Rotator cuff disorders: recognition and management among patients with shoulder pain

Finite element-based evaluation of the supraspinatus tendon biomechanical environment necessitates better clinical management based on tear location and thickness

Partial-thickness rotator cuff tears are a common cause of pain and disability and are central to developing full-thickness rotator cuff tears. However, limited knowledge exists regarding the alterations to the mechanical environment due to these lesions. Computational models that study the alterations to the mechanical environment of the supraspinatus tendon can help advance clinical management to avoid tear progression and provide a basis for surgical intervention. In this study, we use three-dimensional validated finite element models from six intact specimens to study the effects of low- and high-grade tears originating on the articular and bursal surfaces of the supraspinatus tendon. Bursal-sided tears generally had a lower failure load, modulus, and strain than articular-sided tears. Thus, caution should be taken when managing bursal-sided tears as they may be more susceptible to tear progression.

Effect of Tear Size and Location on Supraspinatus Tendon Strain During Activities of Daily Living and Physiotherapy

The supraspinatus tendon plays a crucial role in shoulder abduction, making it one of the common structures affected by injury. Clinically, crescent-shaped tears are the most commonly seen tear shape. By developing six specimen-specific, three-dimensional, supraspinatus-infraspinatus finite element model with heterogeneous material properties, this study aimed to examine the changes in tissue deformation (maximum principal strain) of the supraspinatus tendon due to specimen-specific material properties and rotator cuff tear size. FE models with small- and medium-sized full-thickness crescent-shaped tears were subjected to loads seen during activities of daily living and physiotherapy. Six fresh-frozen cadaveric shoulders were dissected to mechanically test the supraspinatus tendon and develop and validate FE models that can be used to assess changes in strain due to small (< 1 cm, equivalent to 20-30% of the tendon width) and medium-sized (1-3 cm, equivalent to 40-50% of the tendon width) tears that are located in the middle and posterior regions of the supraspinatus tendon. FE predictions of maximum principal strain at the tear tips were examined to determine whether failure strain was reached during activities of daily living (drinking and brushing teeth) and physiotherapy exercises (prone abduction and external rotation at 90° abduction). No significant differences were observed between the middle and posterior tear failure loads for small- and medium-sized tears. For prone abduction, there was a potential risk for tear progression (exceeded failure strain) for medium-sized tears in the supraspinatus tendon's middle and posterior regions. For external rotation at 90° abduction, one model with a middle tear and two with posterior tears experienced failure. For all daily activity loads, the strain never exceeded the failure strain. Our three-dimensional supraspinatus-infraspinatus FE model shows that small tears appear unlikely to progress based on the regional strain response; however, medium-sized tears are at higher risk during more strenuous physiotherapy exercises. Furthermore, differences in patient-specific tendon material properties are important in determining whether the tear will progress. Therefore, patient-specific management plans based on tear size may be beneficial to improve clinical outcomes.

Percutaneous bone marrow concentrate and platelet products versus exercise therapy for the treatment of rotator cuff tears: a randomized controlled, crossover trial with 2-year follow-up

BACKGROUND

Surgical repair is recommended for the treatment of high-grade partial and full thickness rotator cuff tears, although evidence shows surgery is not necessarily superior to non-surgical therapy. The purpose of this study was to compare percutaneous orthobiologic treatment to a home exercise therapy program for supraspinatus tears.

METHODS

In this randomized-controlled, crossover design, participants with a torn supraspinatus tendon received either 'BMC treatment', consisting of a combination of autologous bone marrow concentrate (BMC) and platelet products, or underwent a home exercise therapy program. After three months, patients randomized to exercise therapy could crossover to receive BMC treatment if not satisfied with shoulder progression. Patient-reported outcomes of Numeric Pain Scale (NPS), Disabilities of the Arm, Shoulder, and Hand, (DASH), and a modified Single Assessment Numeric Evaluation (SANE) were collected at 1, 3, 6, 12, and 24 months. Pre- and post-treatment MRI were assessed using the Snyder Classification system.

RESULTS

Fifty-one patients were enrolled and randomized to the BMC treatment group (n = 34) or the exercise therapy group (n = 17). Significantly greater improvement in median ΔDASH, ΔNPS, and SANE scores were reported by the BMC treatment group compared to the exercise therapy group (-11.7 vs -3.8, P = 0.01; -2.0 vs 0.5, P = 0.004; and 50.0 vs 0.0, P < 0.001; respectively) after three months. Patient-reported outcomes continued to progress through the study's two-year follow-up period without a serious adverse event. Of patients with both pre- and post-treatment MRIs, a majority (73%) showed evidence of healing post-BMC treatment.

CONCLUSIONS

Patients reported significantly greater changes in function, pain, and overall improvement following BMC treatment compared to exercise therapy for high grade partial and full thickness supraspinatus tears.

TRIAL REGISTRATION

This protocol was registered with www.

CLINICALTRIALS

gov (NCT01788683; 11/02/2013).

Long-Term Follow-Up of Inpatients with Rotator Cuff Tear Who Received Integrative Korean Medicine Treatment: A Retrospective Analysis and Questionnaire Survey

CONTEXT

Rotator cuff tear is one of the most common causes of shoulder pain and has become a prominent disease most frequently treated by surgery.

OBJECTIVES

To investigate the long-term therapeutic effect of integrative Korean medicine (KM) as a conservative treatment in treating rotator cuff tears.

DESIGN

A multicenter observational study.

SETTINGS

The settings involve four regional network KM hospitals.

PATIENTS

The study participants are 288 patients aged 19-70 with rotator cuff tear identified by radiologist based on magnetic resonance imaging who received integrative KM treatment for the chief complaint of shoulder pain between 1 January 2015 and 31 March 2020.

INTERVENTION

None.

MAIN OUTCOMES

The primary outcome was the pain score in the affected shoulder, measured by the numeric rating scale (NRS). The secondary outcomes were Shoulder Pain and Disability Index (SPADI), 5-Level Quality of life: EuroQol 5-Dimension (EQ-5D-5L), Patient Global Impression of Change (PGIC), and range of motion (ROM) scores.

RESULTS

Eligible patients for MCID achievement analysis for minimally clinical important change were 167, and 109 completed the follow-up survey. The mean NRS pain score in the affected shoulder was 5.80 ± 1.27 at admission, 3.50 ± 1.32 at discharge, and 3.83 ± 2.04 at follow-up.The mean SPADI score was 51.48 ± 20.18 at admission, 37.76 ± 19.23 at discharge, and 24.26 ± 21.80 at follow-up. The improvement at discharge (P-value < 0.001) and follow-up (P-value < 0.001) compared to those at admission was statistically significant. The results also presented a significant improvement in ROM for all motions at discharge after treatment (P-value < 0.001). The number of patients who achieved minimal clinically important difference in NRS was 116 (69.5%) at discharge and 71 (65.1%) at follow-up, and in SPADI was 82 (50.9%) at discharge and 77 (70.6%) at follow-up.

CONCLUSION

The results of this study suggested that integrative KM treatment can help improve pain, functional impairment, QoL, and ROM in patients with a rotator cuff tear TRIAL REGISTRATION: NCT04566939.

The long head of the biceps tendon undergoes multiaxial deformation during shoulder motion

The long head biceps tendon (LHBT) is presumed a common source of shoulder joint pain and injury. Despite common LHBT pathologies, diagnosis and preferred treatment remain frequently debated. This Short Communication reports the development of a subject-specific finite element model of the shoulder joint based on one subject's 3D reconstructed anatomy and 3D in vivo kinematics recorded from bone-fixed electromagnetic sensors. The primary purpose of this study was to use the developed finite element model to investigate the LHBT mechanical environment during a typical shoulder motion of arm raising. Furthermore, this study aimed to assess the viability of material models derived from uniaxial tensile tests for accurate simulation of in vivo motion. The findings of our simulations indicate that the LHBT undergoes complex multidimensional deformations. As such, uniaxial material properties reported in the existing body of literature are not sufficient to simulate accurately the in vivo mechanical behavior of the LHBT. Further experimental tests on cadaveric specimens, such as biaxial tension and combinations of tension and torsion, are needed to describe fully the mechanical behavior of the LHBT and investigate its mechanisms of injury.

Total Intravenous Anesthesia Compared to Inhalational Anesthesia in Patients Undergoing Arthroscopic Rotator Cuff Repair

Background Inhalation anesthesia (IA) and total intravenous anesthesia (TIVA) are common general anesthesia techniques. During rotator cuff repair (RCR), an interscalene block is beneficial for intraoperative and early postoperative pain control. This study aimed to evaluate postoperative outcomes and opioid usage in patients undergoing arthroscopic RCR with an interscalene block and either IA or TIVA. Methodology A retrospective observational study was performed of 478 patients undergoing RCR at a single institution. Demographics, surgical details, intra and postoperative medications, and 90-day outcomes were collected. Univariate and multivariate analyses were performed to evaluate differences between groups. Results In total, 309 (64.6%) patients received IA and 169 (35.3%) received TIVA. Patients receiving IA were more likely to have comorbidities, such as diabetes (p = 0.002), sleep apnea (p = 0.006), gastroesophageal reflux disease (p < 0.001), and hypertension (p < 0.001). After adjusting for differences between groups in the multivariate analysis, patients who received TIVA had significantly shorter surgical time (β = -14.85, p < 0.001) and perioperative time (β = -21.01, p < 0.001) and significantly lower first post-anesthesia care unit Pasero opioid-induced sedation scores (β = -0.022, p = 0.040). Patients who received TIVA were less likely to receive intraoperative narcotics (odds ratio = 0.38; p = 0.031). Conclusions TIVA appears to be a safe and effective anesthetic for patients undergoing arthroscopic RCR. TIVA is a potentially beneficial alternative to IA for this patient population.

