Chronic Rotator Cuff Tears Research Articles

Risk factors of radiographic severity of massive rotator cuff tear

As massive rotator cuff tears progress, various radiographic changes occur; however, the factors associated with radiographic changes remain largely unknown. This study aimed to determine the factors that affect radiographic severity in massive rotator cuff tears using multivariate analyses. We retrospectively reviewed 210 shoulders with chronic massive rotator cuff tears. The dependent variables were superior migration of the humeral head (Hamada grades 2–3), narrowing of the glenohumeral joint (grade 4), and humeral head collapse (grade 5). Baseline variables that were significant in univariate analyses were included in multivariate models. There were 91, 59, 43, and 17 shoulders classified as Hamada grades 1, 2–3, 4, and 5, respectively. Multivariate analysis showed that infraspinatus tear (P = 0.015) and long head of biceps (LHB) tendon rupture (P = 0.007) were associated with superior migration of humeral head. Superior subscapularis tear (P = 0.003) and LHB tendon rupture (P < 0.001) were associated with narrowing of glenohumeral joint. Female sex (P = 0.006) and superior subscapularis tear (P = 0.006) were associated with humeral head collapse. This study identified the rupture of infraspinatus and LHB as risk factors of superior migration of humeral head, and the rupture of subscapularis and LHB and female sex as risk factors of cuff tear arthropathy.

Muscle degeneration in chronic massive rotator cuff tears of the shoulder: Addressing the real problem using a graphene matrix

Massive rotator cuff tears (MRCTs) of the shoulder cause disability and pain among the adult population. In chronic injuries, the tendon retraction and subsequently the loss of mechanical load lead to muscle atrophy, fat accumulation, and fibrosis formation over time. The intrinsic repair mechanism of muscle and the successful repair of the torn tendon cannot reverse the muscle degeneration following MRCTs. To address these limitations, we developed an electroconductive matrix by incorporating graphene nanoplatelets (GnPs) into aligned poly(l-lactic acid) (PLLA) nanofibers. This study aimed to understand 1) the effects of GnP matrices on muscle regeneration and inhibition of fat formation invitro and 2) the ability of GnP matrices to reverse muscle degenerative changes invivo following an MRCT. The GnP matrix significantly increased myotube formation, which can be attributed to enhanced intracellular calcium ions in myoblasts. Moreover, the GnP matrix suppressed adipogenesis in adipose-derived stem cells. These results supported the clinical effects of the GnP matrix on reducing fat accumulation and muscle atrophy. The histological evaluation showed the potential of the GnP matrix to reverse muscle atrophy, fat accumulation, and fibrosis in both supraspinatus and infraspinatus muscles at 24 and 32 wk after the chronic MRCTs of the rat shoulder. The pathological evaluation of internal organs confirmed the long-term biocompatibility of the GnP matrix. We found that reversing muscle degenerative changes improved the morphology and tensile properties of the tendon compared with current surgical techniques. The long-term biocompatibility and the ability of the GnP matrix to treat muscle degeneration are promising for the realization of MRCT healing and regeneration.

Arthroscopic Rotator Cuff Repair with a Fibrin Scaffold Containing Growth Factors and Autologous Progenitor Cells Derived From Humeral cBMA Improves Clinical Outcomes in High Risk Patients

PurposeTo report the clinical outcomes after biologically augmented rotator cuff repair (RCR) with a fibrin scaffold derived from autologous whole blood and supplemented with concentrated bone marrow aspirate (cBMA) harvested at the proximal humerus.MethodsPatients who underwent arthroscopic RCR with biologic augmentation using a fibrin clot scaffold (“Mega- Clot”) containing progenitor cells and growth factors from proximal humerus BMA and autologous whole blood between April 2015 and January 2018 were prospectively followed. Only high-risk patients in primary and revision cases that possessed relevant comorbidities or physically demanding occupation were included. Minimum follow-up for inclusion was 1 year. The visual analog score for pain (VAS), American Shoulder and Elbow Surgeons (ASES), Simple Shoulder Test (SST), Single Assessment Numerical Evaluation (SANE), and Constant-Murley scores were collected preoperatively and at final follow-up. In vitro analyses of the cBMA and fibrin clot using nucleated cell count, colony forming units, and live/dead assays were used to quantify the substrates.ResultsThirteen patients (56.9 ± 7.7 years) were included. The mean follow-up was 26.9 ± 17.7 months (n = 13). There were significant improvements in all outcome scores from the preoperative to the postoperative state: VAS (5.6 ± 2.5 to 3.1 ± 3.2; P < .001), ASES (42.0 ± 17.1 to 65.5 ± 30.6; P < .001), SST (3.2 ± 2.8 to 6.5 ± 4.7; P = .002), SANE (11.5 ± 15.6 to 50.3 ± 36.5; P < .001), and Constant-Murley (38.9 ± 17.5 to 58.1 ± 26.3; P < .001). Six patients (46%) had retears on postoperative MRI, despite all having improvements in pain and function except one. All failures were chronic rotator cuff tears, and all were revision cases except one (1.6 ± 0.5 previous RCRs). The representative sample of harvested cBMA showed an average of 28.5 ± 9.1 × 106 nucleated cells per mL.ConclusionsArthroscopic rotator cuff repairs that are biologically augmented with a fibrin scaffold containing growth factors and autologous progenitor cells derived from autologous whole blood and humeral cBMA can improve clinical outcomes in primary, as well as revision cases in high-risk patients. However, the incidence of retears remains a concern in this population, demanding further improvements in biologic augmentation.Level of EvidenceIV, therapeutic case series.

