on both functional and structural results. Longer follow-up is needed to evaluate potential differences.

Tissue characteristics in tendon-to-bone healing change after rotator cuff repair using botulinumneurotoxin A for temporary paralysis of the supraspinatus muscle in rats

We hypothesized that botulinumneurotoxin A (BoNtA) positively influences tissue characteristics at the re-insertion site when used as an adjuvant prior to rotator cuff repair. One hundred and sixty Sprague-Dawley rats were randomly assigned to either a BoNtA or saline-injected control group. BoNtA or saline solution was injected into the supraspinatus muscle one week prior to repair of an artificially created supraspinatus tendon defect. Post-operatively, one subgroup was immobilized using a cast on the operated shoulder while the other had immediate mobilization. Histologically, the fibrocartilage transition zone was more prominent and better organized in the BoNtA groups when compared to the saline control group. In the immediately mobilized BoNtA groups significantly more collagen 2 at the insertion was detected than in the control groups (p<0.05). Fiber orientation of all BoNtA groups was better organized and more perpendicular to the epiphysis compared with control groups. Tendon stiffness differed significantly (p<0.05) between casted BoNtA and casted saline groups. Tendon viscoelasticity was significantly higher (p<0.05) in the immobilized saline groups no matter if repaired with increased or normal repair load. The results of this study suggest that reduction of load at the healing tendon-to-bone interface leads to improved repair tissue properties.

Does footprint preparation influence tendon-to-bone healing after rotator cuff repair in an animal model?

PURPOSE

The aim of this study was to investigate the influence of footprint spongialization and radiofrequency ablation on rotator cuff repair outcomes compared with an untreated group in a rat model.

METHODS

We randomly assigned 189 Sprague-Dawley rats to either a spongialization, radiofrequency ablation, or untreated group. After separation of the supraspinatus tendon from the greater tubercle, the footprint was prepared by removing the cortical bone with a burr (spongialization), was prepared by ablating soft tissue with a radiofrequency ablation device, or was left unaltered (untreated). Biomechanical testing (after 7 weeks, n = 165) and histologic analysis after 1 and 7 weeks (n = 24) followed reinsertion.

RESULTS

The mean load to failure was 17.51 ± 4.46 N/mm(2) in the spongialization group, 15.56 ± 4.85 N/mm(2) in the radiofrequency ablation group, and 19.21 ± 5.19 N/mm(2) in the untreated group. A significant difference was found between the spongialization and radiofrequency ablation groups (P = .0409), as well as between the untreated and radiofrequency ablation groups (P = .0014). There was no significant difference between the spongialization and untreated groups (P = .2456). The mean area of fibrocartilage transition, characterized by the presence of type II collagen, was larger after 1 and 7 weeks in the spongialization group (0.57 ± 0.1 mm(2) and 0.58 ± 0.1 mm(2), respectively) and untreated group (0.51 ± 0.1 mm(2) and 0.51 ± 0.2 mm(2), respectively) than in the radiofrequency ablation group (0.11 ± 0.1 mm(2) and 0.4 ± 0.1 mm(2), respectively) with P < .05 and P < .01.

CONCLUSIONS

The results of this study show that radiofrequency ablation of the footprint results in a poor biomechanical and histologic outcome in an animal model. No preparation of the footprint has the same effect as spongialization.

CLINICAL RELEVANCE

Different techniques of footprint preparation in rotator cuff repair may influence tendon-to-bone healing.

The future role of mesenchymal stem cells in the management of shoulder disorders

PURPOSE

Biologics may help to optimize the healing environment after rotator cuff repair. Mesenchymal stem cells (MSCs) may have the potential to regenerate a physiological enthesis, thereby improving healing at the repair site after rotator cuff repair.

METHODS

The PubMed database was searched in May 2013. Only in vivo and in vitro studies reporting on stem cell use in the rotator cuff of humans or animals were included. Exclusion criteria consisted of the following: Level V evidence, systematic reviews, and studies reporting preliminary results.

RESULTS

This query resulted in 141 citations. Of these, 90 were excluded based on the title of the study. A final group of 17 studies was included in this review (9 in vivo animal studies, 5 in vitro human studies, 1 in vitro animal study, 1 study reporting in vitro human and in vivo animal results, and 1 study reporting on clinical outcomes of human patients).

CONCLUSIONS

The current literature regarding therapeutic use of MSCs in shoulder surgery is limited. Although in vivo animal studies have shown some promising approaches to enhance tendon-to-bone healing, the use of MSCs for shoulder surgery should still be regarded as an experimental technique. Further basic and clinical research is needed until a procedure can be defined for the routine use of these cells in shoulder surgery.