What is the Optimal Construct to Reduce Failure in Arthroscopic Four Anchor Rotator Cuff Repair?

Background

Re-tear following rotator cuff repair (RCR) is a concerning complication that can lead to poor patient outcomes and necessitate the need for revision surgery. The purpose of our study was to look at the combined construct of knotted vs. knotless medial row and suture vs. suture tape, focusing primarily on re-tear rates following surgery.

Methods

A retrospective observational study of 343 consecutive patients undergoing arthroscopic double row, 4-anchor rotator cuff repair from February 2014 to March 2020 was conducted. Univariate and multivariate statistics were used to assess differences in demographics, comorbidities and tear characteristics between patients who experienced a symptomatic re-tear and those who did not.

Results

The overall symptomatic re-tear rate was 7.6%. Patients who had a knotted medial row repair had a significantly lower rate of re-tear (4.7 vs. 11.3%, p = 0.022). Patients that had a knotted medial row and suture tape repair were significantly less likely to experience a re-tear (OR: 0.180, p = 0.001).

Discussion

The use of suture tape and a knotted medial row repair decreases the incidence of symptomatic re-tear following rotator cuff repair. The combined construct of suture tape and a knotted medial row in rotator cuff repair decreases the risk for symptomatic re-tear following surgery.

Combined Growth Factor Hydrogel Enhances Rotator Cuff Enthesis Healing in Rat But Not Sheep Model

We hypothesized that a combined growth factor hydrogel would improve chronic rotator cuff tear healing in a rat and sheep model. Insulin-like growth factor 1, transforming growth factor β1, and parathyroid hormone were combined into a tyraminated poly-vinyl-alcohol (PVA-Tyr) hydrogel and applied directly at the enthesis. In total, 30 Sprague-Dawley rats and 16 Romney ewes underwent unilateral rotator cuff tenotomy and then delayed repairs were performed after 3-4 weeks. The animals were divided into a control group (repair alone) and treatment group. The rotator cuffs were harvested at 12 weeks after surgery for biomechanical and histological analyses of the repair site. In the rat model, the stress at failure and Young's modulus were higher in the treatment group in comparison with the control group (73% improvement, p = 0.010 and 56% improvement, p = 0.028, respectively). Histologically, the repaired entheses in the treatment group demonstrated improved healing with higher semi-quantitative scores (10.1 vs. 6.55 of 15, p = 0.032). In the large animal model, there was no observable treatment effect. This PVA-Tyr bound growth factor system holds promise for improving rotator cuff healing. However, our approach was not scalable from a small to a large animal model. Further tailoring of this growth factor delivery system is still required. Level of Evidence: Basic Science Study; Biomechanics and Histology; Animal Model Impact Statement Previous studies using single-growth factor treatment to improve enthesis healing after rotator cuff repair have reported promising, but inconsistent results. A novel approach is to combine multiple growth factors using controlled-release hydrogels that mimic the normal healing process. In this study, we report that a combined growth factor hydrogel can improve the histological quality and strength of rotator cuff repair in a rat chronic tear model. This novel hydrogel growth factor treatment has the potential to be used in human clinical applications to improve healing after rotator cuff repair.

The Effect of Pulling Angle on Rotator Cuff Mechanical Properties in a Canine In Vitro Model

The objective of this study was to examine the effect of pulling angle on time-zero mechanical properties of intact infraspinatus tendon or infraspinatus tendon repaired with the modified Mason-Allen technique in a canine model in vitro. Thirty-six canine shoulder samples were used. Twenty intact samples were randomly allocated into functional pull (135°) and anatomic pull (70°) groups (n = 10 per group). The remaining sixteen infraspinatus tendons were transected from the insertion and repaired using the modified Mason-Allen technique before being randomly allocated into functional pull or anatomic pull groups (n = 8 per group). Load to failure testing was performed on all specimens. The ultimate failure load and ultimate stress of the functional pulled intact tendons were significantly lower compared with anatomic pulled tendons (1310.2 ± 167.6 N vs. 1687.4 ± 228.2 N, p = 0.0005: 55.6 ± 8.4 MPa vs. 67.1 ± 13.3 MPa, p = 0.0334). For the tendons repaired with the modified Mason-Allen technique, no significant differences were observed in ultimate failure load, ultimate stress or stiffness between functional pull and anatomic pull groups. The variance of pulling angle had a significant influence on the biomechanical properties of the rotator cuff tendon in a canine shoulder model in vitro. Load to failure of the intact infraspinatus tendon was lower at the functional pulling position compared to the anatomic pulling position. This result indicates that uneven load distribution across tendon fibers under functional pull may predispose the tendon to tear. However, this mechanical character is not presented after rotator cuff repair using the modified Mason-Allen technique.

Ethnicity, sex, and socioeconomic disparities in the treatment of traumatic rotator cuff injuries in Aotearoa/New Zealand

HYPOTHESIS AND BACKGROUND

Traumatic rotator cuff injuries can be a leading cause of prolonged shoulder pain and disability and contribute to significant morbidity and health care costs. Previous studies have shown evidence of sociodemographic disparities with these injuries. The purpose of this nationwide study was to better understand these disparities based on ethnicity, sex, and socioeconomic status, in order to inform future health care strategies.

METHODS

Accident Compensation Corporation (ACC) is a no-fault comprehensive compensation scheme encompassing all of Aotearoa/New Zealand (population in 2018, 4.7 million). Using the ACC database, traumatic rotator cuff injuries were identified between January 2010 and December 2018. Injuries were categorized by sex, ethnicity, age, and socioeconomic deprivation index of the claimant.

RESULTS

During the 9-year study period, there were 351,554 claims accepted for traumatic rotator cuff injury, which totaled more than NZ$960 million. The greatest proportion of costs was spent on vocational support (49.8%), then surgery (26.3%), rehabilitation (13.1%), radiology (8.1%), general practitioner (1.6%), and "Other" (1.1%). Asian, Māori (indigenous New Zealanders), and Pacific peoples were under-represented in the age-standardized proportion of total claims and had lower rates of surgery than Europeans. Māori had higher proportion of costs spent on vocational support and lower proportions spent on radiology, rehabilitation, and surgery than Europeans. Males had higher number and costs of claims and were more likely to have surgery than females. There were considerably fewer claims from areas of high socioeconomic deprivation.

DISCUSSION AND CONCLUSION

This large nationwide study demonstrates the important and growing economic burden of rotator cuff injuries. Indirect costs, such as vocational supports, are a major contributor to the cost, suggesting improving treatment and rehabilitation protocols would have the greatest economic impact. This study has also identified sociodemographic disparities that need to be addressed in order to achieve equity in health outcomes.

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.

Racial disparities in outcomes of arthroscopic rotator cuff repair: A propensity score matched analysis using multiple national data sets

BACKGROUND

Disparities in access, utilization and outcomes exist throughout the healthcare system for minority groups, including racial and ethnic minorities; these disparities have wide-reaching implications for individuals as well as the healthcare system as a whole. This study will examine the impact of race on short and medium term outcomes for patients undergoing rotator cuff repair (RCR) using matched cohorts.

METHODS

Patients undergoing arthroscopic rotator cuff repair from 2016 to 2018 were extracted from two national databases: the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) and TriNetX Research Network. Using the ACS-NSQIP database, univariate analysis was performed to identify differences in comorbidities between white and minority patients. Patients were propensity score matched based on significant differences between groups and 30-day postoperative outcomes were assessed. These comorbidities were then used to propensity score match white and minority patients in the TriNetX database and two-year postoperative outcomes were evaluated.

RESULTS

Following propensity score matching, 3716 patients remained in each group from the ACS-NSQIP database and 4185 patients remained in each group from the TriNetX database. The OR time for minority patients was longer than white patient in the ACS-NSQIP database (92.2 vs. 87.6 min, p < .001). There was no difference in medium-term outcomes for repeat RCR, infection or frozen shoulder between white and minority patients in the TriNetX database.

CONCLUSION

After propensity score matching the only significant short-term outcome between white and minority patients undergoing RCR was a difference in OR time; there were no differences in medium-term outcomes. This may indicate that the source of racial disparities is one of access to healthcare rather than an innate difference in the patients' outcomes. Further study is needed to elucidate this issue.

The Greek version of shoulder rating questionnaire (SRQ): Translation, cultural adaptation, a reliability and validity study in patients with rotator cuff related shoulder pain

BACKGROUND

The Shoulder Rating Questionnaire (SRQ) was created in the English language to assess shoulder disorders in six areas: global function, pain, daily activities, recreational and athletic activities, and work.