Three-dimensionally printed recombinant human parathyroid hormone-soaked nanofiber sheet accelerates tendon-to-bone healing in a rabbit model of chronic rotator cuff tear.

Recombinant human parathyroid hormone (rhPTH) promotes tendon-to-bone healing in humans and animals with rotator cuff tear (RCT). However, problems regarding repeated systemic rhPTH injections in humans exist. This study was conducted to evaluate the effect of topical rhPTH administration using 3-dimensionally (3D) printed nanofiber sheets on tendon-to-bone healing in a rabbit RCT model compared to that of direct topical rhPTH administration. Eighty rabbits were randomly assigned to 5 groups (n=16 each). To create the chronic RCT model, we induced complete supraspinatus tendon tears in both shoulders and left them untreated for 6weeks. All transected tendons were repaired in a transosseous manner with saline injection in group A, hyaluronic acid (HA) injection in group B, 3D-printed nanofiber sheet fixation in group C, rhPTH and HA injection in group D, and 3D-printed rhPTH- and HA-soaked nanofiber sheet fixation in group E. Genetic (messenger RNA expression evaluation) and histologic evaluations (hematoxylin and eosin and Masson trichrome staining) were performed in half of the rabbits at 4weeks postrepair. Genetic, histologic, and biomechanical evaluations (mode of tear and load to failure) were performedin the remaining rabbits at 12weeks. For genetic evaluation, group E showed a higher collagen type I alpha 1 expression level than did the other groups (P=.008) at 4weeks. However, its expression level was downregulated, and there was no difference at 12weeks. For histologic evaluation, group E showed greater collagen fiber continuity, denser collagen fibers, and more mature tendon-to-bone junction than did the other groups (P=.001, P=.001, and P=.003, respectively) at 12weeks. For biomechanical evaluation, group E showed a higher load-to-failure rate than did the other groups (P<.001) at 12weeks. Three-dimensionally printed rhPTH-soaked nanofiber sheet fixation can promote tendon-to-bone healing of chronic RCT.

Tissue-engineered tendon nano-constructs for repair of chronic rotator cuff tears in large animal models.

Chronic rotator cuff tears (RCTs) are one of the most common injuries of shoulder pain. Despite the recent advances in surgical techniques and improved clinical outcomes of arthroscopically repaired rotator cuffs (RCs), complete functional recovery-without retear-of the RC tendon through tendon-to-bone interface (TBI) regeneration remains a key clinical goal to be achieved. Inspired by the highly organized nanostructured extracellular matrix in RC tendon tissue, we propose herein a tissue-engineered tendon nano-construct (TNC) for RC tendon regeneration. When compared with two currently used strategies (i.e., transosseous sutures and stem cell injections), our nano-construct facilitated more significant healing of all parts of the TBI (i.e., tendon, fibrocartilages, and bone) in both rabbit and pig RCT models owing to its enhancements in cell proliferation and differentiation, protein expression, and growth factor secretion. Overall, our findings demonstrate the high potential of this transplantable tendon nano-construct for clinical repair of chronic RCTs.

Histological changes and neural elements in the subacromial bursa on patients with rotator cuff tear: Pilot study.

