Failed healing of rotator cuff repair correlates with altered collagenase and gelatinase in supraspinatus and subscapularis tendons

The immune pathology of bursitis in rheumatic inflammatory diseases, degenerative conditions and mechanical stress: A systematic review

OBJECTIVE

To summarize current insights on the immune pathology of bursitis caused by rheumatic inflammatory diseases, degenerative conditions, or mechanical stress and identify knowledge gaps in this field. Data on tenosynovitis pathology was included for comparison.

METHODS

We performed a systematic review encompassing an electronic database search of all published literatures in PubMed/MEDLINE from inception to February 13, 2023, investigating the immunological changes occurring in the bursa of patients with inflammatory rheumatic diseases, degenerative conditions or mechanical stress (e.g., impingement syndrome).

RESULTS

Thirty-two articles provided data on the immune pathology of bursal tissue inflammation were identified. Histological and immunological perturbations included alterations of tissue morphology, infiltration of macrophages and some T cells, and enhanced expression of proinflammatory cytokines, such as interleukin (IL)-6, IL-1β and tumor necrosis factor alpha (TNF-α). These changes were described for all three underlying causes, although studies on bursitis associated with rheumatic inflammatory diseases were rare. Fibrosis was only reported in subacromial bursitis caused by mechanical stress within our included studies.

CONCLUSION

Current insights on bursitis were outdated and studies on bursitis associated with rheumatic inflammatory diseases are particularly lacking. Substantial overlap of enhanced expression of IL-6, IL-1β, TNF-α and infiltrating macrophages were found in bursitis irrespective of the underlying cause. In depth investigation on bursitis such as high throughput multi-omics are urgently needed to guide disease-specific therapeutic management.

Identification of age-related genes in rotator cuff tendon

Aims

Rotator cuff tear (RCT) is the leading cause of shoulder pain, primarily associated with age-related tendon degeneration. This study aimed to elucidate the potential differential gene expressions in tendons across different age groups, and to investigate their roles in tendon degeneration.

Methods

Linear regression and differential expression (DE) analyses were performed on two transcriptome profiling datasets of torn supraspinatus tendons to identify age-related genes. Subsequent functional analyses were conducted on these candidate genes to explore their potential roles in tendon ageing. Additionally, a secondary DE analysis was performed on candidate genes by comparing their expressions between lesioned and normal tendons to explore their correlations with RCTs.

Results

We identified 49 genes in torn supraspinatus tendons associated with advancing age. Among them, five age-related genes showed DE in lesioned tendons compared to normal tendons. Functional analyses and previous studies have highlighted their specific enrichments in biological functions, such as muscle development (e.g. myosin heavy chain 3 (MYH3)), transcription regulation (e.g. CCAAT enhancer binding brotein delta (CEBPD)), and metal ion homeostasis (e.g. metallothionein 1X (MT1X)).

Conclusion

This study uncovered molecular aspects of tendon ageing and their potential links to RCT development, offering insights for targeted interventions. These findings enhance our understanding of the mechanisms of tendon degeneration, allowing potential strategies to be made for reducing the incidence of RCT.

Exploring the impact of vitamin D on tendon health: a comprehensive review

Tendons are vital components of the musculoskeletal system, facilitating movement and supporting mechanical loads. Emerging evidence suggests that vitamin D, beyond its well-established role in bone health, exerts significant effects on tendon physiology. The aim of this manuscript is to review the impact of vitamin D on tendons, focusing on its mechanisms of action, clinical implications, and therapeutic applications. A comprehensive search of scientific electronic databases was conducted to identify articles on the effects of vitamin D on tendon health. Fourteen studies were included in this review. Five studies were performed in vitro, and nine studies were conducted in vivo. Despite some conflicting results, the included studies showed that vitamin D regulates collagen synthesis, inflammation, and mineralization within tendons through its interaction with vitamin D receptors. Epidemiological studies link vitamin D deficiency with tendon disorders, including tendinopathy and impaired healing. Supplementation with vitamin D shows promise in improving tendon strength and function, particularly in at-risk populations such as athletes and the elderly. Future research should address optimal supplementation strategies and explore the interplay between vitamin D and other factors influencing tendon health. Integrating vitamin D optimization into clinical practice could enhance tendon integrity and reduce the burden of tendon-related pathologies.

Understanding Tendon Fibroblast Biology and Heterogeneity

Tendon regeneration has emerged as an area of interest due to the challenging healing process of avascular tendon tissue. During tendon healing after injury, the formation of a fibrous scar can limit tendon strength and lead to subsequent complications. The specific biological mechanisms that cause fibrosis across different cellular subtypes within the tendon and across different tendons in the body continue to remain unknown. Herein, we review the current understanding of tendon healing, fibrosis mechanisms, and future directions for treatments. We summarize recent research on the role of fibroblasts throughout tendon healing and describe the functional and cellular heterogeneity of fibroblasts and tendons. The review notes gaps in tendon fibrosis research, with a focus on characterizing distinct fibroblast subpopulations in the tendon. We highlight new techniques in the field that can be used to enhance our understanding of complex tendon pathologies such as fibrosis. Finally, we explore bioengineering tools for tendon regeneration and discuss future areas for innovation. Exploring the heterogeneity of tendon fibroblasts on the cellular level can inform therapeutic strategies for addressing tendon fibrosis and ultimately reduce its clinical burden.

The Delayed Presentation of Achilles Tendon Ruptures Is Associated With Marked Alterations in the Gene Expression of COL1A1, MMPs, TIMPs, and IL-6

BACKGROUND

Both acute and chronic Achilles tendon ruptures are affected by alterations in the extracellular matrix during the healing process of the tendon. Yet, these alterations in gene expression patterns are not well characterized.

PURPOSE

To characterize temporal and spatial differences in gene expression patterns after an Achilles tendon rupture and to evaluate if cells from chronic Achilles tendon ruptures have the same ability to form new tendon tissue (tendon constructs) as healthy tendon cells.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 35 patients with surgically treated Achilles tendon ruptures were included in the study and divided into 3 groups: acute (<4 weeks), short-term chronic (1-6 months), and long-term chronic (>6 months). Biopsy specimens were collected during surgical repair and were used to analyze the gene expression within the different groups and to compare mRNA levels in the proximal and distal tendon ends. A complementary in vitro experiment was performed to evaluate if cells from chronic Achilles tendon ruptures can form tendon constructs.

RESULTS

The mRNA levels for COL1A1 and COL3A1 were significantly higher in the short-term chronic group compared with the acute group (P < .05). Both MMP-1 and MMP-13 had the highest mRNA levels in the acute group (P < .01) compared with the long-term chronic group, while MMP-2 had the highest mRNA level in the short-term chronic group. Significant differences between the proximal and distal tendon ends were only detected for the monocyte and macrophage marker CD163 (P < .05), which was more expressed proximally. Cells extracted from chronic Achilles tendon ruptures displayed a similar ability and effectiveness to form tendon constructs as healthy tendon cells.

CONCLUSION

A high collagenase gene activity after an Achilles tendon rupture indicated possible rapid matrix degradation in the acute phase. Chronic ruptures appeared to initiate the healing process even before treatment, indicated by the higher expression of collagen in the short-term chronic group. Cells from chronic Achilles tendon ruptures also displayed an ability to form new tendon tissue in vitro.

CLINICAL RELEVANCE

The study shows a rapid increase in collagenase gene expression, which could lead to matrix degradation that continues for months after an Achilles tendon rupture.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Anterior Cruciate Ligament Tears and Reconstruction Failure

PURPOSE

To characterize the association between a diagnosis of hypovitaminosis D and primary anterior cruciate ligament (ACL) tear, primary anterior cruciate ligament reconstruction (ACLR), and revision ACLR in different sex and age cohorts.

METHODS

In this retrospective cohort study of the PearlDiver claims database, records were queried between January 1, 2011, and October 31, 2018 for all patients aged 10 to 59 years who received a diagnosis of hypovitaminosis D. Rates of primary ACL tears, primary reconstruction, and revision reconstruction were calculated for sex- and age-specific cohorts and compared with a control of patients without a diagnosis of hypovitaminosis D. Incidence rates for primary ACL injuries were calculated, and multivariable logistic regression was used to compare rates of ACL injury, primary reconstruction, and revision reconstruction while controlling for age, sex, Charlson Comorbidity Index, and several other comorbidities.

RESULTS

Among the 328,011 patients (mean age 41.9 ± 12.6 years, 65.8% female) included in both the hypovitaminosis D and control cohorts, the incidence of ACL tears was 115.2 per 100,000 person-years (95% confidence interval [CI] 107.2-123.7) compared with 61.0 (95% CI 55.2-67.2) in the demographic- and comorbidity-matched control cohort. The study cohort was significantly more likely to suffer an ACL tear over a 1- (aOR 1.67, 95% CI 1.41-1.99, P < .001) and 2-year (aOR 1.81, 95% CI 1.59-2.06, P < .001) period. This trend remained for both male patients at the 1- (aOR 1.66, 95% CI 1.29-2.14, P < .001) and 2-year (aOR 1.68, 95% CI 1.37-2.06, P < .001) mark and female patients at the 1- (aOR 1.69, 95% CI 1.33-2.14, P < .001) and 2-year (aOR 1.80, 95% CI 1.51-2.14, P < .001) mark. Finally, patients with vitamin D deficiency had a significantly increased likelihood of undergoing a revision ACLR within 2 years of a primary reconstruction (aOR 1.28, 95% CI 1.05-1.55, P = .012).

CONCLUSIONS

This study reports an association between patients previously diagnosed with hypovitaminosis D and significantly increased rates of both index ACL tears (81% increase within 2 years of diagnosis) and revision ACLR (28% within 2 years). These results identify a population with increased odds of injury and provide valuable knowledge as we expand our understanding of the relationship between vitamin D and musculoskeletal health.