PURPOSE

The study aimed to translate and culturally adapt Shoulder Rating Questionnaire (SRQ) into Greek.

METHODS

The SRQ English version was translated and adapted into the Greek language using forward translation, expert panel synthesis, and backward translation procedures. A pilot testing has been made in the target population, and the final version was created. A cross-sectional study was conducted in clinical settings with the SRQ and the Shoulder Pain and Disability Index. A total of 168 Greek adult patients with rotator cuff-related shoulder pain were recruited from physical therapy clinics. Τhe reliability of the SRQ Greek version was assessed using intraclass correlation coefficients. Internal consistency was assessed using the Cronbach alpha coefficient. Concurrent validity was measured by correlating the Shoulder Rating Questionnaire with the Shoulder Pain and Disability Index using Pearson's correlation coefficient.

RESULTS

The results showed that the SRQ Greek version has excellent internal consistency (Cronbach's α = 0.99), test-retest reliability (ICC = 0.976), and concurrent validity (r > 0.9). No ground or ceiling effects were found. The standard error of measurement and the minimum detectable change of the total score were 5.55 and 15.38.

CONCLUSIONS

The Greek Language Version of the SRQ is a reliable and valid instrument that can be used to evaluate adult patients with shoulder rotator cuff-related disorders in the acute or chronic phases and in clinical trials.

ADSC-Based Cell Therapies for Musculoskeletal Disorders: A Review of Recent Clinical Trials

Recently published clinical trials involving the use of adipose-derived stem cells (ADSCs) indicated that approximately one-third of the studies were conducted on musculoskeletal disorders (MSD). MSD refers to a wide range of degenerative conditions of joints, bones, and muscles, and these conditions are the most common causes of chronic disability worldwide, being a major burden to the society. Conventional treatment modalities for MSD are not sufficient to correct the underlying structural abnormalities. Hence, ADSC-based cell therapies are being tested as a form of alternative, yet more effective, therapies in the management of MSDs. Therefore, in this review, MSDs subjected to the ADSC-based therapy were further categorized as arthritis, craniomaxillofacial defects, tendon/ligament related disorders, and spine disorders, and their brief characterization as well as the corresponding conventional therapeutic approaches with possible mechanisms with which ADSCs produce regenerative effects in disease-specific microenvironments were discussed to provide an overview of under which circumstances and on what bases the ADSC-based cell therapy was implemented. Providing an overview of the current status of ADSC-based cell therapy on MSDs can help to develop better and optimized strategies of ADSC-based therapeutics for MSDs as well as help to find novel clinical applications of ADSCs in the near future.

Image-Guided Versus Blind Corticosteroid Injections in Adults With Shoulder Pain: A Systematic Review and Meta-Analysis

The present study aimed to compare the clinical effects of image-guided versus blind steroid injection to treat shoulder pain, which is always debatable. An electronic search of credible databases was conducted for randomized controlled trials (RCTs) comparing image-guided versus blind steroid injections. The continuous data were pooled as mean difference (MD) or standardized mean difference (SMD), and dichotomous data were grouped as odds ratio (OR) with 95% confidence interval (CI). Sensitivity analysis and leave-one-out analysis were performed. The meta-analysis of 20 RCTs comprising 1136 patients favored image-guided injection based on the MD of the visual analog score (VAS) and shoulder function scores, measured between six weeks follow-up and baseline (MD=0.63, 95% CI [0.13, 1.12], p=0.01 and SMD=0.35, 95% CI [0.05, 0.65], p=0.02, respectively). Meta-analysis did not favor either group regarding the shoulder disability scores or side effects (MD=-2.18, 95% CI [-12.19, 7.83], p=0.67, and OR=0.40, 95% CI [0.14, 1.15], p=0.09, respectively). The image-guided approach was associated with significant improvement in pain and shoulder functionality. However, no significant difference was observed between the two approaches in terms of disability scores and side effects.

The impact of chronic steroid use on early postoperative complications in shoulder surgery

OBJECTIVES

Chronic steroid use has been associated with poor healing and worse long-term outcomes in patients undergoing orthopedic surgery, but the specific risk profile and short-term complications related to chronic steroids in patients undergoing outpatient shoulder surgery are inadequately defined. The purpose of this study is to characterize the effects of chronic steroids on 30-day post-operative complications following arthroscopic and open shoulder surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program was used to identify patients who underwent arthroscopic and open rotator cuff repair, shoulder stabilization, and associated procedures from 2011 to 2018. Patients on chronic steroids were compared with patients not on chronic steroids. Demographic data and 30-day postoperative complications were analyzed. Multivariable logistic regression was used to isolate the effects of chronic steroid use on postoperative complications.

RESULTS

We identified 99,970 patients who underwent shoulder surgery during this period, of which 1.7% (1,662 patients) were on chronic steroids. Patients on chronic steroids were older (58.3 ± 0.30vs52.1 ± 0.05 years, p < 0.01), had higher average BMI (30.6 vs 30.1, p = 0.02), and were more likely to be female (54.9%vs38.0%, p < 0.01) and white (76.2%vs73.1%, p < 0.01). Patients on steroids had a higher American Society of Anesthesiologists class, and higher rates of diabetes, CHF, COPD, hypertension, bleeding disorders, and functionally dependency (all P < 0.01). Patients on chronic steroids were less likely to smoke (P < 0.01). Multivariable logistic regression revealed that chronic steroid use was an independent risk factor for major (OR 2.20[1.51-3.21], p < 0.001), minor (OR 2.32[1.13-3.2], p < 0.001), and infectious complications (OR 1.90[1.13-3.2], p = 0.01).

CONCLUSIONS

Preoperative chronic steroid use is independently associated with increased odds of major, minor, and infectious complications after open and arthroscopic rotator cuff repair, shoulder stabilization, and associated procedures. Patients on chronic steroids should be counseled about their increased risk for these complications, and both preoperative risk stratification and optimization should be employed to minimize perioperative risk.

Hierarchically Demineralized Cortical Bone Combined With Stem Cell-Derived Extracellular Matrix for Regeneration of the Tendon-Bone Interface

BACKGROUND

Poor healing of the tendon-bone interface after rotator cuff repair is one of the main causes of surgical failure. Previous studies demonstrated that demineralized cortical bone (DCB) could improve healing of the enthesis.

PURPOSE

To evaluate the outcomes of hierarchically demineralized cortical bone (hDCB) coated with stem cell-derived extracellular matrix (hDCB-ECM) in the repair of the rotator cuff in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Tendon-derived stem cells (TDSCs) were isolated, cultured, and identified. Then, hDCB was prepared by the graded demineralization procedure. Finally, hDCB-ECM was fabricated via 2-week cell culture and decellularization, and the morphologic features and biochemical compositions of the hDCB-ECM were evaluated. A total of 24 rabbits (48 samples) were randomly divided into 4 groups: control, DCB, hDCB, and hDCB-ECM. All rabbits underwent bilateral detachment of the infraspinatus tendon, and the tendon-bone interface was repaired with or without scaffolds. After surgery, 8 rabbits were assessed by immunofluorescence staining at 2 weeks, and the others were assessed by micro-computed tomography (CT) examination, immunohistochemical staining, histological staining, and biomechanical testing at 12 weeks.

RESULTS

TDSCs were identified to have universal stem cell characteristics including cell markers, clonogenicity, and multilineage differentiation. The hDCB-ECM contained 3 components (bone, partial DCB, and DCB coated with ECM) with a gradient of calcium and phosphorus elements, and the ECM had stromal cell-derived factor 1, biglycan, and fibromodulin. Macroscopic observations demonstrated the absence of infection and rupture around the enthesis. The results of immunofluorescence staining showed that hDCB-ECM promoted stromal cell recruitment. Results of micro-CT analysis, immunohistochemical staining, and histological staining showed that hDCB-ECM enhanced bone and fibrocartilage formation at the tendon-bone interface. Biomechanical analysis showed that the hDCB-ECM group had higher ultimate tensile stress and Young modulus than the DCB group.

CONCLUSION

The administration of hDCB-ECM promoted healing of the tendon-bone interface.

CLINICAL RELEVANCE

hDCB-ECM could provide useful information for the design of scaffolds to repair the tendon-bone interface, and further studies are needed to determine its effectiveness.

How does rerupture affect sleep and quality of life in patients undergoing arthroscopic rotator cuff repair?

Background/aim

Sleep disturbance and related improvement in quality of life as a result of arthroscopic repair in rotator cuff tear (RCT) patients can be considered as an important parameter. The aim of our study is to evaluate the rotator cuff by ultrasonography (USG) in the first postoperative year and to examine whether there is a difference between sleep disturbance and quality of life between cases of rupture and healthy patients. In addition, we aim to compare the preoperative and at least the first postoperative year’s sleep disturbances and quality of life among patients who underwent arthroscopic RCT repair and to examine the effects of factors affecting this situation.

Materials and methods

We retrospectively reviewed the records of patients who were operated on for RCT. In this process, 257 patients were examined and 76 patients who met the inclusion criteria were included in the study. The Pittsburgh sleep quality index (PSQI), Constant–Murley shoulder score (CSS), and Oxford shoulder score (OSS) were used to evaluate the results preoperatively and at the last control visit of each patient. In the USG performed in the postoperative first year, the rotor cuff was evaluated in terms of rerupture.