Collagen fibre implant for tendon and ligament biological augmentation. In vivo study in an ovine model

PURPOSE

Although most in vitro studies indicate that collagen is a suitable biomaterial for tendon and ligament tissue engineering, in vivo studies of implanted collagen for regeneration of these tissues are still lacking. The objectives of this study were the following: (1) to investigate the regeneration of the central third of the ovine patellar tendon using implants made of an open array of collagen fibres (reconstituted, extruded bovine collagen); and (2) to compare two collagen crosslinking chemistries: carbodiimide and carbodiimide associated with ethyleneglycoldiglycidylether.

METHODS

Forty-eight Welsh Mountain sheep were operated on their right hind leg. The central third of patellar tendon was removed and substituted with carbodiimide (n = 16) and carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants (n = 16). In the control group the defect was left empty (n = 16). The central third of contralateral unoperated tendons was used as positive controls. Half of the sheep in each group were killed at 3- and 6-month time points. After proper dissection, tendon sub-units (medial, central and lateral) were tested to failure (n = 6 for each group), whilst 2 non-dissected samples were used for histology.

RESULTS

Both the implants had significantly lower stress to failure and modulus with respect to native tendon at both 3- and at 6-month time points. The implants did not statistically differ in stress to failure, whilst carbodiimide-crosslinked implants had significantly higher modulus than carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants both at 3 and at 6 months. Histology showed carbodiimide-crosslinked implants to have a better integration with the native tendon than carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants. Carbodiimide-crosslinked implants appeared partially resorbed and showed increased tissue ingrowth with respect to carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants.

CONCLUSIONS

To deliver collagen implants as an open array of fibres allows optimal tendon-implant integration and good ingrowth of regenerated tissue. In the present study the resorption rate of both the examined implants was too low due to the high level of crosslinking. This led to only minor substitution of the implant with regenerated tissue, which in turn produced a low-strength implanted region. Further studies are needed to find the right balance between strength and resorption rate of collagen fibres.

Evaluation of patients undergoing rotator cuff suture with the modified mason-allen technique

OBJECTIVE

: The purpose of this study was to clinically evaluate patients who underwent Arthroscopic Rotator Cuff Repair (RC) using the Modified Manson-Allen technique.

METHODS

: We evaluated 79 patients who underwent shoulder arthroscopy. The lesions were repaired using the modified Mason-Allen suture between 2003 and 2009, divided by Cofield classification and clinically evaluated by the scoring system of the University of Los Angeles (UCLA) in the pre- and postoperative periods.

RESULTS

: The evaluation of lesion sizes showed 7 small lesions (<1cm), 55 average lesions (1-3cm) and 17 large lesions (3-5cm), and in this last group there were 5 reruptures and the patients were reoperated by the same technique. Comparing the pre (14.1) and postoperative (32.6) values by UCLA system there was a significant improvement of score (142.3%), regardless of lesion size. The modified Mason-Allen suture provided satisfactory clinical results, regardless of lesion size, similar to those found in literature. The rerupture rate was high in large lesions. New suture techniques have been developed with the aim of reducing the incidence of rerupture.

CONCLUSION

: The modified Mason-Allen suture technique provided clinical improvement, regardless of lesion size. Level of Evidence IV, Cases Series .

Effects of selective paralysis of the supraspinatus muscle using botulinum neurotoxin a in rotator cuff healing in rats

We hypothesized that a temporary rotator cuff paralysis using botulinum-neurotoxin A (BoNtA) would lead to an improved tendon-to-bone healing after repair of supraspinatus lesions. One hundred sixty Sprague-Dawley rats were randomly assigned to either the BoNtA or the control (saline) group. BoNtA/saline-solution was injected into the supraspinatus muscle 1 week prior to surgery. A supraspinatus defect was made; we distinguished between a lesion with normal and increased repair load. Furthermore, one subgroup had the operated shoulder immobilized in a cast. Histologic analysis and biomechanical testing followed. Specimens from the BoNtA-group, which were treated with an increased repair load, showed less cellularity and more organization in the interface tissue compared to the saline control group. In addition, we found that the collagen 1-3 quotient in the BoNtA specimen was significantly (p = 0.0051) higher than in the control group. Ultimate load at failure between the groups was not significantly different (p > 0.05). We did not observe any significant differences between the mobilized and immobilized specimen (p = 0.2079). The study shows that tendon-to-bone healing after rotator cuff repair can be altered positively using BoNtA pre-operatively. Tears with increased repair load seem to benefit the most-at least histologically.

Efficacy of marrow-stimulating technique in arthroscopic rotator cuff repair: a prospective randomized study

PURPOSE

To evaluate the efficacy of a marrow-stimulating technique with microfractures of the greater tuberosity during arthroscopic rotator cuff repair.

METHODS

Eighty patients with a full-thickness rotator cuff tear underwent an arthroscopic single-row repair. Patients were divided into 2 groups of 40 cases each. In group 1, standard repair was performed; in group 2, microfractures of the greater tuberosity were performed to enhance tendon repair. Clinical outcome was assessed with the Disabilities of the Arm, Shoulder and Hand (DASH) score and normalized Constant score. Tendon integrity was assessed with magnetic resonance imaging. Multivariate analysis was performed to determine which predictors were independently associated with the outcome. Significance was set at P < .05.