LEVEL OF EVIDENCE

Level III, retrospective database study.

Momordica charantia Enhances Tendon Healing in Rats: An Experimental Study

Momordica charantia (MC) is a traditional plant widely used since ancient times for wound healing. This study evaluated its potential effects on tendon healing. Adult male Wistar albino rats (n = 32, 8 rats in each group) were anesthetized, and their Achilles tendons were prepared for surgical procedures. Group 1 (Cont = control group) was not subjected to any surgery and was used as a control group for baseline values. Group 2 (PR = primary repair group) underwent primary repair (PR) with a monofilament suture after a full-thickness incision of the Achilles tendon. A full-thickness incision was also made to the Achilles tendon of group 3 (CT = collagen tube-administered group), followed by PR and collagen tube insertion. In group 4 (MC = M. charantia-administered group), 1 mL of MC extract was applied locally on the collagen tube in addition to the surgical procedure applied to group 3. The Achilles tendons were excised on the postoperative 40th day and examined stereologically, histologically, and bioinformatically. Data showed that the total volume of the collagen fibers was higher in MC and CT groups than in the PR group. The total volume of the tendon was decreased in MC and CT groups than in the Cont group. The ratios between the volumes of the collagen fibers and total tendon in the MC and CT groups were significantly different from PR, but not different from the Cont group. Additionally, MC improved tenoblastic activity, collagen production, and neovascularization. Bioinformatic interactions showed that the proteases of MC could trigger the signals playing a role on vasculogenesis, reducing inflammation, and contributing to tenoblast activation and collagen remodeling. MC extract ameliorates the healing of injured tendon and can provide satisfactory tendon repair. Further works are recommended to explore the healing capacity of MC.

Association of Severe Histological Degeneration of the Torn Supraspinatus Tendon and Retear After Arthroscopic Repair of Full-Thickness Rotator Cuff Tears Using the Suture Bridge Technique

BACKGROUND

Previous studies have demonstrated several prognostic factors for retear after arthroscopic rotator cuff repair (ARCR). However, studies that histologically evaluate the quality of the torn rotator cuff (RC) tendon and its association with postoperative outcomes are limited.

PURPOSE

To investigate factors associated with retear after ARCR using the suture bridge (SB) technique, including the degree of histological degeneration of the RC tendon edge.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The authors retrospectively evaluated 187 patients who underwent ARCR for full-thickness tears using the SB technique; intraoperative biopsy samples were taken to assess the degree of histological degeneration using the Bonar score. The cohort was divided into healed (n = 165) and retear (n = 22) groups according to magnetic resonance imaging results obtained ≥6 months postoperatively. The evaluation included preoperative patient data (age, sex, symptom duration, trauma history, history of heavy manual work, smoking habit, hypertension, diabetes mellitus, and hyperlipidemia) and radiological data (Hamada classification, Patte classification, Goutallier classification, and global fatty degeneration index [GFDI]). Additionally, intraoperative data (anteroposterior tear size, Lafosse classification for concomitant subscapularis tendon tear, and long head of biceps injury) and preoperative and postoperative clinical findings (active range of motion, University of California, Los Angeles [UCLA], score) were evaluated.

RESULTS

The retear rate was 11.8%. The retear group had a higher percentage of men (P = .031), higher Bonar score (P < .001), higher mean GFDI value (P = .002), higher rate of tear retraction degree (P = .010), and larger anteroposterior tear size (P = .020) than the healed group. The retear group had lower postoperative internal rotation (P = .031) and lower UCLA score (P < .001). Multivariate logistic regression analysis with a stepwise variable selection revealed anteroposterior tear size (odds ratio [OR], 2.4; 95% CI, 1.3-4.5; P = .004) and Bonar score (OR, 1.7; 95% CI, 1.3-2.4; P < .001) as independent predictors for a retear.

CONCLUSION

The results indicate that end-stage severe tendon degeneration might affect retear. Therefore, further investigation on the progression mechanisms of tendon degeneration and development of methods to assess degenerative tissue might improve clinical outcomes after ARCR.

Exosomes Derived From Kartogenin-Preconditioned Mesenchymal Stem Cells Promote Cartilage Formation and Collagen Maturation for Enthesis Regeneration in a Rat Model of Chronic Rotator Cuff Tear

BACKGROUND

Poor tendon-to-bone healing in chronic rotator cuff tears (RCTs) is related to unsatisfactory outcomes. Exosomes derived from mesenchymal stem cells reportedly enhance rotator cuff healing. However, the difficulty in producing exosomes with a stronger effect on enthesis regeneration must be resolved.

PURPOSE

To study the effect of exosomes derived from kartogenin (KGN)-preconditioned human bone marrow mesenchymal stem cells (KGN-Exos) on tendon-to-bone healing in a rat model of chronic RCT.

STUDY DESIGN

Controlled laboratory study.

METHODS

Exosome-loaded sodium alginate hydrogel (SAH) was prepared. Moreover, exosomes were labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR) or 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (Dil) for in vivo tracking. Bilateral rotator cuff repair (RCR) was conducted in an established chronic RCT rat model. A total of 66 rats were randomized to control, untreated exosome (un-Exos), and KGN-Exos groups to receive local injections of pure SAH, un-Exos, or KGN-Exos SAH at the repaired site. The presence of DiR/Dil-labeled exosomes was assessed at 1 day and 1 week, and tendon-to-bone healing was evaluated histologically, immunohistochemically, and biomechanically at 4 and 8 weeks.

RESULTS

Both un-Exos and KGN-Exos exhibited sustained release from SAH for up to 96 hours. In vivo study revealed that un-Exos and KGN-Exos were localized to the repaired site at 1 week. Moreover, the KGN-Exos group showed a higher histological score and increased glycosaminoglycan and collagen II expression at 4 and 8 weeks. In addition, more mature and better-organized collagen fibers with higher ratios of collagen I to collagen III were observed at 8 weeks in the tendon-to-bone interface compared with those in the control and un-Exos groups. Biomechanically, the KGN-Exos group had the highest failure load (28.12 ± 2.40 N) and stiffness (28.57 ± 2.49 N/mm) among the 3 groups at 8 weeks.

CONCLUSION

Local injection of SAH with sustained KGN-Exos release could effectively promote cartilage formation as well as collagen maturation and organization for enthesis regeneration, contributing to enhanced biomechanical properties after RCR.

CLINICAL RELEVANCE

KGN-Exos injection may be used as a cell-free therapeutic option to accelerate tendon-to-bone healing in chronic RCT.

Tumour necrosis factor alpha, interleukin 1 beta and interferon gamma have detrimental effects on equine tenocytes that cannot be rescued by IL-1RA or mesenchymal stromal cell-derived factors

Tendon injuries occur commonly in both human and equine athletes, and poor tendon regeneration leads to functionally deficient scar tissue and an increased frequency of re-injury. Despite evidence suggesting inadequate resolution of inflammation leads to fibrotic healing, our understanding of the inflammatory pathways implicated in tendinopathy remains poorly understood, meaning successful targeted treatments are lacking. Here, we demonstrate IL-1β, TNFα and IFN-γ work synergistically to induce greater detrimental consequences for equine tenocytes than when used individually. This includes altering tendon associated and matrix metalloproteinase gene expression and impairing the cells' ability to contract a 3-D collagen gel, a culture technique which more closely resembles the in vivo environment. Moreover, these adverse effects cannot be rescued by direct suppression of IL-1β using IL-1RA or factors produced by BM-MSCs. Furthermore, we provide evidence that NF-κB, but not JNK, P38 MAPK or STAT 1, is translocated to the nucleus and able to bind to DNA in tenocytes following TNFα and IL-1β stimulation, suggesting this signalling cascade may be responsible for the adverse downstream consequences of these inflammatory cytokines. We suggest a superior approach for treatment of tendinopathy may therefore be to target specific signalling pathways such as NF-κB.

Mesenchymal Stem Cell Delivery via Topographically Tenoinductive Collagen Biotextile Enhances Regeneration of Segmental Tendon Defects

BACKGROUND

Successful management of massive rotator cuff (RC) tendon tears represents a treatment challenge because of the limited intrinsic healing capacity of native tendons and the risk of repair failure. Biologic augmentation of massive RC tears utilizing scaffolds-capable of regenerating bulk tendon tissue to achieve a mechanically functional repair-represents an area of increasing clinical interest.

PURPOSE

To investigate the histological and biomechanical outcomes after the use of a novel biologic scaffold fabricated from woven electrochemically aligned collagen (ELAC) threads as a suture-holding, fully load-bearing, defect-bridging scaffold with or without mesenchymal stem cells (MSCs) compared with direct repair in the treatment of critically sized RC defects using a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 34 New Zealand White rabbits underwent iatrogenic creation of a critically sized defect (6 mm) in the infraspinatus tendon of 1 shoulder, with the contralateral shoulder utilized as an intact control. Specimens were divided into 4 groups: (1) gap-negative control without repair; (2) direct repair of the infraspinatus tendon-operative control; (3) tendon repair using ELAC; and (4) tendon repair using ELAC + MSCs. Repair outcomes were assessed at 6 months using micro-computed tomography, biomechanical testing, histology, and immunohistochemistry.

RESULTS

Specimens treated with ELAC demonstrated significantly less tendon retraction when compared with the direct repair group specimens (P = .014). ELAC + MSCs possessed comparable biomechanical strength (178 ± 50 N) to intact control shoulders (199 ± 35 N) (P = .554). Histological analyses demonstrated abundant, well-aligned de novo collagen around ELAC threads in both the ELAC and the ELAC + MSC shoulders, with ELAC + MSC specimens demonstrating increased ELAC resorption (7% vs 37%, respectively; P = .002). The presence of extracellular matrix components, collagen type I, and tenomodulin, indicating tendon-like tissue formation, was appreciated in both the ELAC and the ELAC + MSC groups.