Objective:This study aimed to investigate the neural elements of the subacromial bursa (SAB) in rotator cuff tears.Materials and methods:Twenty patients with rotator cuff tears were recruited, and their visual analog scale (VAS) score, duration of symptoms, and range of motion (ROM), including flexion, external rotation, and internal rotation were evaluated. Tear size was measured using magnetic resonance imaging (MRI). The SAB specimens obtained during arthroscopic rotator cuff repair were studied using routine hematoxylin and eosin staining and immunohistochemistry (S-100 protein and PGP 9.5 protein). The SAB specimen for the control group was obtained from 2 fresh cadavers and 2 patients with acute humeral shaft fracture. The Mann-Whitney U test was applied to assess the difference between histological findings of the rotator cuff tear group and control group. The correlation between the histological findings and clinical features was evaluated using the Spearman correlation coefficient.Results:The mean duration of symptom was 10.2 ± 6.4 months. The preoperative average VAS score was 2.9 ± 1.2. The degrees of preoperative ROM in forward flexion and external and internal rotations were 143.8 ± 19.5, 49.5 ± 23.1, and –4.3 ± 4.2, respectively. The tear was 2.0 ± 0.9 cm. For histological findings, the number of neural elements per low power field in the rotator cuff tear group was significantly less than the control group in both immunohistochemical stainings (S-100: 0.5 ± 0.7 vs 2.8 ± 0.5, p < .01; PGP 9.5: 0.4 ± 0.7 vs 3.5 ± 0.6, p < .01). During the correlation analysis, the number of neural elements in the PGP 9.5 staining was negatively correlated with the ROM in forward flexion and external rotation.Conclusion:This study revealed that chronic rotator cuff tears may induce degeneration of neural elements in SAB.

Insurance status is not a predictor of rotator cuff tear magnitude.

BackgroundRotator cuff tear (RCT) chronicity is an important factor in considering treatment options and outcomes for surgical repair. Many factors may contribute to delayed treatment, including timely access to care due to insurance status. The purpose of this study was to evaluate the relationship between the magnitude of RCT on presentation and insurance status. We hypothesize that publicly insured patients will have a greater incidence of chronic RCTs and shoulder pathology on initial presentation.MethodsRetrospective chart review of patients undergoing RCT repair at an academic tertiary care institution from 2005 to 2019. Demographic data, including age, race, sex, and insurance carrier, were collected. Insurance carriers were categorized into public (Medicare and Medicaid) or private insurance coverage. Individual magnetic resonance imagings were then reviewed by a board-certified musculoskeletal radiologist for supraspinatus (SS), infraspinatus (IS), subscapularis, and biceps tendon tears, as well as acromioclavicular arthritis. In addition, rotator cuff atrophy was evaluated by the scapular ratio. Univariate analysis of variance and logistic regression analyses were used to compare demographics and rotator cuff pathology between those with Medicaid and Medicare, as well as between publicly and privately insured patients.ResultsOf the 492 patients in this study, 192 had private insurance, and 300 had public insurance (Medicaid: 50 and Medicare: 250). Insurance status was not found to be associated with differences in RCTs between Medicare and Medicaid patients. Those with Medicaid or Medicare (public), presented more frequently with SS or IS atrophy (SS atrophy, P = .002; IS atrophy, P = .039) than those with private insurance. However, after adjusting for age, no significant differences in rotator cuff tendon tear or atrophy frequencies were found between insurance groups.ConclusionsPatients with private and public insurance tend to present with similar chronicity and magnitude of RCTs. Insurance status does not appear to influence timely access to surgical care for patients with RCTs at an academic medical center.

Loading Mesenchymal Stem Cell–Derived Exosomes Into a Traditionally Designed Rotator Cuff Patch: A Potential Strategy to Enhance the Repair of Chronic Rotator Cuff Tear Associated With Degenerative Changes