Results

It was observed that 14 (18.4%) patients’ rotor cuffs were reruptured and those of 62 (81.6%) patients were intact. The preoperative PSQI, CSS, and OSS values of the patients were calculated as an average of 10.79 ± 3.58, 35.61 ± 8.88, and 17.61 ± 4.20 and the mean postoperative values were calculated as 5.45 ± 1.68, 81.55 ± 5.27, and 38.05 ± 3.06, respectively. The postoperative PSQI value was statistically significantly lower in patients with tears of <1 cm (PSQI: 4.29 ± 0.73) than in those with tears of 1–3 cm (PSQI: 5.50 ± 2.17) and 3–5 cm (PSQI: 5.88 ± 1.25) (P < 0.001). The mean CSS and OSS values were significantly higher in postoperative measurements for all tear types. According to the size of the tear, postoperative CSS and OSS values were statistically significantly lower in patients with tears of 3–5 cm (CSS: 78.59 ± 4.50 and OSS: 36.18 ± 2.47) than those with <1 cm (CSS: 85.43 ± 2.14 and OSS: 40.57 ± 1.55) and 1–3 cm (CSS: 83.21 ± 5.35 and OSS: 39.07 ± 2.94) tears (P < 0.001).

Conclusion

In the USG performed in the postoperative first year, it was determined that the patients with healthy rotator cuffs recovered better than those with rerupture.

Evaluation of Diagnostic Precision of Ultrasound for Rotator Cuff Disorders in Patients with Shoulder Pain

Background

Rotator cuff disorders are a leading cause of shoulder symptoms. Accurate imaging, detecting the type of the involved muscle, and severity of the injury have important effects on the choice of treatment. Accordingly, the current study was conducted to evaluate the diagnostic accuracy of ultrasound for rotator cuff disorders in patients suffering from shoulder pain and to explore the precision of ultrasound in determining the exact dimensions of a tear in comparison with magnetic resonance imaging (MRI).

Methods

This prospective research was performed on patients clinically suspected of rotator cuff tendinopathy. An ultrasound of the shoulder was initially performed for the candidates. In this study, MRI was regarded as the modality of choice for examining the images of shoulder disorders. The European Society of Musculoskeletal Radiology (ESSR) guidelines were used to design the protocols and implement imaging measures. Based on the reference standard of MRI, the specificity and sensitivity as well as positive and negative predictive values of ultrasound in detection of rotator cuff disorders were calculated.

Results

A total of48 patients (22 women, 23 dominant right hands) with an average age of 51.6±8.3 years were enrolled in this study. Based on MRI findings, rotator cuff disorders were detected in 43 patients (89.5%). The most commonly observed disorders were partial-thickness rotator cuff tear (n=17, 35.4%), full-thickness rotator cuff tear (n=16, 33.3%), and tendinopathy (n=10, 20.8%). Among rotator cuff disorders, the highest sensitivity of ultrasound was observed in the detection of full-thickness tear (93.7%) and rotator cuff tendinopathy (90%). The highest specificity was found in the detection of full-thickness rotator cuff tear (100%) and partial-thickness rotator cuff tear (96.7%).

Conclusion

Based on our findings, ultrasound could be considered as a high-quality diagnostic tool to rule in partial and full-thickness rotator cuff tears and rule out the rotator cuff pathologies.

Preoperative Fatty Infiltration of the Teres Minor Negatively Affects Postoperative Outcomes in Patients With Rotator Cuff Pathology

Background

The teres minor is a critical component of the rotator cuff and serves as one of the few external rotators of the humerus. Information is lacking regarding the effect of teres minor atrophy in isolation and in the setting of concomitant full-thickness rotator cuff tears on outcomes in patients undergoing rotator cuff surgery.

Purpose

To investigate the effect of preoperative teres minor fatty infiltration on postoperative clinical outcomes in patients with and without full-thickness rotator cuff pathology.

Study Design

Cohort study; Level of evidence, 3.

Methods

A retrospective review of patients undergoing primary arthroscopic shoulder surgery between 2014 and 2016 was performed. Preoperative magnetic resonance imaging was used to determine fatty infiltration for each rotator cuff muscle using the modified Goutallier classification. American Shoulder and Elbow Surgeons (ASES) as well as the shortened version of Disabilities of the Arm, Shoulder and Hand (QuickDASH) scores were obtained preoperatively and during follow-up. Exclusion criteria included prior surgery on the ipsilateral shoulder or a diagnosis of inflammatory arthropathy. For analysis, patients were dichotomized to grade 0 or grade 1-4 atrophy of the teres minor as well as to full-thickness or partial-thickness rotator cuff pathology.

Results

A total of 36 of 47 (76.6%) patients (mean age, 63 years; range, 45-76 years) were available for postoperative follow-up at a mean of 40 months (range, 30-48 months). Postoperative ASES score was significantly higher and QuickDASH score was significantly lower among all patients in the grade 0 group compared with the grade 1-4 group. Postoperative ASES and QuickDASH scores were not significantly different in patients with partial-thickness rotator cuff tears at any time point. However, the postoperative ASES score was significantly higher and QuickDASH score was significantly lower in the grade 0 versus grade 1-4 group for patients with full-thickness rotator cuff pathology.

Conclusion

Preoperative teres minor atrophy in patients undergoing surgery for rotator cuff pathology may impair postoperative clinical outcomes, especially in patients with full-thickness tears.

Regeneration of the rotator cuff tendon-to-bone interface using umbilical cord-derived mesenchymal stem cells and gradient extracellular matrix scaffolds from adipose tissue in a rat model

Regeneration of the gradient structure of the tendon-to-bone interface (TBI) is a crucial goal after rotator cuff repair. The purpose of this study was to investigate the efficacy of a biomimetic hydroxyapatite-gradient scaffold (HA-G scaffold) isolated from adipose tissue (AD) with umbilical cord derived mesenchymal stem cells (UC MSCs) on the regeneration of the structure of the TBI by analyzing the histological and biomechanical changes in a rat repair model. As a result, the HA-G scaffold had progressively increased numbers of hydroxyapatite (HA) particles from the tendon to the bone phase. After seeding UC MSCs to the scaffold, specific matrices, such as collagen, glycoaminoglycan, and calcium, were synthesized with respect to the HA density. In a rat repair model, compared to the repair group, the UC MSCs seeded HA-G scaffold group had improved collagen organization and cartilage formation by 52% at 8 weeks and 262.96% at 4 weeks respectively. Moreover, ultimate failure load also increased by 30.71% at 4 weeks in the UC MSCs seeded HA-G scaffold group compared to the repair group. Especially, the improved values were comparable to values in normal tissue. This study demonstrated that HA-G scaffold isolated from AD induced UC MSCs to form tendon, cartilage and bone matrices similar to the TBI structure according to the HA density. Furthermore, UC MSC-seeded HA-G scaffold regenerated the TBI of the rotator cuff in a rat repair model in terms of histological and biomechanical properties similar to the normal TBI. Statement of Significance We found specific extracellular matrix (ECM) formation in the biomimetic-hydroxyapatite-gradient-scaffold (HA-G-scaffold) in vitro as well as improved histological and biomechanical results of repaired rotator cuff after the scaffold implantation in a rat model. This study has four strengths; An ECM scaffold derived from human adipose tissue; only one-layer used for a gradient scaffold not a multilayer used to mimic the unique structure of the gradient tendon-to-bone-interface (TBI) of the rotator cuff; UC-MSCs as a new cell source for TBI regeneration; and the UC-MSCs synthesized specific matrices with respect to the HA density without any other stimuli. This study suggested that the UC-MSC seeded HA-G-scaffold could be used as a promising strategy for the regeneration of rotator cuff tears.

Is residual tendon a predictor of outcome following arthroscopic rotator cuff repair? A preliminary outlook at short-term follow-up

BACKGROUND

Multiple factors including muscle atrophy, fatty infiltration, smoking, advanced patient age, and increasing tear size have been identified as risk factors for retear after rotator cuff repair. However, little is known about what effect the length of the residual rotator cuff tendon has on the success of repair and patient outcomes.

METHODS

This study included 64 patients. Patients were stratified based on a residual tendon length of greater than 15 mm (group 1, residual tendon) or 15 mm or less (group 2, no residual tendon). Rotator cuff tendon integrity was then evaluated using ultrasound imaging at 6 months. Outcome measures included the Single Assessment Numeric Evaluation score, visual analog scale score, EQ5D Index score, Global Rating of Change score, and Penn Shoulder Score.

RESULTS

No differences were found between groups regarding demographic data or repair configuration. Assessment of tendon healing demonstrated an increased rate of tendons that had "not healed" in group 2 (19.3% [n = 5] vs. 13.2% [n = 5]), but this difference was not statistically significant (P = .55). Functional outcome scores improved significantly from preoperatively to final follow-up in both groups and displayed no differences at 6-month follow-up.

CONCLUSION

A smaller residual tendon length was not a negative predictor of clinical outcomes following arthroscopic rotator cuff repair in patients with short-term follow-up. Although there was a trend toward a decreased rate of healing in patients with smaller residual tendons, this was not significant.