CONCLUSION

The application of MSCs to ELAC scaffolds improved biomechanical and histological outcomes when compared with direct repair for the treatment of critically sized defects of the RC in a rabbit model.

CLINICAL RELEVANCE

This study demonstrates the feasibility of repairing segmental tendon defects with a load-bearing, collagen biotextile in an animal model, showing the potential applicability of RC repair supplementation using allogeneic stem cells.

Macroscopic aspects of glenohumeral synovitis are related to rotator cuff tear severity

BACKGROUND

The microscopic pattern of inflammatory mediators associated with rotator cuff pathology is well documented; however, little is known regarding the contemporary presence of macroscopic inflammatory joint involvement. Our aim was to investigate shoulder synovitis in a large group of patients with different sized rotator cuff tears (RCTs) and to correlate the degree of macroscopic inflammatory changes of the glenohumeral joint with RCT severity.

MATERIALS AND METHODS

A total of 296 consecutive patients (169 F, 127 M; mean age ± standard deviation: 60.75 ± 7.91) submitted to arthroscopic RCT repair were enrolled. RCT was classified intraoperatively. Glenohumeral synovitis was investigated according to 4 parameters (Davis classification 2017: capsule color, villous projections, capillaries, and axillary recess). A total score was calculated, and a 3-grade severity scale was introduced. Statistics was performed.

RESULTS

Intraclass correlation coefficient (ICC) results show good to excellent reliability: capsule color (ICC: 0.95; 95% confidence interval [CI]: 0.89-0.99), villous projections (ICC: 0.90; 95% CI: 0.85-0.95), capillaries (ICC: 0.91; 95% CI: 0.86-0.95), and axillary recess (ICC: 0.55; 95% CI: 0.80-0.89).The synovitis total score was found to be 1.47 ± 1.16, 2.86 ± 1.84, and 3.99 ± 1.64 in patients with type I, II, and III RCTs, respectively. A significant difference was found between groups (P < .001). The prevalence of all the examined parameters was found to be significantly different between the different sized RCT groups (capsule color: P < .001; villous projections: P < .001; capillaries: P < .001; and axillary recess: P < .001). According to a 3-grade severity scale, the prevalence of absent, mild, and severe glenohumeral synovitis significantly differed between the RCT severity groups (P < .001).

CONCLUSIONS

The present study demonstrated that synovitis is a constant finding of rotator cuff pathology; it is present in 75% of patients with RCTs and correlates with tear severity. Whether synovitis is the cause or effect of RCT is still questionable. Further studies are also needed to better understand its role as a pain generator, as documented in other diseases.

Relationship of superoxide dismutase to rotator cuff injury/tear in a rat model

Rotator cuff degeneration is one of the several factors that lead to rotator cuff tears. Oxidative stress and superoxide dismutase have been reported to be related to rotator cuff degeneration; however, the precise mechanism still remains unclear. In this study, we investigated the relationship of oxidative stress and superoxide dismutase to the degeneration of the rotator cuff using rat models. Eighty-four rats were used to create a collagenase-induced rotator cuff injury model (injury model) and a rotator cuff tear model (tear model). The controls were administered saline and had only a deltoid incision, respectively. We evaluated degeneration morphology of the rotator cuff using a degeneration score; dihydroethidium fluorescence intensity, which detects oxidative stress; gene expression; and superoxide dismutase activity. The rotator cuffs in the injury and tear models significantly increased degeneration scores and dihydroethidium fluorescence intensity. On the other hand, gene expression of superoxide dismutase isoform, superoxide dismutase 1, and superoxide dismutase activity were significantly decreased in the injury model but showed no significant difference in the tear model. These findings suggested that superoxide dismutase might not be associated with rotator cuff degeneration after tear but may be involved in degenerative rotator cuff without tear. However, we found that rotator cuff degeneration involves oxidative stress both with and without tear. Based on these findings, it is presumed that different treatments may be appropriate, depending on the state of rotator cuff degeneration, because the mechanisms of the degeneration may be different.

Subacromial Bursa: A Neglected Tissue Is Gaining More and More Attention in Clinical and Experimental Research

The subacromial bursa has long been demolded as friction-reducing tissue, which is often linked to shoulder pain and, therefore, partially removed during shoulder surgery. Currently, the discovery of the stem cell potential of resident bursa-derived cells shed a new light on the subacromial bursa. In the meanwhile, this neglected tissue is gaining more attention as to how it can augment the regenerative properties of adjacent tissues such as rotator cuff tendons. Specifically, the tight fibrovascular network, a high growth factor content, and the large progenitor potential of bursa-derived cells could complement the deficits that a nearby rotator cuff injury might experience due to the fact of its low endogenous regeneration potential. This review deals with the question of whether bursal inflammation is only a pain generator or could also be an initiator of healing. Furthermore, several experimental models highlight potential therapeutic targets to overcome bursal inflammation and, thus, pain. More evidence is needed to fully elucidate a direct interplay between subacromial bursa and rotator cuff tendons. Increasing attention to tendon repair will help to guide future research and answer open questions such that novel treatment strategies could harvest the subacromial bursa's potential to support healing of nearby rotator cuff injuries.

Distinct Gene Expression Profile in Patients With Poor Postoperative Outcomes After Rotator Cuff Repair: A Case-Control Study

BACKGROUND

Impaired healing after rotator cuff repair is a major concern, with retear rates as high as 94%. A method to predict whether patients are likely to experience poor surgical outcomes would change clinical practice. While various patient factors, such as age and tear size, have been linked to poor functional outcomes, it is currently very challenging to predict outcomes before surgery.

PURPOSE

To evaluate gene expression differences in tissue collected during surgery between patients who ultimately went on to have good outcomes and those who experienced a retear, in an effort to determine if surgical outcomes can be predicted.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Rotator cuff tissue was collected at the time of surgery from 140 patients. Patients were tracked for a minimum of 6 months to identify those with good or poor outcomes, using clinical functional scores and follow-up magnetic resonance imaging to confirm failure to heal or retear. Gene expression differences between 8 patients with poor outcomes and 28 patients with good outcomes were assessed using a multiplex gene expression analysis via NanoString and a custom-curated panel of 145 genes related to various stages of rotator cuff healing.

RESULTS

Although significant differences in the expression of individual genes were not observed, gene set enrichment analysis highlighted major differences in gene sets. Patients who had poor healing outcomes showed greater expression of gene sets related to extracellular matrix production (P < .0001) and cellular biosynthetic pathways (P < .001), while patients who had good healing outcomes showed greater expression of genes associated with the proinflammatory (M1) macrophage phenotype (P < .05).

CONCLUSION

These results suggest that a more proinflammatory, fibrotic environment before repair may play a role in poor healing outcome. With validation in a larger cohort, these results may ultimately lead to diagnostic methods to preoperatively predict those at risk for poor surgical outcomes.

The Relationship of Staged, Bilateral Arthroscopic Primary Rotator Cuff Repair Timing and Postoperative Complications

BACKGROUND

Although previous studies have reported acceptable clinical outcomes after simultaneous, single-stage bilateral and staged bilateral rotator cuff repair (RCR), few studies have been adequately powered to compare postoperative complication rates at various time intervals between procedures.

PURPOSE

To examine the relationship between the timing of bilateral arthroscopic RCR and complications.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Patients from the Medicare data set within the PearlDiver database who underwent bilateral RCR between 2005 and 2014 were identified. These patients were then stratified by time between surgeries into cohorts: (1) single stage, (2) <3 months, (3) 3 to 6 months, (4) 6 to 9 months, (5) 9 months to 1 year, and (6) 1 to 2 years. Surgical and medical complications of these cohorts were compared with those of a control cohort of patients who underwent bilateral RCR >2 years apart using a regression analysis.

RESULTS

A total of 11,079 patients who underwent bilateral RCR were identified. Patients who underwent single-stage bilateral arthroscopic RCR experienced higher rates of revision RCR (odds ratio [OR], 2.1; P < .0001), reverse total shoulder arthroplasty (RTSA) (OR, 2.47; P < .0001), and postoperative infection (OR, 2.18; P = .007) in addition to higher rates of venous thromboembolism (VTE) (OR, 1.78; P = .031) and emergency department visits (OR, 1.51; P = .002) compared with the control group. Patients who underwent bilateral RCR with a <3-month interval had higher rates of revision surgery (OR, 1.56; P = .003), RTSA (OR, 1.89; P = .002), and lysis of adhesions (OR, 2.31; P < .0001) in addition to increased rates of VTE (OR, 1.92; P = .015) and emergency department visits (OR, 1.62; P < .0001) compared with the control group. There were no differences in any surgical or medical complications when surgeries were staged by ≥3 months compared with controls.

CONCLUSION

Patients with Medicare undergoing single-stage and staged bilateral RCR who had the second repair within 3 months had significantly higher rates of multiple medical and surgical complications compared with patients waiting >2 years between procedures.

Known data on applied regenerative medicine in tendon healing

Tendons and ligaments are important structures in the musculoskeletal system. Ligaments connect various bones and provide stability in complex movements of joints in the knee. Tendon is made of dense connective tissue and transmits the force of contraction from muscle to bone. They are injured due to direct trauma in sports or roadside accidents. Tendon healing after repair is often poor due to the formation of fibro vascular scar tissues with low mechanical property. Regenerative techniques such as PRP (platelet-rich plasma), stem cells, scaffolds, gene therapy, cell sheets, and scaffolds help augment repair and regenerate tissue in this context. Therefore, it is of interest to document known data (repair process, tissue regeneration, mechanical strength, and clinical outcome) on applied regenerative medicine in tendon healing.