Background: Retraction and degenerative changes of chronic rotator cuff tears limit the healing capacity after routine surgical repair. Purpose: To fabricate a mesenchymal stem cell–derived exosome (MSC–Exos) loaded patch and evaluate the effect of this patch on the activity of rabbit tenocytes in vitro and on the repair of chronic rotator cuff tears associated with degenerative changes in vivo. Study Design: Controlled laboratory study. Methods: The MSC–Exos loaded patch was fabricated using a dynamic wet-spinning system. In the in vitro studies, the proliferation and migration activities of tenocytes were evaluated by culturing tenocytes with saline, a fiber-aligned patch, or an MSC–Exos loaded patch. In the in vivo studies, a rabbit model of chronic rotator cuff tear was established and directly repaired, repaired with fiber-aligned patch augmentation (RFPA group), and repaired with MSC–Exos loaded patch augmentation (REPA group). Histological and biomechanical analyses were performed at 4, 8, and 12 weeks after surgery. Results: An MSC–Exos loaded patch with inner aligned fibers, a loose microstructure, and reliable initial strength was fabricated using a dynamic wet-spinning system. The MSC–Exos loaded patch significantly promoted tenocyte proliferation and migration activities in vitro. In vivo, the REPA group exhibited significantly higher tendon maturing scores at 8 and 12 weeks after surgery compared with both the control and the RFPA groups. Fatty infiltration was significantly reduced in the REPA group at 4, 8, and 12 weeks compared with both the control and the RFPA groups. Biomechanical properties, including load to failure and stress, were also significantly improved at 12 weeks in the REPA group compared with both the control and the RFPA groups. Conclusion: Results in the present study suggested that an MSC–Exos loaded patch was able to enhance the repair of a chronic rotator cuff tear by providing mechanical support and minimizing degeneration. Clinical Relevance: This work supported the idea that loading bioactive MSC–Exos into a traditionally designed rotator cuff patch might exert a better effect on the repair of chronic rotator cuff tears than augmented patch repair alone.

The responsiveness and validity of the Rotator Cuff Quality of Life (RC-QOL) index in a 2-year follow-up study.

BackgroundThe Rotator Cuff Quality of Life (RC-QOL) index was developed to evaluate quality of life in patients with rotator cuff disease. This study provides additional psychometric testing in accordance with the Consensus-Based Standards for the Selection of Health Measurement Instruments guidelines.MethodsThis was a 2-year follow-up study on 66 patients (mean age, 59 ± 10 years) originally presenting with chronic full-thickness rotator cuff tears to a tertiary care center. The methodology involved testing internal consistency, content validity, and criterion validity. Responsiveness was evaluated using 3 strategies: 1) standardized response mean of the raw change scores; 2) Guyatt’s Responsiveness Index; and 3) Global Rating Scales of improvement correlated to a quality of life measure.ResultsContent validity was confirmed with a Cronbach α of 0.92 (95% confidence interval, 0.92-0.95) and absence of floor and ceiling effects. Criterion validity was confirmed using the Western Ontario Rotator Cuff Index as a reference standard (r = 0.87, P < .001). The effect size of distribution-based methods of determining responsiveness was large (0.99-1.09) compared to that of mixed- and anchor-based methods (0.47-0.89). All responsiveness calculations met minimum requirements for acceptable thresholds.ConclusionThe RC-QOL is a valid and responsive measure of health-related quality of life in patients with chronic rotator cuff pathology. The results of this study added to the methodologic quality assessment of the RC-QOL, completing 7 of 10 Consensus-Based Standards for the Selection of Health Measurement Instruments criteria.

An Arthroscopy-Assisted Mini-Invasive Technique to Create a Chronic Rabbit Model With Massive and Retracted Supraspinatus Rotator Cuff Tears

Understanding the pathophysiology of rotator cuff tears (RCTs) in animal models is of great importance, as it helps in the development of repair strategies and therapeutic treatments for rotator cuff diseases in humans. This Technical Note describes a comprehensive step-by-step description of an arthroscopic-assisted minimally invasive RCT model in rabbits. This technique is beneficial because the rabbit has rotator cuffs anatomically similar to those of humans, and it has been widely used as a preclinical animal model in the basic science literature. Compared with other small animals (e.g., mice and rats), the advantage of the rabbit model is that it can test the effectiveness and healing process of new surgical repair techniques that require relatively larger anatomical structures. Moreover, it is more cost-effective compared with larger animal models, such as sheep and canines. This arthroscopic-assisted mini-invasive technique to create an RCT model may have a better effect on simulating the degenerative and chronic RCT state in humans than the commonly used open surgery, along with an earlier return to activities, less scarring and tissue adhesion, fewer injuries to the deltoid, and fewer complications.

Abaloparatide Improves Rotator Cuff Healing via Anabolic Effects on Bone Remodeling in a Chronic Rotator Cuff Tear Model of Rat With Osteoporosis: A Comparison With Denosumab