Shock wave therapy for rotator cuff disease with or without calcification

BACKGROUND

Shock wave therapy has seen widespread use since the 1990s to treat various musculoskeletal disorders including rotator cuff disease, but evidence of its efficacy remains equivocal.

OBJECTIVES

To determine the benefits and harms of shock wave therapy for rotator cuff disease, with or without calcification, and to establish its usefulness in the context of other available treatment options.

SEARCH METHODS

We searched Ovid MEDLINE, Ovid Embase, CENTRAL, ClinicalTrials.gov and the WHO ICTRP up to November 2019, with no restrictions on language. We reviewed the reference lists of retrieved trials to identify potentially relevant trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that used quasi-randomised methods to allocate participants, investigating participants with rotator cuff disease with or without calcific deposits. We included trials of comparisons of extracorporeal or radial shock wave therapy versus any other intervention. Major outcomes were pain relief greater than 30%, mean pain score, function, patient-reported global assessment of treatment success, quality of life, number of participants experiencing adverse events and number of withdrawals due to adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data and assessed the certainty of evidence using GRADE. The primary comparison was shock wave therapy compared to placebo.

MAIN RESULTS

Thirty-two trials (2281 participants) met our inclusion criteria. Most trials (25) included participants with rotator cuff disease and calcific deposits, five trials included participants with rotator cuff disease and no calcific deposits, and two trials included a mixed population of participants with and without calcific deposits. Twelve trials compared shock wave therapy to placebo, 11 trials compared high-dose shock wave therapy (0.2 mJ/mm² to 0.4 mJ/mm² and above) to low-dose shock wave therapy. Single trials compared shock wave therapy to ultrasound-guided glucocorticoid needling, ultrasound-guided hyaluronic acid injection, transcutaneous electric nerve stimulation (TENS), no treatment or exercise; dual session shock wave therapy to single session therapy; and different delivery methods of shock wave therapy. Our main comparison was shock wave therapy versus placebo and results are reported for the 3 month follow up. All trials were susceptible to bias; including selection (74%), performance (62%), detection (62%), and selective reporting (45%) biases. No trial measured participant-reported pain relief of 30%. However, in one trial (74 participants), at 3 months follow up, 14/34 participants reported pain relief of 50% or greater with shock wave therapy compared with 15/40 with placebo (risk ratio (RR) 1.10, 95% confidence interval (CI) 0.62 to 1.94); low-quality evidence (downgraded for bias and imprecision). Mean pain (0 to 10 scale, higher scores indicate more pain) was 3.02 points in the placebo group and 0.78 points better (0.17 better to 1.4 better; clinically important change was 1.5 points) with shock wave therapy (9 trials, 608 participants), moderate-quality evidence (downgraded for bias). Mean function (scale 0 to 100, higher scores indicate better function) was 66 points with placebo and 7.9 points better (1.6 better to 14 better, clinically important difference 10 points) with shock wave therapy (9 trials, 612 participants), moderate-quality evidence (downgraded for bias). Participant-reported success was reported by 58/150 people in shock wave therapy group compared with 35/137 people in placebo group (RR 1.59, 95% CI 0.87 to 2.91; 6 trials, 287 participants), low-quality evidence (downgraded for bias and imprecision). None of the trials measured quality of life. Withdrawal rate or adverse event rates may not differ between extracorporeal shock wave therapy and placebo, but we are uncertain due to the small number of events. There were 11/34 withdrawals in the extracorporeal shock wave therapy group compared with 13/40 withdrawals in the placebo group (RR 0.75, 95% CI 0.43 to 1.31; 7 trials, 581 participants) low-quality evidence (downgraded for bias and imprecision); and 41/156 adverse events with extracorporeal shock wave therapy compared with 10/139 adverse events in the placebo group (RR 3.61, 95% CI 2.00 to 6.52; 5 trials, 295 participants) low-quality evidence (downgraded for bias and imprecision). Subgroup analyses indicated that there were no between-group differences in pain and function outcomes in participants who did or did not have calcific deposits in the rotator cuff.

AUTHORS' CONCLUSIONS

Based upon the currently available low- to moderate-certainty evidence, there were very few clinically important benefits of shock wave therapy, and uncertainty regarding its safety. Wide clinical diversity and varying treatment protocols means that we do not know whether or not some trials tested subtherapeutic doses, possibly underestimating any potential benefits. Further trials of extracorporeal shock wave therapy for rotator cuff disease should be based upon a strong rationale and consideration of whether or not they would alter the conclusions of this review. A standard dose and treatment protocol should be decided upon before further research is conducted. Development of a core set of outcomes for trials of rotator cuff disease and other shoulder disorders would also facilitate our ability to synthesise the evidence.

The Effect of Delayed Injection of Leukocyte-Rich Platelet-Rich Plasma Following Rotator Cuff Repair on Patient Function: A Randomized Double-Blind Controlled Trial

PURPOSE

To investigate the effect of delayed application of leukocyte-rich platelet-rich plasma (PRP) on rotator cuff repair results as assessed by outcome scores and imaging at one year.

METHODS

Patients with a symptomatic rotator cuff tear awaiting arthroscopic repair were approached to take part in the study. Final eligibility for the study was confirmed at the time of surgery. A total of 97 patients were randomized to an ultrasound guided injection of leukocyte-rich PRP or normal saline between 10 and 14 days postsurgery. A total of 87 patients completed clinical evaluation and underwent magnetic resonance imaging imaging at 1 year. Outcome scores included the American Shoulder and Elbow Score, Constant score, Western Ontario Rotator Cuff Index, and the Disabilities of the Arm, Shoulder and Hand Score. Structural integrity of the repair was assessed according to the Sugaya grading. Muscle fatty infiltration was assessed on magnetic resonance imaging using the Goutallier classification.

RESULTS

At 1 year postsurgery, there was no significant difference between the treatment groups on any of the patient-reported outcome measures or Constant score. On postoperative imaging analysis, there was no difference in the retear rates (Sugaya 4 and 5) between the groups (21% in control group vs 15.3% in PRP group). Fatty infiltration on postoperative imaging was found to be significantly higher in the normal saline group compared with the PRP group (Kendall's tau-b P = .032).

CONCLUSIONS

The delayed application of PRP postrotator cuff repair did not improve function as measured by patient-reported outcome measures and Constant score at 1 year postoperatively.

LEVEL OF EVIDENCE

Level II, prospective randomized therapeutic trial.

Surgery for rotator cuff tears

BACKGROUND

This review is one in a series of Cochrane Reviews of interventions for shoulder disorders.

OBJECTIVES

To synthesise the available evidence regarding the benefits and harms of rotator cuff repair with or without subacromial decompression in the treatment of rotator cuff tears of the shoulder.

SEARCH METHODS

We searched the CENTRAL, MEDLINE, Embase, Clinicaltrials.gov and WHO ICRTP registry unrestricted by date or language until 8 January 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs) including adults with full-thickness rotator cuff tears and assessing the effect of rotator cuff repair compared to placebo, no treatment, or any other treatment were included. As there were no trials comparing surgery with placebo, the primary comparison was rotator cuff repair with or without subacromial decompression versus non-operative treatment (exercises with or without glucocorticoid injection). Other comparisons were rotator cuff repair and acromioplasty versus rotator cuff repair alone, and rotator cuff repair and subacromial decompression versus subacromial decompression alone. Major outcomes were mean pain, shoulder function, quality of life, participant-rated global assessment of treatment success, adverse events and serious adverse events. The primary endpoint for this review was one year.

DATA COLLECTION AND ANALYSIS

We used standard methodologic procedures expected by Cochrane.

MAIN RESULTS

We included nine trials with 1007 participants. Three trials compared rotator cuff repair with subacromial decompression followed by exercises with exercise alone. These trials included 339 participants with full-thickness rotator cuff tears diagnosed with magnetic resonance imaging (MRI) or ultrasound examination. One of the three trials also provided up to three glucocorticoid injections in the exercise group. All surgery groups received tendon repair with subacromial decompression and the postoperative exercises were similar to the exercises provided for the non-operative groups. Five trials (526 participants) compared repair with acromioplasty versus repair alone; and one trial (142 participants) compared repair with subacromial decompression versus subacromial decompression alone. The mean age of trial participants ranged between 56 and 68 years, and females comprised 29% to 56% of the participants. Symptom duration varied from a mean of 10 months up to 28 months. Two trials excluded tears with traumatic onset of symptoms. One trial defined a minimum duration of symptoms of six months and required a trial of conservative therapy before inclusion. The trials included mainly repairable full-thickness supraspinatus tears, six trials specifically excluded tears involving the subscapularis tendon. All trials were at risk of bias for several criteria, most notably due to lack of participant and personnel blinding, but also for other reasons such as unclearly reported methods of random sequence generation or allocation concealment (six trials), incomplete outcome data (three trials), selective reporting (six trials), and other biases (six trials). Our main comparison was subacromial decompression versus non-operative treatment and results are reported for the 12 month follow up. At one year, moderate-certainty evidence (downgraded for bias) from 3 trials with 258 participants indicates that surgery probably provides little or no improvement in pain; mean pain (range 0 to 10, higher scores indicate more pain) was 1.6 points with non-operative treatment and 0.87 points better (0.43 better to 1.30 better) with surgery.. Mean function (zero to 100, higher score indicating better outcome) was 72 points with non-operative treatment and 6 points better (2.43 better to 9.54 better) with surgery (3 trials; 269 participants), low-certainty evidence (downgraded for bias and imprecision). Participant-rated global success rate was 873/1000 after non-operative treatment and 943/1000 after surgery corresponding to (risk ratio (RR) 1.08, 95% confidence interval (CI) 0.96 to 1.22; low-certainty evidence (downgraded for bias and imprecision). Health-related quality of life was 57.5 points (SF-36 mental component score, 0 to 100, higher score indicating better quality of life) with non-operative treatment and 1.3 points worse (4.5 worse to 1.9 better) with surgery (1 trial; 103 participants), low-certainty evidence (downgraded for bias and imprecision). We were unable to estimate the risk of adverse events and serious adverse events as only one event was reported across the trials (very low-certainty evidence; downgraded once due to bias and twice due to very serious imprecision).