Mitochondrial Transplantation Modulates Inflammation and Apoptosis, Alleviating Tendinopathy Both In Vivo and In Vitro

Tendinopathy is a common musculoskeletal condition causing pain and dysfunction. Conventional treatment and surgical procedures for tendinopathy are insufficient; accordingly, recent research has focused on tendon-healing regenerative approaches. Tendon injuries usually occur in the hypoxic critical zone, characterized by increased oxidative stress and mitochondrial dysfunction; thus, exogenous intact mitochondria may be therapeutic. We aimed to assess whether mitochondrial transplantation could induce anti-inflammatory activity and modulate the metabolic state of a tendinopathy model. Exogenous mitochondria were successfully delivered into damaged tenocytes by centrifugation. Levels of Tenomodulin and Collagen I in damaged tenocytes were restored with reductions in nuclear factor-κB and matrix metalloproteinase 1. The dysregulation of oxidative stress and mitochondrial membrane potential was attenuated by mitochondrial transplantation. Activated mitochondrial fission markers, such as fission 1 and dynamin-related protein 1, were dose-dependently downregulated. Apoptosis signaling pathway proteins were restored to the pre-damage levels. Similar changes were observed in a collagenase injection-induced rat model of tendinopathy. Exogenous mitochondria incorporated into the Achilles tendon reduced inflammatory and fission marker levels. Notably, collagen production was restored. Our results demonstrate the therapeutic effects of direct mitochondrial transplantation in tendinopathy. These effects may be explained by alterations in anti-inflammatory and apoptotic processes via changes in mitochondrial dynamics.

Synergistic enhancement of tendon-to-bone healing via anti-inflammatory and pro-differentiation effects caused by sustained release of Mg2+/curcumin from injectable self-healing hydrogels

Poor healing response after rotator cuff reconstruction is multifactorial, with the inflammatory microenvironment and deficiency of stem cell differentiation factors at the lesion site being most relevant. However, there is a lack of effective tissue engineering strategies that can simultaneously exert anti-inflammatory and pro-differentiation effects to promote rotator cuff healing.

Methods: In this study, we synthesized and characterized a novel active drug delivery vector that successfully overcame the challenge of simultaneous high-efficiency loading and controlled release of Mg²⁺ and curcumin. The anti-inflammatory and pro-differentiation effects of the composite hydrogel were evaluated in vitro and in vivo. Moreover, healing of the rotator cuff tendon-to-bone interface was studied by histology, immunofluorescence, and biomechanical tests.

Results: The composite hydrogel exhibited excellent biocompatibility and injectability, good adhesiveness, and rapid self-healing. The released curcumin showed obvious anti-inflammatory and antioxidation effects, which protected stem cells and tendon matrix. Furthermore, released Mg²⁺ promoted stem cell aggregation and chondrogenesis. Moreover, biomechanical tests and histological results of a rat rotator cuff tear model at 8 weeks after surgery indicated that the composite hydrogel significantly enhanced tendon-to-bone healing.

Conclusions: The composite hydrogel mediated sustained in situ release of curcumin and Mg²⁺ to effectively promote rotator cuff tendon-to-bone healing via anti-inflammatory and pro-differentiation effects. Therefore, this composite hydrogel offers significant promise for rotator cuff repair.

Vitamin D deficiency and total shoulder arthroplasty complications

INTRODUCTION

The primary objective of this study was to examine the relationship between vitamin D deficiency and implant-related and medical complications following total shoulder arthroplasty.

METHODS

Using the PearlDiver database, patients who underwent total shoulder arthroplasty from 2005 to 2016 with vitamin D deficiency were identified. These were compared to a 3:1 control group matched by age, sex, and presence of a concomitant osteoporosis diagnosis. Primary outcome measures were implant-related complications (loosening, periprosthetic fracture, periprosthetic joint infection, and revision total shoulder arthroplasty) in addition to medical complications within 90 days of surgery. A multivariable logistic regression analysis was utilized to control for patient demographics and comorbidities.

RESULTS

One thousand and six hundred and seventy-four patients with vitamin D deficiency were identified and compared to 5022 controls. There was a significantly higher rate of revision total shoulder arthroplasty in the vitamin D deficient patients compared to controls (2.3% versus 0.8%, odds ratio 3.3, p < 0.0001). After controlling for confounding variables, there were no significant differences in any of the remaining implant-related or medical complications with the exception of higher rates of urinary tract infections in patients with vitamin D deficiency.

CONCLUSIONS

Vitamin D deficiency is associated with a higher rate of all-cause revision total shoulder arthroplasty but not medical complications compared to controls.Level of evidence: Level III case control study.

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

METHODS

A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

RESULTS

The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

CONCLUSION

This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.

Vitamin D and the athlete-patient: state of the art

Vitamin D deficiency is common in athletes. The conventional measurement of vitamin D levels provides a general indicator of body stores. However, there are nuances in its interpretation as values of 25(OH)D do not correlate absolutely with the amount of 'bioavailable' vitamin to the cells. Vitamin D should be regarded as a hormone and influences between 5% and 10% of our total genome. Determining the precise effect of the vitamin, isolated from the actions of other cofactors, is not straightforward and restricts our complete understanding of all of its actions. Deficiency has harmful effects on not only bone and muscle but also wider areas, including immunity and respiratory and neurological activities. More caution should be applied regarding the ability of supranormal vitamin D levels to elevate athletic performance. Hopefully, future research will shed more light on optimal levels of vitamin D and supplementation regimes, and improved understanding of its intracellular control of our genetic mechanisms and how extrinsic influences modify its activity.

Genetic Aspects in Shoulder Disorders

The influence of genetic inheritance has been increasingly investigated in shoulder disorders, such as rotator cuff injury, instability and frozen shoulder. Although the initial findings are enlightening, it is necessary to progressively build a database of genetic markers to catalog genomic profiles that, later, may contribute for predicting the risk of the disease, as well as to the development of better diagnostic and treatment tools. The present article seeks to update what is evidence of genetic studies in the literature for these diseases, from polymorphism analyses, expression of candidate genes in tissues and broad genomic association studies (GWAS). However, it is necessary to point out that there is great difficulty in replicating and using the findings, mainly due to the lack of statistical power, the high rate of false-positive results and the large number of variables involved.

Role of matrix metalloproteases 1/3 gene polymorphisms in patients with rotator cuff tear

An association of Matrix Metalloproteinases-1/3 (MMP-1/3) rs1799750/rs3025058 polymorphism with increased risk of rotator cuff tear (RCT) has been reported in a Brazilian population. However, this significant association has not been confirmed in the Chinese population. Genotyping was conducted by polymerase chain reaction (PCR)-restriction fragment length polymorphism and direct sequencing. Our results demonstrated that individuals with the TT genotype had a significantly higher risk of RCT compared with those with the CC genotype. The increased risk of RCT progression was associated with the 2G allele of the rs1799750 polymorphism. No significant association was observed for genotypic and allelic frequencies of the rs3025058 polymorphism. A significant association of the MMP-1 rs1799750 polymorphism was observed with smokers, drinkers and people aged ≥60 years and non-diabetic people. Additionally, the MMP-1 rs1799750 polymorphism was associated with pre-operative stiffness in RCT patients. In conclusion, a significant correlation was identified between the MMP-1 rs1799750 polymorphism and RCT. The MMP-1 rs1799750 polymorphism might be considered as a biomarker of genetically high-risk RCT, helping to clarify the mechanism of RCT.

Effectiveness of Amniotic Fluid Injection in the Treatment of Trigger Finger: A Pilot Study

Purpose

To assess the efficacy and safety of amniotic fluid therapy injections in patients with mild to moderate trigger finger.

Methods

All participants received 1 mL of amniotic fluid injected into the tendon sheath of the affected tendon. Pretreatment and posttreatment data were collected for triggering frequency, Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores, and numerical pain rating scale scores.

Results

Of 111 digits from 96 patients, 51% experienced clinically notable improvement and did not receive an alternative treatment. Average length of follow-up was 11 months. From baseline to end of follow-up, average pain score (0–10) decreased from 5.19 to 1.19 (P < .001), median triggering per day decreased from 5 to 0 (P < .001), and median DASH score (1–100) decreased from 20 to 6.03 (P < .001). There was a 50% success rate in patients with diabetes and a 52.6% success rate in digits diagnosed with concomitant Dupuytren contracture in the same hand.

Conclusions

Amniotic fluid therapy injections may offer a biologic alternative for conservative treatment of trigger finger, particularly for patients with diabetes. Decreased pain, decreased triggering, and improved DASH scores offer preliminary evidence supporting the use of amniotic injections for stenosing tenosynovitis.

Type of study/level of evidence

Therapeutic IV.

[Circular RNA expression pattern and competing endogenous RNA network involved in rotator cuff tendinopathy]

Objective

To detect the differentially expressed circular RNA (circRNA) in rotator cuff tendinopathy and analyze the potential molecular mechanism of these parental genes.

Methods

Ten supraspinatus tendons donated from patients who underwent tendon repair surgery between June 2018 and June 2019 were used for RNA-sequence. All rotator cuff tendinopathy and normal tendon samples were confirmed by MRI, histological staining, and observation by arthroscopy. All pathological tendons were matched with tendon samples for patients' age, gender, body mass index, and Bonar score. The bioinformatic analysis was performed based on the differentially expressed circRNA and their parental genes, including gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and competing endogenous RNA (ceRNA) network construction.