Background: Because of poor clinical outcomes, rotator cuff healing in patients with osteoporosis has recently gained attention. Antiresorptive therapy for osteoporosis has been reported to improve healing after repair. However, the comparative effectiveness of anabolic and antiresorptive agents has not been investigated. Hypothesis: Anabolic therapy with abaloparatide (ABL) would outperform antiresorptive therapy with denosumab (Dmab) to improve rotator cuff healing in the osteoporotic status. Study Design: Controlled laboratory study. Methods: A chronic rotator cuff tear model was established in ovariectomy-induced postmenopausal osteoporotic rats. Then, bilateral rotator cuff repairs were conducted in all experimental rats, which were randomly divided into control (CON), Dmab, and ABL groups to receive the corresponding subcutaneous injections. The rats sacrificed at 2 weeks (the early healing period) were used to detect osteoblast and osteoclast activities, related gene expression (osteoclastogenesis, osteogenesis, and chondrogenesis), new bone formation, and mineralization. In the rats sacrificed at 4 and 8 weeks, the bone mineral density and bone architecture at the repaired site were assessed by micro–computed tomography, and rotator cuff healing was evaluated using histological and biomechanical analyses. Results: At 8 weeks, significantly higher failure load and stiffness were observed in the ABL (25.13 ± 3.54 N, P < .001; 21.65 ± 3.08 N/mm, P < .001; respectively), and Dmab (21.21 ± 2.55 N, P < .001; 16.15 ± 2.07 N/mm, P = .008; respectively) groups than in the CON group (13.36 ± 1.70 N; 11.20 ± 2.59 N/mm; respectively), whereas the ABL treatment provided better failure load and stiffness than Dmab (P = .019; P = .003). Although tendon-to-bone healing was improved by Dmab, the most mature tendon insertion at the interface was observed in the ABL group, including a more organized collagen and fibrocartilage and higher bone quality. ABL significantly promoted bone remodeling via coupling between osteoclasts and osteoblasts (osteoblast to osteoclast ratio: 4.80 ± 0.39; P = .022), thereby stimulating more new bone formation and mineralization at the tendon-to-bone healing interface than Dmab (osteoblast to osteoclast ratio: 3.21 ± 0.75) at 2 weeks. Moreover, ABL had significant effects on gene expression [Runt-realted transcription factor 2 (Runx2, collagen type I-alpha 1 (Col1A1]), and sclerostin for osteogenesis; aggrecan and collagen type II (Col2) for chondrogenesis] in mineralized tissues, indicative of enhanced bone and fibrocartilage formation when compared with the CON and Dmab groups. Conclusion: ABL promoted rotator cuff healing in osteoporotic rats by significantly increasing the mineralized tissue quality and collagen maturity at the reattachment site, leading to improved biomechanical properties, and was superior to Dmab in both biomechanical and histological analyses. Clinical Relevance: Anabolic therapy with ABL may outperform antiresorptive therapy with Dmab in improving outcomes after rotator cuff repair in osteoporotic patients.

Translational therapy from preclinical animal models for muscle degeneration after rotator cuff injury.

Chronic rotator cuff tears are debilitating diseases which significantly affect patients’ quality of life and pose substantial financial burden to the society. The intraoperative reparability of injured tendon and postoperative probability of tendon retear are highly associated with the quality of torn muscles, specifically, the severity of muscle atrophy and fatty infiltration. Animal models that reproduce the characteristic muscle pathology after rotator cuff injury have been developed and used to provide insight into the underlying biology and pathophysiology. In this review, we briefly summarize the current information obtained from preclinical animal studies regarding the degenerative change of cuff muscle subsequent to tendon release and/or suprascapular nerve denervation. Importantly, we focus on the potential translational therapeutic targets or agents for the prevention or reversal of muscle atrophy and fatty infiltration. While further studies are warranted to assess the safety and efficacy of novel therapies derived from these preclinical animal research, we believe that their clinical translation for the treatment of rotator cuff disorders is on the horizon.The Translational potential of this articleNovel therapeutic strategies described in this review from preclinical animal studies hold a great translational potential for preventing or reversing rotator cuff muscle pathology, while further assessments on their safety and efficacy are warranted.

The effect of sagittal orientation of the acromion relative to the scapular spine on the location of rotator cuff tears.

The aim of this study was to investigate the effect of the angle between the scapular spine and acromion in the sagittal plane on the location of chronic rotator cuff tears (RCTs). The magnetic resonance images of patients who had undergone an arthroscopic shoulder surgery were evaluated. The patients were divided into two groups: patients who had undergone RCT repair and those who had experienced different shoulder surgery as a control group. The RCT group (study group) was then subgrouped in terms of the location of the tear as posterior-superior RCT type 3, 4, 5 or combination (group A) and anterior-superior RCT type 1,2,3 or combination using the Patte sagittal classification (group B). A novel angle, scapular spine-acromion angle (SSAA), was described in the sagittal plane and compared between the groups and subgroups. A total of 96 patients underwent an arthroscopic RCT repair with a mean age of 59.5 years (range, 36-65 years), and the control group was composed of 40 patients with a mean age of 52.5 (range, 41-63 years). Comparison the group B (mean value: 73.41°±5.98°, median: 73,8°, range: 60.6°-89.7°) has significantly higher degrees of SSAA than group A (mean value: 63.92°±6.82°, median: 64,8°, range: 52.3°-77.9°) (P < 0.001). This study demonstrated a higher incidence of posterior- superior RCTs in patients with lower SSAA and anterior-superior RCTs in patients with higher SSAA in the sagittal plane compared to the control group. So sagittal acromial orientation might influence the RCT location. Level III, Diagnostic Study.