AUTHORS' CONCLUSIONS

At the moment, we are uncertain whether rotator cuff repair surgery provides clinically meaningful benefits to people with symptomatic tears; it may provide little or no clinically important benefits with respect to pain, function, overall quality of life or participant-rated global assessment of treatment success when compared with non-operative treatment. Surgery may not improve shoulder pain or function compared with exercises, with or without glucocorticoid injections. The trials included have methodology concerns and none included a placebo control. They included participants with mostly small degenerative tears involving the supraspinatus tendon and the conclusions of this review may not be applicable to traumatic tears, large tears involving the subscapularis tendon or young people. Furthermore, the trials did not assess if surgery could prevent arthritic changes in long-term follow-up. Further well-designed trials in this area that include a placebo-surgery control group and long follow-up are needed to further increase certainty about the effects of surgery for rotator cuff tears.

A value-based care analysis of magnetic resonance imaging in patients with suspected rotator cuff tendinopathy and the implicated role of conservative management

BACKGROUND

Magnetic resonance imaging (MRI) is often used to evaluate the integrity of the rotator cuff in patients with suspected full-thickness rotator cuff tears or other cuff tendinopathies. The value of advanced imaging value comes into question when it is used as the initial musculoskeletal imaging test before a trial of conservative therapy in patients with atraumatic shoulder pain, minimal to no strength deficits on examination, and suspected cuff tendinopathy.

METHODS

A prospective study of a group of patients suspected to have cuff tendinopathy based on clinical findings was performed. Every patient underwent MRI and was offered an initial trial of conservative management. Patients had an average follow-up of 28.3 ± 5.3 months after imaging to determine whether surgery was performed.

RESULTS

A total of 51 patients were included in this study. Of this cohort, 46 (90.2%) patients did not go on to surgical intervention, whereas 5 (9.8%) patients did at an average 68.3 days after imaging. These results suggest that over 90.2% of patients (46 of 51) had premature MRI, posing an unnecessary economic burden of $181,619 in advanced imaging charges.

CONCLUSIONS

The use of MRI before a trial of conservative management in patients with atraumatic shoulder pain, minimal to no strength deficits on physical examination, and suspected cuff tendinopathy other than full-thickness tears provides negative value in the management of these patients, at both the individual and population level.

Use of stem cells and growth factors in rotator cuff tendon repair

The management of rotator cuff tears continues to prove challenging for orthopaedic surgeons. Such tears affect most age groups and can lead to significant morbidity in patients. The aetiology of these tears is likely to be multifactorial; however, an understanding of the mechanisms involved is still under review. Despite advancements in surgical operative techniques and the materials used, post-operative recurrence rates after surgical repair remain high. A growing area of research surrounds biological adjuncts used to improve the healing potential of the repaired tissues. This review of recent publications focuses on the strengths and limitations of using stem cells and growth factors in rotator cuff repair.

Musculoskeletal Disorders a Universal Source of Pain and Disability Misunderstood and Mismanaged: A Critical Analysis Based on the U.S. Model of Care

Musculoskeletal disorders are the leading source of pain and disability globally but are especially prevalent in the industrialized nations including the U.S. In addition to the substantial individual suffering caused the rising monetary costs of these disorders are noteworthy. In the U.S. alone the annual costs have been estimated to be $874 billion 5.7% of the annual U.S. G.D.P. Despite these expenditures the care provided to patients with musculoskeletal disorders is highly variable and has regularly been shown to have suboptimal outcomes. The many reasons for this ineffective care include the mutable nature of the prevailing syndromes and their limited and variable understanding. The care rendered by a broad and incongruent group of providers who practice disparate methodologies and employ variable treatments. Disorderedly triage comprised of arbitrary selection of providers, care methodologies, and treatments, which is prone to a range of extraneous influences. Treatments that are unable to apprehend the causative pathological processes, which are therefore progressive, cause irreversible damage to the respective musculoskeletal structures, and result in enduring pain and disability. The overall lack of preventative care and the consequent prevalence of these disorders especially in specific work environments and with certain high-risk life styles. This article makes recommendations for better understanding, prevention, early recognition, timely employment of disease altering therapies, streamlining the existing care, and policy initiatives for waste confinement and improvement. These discernments may improve the overall quality of care provided to these patients, diminish the staggering pain and disability caused, and can reduce the immense costs incurred.

Engineered tendon-fibrocartilage-bone composite and bone marrow-derived mesenchymal stem cell sheet augmentation promotes rotator cuff healing in a non-weight-bearing canine model

Reducing rotator cuff failure after repair remains a challenge due to suboptimal tendon-to-bone healing. In this study we report a novel biomaterial with engineered tendon-fibrocartilage-bone composite (TFBC) and bone marrow-derived mesenchymal stem cell sheet (BMSCS); this construct was tested for augmentation of rotator cuff repair using a canine non-weight-bearing (NWB) model. A total of 42 mixed-breed dogs were randomly allocated to 3 groups (n = 14 each). Unilateral infraspinatus tendon underwent suture repair only (control); augmentation with engineered TFBC alone (TFBC), or augmentation with engineered TFBC and BMSCS (TFBC + BMSCS). Histomorphometric analysis and biomechanical testing were performed at 6 weeks after surgery. The TFBC + BMSCS augmented repairs demonstrated superior histological scores, greater new fibrocartilage formation and collagen fiber organization at the tendon-bone interface compared with the controls. The ultimate failure load and ultimate stress were 286.80 ± 45.02 N and 4.50 ± 1.11 MPa for TFBC + BMSCS group, 163.20 ± 61.21 N and 2.60 ± 0.97 MPa for control group (TFBC + BMSCS vs control, P = 1.12E-04 and 0.003, respectively), 206.10 ± 60.99 N and 3.20 ± 1.31 MPa for TFBC group (TFBC + BMSCS vs TFBC, P = 0.009 and 0.045, respectively). In conclusion, application of an engineered TFBC and BMSCS can enhance rotator cuff healing in terms of anatomic structure, collagen organization and biomechanical strength in a canine NWB model. Combined TFBC and BMSCS augmentation is a promising strategy for rotator cuff tears and has a high potential impact on clinical practice.

Ultrasound-Guided Prolotherapy with Polydeoxyribonucleotide for Painful Rotator Cuff Tendinopathy

Background

Rotator cuff tendinopathy is a primary cause of shoulder pain and dysfunction. Several effective nonsurgical treatment methods have been described for chronic rotator cuff tendinopathy. Prolotherapy with polydeoxyribonucleotide (PDRN), which consists of active deoxyribonucleotide polymers that stimulate tissue repair, is a nonsurgical regenerative injection that may be a viable treatment option. The objective of this study was to assess the efficacy of PDRN in the treatment of chronic rotator cuff tendinopathy.

Method

The records of patients with chronic rotator cuff tendinopathy (n=131) were reviewed retrospectively, and the patients treated with PDRN prolotherapy (n=32) were selected. We measured the main outcome of the shoulder pain and disability index score on a numerical rating scale of average shoulder pain.

Results

Compared with baseline data, significant improvements in the shoulder pain and disability index and pain visual analog scale scores were demonstrated at one week after the end of treatment, and at one month and three months later.

Conclusions

PDRN prolotherapy may improve the conservative treatment of painful rotator cuff tendinopathy for a specific subset of patients.

Cost-effectiveness of magnetic resonance imaging versus ultrasound for the detection of symptomatic full-thickness supraspinatus tendon tears

BACKGROUND

The purpose of this study was to determine the value of magnetic resonance imaging (MRI) and ultrasound-based imaging strategies in the evaluation of a hypothetical population with a symptomatic full-thickness supraspinatus tendon (FTST) tear using formal cost-effectiveness analysis.

METHODS

A decision analytic model from the health care system perspective for 60-year-old patients with symptoms secondary to a suspected FTST tear was used to evaluate the incremental cost-effectiveness of 3 imaging strategies during a 2-year time horizon: MRI, ultrasound, and ultrasound followed by MRI. Comprehensive literature search and expert opinion provided data on cost, probability, and quality of life estimates. The primary effectiveness outcome was quality-adjusted life-years (QALYs) through 2 years, with a willingness-to-pay threshold set to $100,000/QALY gained (2016 U.S. dollars). Costs and health benefits were discounted at 3%.