Results

There were 94 differentially expressed circRNAs, including 31 up-regulated and 63 down-regulated, detected between the rotator cuff tendinopathy and normal tendon samples with |log2 fold change (FC)| >2, P<0.05. GO analysis showed that the genes were mostly enriched in response to cyclic adenosine monophosphate (cAMP). KEGG pathway analysis showed that the most genes were enriched in extracellular matrix-receptor interaction, protein digestion and absorption, cell cycle, and nuclear factor κB signaling pathway. ceRNA networks showed the interactions among circRNAs, mRNAs, and miRNAs. And circRNA.8951-has-miR-6089-DNMT3B was the most sum max energy.

Conclusion

This bioinformatic study reveals several potential therapeutic targets for rotator cuff tendinopathy, which paves the way to better treatment and prevention of this disorder.

The role of the immune system in tendon healing: a systematic review

INTRODUCTION

The role of the immune system in tendon healing relies on polymorphonucleocytes, mast cells, macrophages and lymphocytes, the 'immune cells' and their cytokine production. This systematic review reports how the immune system affects tendon healing.

SOURCES OF DATA

We registered our protocol (registration number: CRD42019141838). After searching PubMed, Embase and Cochrane Library databases, we included studies of any level of evidence published in peer-reviewed journals reporting clinical or preclinical results. The PRISMA guidelines were applied, and risk of bias and the methodological quality of the included studies were assessed. We excluded all the articles with high risk of bias and/or low quality after the assessment. We included 62 articles assessed as medium or high quality.

AREAS OF AGREEMENT

Macrophages are major actors in the promotion of proper wound healing as well as the resolution of inflammation in response to pathogenic challenge or tissue damage. The immune cells secrete cytokines involving both pro-inflammatory and anti-inflammatory factors which could affect both healing and macrophage polarization.

AREAS OF CONTROVERSY

The role of lymphocytes, mast cells and polymorphonucleocytes is still inconclusive.

GROWING POINTS

The immune system is a major actor in the complex mechanism behind the healing response occurring in tendons after an injury. A dysregulation of the immune response can ultimately lead to a failed healing response.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further studies are needed to shed light on therapeutic targets to improve tendon healing and in managing new way to balance immune response.

Adipose Stem Cell-Derived Exosomes Decrease Fatty Infiltration and Enhance Rotator Cuff Healing in a Rabbit Model of Chronic Tears

BACKGROUND

Fatty infiltration and poor tendon-bone healing in chronic rotator cuff tears (RCTs) are associated with unsatisfactory prognosis. Adipose stem cell-derived exosomes (ASC-Exos), having multiple biological effects, can prevent muscle degeneration in acute RCTs. However, the effects of ASC-Exos on fatty infiltration and tendon-bone healing in chronic RCTs remain unknown.

PURPOSE

To study the effects of ASC-Exos on fatty infiltration and tendon-bone healing in a chronic RCT rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

At week 0, we randomly allocated 35 rabbits to receive sham surgery (14 rabbits) or establish a bilateral RCT model (21 rabbits, detachment of the supraspinatus tendon). At week 6, a total of 7 rabbits received sham surgery, and 7 rabbits with RCT were sacrificed for fatty infiltration assay. The remaining 14 rabbits with bilateral RCTs were randomly assigned to a saline group (7 rabbits that received local saline injection and rotator cuff repair) or an ASC-Exos group (7 rabbits that received local ASC-Exos injection and rotator cuff repair). At week 18, all rabbits were sacrificed for histological examination and biomechanical testing.

RESULTS

At week 18, the ASC-Exos group showed significantly lower fatty infiltration (14.01% ± 2.85%) compared with the saline group (21.79% ± 3.07%) (P < .001), and no statistical difference compared with the time of repair (10.88% ± 2.64%) (P = .127). For tendon-bone healing, the ASC-Exos group showed a higher histological score and more newly regenerated fibrocartilage at the repair site than did the saline group. Regarding biomechanical testing, the ASC-Exos group showed significantly higher ultimate load to failure, stiffness, and stress than the saline group.

CONCLUSION

Local injection of ASC-Exos in chronic RCTs at the time of repair could prevent the progress of fatty infiltration, promote tendon-bone healing, and improve biomechanical properties.

CLINICAL RELEVANCE

ASC-Exos injection may be used as a cell-free adjunctive therapy to inhibit fatty infiltration and improve rotator cuff healing in the repair of chronic RCTs.

A systematic review of inflammatory cells and markers in human tendinopathy

BACKGROUND

This article systematically reviews the current evidence regarding inflammation in Tendinopathy with the aim to increase understanding of a potential common pathophysiology.

METHODS

Following the PRISMA statements, the terms: (tendinopathy OR (tendons AND rupture)) AND (inflammation OR (inflammation AND cells) OR immune system OR inflammation mediators OR bacteria) were used. One thousand four hundred thirty-one articles were identified which was screened down to 53.

RESULTS

39/53 studies mentioned inflammatory cells but had contradicting conclusions. Macrophages were the most common cell type and inflammatory markers were detectable in all the articles which measure them.

CONCLUSIONS

The included studies show different conclusions, but this heterogeneity is not unexpected since the clinical criteria of 'tendinopathy' encompass a huge clinical spectrum. Different 'tendinopathy' conditions may have different pathophysiology, and even the same clinical condition may be at different disease stages during sampling, which can alter the histological and biochemical picture. Control specimen sampling was suboptimal since the healthy areas of the pathological-tendon may actually be sub-clinically diseased, as could the contralateral tendon in the same subject. Detection of inflammatory cells is most sensitive using immunohistochemistry targeting the cluster of differentiation markers, especially when compared to the conventional haematoxylin and eosin staining methods. The identified inflammatory cell types favour a chronic inflammatory process; which suggests a persistent stimulus. This means NSAID and glucocorticoids may be useful since they suppress inflammation, but it is noted that they may hinder tendon healing and cause long term problems. This systematic review demonstrates a diversity of data and conclusions in regard to inflammation as part of the pathogenesis of Tendinopathy, ranging from ongoing or chronic inflammation to non-inflammatory degeneration and chronic infection. Whilst various inflammatory markers are present in two thirds of the reviewed articles, the heterogenicity of data and lack of comparable studies means we cannot conclude a common pathophysiology from this systematic review.

Tendon healing in presence of chronic low-level inflammation: a systematic review

BACKGROUND

Tendinopathy is a common musculoskeletal condition affecting subjects regardless of their activity level. Multiple inflammatory molecules found in ex vivo samples of human tendons are related to the initiation or progression of tendinopathy. Their role in tendon healing is the subject of this review.

SOURCES OF DATA

An extensive review of current literature was conducted using PubMed, Embase and Cochrane Library using the term 'tendon', as well as some common terms of tendon conditions such as 'tendon injury OR (tendon damage) OR tendonitis OR tendinopathy OR (chronic tendonitis) OR tendinosis OR (chronic tendinopathy) OR enthesitis' AND 'healing' AND '(inflammation OR immune response)' as either key words or MeSH terms.

AREAS OF AGREEMENT

An environment characterized by a low level of chronic inflammation, together with increased expression of inflammatory cytokines and growth factors, may influence the physiological tendon healing response after treatment.

AREAS OF CONTROVERSY

Most studies on this topic exhibited limited scientific translational value because of their heterogeneity. The evidence associated with preclinical studies is limited.

GROWING POINTS

The role of inflammation in tendon healing is still unclear, though it seems to affect the overall outcome. A thorough understanding of the biochemical mediators of healing and their pathway of pain could be used to target tendinopathy and possibly guide its management.

AREAS TIMELY FOR DEVELOPING RESEARCH

We require further studies with improved designs to effectively evaluate the pathogenesis and progression of tendinopathy to identify cellular and molecular targets to improve outcomes.

Tendinopathy: Investigating the Intersection of Clinical and Animal Research to Identify Progress and Hurdles in the Field

Biological treatments, surgical interventions, and rehabilitation exercises have been successfully used to treat tendinopathy, but the development of effective treatments has been hindered by the lack of mechanistic data regarding the pathogenesis of the disease. While insightful, clinical studies are limited in their capacity to provide data regarding the pathogenesis of tendinopathies, emphasizing the value of animal models and cell culture studies to fill this essential gap in knowledge. Clinical pathological findings from imaging studies or histological analysis are not universal across patients with tendinopathy and have not been clearly associated with the onset of symptoms. There are several unresolved controversies, including the cellular changes that accompany the tendinopathic disease state and the role of inflammation. Additional research is needed to correlate the manifestations of the disease with its pathogenesis, with the goal of reaching a field-wide consensus on the pathology of the disease state. Such a consensus will allow standardized clinical practices to more effectively diagnose and treat tendinopathy.

Changes in the expression of matrix extracellular genes and TGFB family members in rotator cuff tears

Lack of synthesis of extracellular matrix compounds may contribute to degeneration of the tendons. Thus, we aimed to evaluate the expression of extracellular matrix and TGFB family members in ruptured and non-ruptured tendons of the rotator cuff, as well as the effect of clinical factors on gene expression in tendon samples, and the relationship between histological findings and altered gene expression. Injured and non-injured supraspinatus tendon samples and subscapular non-injured tendon samples were collected from 38 patients with rotator cuff tears. Non-injured supraspinatus tendons were obtained from eight controls. Specimens were used for histological evaluation, quantification of collagen fibers, and mRNA and protein expression analyses. Increased COL1A1, COL1A2, COL3A1, COL5A1, FN1, TNC, and TGFBR1 mRNA expression was observed in the tear samples (p < 0.05). Duration of symptoms was correlated with the levels of collagen type I/III fibers (p = 0.032; ρ = 0.0447) and FN1 immunostaining (p = 0.031; ρ = 0.417). Smoking was associated with increased frequency of microcysts, myxoid degeneration, and COL5A1, FN1, TNC, and TGFB1 mRNA expression (p < 0.05). FN1 immunostaining was correlated with the number of years of smoking (p = 0.048; ρ = 0.384). Lower levels of collagen type I/III fibers were detected in samples with fissures (0 = 0.046). High frequency of microcysts was associated with increased COL5A1, FN1, and TNC expression (p < 0.05, for all comparisons). Neovascularization was associated with reduced FN1 (p = 0.035) and TGFBR1 expression (p = 0.034). Our findings show differential expression of matrix extracellular genes and TGFB family members in the degeneration process involved in rotator cuff tears. These molecular alterations are influenced by clinical factors. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2542-2553, 2018.