RESULTS

The mean follow-up was 28.1 ± 3 months. Seven patients were lost to follow-up (2 in group 1 and 5 in group 2). Comparison between groups did not show significant differences for baseline characteristics. The mean DASH score was 28.6 ± 21.3 points in group 1 and 23.3 ± 20.1 points in group 2. Although the difference was not statistically significant, the confidence interval included a 10-point value (minimal clinically important difference) in favor of the microfracture group. The difference in the Constant score between groups was not significant. The tendon healing rate was 52.6% in group 1 and 65.7% in group 2, without a significant difference between groups. Subgroup analysis for tear size showed that group 2 had a significantly greater healing rate than group 1 for large tears (P = .040). Multivariate analysis showed that age, timing of symptoms, tear location, tendon retraction, and fatty infiltration significantly affected the outcomes.

CONCLUSIONS

Postoperative magnetic resonance imaging did not show any significant difference between groups in structural integrity. However, subgroup analysis showed a significantly greater healing rate in the microfracture group for large tears involving the supraspinatus and infraspinatus.

LEVEL OF EVIDENCE

Level I, high-quality randomized controlled trial with no statistically significant difference but narrow confidence intervals.

Refixation of the supraspinatus tendon in a rat model--influence of continuous growth factor application on tendon structure

The purpose was to evaluate histological changes of the supraspinatus tendon (SSP) after refixation under continuous growth factor application over 20 days in comparison to the native healing process. In a chronic rat tendon tear model (15 rats/group), a transosseous SSP refixation was performed and growth factors (control, G-CSF, b-FGF, combination) were continuously released into the subacromial space by an osmotic pump. Tendon healing was evaluated histologically by a modified MOVIN-Score, and Collagen I/III content was determined by immunohistology at 6 weeks. A modified MOVIN sum score showed significant lower counts for G-CSF and b-FGF in comparison to the control group (p = 0.050/p = 0.027) and the combined group (p = 0.050/p = 0.043). Collagen III was significantly reduced in the combined group compared to the control group (p = 0.028). Collagen I showed no significant differences. The Collagen I/III ratio was nearly doubled for b-FGF and the combined group compared to the control. At the study endpoint, 33% of pump dislocations were detected. The continuous application of both isolated growth factors (G-CSF/b-FGF) achieved improved tendon-remodeling. However, the continuous application via an osmotic pump showed a relative high dislocation rate when applied in the rat model.

Augmentation techniques for rotator cuff repair

INTRODUCTION

There is a high rate of recurrence of tear and failed healing after rotator cuff repair. Several strategies have proposed to augment rotator cuff repairs to improve postoperative outcome and shoulder performance. We systematically review the literature on clinical outcome following rotator cuff augmentation.

SOURCES OF DATA

We performed a comprehensive search of Medline, CINAHL, Embase and the Cochrane Central Registry of Controlled Trials, from inception of the database to 20 June 2012, using various combinations of keywords. The reference lists of the previously selected articles were then examined by hand. Only studies focusing on clinical outcomes of human patients who had undergone augmented rotator cuff repair were selected. We then evaluated the methodological quality of each article using the Coleman methodology score (CMS), a 10 criteria scoring list assessing the methodological quality of the selected studies (CMS).

AREAS OF AGREEMENT

Thirty-two articles were included in the present review. Two were retrospective studies, and 30 were prospective. Biologic, synthetic and cellular devices were used in 24, 7 and 1 studies, respectively. The mean modified Coleman methodology score was 64.0.

AREAS OF CONTROVERSY

Heterogeneity of the clinical outcome scores makes it difficult to compare different studies.

GROWING POINTS

None of the augmentation devices available is without problems, and each one presents intrinsic weaknesses. There is no dramatic increase in clinical and functional assessment after augmented procedures, especially if compared with control groups.

RESEARCH

More and better scientific evidence is necessary to use augmentation of rotator cuff repairs in routine clinical practice.

Recent advances in shoulder research

Shoulder pathology is a growing concern for the aging population, athletes, and laborers. Shoulder osteoarthritis and rotator cuff disease represent the two most common disorders of the shoulder leading to pain, disability, and degeneration. While research in cartilage regeneration has not yet been translated clinically, the field of shoulder arthroplasty has advanced to the point that joint replacement is an excellent and viable option for a number of pathologic conditions in the shoulder. Rotator cuff disease has been a significant focus of research activity in recent years, as clinicians face the challenge of poor tendon healing and irreversible changes associated with rotator cuff arthropathy. Future treatment modalities involving biologics and tissue engineering hold further promise to improve outcomes for patients suffering from shoulder pathologies.