Stem cell sheet interpositioned between the tendon and bone would be better for healing than stem cell sheet overlaid above the tendon-to-bone junction in rotator cuff repair of rats.

BackgroundAlthough stem cells might enhance natural enthesis healing in surgical rotator cuff repair, not much attention has been given to the delivery and location of delivering stem cells. The purpose of this study to know where to locate those stem cells during repair.MethodsAnimal model of chronic rotator cuff tear was created in 24 rats. Adipose-derived stem cells were engineered as a sheet and transplanted 1) between a torn tendon and humerus (interposition group) or 2) over a repaired tendon-to-bone junction (overlay group) at the time of surgical repair. Tracking of stem cells with overexpression of green fluorescent protein (GFP) were carried out at the time of sacrifice in additional 4 shoulders in each group. Histological and Biomechanical evaluation was performed to compare the differences in tendon-to-bone healing.ResultsHistology showed increased fibrocartilage, a clear boundary at the mineralized fibrocartilage, abundant collagen type III, and higher total scores, especially in the interposition group. GFP-overexpression was observed at the transplanted site at 2 weeks after repair. Although two groups where stem cell sheets applied showed higher load to failure than the repair-only group, the load to failure was not different between the interposition and overlay group.ConclusionIn the chronic rotator cuff repair model, stem cell sheets enhanced regeneration of the tendon-to-bone junction. This regeneration was effective when the stem cell sheet was interpositioned at the tendon-to-bone interface.Level of evidenceBasic Science Study; In Vivo Animal Model; Histology and Biomechanics.

Regeneration of Chronic Rotator Cuff Tear in a Rabbit Model: Synergetic Benefits of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells, Polydeoxyribonucleotides, and Microcurrent Therapy.

Objective To investigate synergic therapeutic effects of combined injection of intralesional mesenchymal stem cells derived from human umbilical cord blood (UCB-MSCs) and polydeoxyribonucleotide (PDRN) combined with microcurrent therapy (MIC) on full thickness rotator cuff tendon tear (FTRCTT) in rabbit models. Methods Thirty-two rabbit models were assigned to 4 different groups. FTRCTT in the supraspinatus tendon was created. After 6 weeks, 4 types of procedures (0.2 mL normal saline injection, group 1 (G1-NS); 0.2 mL SC injection, group 2 (G2-MSC); 0.2 mL SC and weekly four injections of 0.2 mL PDRN with sham MIC, group 3 (G3-MSC+PDRN+sham MIC); and 0.2 mL SC and weekly four injections of 0.2 mL PDRN with MIC for four weeks, group 4 (G4-MSC+PDRN+MIC)) were performed in FTRCTT. Gross morphologic and histological changes of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule (PECAM-1) and motion analysis were performed. Results There was a significant difference in gross morphologic changes between baseline and week 4 posttreatment in group 4 compared to the other three groups (p = 0.01). In groups 3 and 4, all parameters of histochemical and motion analysis have been found to be significantly greater than the ones in groups 1 and 2 (p < 0.05). In group 4, PCNA-, VEGF-, and PECAM-1-stained cells, as well as walking distance, were significantly greater than the ones in group 3 (p < 0.05). Conclusion The treatment with UCB-MSCs and PDRN combined with MIC might be the most effective in rabbit models' traumatic FRTCTT.

The "Second Hit" of Repair in a Rabbit Model of Chronic Rotator Cuff Tear.