Enthesis Repair: Challenges and Opportunities for Effective Tendon-to-Bone Healing

On May 22, 2017, the National Institutes of Health (NIH)/National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) hosted a roundtable on "Innovative Treatments for Enthesis Repair." A summary of the roundtable discussion, as well as a list of the extramural participants, can be found at https://www.niams.nih.gov/about/meetings-events/roundtables/roundtable-innovative-treatments-enthesis-repair. This paper reviews the challenges and opportunities for developing effective treatment strategies for enthesis repair that were identified at the roundtable discussion.

Sustained Delivery of Transforming Growth Factor β1 by Use of Absorbable Alginate Scaffold Enhances Rotator Cuff Healing in a Rabbit Model

BACKGROUND

The failure rate for healing after rotator cuff repair is relatively high.

PURPOSE

To establish a system for sustained release of transforming growth factor β1 (TGF-β1) using an alginate scaffold and evaluate the effects of the sustained release of TGF-β1 on rotator cuff healing in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Before the in vivo animal study, a standard MTS assay was performed to evaluate cell proliferation and metabolic activity on the alginate scaffold. Additionally, an enzyme-linked immunosorbent assay was performed to confirm the capacity of the sustained release of TGF-β1-containing alginate scaffold. Once the in vitro studies were completed, bilateral supraspinatus tendon repairs were performed in 48 rabbits that were allocated to 3 groups (n = 16 each) (group 1, supraspinatus repair only; group 2, supraspinatus repair with TGF-β1 single injection; group 3, supraspinatus repair with TGF-β1 sustained release via an alginate-based delivery system). Biomechanical and histological analyses were performed to evaluate the quality of tendon-to-bone healing at 12 weeks after rotator cuff repair.

RESULTS

The cell proliferation rate of the alginate scaffold was 122.30% compared with the control (fresh medium) group, which confirmed that the alginate sheet had no cytotoxicity and enhanced cell proliferation. Additionally, the level of TGF-β1 was found to increase with time on the alginate scaffold. Biomechanically, group 3 exhibited a significantly heightened ultimate failure load compared with groups 1 and 2 (group 1, 74.89 ± 29.82 N; group 2, 80.02 ± 34.42 N; group 3, 108.32 ± 32.48 N; P = .011) and more prevalent midsubstance tear compared with group 1 ( P = .028). However, no statistical differences were found in the cross-sectional area of the supraspinatus tendon (group 1, 32.74 ± 9.38; group 2, 33.76 ± 8.89; group 3, 34.80 ± 14.52; P = .882) and ultimate stress (group 1, 2.62 ± 1.13 MPa; group 2, 2.99 ± 1.81 MPa; group 3, 3.62 ± 2.24 MPa; P = .317). Histologically, group 3 exhibited a significantly heightened modified total Bonar score (group 1, 5.00 ± 1.54; group 2, 6.12 ± 1.85; group 3, 7.50 ± 1.31; P = .001). In addition, the tendon-to-bone interface for group 3 demonstrated better collagen orientation, continuity, and organization, and the area of new fibrocartilage formation was more evident in group 3.

CONCLUSION

At 12 weeks after rotator cuff repair, the authors found improved biomechanical and histological outcomes for sustained release of TGF-β1 using alginate scaffold in a rabbit model.

CLINICAL RELEVANCE

The alginate-bound growth factor delivery system might improve healing after rotator cuff repair in humans.

Increasing age and tear size reduce rotator cuff repair healing rate at 1 year

Background and purpose - There is a need to understand the reasons why a high proportion of rotator cuff repairs fail to heal. Using data from a large randomized clinical trial, we evaluated age and tear size as risk factors for failure of rotator cuff repair. Patients and methods - Between 2007 and 2014, 65 surgeons from 47 hospitals in the National Health Service (NHS) recruited 447 patients with atraumatic rotator cuff tendon tears to the United Kingdom Rotator Cuff Trial (UKUFF) and 256 underwent rotator cuff repair. Cuff integrity was assessed by imaging in 217 patients, at 12 months post-operation. Logistic regression analysis was used to determine the influence of age and intra-operative tear size on healing. Hand dominance, sex, and previous steroid injections were controlled for. Results - The overall healing rate was 122/217 (56%) at 12 months. Healing rate decreased with increasing tear size (small tears 66%, medium tears 68%, large tears 47%, and massive tears 27% healed). The mean age of patients with a healed repair was 61 years compared with 64 years for those with a non-healed repair. Mean age increased with larger tear sizes (small tears 59 years, medium tears 62 years, large tears 64 years, and massive tears 66 years). Increasing age was an independent factor that negatively influenced healing, even after controlling for tear size. Only massive tears were an independent predictor of non-healing, after controlling for age. Interpretation - Although increasing age and larger tear size are both risks for failure of rotator cuff repair healing, age is the dominant risk factor.

Differences of RNA Expression in the Tendon According to Anatomic Outcomes in Rotator Cuff Repair

BACKGROUND

Despite increased understanding of the pathophysiology of rotator cuff tears and the evolution of rotator cuff repair, healing failure remains a substantial problem. The critical roles played by biological factors have been emphasized, but little is known of the implications of gene expression profile differences at the time of repair.

PURPOSE

To document the relationship between the perioperative gene expression of healed and unhealed rotator cuffs by RNA microarray analysis.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Superior (supraspinatus involvement) and posterosuperior (supraspinatus and infraspinatus involvement) tears were included in the study. Samples of rotator cuff tendons were prospectively collected during rotator cuff surgery. Three samples were harvested at the tendon ends of tears from the anterior, middle (apex), and posterior parts using an arthroscopic punch. Seven patients with an unhealed rotator cuff were matched one-to-one with patients with a healed rotator cuff by sex, age, tear size, and fatty degeneration of rotator cuff muscles. mRNA microarray analysis was used to identify genetic differences between healed and unhealed rotator cuff tendons. Gene ontology and gene association files were obtained from the Gene Ontology Consortium, and the Gene Ontology system in DAVID was used to identify enhanced biological processes.

RESULTS

Microarray analyses identified 262 genes that were differentially expressed by at least 1.5-fold between the healed and unhealed groups. Overall, in the healed group, 103 genes were significantly downregulated, and 159 were significantly upregulated. DAVID Functional Annotation Cluster analysis showed that in the healed group, the genes most upregulated were related to the G protein-coupled receptor protein signaling pathway and to the neurological system. On the other hand, the genes most downregulated were related to immune and inflammatory responses. BMP5 was the gene most upregulated in the healed group, and the majority of downregulated genes were involved in the immune/inflammatory response.

CONCLUSION

The downregulation of inflammatory response genes and the upregulation of cell differentiation genes in torn rotator cuffs at the time of surgery are related to rotator cuff healing. These results provide useful baseline information for future biological studies on rotator cuff healing.

Novel Tenascin-C Haplotype Modifies the Risk for a Failure to Heal After Rotator Cuff Repair

BACKGROUND

Several single-nucleotide polymorphisms (SNPs) in the TNC gene have recently been found to be associated with degenerative rotator cuff tears.

HYPOTHESIS

Exonic SNPs in the TNC gene are related to the risk for a failure to heal after rotator cuff repair.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 302 patients from the Vienna area and European Caucasian ancestry underwent mini-open rotator cuff repair for a full-thickness superior or posterosuperior tear and were assessed for the integrity of the repair 1 year postoperatively with a real-time 7.5- to 10-MHz ultrasound linear array transducer. Outcomes were classified as intact (complete footprint coverage), small (<200 mm²), or large (≥200 mm²) recurrent defect. Patients were genotyped for 15 previously identified risk SNPs within a 49-kbp segment of the TNC gene with the KASP genotyping technology or the Ion-Torrent Personal Genome Machine System.

RESULTS

All recurrent defects were atraumatic failures, and the overall failure rate was 39.7%. Of the traditional risk factors, only the initial tear size was significantly associated with a failure to heal. In a multinomial logistic regression model, the T allele at rs1138545 [C>T] was protective for a large recurrent defect (odds ratio = 0.16; 95% CI, 0.09-0.31). The role of rs1138545 was further backed by haplotype analysis, which showed that the combination of the C allele at rs1138545 [C>T], the A allele at rs2104772 [A>T], and the G allele at rs10759752 [A>G] formed the risk-related haplotype [CAG]. The CAG haplotype was associated with large recurrent defects ( P < .0001; haplotype frequency, 0.394; haplotype score, 4.518). Exonic marker rs1138545 transcribed into all isoforms of the TNC protein, whereas exonic marker rs2104772, which has been associated with Achilles tendinopathy before, transcribed only into large isoforms of the TNC protein.

CONCLUSION

Recurrent defects after rotator cuff repairs are clinically relevant, and a heritable component of the disorder is plausible on the basis of a genetic association with 8 TNC variants. Characterization of TNC sequences that favor tendon healing will help engineer new products in regenerative medicine.