RESULTS

Ultrasound was the least costly strategy ($1385). MRI was the most effective (1.332 QALYs). Ultrasound was the most cost-effective strategy but was not dominant. The incremental cost-effectiveness ratio for MRI was $22,756/QALY gained, below the willingness-to-pay threshold. Two-way sensitivity analysis demonstrated that MRI was favored over the other imaging strategies over a wide range of reasonable costs. In probabilistic sensitivity analysis, MRI was the preferred imaging strategy in 78% of the simulations.

CONCLUSION

MRI and ultrasound represent cost-effective imaging options for evaluation of the patient thought to have a symptomatic FTST tear. The results indicate that MRI is the preferred strategy based on cost-effectiveness criteria, although the decision between MRI and ultrasound for an imaging center is likely to be dependent on additional factors, such as available resources and workflow.

Autologous tendon-derived cell-seeded nanofibrous scaffolds improve rotator cuff repair in an age-dependent fashion

Rotator cuff tendon tears are one of the most common shoulder pathologies, especially in the aging population. Due to a poor healing response and degenerative changes associated with aging, rotator cuff repair failure remains common. Although cell-based therapies to augment rotator cuff repair appear promising, it is unknown whether the success of such a therapy is age-dependent. We hypothesized that autologous cell therapy would improve tendon-to-bone healing across age groups, with autologous juvenile cells realizing the greatest benefit. In this study, juvenile, adult, and aged rats underwent bilateral supraspinatus tendon repair with augmentation of one shoulder with autologous tendon-derived cell-seeded polycaprolactone scaffolds. At 8 weeks, shoulders treated with cells in both juvenile and aged animals exhibited increased cellularity, increased collagen organization, and improved mechanical properties. No changes between treated and control limbs were seen in adult rats. These findings suggest that cell delivery during supraspinatus repair initiates earlier matrix remodeling in juvenile and aged animals. This may be due to the relative "equilibrium" of adult tendon tissue with regards to catabolic and anabolic processes, contrasted with actively growing juvenile tendons and degenerative aged tendons. This study demonstrates the potential for autologous cell-seeded scaffolds to improve repairs in both the juvenile and aged population. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1250-1257, 2017.

Evaluation of the Bone-ligament and tendon insertions based on Raman spectrum and its PCA and CLS analysis

Injuries to the Anterior Cruciate Ligament (ACL) and Rotator Cuff Tendon (RCT) are common in physically active and elderly individuals. The development of an artificial prosthesis for reconstruction/repair of ACL and RCT injuries is of increasing interest due to the need for viable tissue and reduced surgically-related co-morbidity. An optimal prosthesis design is still elusive, therefore an improved understanding of the bone-soft tissue interface is extremely urgent. In this work, Raman spectral mapping was used to analyze, at the micron level, the chemical composition and corresponding structure of the bone-soft tissue interface. Raman spectroscopic mapping was performed using a Raman spectrometer with a 785 nm laser coupled to a microscope. Line-mapping procedure was performed on the ACL and RCT bone insertion sites. The classical least squares (CLS) fitting model was created from reference spectra derived from pure bone and soft-tissue components, and spectral maps collected at multiple sites from ACL and RCT specimens. The results suggest that different source of interface shows different boundary, even they seems have the same components. Compared to the common histology results, it provided intact molecular information that can easily distinguished some relative component change.

Biologic and Synthetic Grafts in the Reconstruction of Large to Massive Rotator Cuff Tears

Rotator cuff injuries are common in both young and elderly patients. Despite improvements in instrumentation and surgical techniques, the failure rates following tendon reconstruction remain unacceptably high. To improve outcomes, graft patches have been developed to provide mechanical strength and to furnish a scaffold for biologic growth across the delicate tendon-bone junction. Although no patch effectively re-creates the structured, highly organized system of prenatal tendon development, augmenting rotator cuff repair may help restore native tendon-to-bone attachment while reproducing the mechanical and biologic properties of native tendon. An understanding of biologically and synthetically derived grafts, along with knowledge of the preliminary data available regarding their combined use with growth factors and stem cells, is needed to improve management and treatment outcomes. The current literature has not been consistent in showing patch augmentation to be beneficial over traditional repair, but novel scaffolding materials may help facilitate rotator cuff tendon repair that is histologically and biomechanically comparable to native tendon.

Rotator cuff repair: a review of surgical techniques, animal models, and new technologies under development

Rotator cuff tears are the most common musculoskeletal injury occurring in the shoulder. Current surgical repair fails to heal in 20% to 95% of patients, depending on age, size of the tear, smoking, time of repair, tendon quality, muscle quality, healing response, and surgical treatments. These problems are worsened by the limited healing potential of injured tendons attributed to the presence of degenerative changes and relatively poor vascularity of the cuff tendons. Development of new techniques to treat rotator cuff tears requires testing in animal models to assess safety and efficacy before clinical testing. Hence, it is important to evaluate appropriate animal models for rotator cuff research with degeneration of tendons, muscular atrophy, and fatty infiltration similar to humans. This report reviews current clinical treatments and preclinical approaches for rotator cuff tear repair. The review will focus on current clinical surgical treatments, new repair strategies under clinical and preclinical development, and will also describe different animal models available for rotator cuff research. These findings and future directions for rotator cuff tear repair will be discussed.

Polydeoxyribonucleotide Injection in the Treatment of Chronic Supraspinatus Tendinopathy: A Case-Controlled, Retrospective, Comparative Study With 6-Month Follow-Up

OBJECTIVE

To determine the efficacy of polydeoxyribonucleotide (PDRN) injection for rotator cuff disease (RCD).

DESIGN

Case-controlled, retrospective, comparative study.

SETTING

Outpatient clinic at a university-affiliated tertiary care hospital.

PARTICIPANTS

Patients (N=106) with chronic nontraumatic refractory RCD who were unresponsive to at least 1 month of conservative treatment: 55 patients received PDRN injection (PDRN group) and 51 continued conservative treatment (control group).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Shoulder Pain and Disability Index, score on a visual analog scale of the average shoulder pain level, number of analgesic ingestions per day, isometric strength of shoulder abductor, active range of motion (flexion, abduction, internal rotation, external rotation), and maximal tear size of tendon on ultrasonography at pretreatment and 3 and 6 months postinjection.

RESULTS

There was no significant difference between the 2 groups in terms of age, sex, shoulder affected, duration of symptoms, and ultrasonographic findings at pretreatment. Compared with the control group, the treatment group showed a significant improvement in Shoulder Pain and Disability Index, visual analog scale score, and number of analgesic ingestions per day. However, there was no difference in isometric strength, active range of motion, and maximal tear size of tendon. No adverse events were reported.

CONCLUSIONS

To our knowledge, this is the first study to assess the efficacy of PDRN injection for patients with RCD. The PDRN injection group showed improvement in pain and subjective disability in patients with RCD and continued to show improvement for 3 months thereafter; the PDRN injection can be an optional treatment for patients with chronic RCD who show no response to other treatments.

Common sports-related shoulder injuries

Shoulder pain is commonly treated in general practice; its causes are often multi-factorial. The focus of this article is on sports-related shoulder injuries likely to be seen in the community. This article aims to overview the presentation, assessment and management of these conditions in general practice.

Using the zebrafish to understand tendon development and repair

Tendons are important components of our musculoskeletal system. Injuries to these tissues are very common, resulting from occupational-related injuries, sports-related trauma, and age-related degeneration. Unfortunately, there are few treatment options, and current therapies rarely restore injured tendons to their original function. An improved understanding of the pathways regulating their development and repair would have significant impact in stimulating the formulation of regenerative-based approaches for tendon injury. The zebrafish provides an ideal system in which to perform genetic and chemical screens to identify new pathways involved in tendon biology. Until recently, there had been few descriptions of tendons and ligaments in the zebrafish and their similarity to mammalian tendon tissues. In this chapter, we describe the development of the zebrafish tendon and ligament tissues in the context of their gene expression, structure, and interactions with neighboring musculoskeletal tissues. We highlight the similarities with tendon development in higher vertebrates, showing that the craniofacial tendons and ligaments in zebrafish morphologically, molecularly, and structurally resemble mammalian tendons and ligaments from embryonic to adult stages. We detail methods for fluorescent in situ hybridization and immunohistochemistry as an assay to examine morphological changes in the zebrafish musculoskeleton. Staining assays such as these could provide the foundation for screen-based approaches to identify new regulators of tendon development, morphogenesis, and repair. These discoveries would provide new targets and pathways to study in the context of regenerative medicine-based approaches to improve tendon healing.

Proposal and Evaluation of a Telerehabilitation Platform Designed for Patients With Partial Rotator Cuff Tears: A Preliminary Study

Objective

To propose and evaluate the effectiveness of a telerehabilitation platform designed for patients with rotator cuff (RC) tears.

Methods

During the first study phase, a virtual service platform that included information on RC tear pathology, joint care, and a series of instructions regarding therapeutic exercise was designed and created. Subsequently, in the clinical phase, a quasi-experimental study was performed. The platform was tested on patients and evaluated at baseline and at 1, 2, 3, and 6 months with respect to their pain levels and functionality on the Constant-Murley (CM) scale.