The rabbit supraspinatus is a useful translational model for rotator cuff (RC) repair because it recapitulates muscle atrophy and fat accumulation observed in humans after a chronic tear (the “first hit”). However, a timeline of RC tissue response after repair, especially with regard to recent evidence of muscle degeneration and lack of regeneration, is currently unavailable. Thus, the purpose of this study was to characterize the progression of muscle and fat changes over time after the repair of a chronic RC tear in the rabbit model. Two rounds of experiments were conducted in 2017–2018 and 2019–2020 with N = 18 and 16 skeletally mature New Zealand White rabbits, respectively. Animals underwent left supraspinatus tenotomy with repair 8 weeks later. The unoperated right shoulder served as control. The rabbits were sacrificed at 1-, 2-, 4-, and 8-weeks post-repair for histological and biochemical analysis. Atrophy, measured by fiber cross-sectional area and muscle mass, was greatest around 2 weeks after repair. Active muscle degeneration peaked at the same time, involving 8% of slide areas. There was no significant regeneration at any timepoint. Fat accumulation and fibrosis were significantly increased across all time points compared to contralateral. Statement of Clinical Significance: These results demonstrate model reproducibility and a “second hit” phenomenon of repair-induced muscle atrophy and degeneration which partially recovers after a short time, while increased fat and fibrosis persist.

Protocatechuic acid impacts rotator cuff healing and reduces fatty degeneration in a chronic rotator cuff tear model in rats.

BackgroundThe purpose of this study was to verify the effect of protocatechuic acid (PCA) on tendon healing and fatty degeneration in a chronic rotator cuff model.MethodsTwenty-eight Sprague-Dawley male rats were randomly allocated into two groups: Saline+repair (SR) and PCA+repair (PR). The right shoulder was used for experimental interventions, and the left served as a control. PCA (30 mg/kg/day) was administered intraperitoneally at the site of infraspinatus tendon detachment in rats in the PR group, and the same volume of saline was administered to the same site in the SR group. The torn tendon was repaired 4 weeks after infraspinatus detachment. Four weeks after repair, hematoxylin and eosin (H&E), S100, and CD68 stains were performed to evaluate the degree of fatty degeneration and H&E and Masson trichrome stains were performed to assess tendon healing. Superoxide dismutase (SOD) was measured to test the efficacy of PCA as an antioxidant.ResultsResults from histological evaluation indicated that SOD and CD68 levels at the musculotendinous region and collagen fiber parallel to the orientation at the tendon-to-bone junction were not significantly different between the SR and PR groups. The mean load-to-failure of the PR group (20.32±9.37 N) was higher than that of the SR group (16.44±6.90 N), although this difference was not statistically significant (p=0.395). The SOD activity in the operative side infraspinatus muscle of the PR group was higher than that of the SR group, but the difference was not statistically significant (p=0.053).ConclusionsThe use of PCA could improve tendon healing and decrease fatty degeneration after rotator cuff repair.

Rotator cuff repair protected with subacromial balloon spacer shows a low rate of non-healing.

The purpose of this study was to evaluate clinical outcomes and tendon integrity on magnetic resonance imaging (MRI) of chronic posterosuperior rotator cuff tears treated with single-row tensionless repair and subacromial balloon spacer as protection with a minimum follow-up of 2years. The hypothesis of this study was that this procedure would have acceptable clinical outcomes and tendon-healing rate without increased complications. This is a retrospective study of patients with chronic posterosuperior rotator cuff tears repaired with a single-row technique protected with a subacromial balloon device. Patients were followed up for a minimum of 2years. Clinical outcomes were evaluated with American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) and Numerical Rating Scale (NRS) for pain. MRI study was obtained likewise after at least 2years to assess tendon-healing rate. Statistical comparison was performed between pre-operative and at least 2-year clinical and imaging follow-up. Thirty-two patients were included in the study with a mean follow-up of 27 ± 7 (range 24-48). The mean age of this cohort was 58 ± 6 (range 41-66) including 15 males and 17 females. The tear size was on average 2.3cm (range 2-4) and a mean of 2.1 triple-loaded anchors were used (range 2-3). The ASES score significantly increased from a mean of 39 ± 12 points to a mean of 89 ± 12 at the final follow-up (P < 0.001). Similarly, pain significantly reduced from a mean pre-operative NRS of 6.8 ± 1.4 to 0.8 ± 1.5 at the final follow-up (P < 0.001). MRI scans showed that repair occurred in 26 patients (81.3%). Significant higher ASES score was reached at final follow-up in patients with a "healed" (Sugaya I-III) tendon when compared to patients with an evidence of tendon discontinuity on MRI study (Sugaya IV-V), 93 ± 9 and 74 ± 13, respectively (P < 0.001). Arthroscopic repair of chronic posterosuperior rotator cuff tears using a single-row tensionless repair and subacromial spacer as protection resulted in an 81.3% of tendon integrity at a mean follow-up of 27months. Clinical outcomes and pain scores significantly improved without severe complications reported after a minimum follow-up of 2years. III.