Time-Dependent Alterations of MMPs, TIMPs and Tendon Structure in Human Achilles Tendons after Acute Rupture

A balance between matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) is required to maintain tendon homeostasis. Variation in this balance over time might impact on the success of tendon healing. This study aimed to analyze structural changes and the expression profile of MMPs and TIMPs in human Achilles tendons at different time-points after rupture. Biopsies from 37 patients with acute Achilles tendon rupture were taken at surgery and grouped according to time after rupture: early (2–4 days), middle (5–6 days), and late (≥7 days), and intact Achilles tendons served as control. The histological score increased from the early to the late time-point after rupture, indicating the progression towards a more degenerative status. In comparison to intact tendons, qRT-PCR analysis revealed a significantly increased expression of MMP-1, -2, -13, TIMP-1, COL1A1, and COL3A1 in ruptured tendons, whereas TIMP-3 decreased. Comparing the changes over time post rupture, the expression of MMP-9, -13, and COL1A1 significantly increased, whereas MMP-3 and -10 expression decreased. TIMP expression was not significantly altered over time. MMP staining by immunohistochemistry was positive in the ruptured tendons exemplarily analyzed from early and late time-points. The study demonstrates a pivotal contribution of all investigated MMPs and TIMP-1, but a minor role of TIMP-2, -3, and -4, in the early human tendon healing process.

Early postoperative fluoroquinolone use is associated with an increased revision rate after arthroscopic rotator cuff repair

PURPOSE

To evaluate the association of postoperative fluoroquinolone use following arthroscopic primary rotator cuff repair with failure requiring revision rotator cuff repair.

METHODS

An insurance database was queried for patients undergoing rotator cuff repair from 2007 to 2015. These patients were divided into three groups: (1) patients prescribed fluoroquinolones within 6 months postoperatively (divided into 0-2, 2-4, and 4-6 months), (2) a matched negative control cohort of patients not prescribed fluoroquinolones, and (3) a matched positive control cohort of patients prescribed fluoroquinolones between 6 and 18 months following rotator cuff repair. Rates of failure requiring revision rotator cuff repair were compared within 2 years.

RESULTS

A total of 1292 patients were prescribed fluoroquinolones within 6 months after rotator cuff repair, including 442 within 2 months, 433 within 2 to 4 months, and 417 within 4 to 6 months, and were compared to 5225 matched negative controls and 1597 matched positive controls. The rate of revision rotator cuff repair was significantly higher in patients prescribed fluoroquinolones within 2 months (6.1 %) compared to matched negative (2.2 %, P = 0.0009) and positive controls (2.4 %, P = 0.0026). There were no significant differences in the rate of revision rotator cuff repair when fluoroquinolones were prescribed >2 months after rotator cuff repair.

CONCLUSIONS

Early use of fluoroquinolones following rotator cuff repair was independently associated with significantly increased rates of failure requiring revision rotator cuff repair. This is the first clinical study examining the association of postoperative fluoroquinolone use with failure following arthroscopic rotator cuff repair.

LEVEL OF EVIDENCE

III.

Altered Gene and Protein Expressions in Torn Rotator Cuff Tendon Tissues in Diabetic Patients

PURPOSE

To analyze and compare the gene and protein expression characteristics in torn rotator cuff tendon tissues between diabetic and nondiabetic patients.

METHODS

This was a pilot study. Twelve samples of rotator cuff tendon tissue from diabetic patients (mean age, 62.3 ± 9.9 years) and 12 age- and sex-matched nondiabetic tendon tissues (62.3 ± 9.9 years) were acquired from the torn tendon end of medium rotator cuff tears during arthroscopic surgery, after applying the same inclusion and exclusion criteria. Expressions of various genes of interest, including collagens I and III, matrix metalloprotease (MMP)-2, MMP-3, MMP-9, MMP-13, interleukin (IL)-1, IL-6, insulin-like growth factor-1, vascular endothelial growth factor, tenomodulin, tumor necrosis factor-α, and p53, were analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, immunohistochemistry and western blot assay were performed for the genes that revealed significantly different expressions in real-time qRT-PCR between groups.

RESULTS

Gene expression levels of MMP-9, MMP-13, IL-6, and tenomodulin were significantly higher in the diabetic than in the nondiabetic group by real-time qRT-PCR analyses (P = .011, .004, .009, and .010, respectively). The density of cells expressing MMP-9 and IL-6 was significantly increased in the torn tendons of the diabetic patients on immunohistochemical analysis, and the density of MMP-9 and IL-6 protein expressions was significantly higher in the diabetic group on western blot (P = .018 and .044, respectively).

CONCLUSIONS

Diabetic torn cuff tendon tissues showed MMP-9 and IL-6 overexpressions compared with controls.

CLINICAL RELEVANCE

The overexpressions of MMP-9 and IL-6 may be one of the explanations for the high healing failure rate after rotator cuff repair in the diabetic patients.

Decreased Synovial Inflammation in Atraumatic Hip Microinstability Compared With Femoroacetabular Impingement

PURPOSE

To compare the inflammatory profile of hip synovial tissue in those with atraumatic microinstability to patients with femoroacetabular impingement (FAI).

METHODS

Patients with cam and mixed-type FAI (FAI group) and patients with hip instability underwent sampling of the anterolateral synovium. Demographic data, intraoperative measurements, and functional outcome scores (International Hip Outcomes Tool and Short Form-12) were recorded. Cryosections were stained and examined under light microscopy as well as confocal fluorescent microscopy for anti-CD45 (common leukocyte antigen), anti-CD31 (endothelial), and anti-CD68 (macrophage) cell surface markers. A grading system was used to quantify synovitis under light microscopy whereas digital image analysis was used to quantify immunofluorescence staining area. Comparison were made with Student t test, Mann-Whitney U, χ², and regression analysis.

RESULTS

There were 12 patients in the FAI group and 5 in the instability group. Mean age was not significantly different (P > .05), but there was a significantly greater proportion of females in the instability group versus the FAI group (P < .001). There was a significant correlation (r = 0.653; P = .005) between number of turns needed for 10 mm of distraction and increased synovitis. Synovitis scores also were increased significantly in patients with cam morphology and articular cartilage damage (P = .024) versus those without. Immunohistochemistry did not reveal differences (P > .082) between the instability and FAI groups, but CD68 staining was significantly greater in those with cam morphology and cartilage damage (P < .045). CD45+/CD68- cells were noted in the perivascular area while CD45+/CD68+ cells were noted within the synovial lining in both groups.

CONCLUSIONS

Increased synovial inflammation was associated with an increased number of turns to achieve joint distraction. Both instability and FAI groups demonstrated baseline levels of synovial inflammation. Synovitis scores also were increased in patients with cartilage damage.

CLINICAL RELEVANCE

An understanding of the molecular and cellular mechanisms behind both hip instability and FAI may lead to novel therapeutic anti-inflammatory therapy, which may serve as an adjunct to treatment of mechanical abnormalities in this conditions.

Morphologic Risk Factors in Predicting Symptomatic Structural Failure of Arthroscopic Rotator Cuff Repairs: Tear Size, Location, and Atrophy Matter

PURPOSE

To evaluate whether morphologic characteristics of rotator cuff tear have prognostic value in determining symptomatic structural failure of arthroscopic rotator cuff repair independent of age or gender.

METHODS

Arthroscopic rotator cuff repair cases performed by five fellowship-trained surgeons at our institution from 2006 to 2013 were retrospectively reviewed. Data extraction included demographics, comorbidities, repair technique, clinical examination, and radiographic findings. Failure in symptomatic patients was defined as structural defect on postoperative magnetic resonance imaging or pseudoparalysis on examination. Failures were age and gender matched with successful repairs in a 1:2 ratio.

RESULTS

A total of 30 failures and 60 controls were identified. Supraspinatus atrophy (P = .03) and tear size (18.3 mm failures v 13.9 mm controls; P = .02) were significant risk factors for failure, as was the presence of an infraspinatus tear greater than 10 mm (62% v 17%, P < .01). Single-row repair (P = .06) and simple suture configuration (P = .17) were more common but similar between groups. Diabetes mellitus and active tobacco use were not significantly associated with increased failure risk but psychiatric medication use was more frequent in the failure group.

CONCLUSIONS

This study confirms previous suspicions that tear size and fatty infiltration are associated with failure of arthroscopic rotator cuff repair but independent of age or gender in symptomatic patients. There is also a quantitative cutoff on magnetic resonance imaging for the size of infraspinatus involvement that can be used clinically as a predicting factor. Although reported in the literature, smoking and diabetes were not associated with failure.

LEVEL OF EVIDENCE

Level III, retrospective case control.

Gene expression profiles of changes underlying different-sized human rotator cuff tendon tears

BACKGROUND

Progressive cellular and extracellular matrix (ECM) changes related to age and disease severity have been demonstrated in rotator cuff tendon tears. Larger rotator cuff tears demonstrate structural abnormalities that potentially adversely influence healing potential. This study aimed to gain greater insight into the relationship of pathologic changes to tear size by analyzing gene expression profiles from normal rotator cuff tendons, small rotator cuff tears, and large rotator cuff tears.

METHODS

We analyzed gene expression profiles of 28 human rotator cuff tendons using microarrays representing the entire genome; 11 large and 5 small torn rotator cuff tendon specimens were obtained intraoperatively from tear edges, which we compared with 12 age-matched normal controls. We performed real-time polymerase chain reaction and immunohistochemistry for validation.

RESULTS

Torn rotator cuff tendons demonstrated upregulation of a number of key genes, such as matrix metalloproteinase 3, 10, 12, 13, 15, 21, and 25; a disintegrin and metalloproteinase (ADAM) 12, 15, and 22; and aggrecan. Amyloid was downregulated in all tears. Small tears displayed upregulation of bone morphogenetic protein 5. Chemokines and cytokines that may play a role in chemotaxis were altered; interleukins 3, 10, 13, and 15 were upregulated in tears, whereas interleukins 1, 8, 11, 18, and 27 were downregulated.