Results

Eleven patients were included, 5 women and 6 men, with a median age of 55 years (range, 42–68 years). Pain diminished from a baseline value of 64 mm (range, 40–80 mm) to 16 mm (range, 0–30 mm) at 6 months (p<0.001). Points on the CM scale rose from a baseline value of 54 points (range, 51–66 points) to 85 points (range, 70–100 points) at 6 months (p=0.001). Functionality in daily living and work activities, movement, and strength exhibited significant changes at 6 months (p<0.05).

Conclusion

Significant changes were observed in pain and functionality in this group of participants who used a telerehabilitation platform. To the best of our knowledge, this is the first study that included a specific program for RC tears.

The Current Perspectives of Stem Cell Therapy in Orthopedic Surgery

CONTEXT

Musculoskeletal injuries may be painful, troublesome, life limiting and also one of the global health problems. There has been considerable amount of interest during the past two decades to stem cells and tissue engineering techniques in orthopedic surgery, especially to manage special and compulsive injuries within the musculoskeletal system.

EVIDENCE ACQUISITION

The aim of this study was to present a literature review regarding the most recent progress in stem cell procedures and current indications in orthopedics clinical care practice. The Medline and PubMed library databases were searched for the articles related with stem cell procedures in the field of orthopedic surgery and additionally the reference list of each article was also included to provide a comprehensive evaluation.

RESULTS

Various sources of stem cells have been studied for orthopedics clinical care practice. Stem cell therapy has successfully used for major orthopedic procedures in terms of bone-joint injuries (fractures-bone defects, nonunion, and spinal injuries), osteoarthritis-cartilage defects, ligament-tendon injuries, femoral head osteonecrosis and osteogenesis imperfecta. Stem cells have also used in bone tissue engineering in combining with the scaffolds and provided faster and better healing of tissues.

CONCLUSIONS

Large amounts of preclinical studies have been made of stem cells and there is an increasing interest to perform these studies within the human population but preclinical studies are insufficient; therefore, much more and efficient studies should be conducted to evaluate the efficacy and safety of stem cells.

Risk Factors, Pathobiomechanics and Physical Examination of Rotator Cuff Tears

Background:

It is important to appreciate the risk factors for the development of rotator cuff tears and specific physical examination maneuvers.

Methods:

A selective literature search was performed.

Results:

Numerous well-designed studies have demonstrated that common risk factors include age, occupation, and anatomic considerations such as the critical shoulder angle. Recently, research has also reported a genetic component as well. The rotator cuff axially compresses the humeral head in the glenohumeral joint and provides rotational motion and abduction. Forces are grouped into coronal and axial force couples. Rotator cuff tears are thought to occur when the force couples become imbalanced.

Conclusion:

Physical examination is essential to determining whether a patient has an anterosuperior or posterosuperior tear. Diagnostic accuracy increases when combining a series of examination maneuvers.

Stem cell procedures in arthroscopic surgery

The stem cell as the building block necessary for tissue reparation and homeostasis plays a major role in regenerative medicine. Their unique property of being pluripotent, able to control immune process and even secrete a whole army of anabolic mediators, draws interest. While new arthroscopic procedures and techniques involving stem cells have been established over the last decade with improved outcomes, failures and dissatisfaction still occur. Therefore, there is increasing interest in ways to improve the healing response. MSCs are particularly promising for this task given their regenerative potential. While methods of isolating those cells are no longer poses a challenge, the best way of application is not clear. Several experiments in the realm of basic science and animal models have recently been published, addressing this issue, yet the application in clinical practice has lagged. This review provides an overview addressing the current standing of MSCs in the field of arthroscopic surgery.

Rotator cuff tears: Review of epidemiology, clinical assessment and operative treatment

Rotator cuff tears (RTCs) are the most common cause of shoulder disability. There has been a proportional increase in the prevalence of RCT in accordance with the rising trend of an ageing population. In this article we review the current literature encompassing RCT epidemiology, risk factors and aetiopathogenesis. We also summarize the current diagnostic modalities, treatment options, rehabilitation and outcomes.

Platelets and plasma stimulate sheep rotator cuff tendon tenocytes when cultured in an extracellular matrix scaffold

The addition of platelet-rich plasma (PRP) to rotator cuff repair has not translated into improved outcomes after surgery. However, recent work stimulating ligament healing has demonstrated improved outcomes when PRP or whole blood is combined with an extracellular matrix carrier. The objective of this study was to evaluate the effect of three components of blood (plasma, platelets, and macrophages) on the in vitro activity of ovine rotator cuff cells cultured in an extracellular matrix environment. Tenocytes were obtained from six ovine infraspinatus tendons and cultured over 14 days in an extracellular matrix scaffold with the following additives: (1) plasma (PPP), (2) plasma and platelets (PAP), (3) plasma and macrophages (PPPM), (4) plasma, platelets and macrophages (PAPM), (5) phosphate buffered saline (PBS), and (6) PBS with macrophages (PBSM). Assays measuring cellular metabolism (AlamarBlue), proliferation (Quantitative DNA assay), synthesis of collagen and cytokines (SIRCOL, TNF-α and IL-10 ELISA, and MMP assay), and collagen gene expression (qPCR) were performed over the duration of the experiment, as well as histology at the conclusion. Plasma was found to stimulate cell attachment and spreading on the scaffold, as well as cellular proliferation. Platelets also stimulated cell proliferation, cellular metabolism, transition of cells to a myofibroblast phenotype, and contraction of the scaffolds. The addition of macrophages did not have any significant effect on the sheep rotator cuff cells in vitro. In vivo studies are needed to determine whether these changes in cellular function will translate into improved tendon healing.

Early mobilisation following mini-open rotator cuff repair: a randomised control trial

This study compared the clinical outcomes following mini-open rotator cuff repair (MORCR) between early mobilisation and usual care, involving initial immobilisation. In total, 189 patients with radiologically-confirmed full-thickness rotator cuff tears underwent MORCR and were randomised to either early mobilisation (n = 97) or standard rehabilitation (n = 92) groups. Patients were assessed at six weeks and three, six, 12 and 24 months post-operatively. Six-week range of movement comparisons demonstrated significantly increased abduction (p = 0.002) and scapular plane elevation (p = 0.006) in the early mobilisation group, an effect which was not detectable at three months (p > 0.51) or afterwards. At 24 months post-operatively, patients who performed pain-free, early active mobilisation for activities of daily living showed no difference in clinical outcomes from patients immobilised for six weeks following MORCR. We suggest that the choice of rehabilitation regime following MORCR may be left to the discretion of the patient and the treating surgeon.

Effects of low-intensity non-coherent light therapy on the inflammatory process in the calcaneal tendon of ovariectomized rats

The aim of this experimental study was to investigate the effects of low-intensity light-emitting diode (LED) phototherapy on the inflammatory process in the calcaneal tendon of ovariectomized rats (OVX) through the involvement of the inflammatory mediators interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha (TNF-α). Thirty-five female Wistar rats were divided into 4 groups: 3 groups of OVX rats totaling 30 rats (untreated OVX rats [OVX injury group], treated OVX rats [OVX LED group], and control OVX rats; subgroups existed based on the sampling times, which were 3, 7, and 14 days) and 1 group of non-OVX rats (not OVX; n = 5). Tendon injury was induced by trauma using a 208-g mass placed at 20 cm from the right tendon of each animal with energy of 0.70 J. The animals were treated 12 h after tendonitis with LED therapy and every 48 h thereafter until euthanasia (at 3, 7, or 14 days). The tendons were dissected and stored in liquid nitrogen at -196 °C, thawed only at the time of immunoenzymatic testing (ELISA). Groups treated with LED showed a decrease in the number of pro-inflammatory cells, IL-6, and TNF-α (p <0.05), and an increase in IL-10 (p < 0.05) when compared to the not OVX group (p < 0.05). It was concluded that low-intensity LED treatment using the parameters and wavelength of 945 nm in the time periods studied reduced the release of IL-6 and TNF-α and increased the release of IL-10, thereby improving the inflammatory response in OVX rats.

Regenerative biology of tendon: mechanisms for renewal and repair

Understanding the molecular and cellular mechanisms underlying tissue turnover and repair are essential towards addressing pathologies in aging, injury and disease. Each tissue has distinct means of maintaining homeostasis and healing after injury. For some, resident stem cell populations mediate both of these processes. These stem cells, by definition, are self renewing and give rise to all the differentiated cells of that tissue. However, not all organs fit with this traditional stem cell model of regeneration, and some do not appear to harbor somatic stem or progenitor cells capable of multilineage in vivo reconstitution. Despite recent progress in tendon progenitor cell research, our current knowledge of the mechanisms regulating tendon cell homeostasis and injury response is limited. Understanding the role of resident tendon cell populations is of great importance for regenerative medicine based approaches to tendon injuries and disease. The goal of this review is to bring to light our current knowledge regarding tendon progenitor cells and their role in tissue maintenance and repair. We will focus on pressing questions in the field and the new tools, including model systems, available to address them.