The Biomechanical and Histological Processes of Rerouting Biceps to Treat Chronic Irreparable Rotator Cuff Tears in a Rabbit Model

Background: Recently, the biceps was rerouted into a newly fabricated bicipital groove for in situ superior capsular reconstruction (SCR), resulting in promising time-zero cadaveric and clinical outcomes. However, no studies have determined the in vivo biomechanical and histological processes after the biceps is transposed to a nonanatomic position. Purpose: To explore the in vivo biomechanical and histological processes of the rerouting biceps tendon to treat chronic irreparable rotator cuff tears (IRCTs) in a rabbit model. Study Design: Controlled laboratory study. Methods: A total of 94 skeletally mature male rabbits were used to create a chronic IRCT model in the supraspinatus tendon. Then, the biceps rerouting procedures were performed in rabbits with chronic IRCT. Eighteen rabbits were sacrificed at 1, 3, 6, 9, and 12 weeks postoperatively for biomechanical testing, micro—computed tomography scanning, and histological analysis. The biomechanical and histological changes of intra- and extra-articular portions of the rerouting biceps were evaluated at each time point, with the contralateral native superior capsule (NSC) and the native biceps (NB) as controls, respectively. The morphology and bone formation of the fabricated bicipital grooves were evaluated, with native grooves as controls. Results: The intra-articular rerouting biceps tendon was progressively remodeled over time, displaying denser fibers and more mature collagen than those of the NSC, with gradual improvements in the tendon-to-bone healing interface from 6 to 12 weeks. Consequently, the failure load and stiffness of the intra-articular rerouting biceps portion increased with time and were significantly higher than those of the NSC from 9 weeks. Similarly, the extra-articular portion of the rerouting biceps progressively healed into a new bicipital groove, as demonstrated by a smaller tendon-to-bone interface from 6 to 12 weeks, resulting in greater failure load and stiffness at 9 and 12 weeks than those of the NB attachment. The newly fabricated bicipital groove showed similar morphology to that of the native groove with sufficient trabecular bone formed underneath. Conclusion: The rerouting biceps could progressively remodel and heal into the newly fabricated bicipital groove over time, resulting in greater biomechanical performances in intra- and extra-articular portions than the NSC and the NB attachment. Clinical Relevance: The biceps rerouting technique may be a feasible procedure to perform in situ SCR to treat IRCT in the future clinical practice; however, more clinical evidence is required.

Risk Factors for Loss of Active Shoulder Range of Motion in Massive Rotator Cuff Tears.

Background:Patients with massive rotator cuff tears often exhibit loss of active range of shoulder motion, which can interfere with activities of daily living. The risk factors for loss of motion remain largely unknown.Purpose:To clarify the predictive factors that affect the range of motion in chronic massive rotator cuff tears using multivariate analyses.Study Design:Case-control study; Level of evidence, 3.Methods:The authors retrospectively reviewed 204 consecutive patients who were evaluated at their institution with chronic massive rotator cuff tears. In this study, the dependent variable was determined to be active anterior elevation limited to ≤90° or external rotation (ER) with the arm at the side limited to ≤0°. Explanatory variables included age; sex; affected side; duration of symptoms; smoking history; existence of diabetes, hypertension, or rheumatoid arthritis; involved tendons; presence of a 3-tendon tear; rupture of the long head of biceps tendon; superior migration of the humeral head; and cuff tear arthropathy. Baseline variables that were observed to be significant in the univariate analyses were included in multivariate models, which used logistic regression to identify independent predictors of loss of motion.Results:Overall, 73 patients (35.8%) exhibited limited anterior elevation, and 27 (13.2%) exhibited limited ER. Multivariate analyses showed that inferior subscapularis tear (odds ratio [OR], 14.66; 95% CI, 2.95-72.93; P = .001), smoking (OR, 4.13; 95% CI, 1.94-8.79; P < .001), superior migration of humeral head (OR, 3.92; 95% CI, 1.80-8.53; P = .001), and 3-tendon tear (OR, 3.29; 95% CI, 1.32-8.20; P = .011) were significantly associated with the loss of anterior elevation. Teres minor tear (OR, 73.37; 95% CI, 9.54-564.28; P < .001) and superior migration of the humeral head (OR, 3.55; 95% CI, 1.04-12.19; P = .044) were significantly associated with loss of ER.Conclusion:In the current study, a history of smoking, type of torn tendons, and superior migration of the humeral head were associated with loss of active shoulder motion. In particular, the status of inferior subscapularis or teres minor contributed to the onset of pseudoparalysis in massive rotator cuff tears.