CONCLUSIONS

The gene expression profiles of normal controls and small and large rotator cuff tear groups differ significantly. Extracellular matrix remodeling genes were found to contribute to rotator cuff tear pathogenesis. Rotator cuff tears displayed upregulation of a number of matrix metalloproteinase (3, 10, 12, 13, 15, 21, and 25), a disintegrin and metalloproteinase (ADAM 12, 15, and 22) genes, and downregulation of some interleukins (1, 8, and 27), which play important roles in chemotaxis. These gene products may potentially have a role as biomarkers of failure of healing or therapeutic targets to improve tendon healing.

The Properties of 3 Different Plasma Formulations and Their Effects on Tendinopathic Cells

BACKGROUND

Tendinopathies are attributed to failure of the healing process and inadequate tissue remodeling. Plasma injections can trigger regenerative responses by modifying the molecular microenvironment.

PURPOSE

To examine the differences in the mitotic, chemotactic, anabolic, and inflammatory effects between leukocyte- and platelet-rich plasma (L-PRP), platelet-rich plasma (PRP), and platelet-poor plasma (PPP).

STUDY DESIGN

Controlled laboratory study.

METHODS

Tendinopathic cells were cultured in 3-dimensional (3D) hydrogels formed using PPP, PRP, and L-PRP. Cell migration was evaluated using a μ-Slide chemotaxis chamber with video microscopy. Proliferation was assessed using XTT assays. Expression of genes associated with matrix turnover, including type 1 collagen (COL1A1), COL3A1, aggrecan, decorin, fibronectin, matrix metalloproteinase 1 (MMP-1), MMP-3, A Disintegrin-Like And Metalloprotease With Thrombospondin Type 1 Motif proteins 4 (ADAMTS-4), and ADAMTS-5, was assessed using real-time reverse-transcription polymerase chain reaction. Secreted inflammatory proteins, including interleukin (IL)-1β, IL-6, IL-8, monocyte chemotactic protein 1 (MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES), as well as vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF), were quantified using enzyme-linked immunosorbent assay.

RESULTS

Tendinopathic cells migrate at a higher velocity along L-PRP and PRP than along PPP gradients. PRP and L-PRP promote hypercellularity. PPP and PRP showed more pronounced anabolic properties, as demonstrated by enhanced COL1A1 and COL3A1 and reduced MMP-1 expression. Decorin, fibronectin, and aggrecan were downregulated in L-PRP compared with PPP and PRP. L-PRP and PRP were shown to be more proinflammatory than PPP in terms of IL-6 secretion, but cells in PPP showed MCP-1(high) phenotype. CTGF secretion was significantly reduced in L-PRP compared with PPP and PRP.

CONCLUSION

The main advantages of L-PRP and PRP use, compared with PPP, include their stronger chemotactic and proliferative properties. While PPP and PRP stimulate matrix anabolism, L-PRP is more proinflammatory. Emphasis should be placed on the temporal needs and biological characteristics of injured tendons, and plasma formulations need to be tailored accordingly.

CLINICAL RELEVANCE

Versatile systems allowing the preparation of different plasma formulations, such as PPP, PRP, or L-PRP, can help refine clinical applications by taking advantage of their different biological properties.

Vitamin D and the immunomodulation of rotator cuff injury

Tendon-to-bone healing after rotator cuff repair surgery has a failure rate of 20%–94%. There has been a recent interest to determine the factors that act as determinants between successful and unsuccessful rotator cuff repair. Vitamin D level in patients is one of the factors that have been linked to bone and muscle proliferation and healing, and it may have an effect on tendon-to-bone healing. The purpose of this article is to critically review relevant published research that relates to the effect of vitamin D on rotator cuff tears and subsequent healing. A review of the literature was conducted to identify all studies that investigate the relationship between vitamin D and tendon healing, in addition to its mechanism of action. The data were then analyzed in order to summarize what is currently known about vitamin D, rotator cuff pathology, and tendon-to-bone healing. The activated metabolite of vitamin D, 1α,25-dihydroxyvitamin D₃, affects osteoblast proliferation and differentiation. Likewise, vitamin D plays a significant role in the tendon-to-bone healing process by increasing the bone mineral density and strengthening the skeletal muscles. The 1α,25-dihydroxyvitamin D₃ binds to vitamin D receptors on myocytes to stimulate growth and proliferation. The form of vitamin D produced by the liver, calcifediol, is a key initiator of the myocyte healing process by moving phosphate into myocytes, which improves function and metabolism. Investigation into the effect of vitamin D on tendons has been sparse, but limited studies have been promising. Matrix metalloproteinases play an active role in remodeling the extracellular matrix (ECM) of tendons, particularly deleterious remodeling of the collagen fibers. Also, the levels of transforming growth factor-β3 positively influence the success of the surgery for rotator cuff repair. In the tendon-to-bone healing process, vitamin D has been shown to successfully influence bone and muscle healing, but more research is needed to delve into the mechanisms of vitamin D as a factor in skeletal tendon health and healing.

Pectoralis major transfer for treatment of irreparable subscapularis tear: a systematic review

PURPOSE

Irreparable ruptures of the subscapularis tendon lead to impaired function of the shoulder and presents a surgically complex problem. Transfer of the pectoralis major tendon has been reported as a possible treatment option. The purpose of this systematic review is to critically examine the outcomes of pectoralis major transfers for the treatment of irreparable subscapularis tears.

METHODS

A systematic review of the literature was performed using search of electronic databases. No language restrictions were applied. Case reports, review articles, and operative techniques without outcome data were excluded. All the outcomes reported by each study were analyzed and when possible, data were pooled to generate frequency-weighted values to summarize outcomes.

RESULTS

Eight studies with a total 195 shoulders were included in this systematic review. The mean age of patients was 58.8 years (range 18-81 years) and the mean follow-up was 33.4 months (range 6-80 months). Constant scores improved from a mean pre-operative score of 37.8 ± 6.8, to a mean postoperative score of 61.3 ± 6.5 (p < 0.0001). Pain scores could not be pooled as different scales were used. Nevertheless, a trend in pain reduction was noted in all papers. Functional outcomes were less favorable in patients with massive rotator cuff tears or previous shoulder replacements. Moreover, the Constant scores were significantly higher in patients following subcoracoid transfer of the pectoralis major tendon compared to patients who received supracoracoid transfer (p < 0.001). The overall reported incidence of postoperative nerve palsy is low (one transient musculocutaneous nerve palsy and one axillary nerve dysfunction out of 195 cases).

CONCLUSIONS

The systematic review based on frequency-weighted means demonstrated improvement in shoulder function, strength and pain relief after pectoralis major transfer for irreparable subscapularis tear.

LEVEL OF EVIDENCE

IV.

Association of synovial inflammation and inflammatory mediators with glenohumeral rotator cuff pathology

HYPOTHESIS

We hypothesized that patients with full-thickness rotator cuff tears would have greater synovial inflammation compared with those without rotator cuff tear pathology, with gene expression relating to histologic findings.

METHODS

Synovial sampling was performed in 19 patients with full-thickness rotator cuff tears (RTC group) and in 11 patients without rotator cuff pathology (control group). Cryosections were stained and examined under light microscopy and confocal fluorescent microscopy for anti-cluster CD45 (common leukocyte antigen), anti-CD31 (endothelial), and anti-CD68 (macrophage) cell surface markers. A grading system was used to quantitate synovitis under light microscopy, and digital image analysis was used to quantify the immunofluorescence staining area. Quantitative polymerase chain reaction was performed for validated inflammatory markers. Data were analyzed with analysis of covariance, Mann-Whitney U, and Spearman rank order testing, with significance set at α = .05.

RESULTS

The synovitis score was significantly increased in the RTC group compared with controls. Immunofluorescence demonstrated significantly increased staining for CD31, CD45, and CD68 in the RTC vs control group. CD45+/68- cells were found perivascularly, with CD45+/68+ cells toward the joint lining edge of the synovium. Levels of matrix metalloproteinase-3 (MMP-3) and interleukin-6 were significantly increased in the RTC group, with a positive correlation between the synovitis score and MMP-3 expression.

CONCLUSIONS

Patients with full-thickness rotator cuff tears have greater levels of synovial inflammation, angiogenesis, and MMP-3 upregulation compared with controls. Gene expression of MMP-3 correlates with the degree of synovitis.

Do Matrix Metalloproteases and Tissue Inhibitors of Metalloproteases in Tenocytes of the Rotator Cuff Differ with Varying Donor Characteristics?

An imbalance between matrix metalloproteases (MMPs) and the tissue inhibitors of metalloproteases (TIMPs) may have a negative impact on the healing of rotator cuff tears. The aim of the project was to assess a possible relationship between clinical and radiographic characteristics of patients such as the age, sex, as well as the degenerative status of the tendon and the MMPs and TIMPs in their tenocyte-like cells (TLCs). TLCs were isolated from ruptured supraspinatus tendons and quantitative Real-Time PCR and ELISA was performed to analyze the expression and secretion of MMPs and TIMPs. In the present study, MMPs, mostly gelatinases and collagenases such as MMP-2, -9 and -13 showed an increased expression and protein secretion in TLCs of donors with higher age or degenerative status of the tendon. Furthermore, the expression and secretion of TIMP-1, -2 and -3 was enhanced with age, muscle fatty infiltration and tear size. The interaction between MMPs and TIMPs is a complex process, since TIMPs are not only inhibitors, but also activators of MMPs. This study shows that MMPs and TIMPs might play an important role in degenerative tendon pathologies.