Rotator Cuff Tendon Research Articles

Do Intact Rotator Cuff Tendons And Soft Tissue Tensioning Affect Stress Shielding In Reverse Total Shoulder Arthroplasty?

Do Intact Rotator Cuff Tendons And Soft Tissue Tensioning Affect Stress Shielding In Reverse Total Shoulder Arthroplasty?

Supraspinatus Muscle Regeneration Following Rotator Cuff Tear: A Study of the Biomarkers Pax7, MyoD, and Myogenin.

The success of rotator cuff tendon repair relies on both tendon healing and muscle recovery. The objective of this descriptive study was to investigate the regenerative potential of the supraspinatus muscle in rotator cuff tear conditions by quantifying the expression of Pax7, MyoD, and myogenin, basic factors that regulate myogenesis. Muscle biopsies were collected from thirty-three patients aged 34 to 73 years who underwent surgery for a rotator cuff tear affecting the supraspinatus muscle. Among these patients, twenty-seven percent were women, and the age of the lesions ranged from 2 to 72 months post-initial trauma. Biopsies were harvested from the supraspinatus muscle at the end closest to the tendon, and control biopsies were harvested from the ipsilateral deltoid muscle. The densities of immunohistochemically stained Pax7+, MyoD+, and myogenin+ nuclei/mm2 were used to estimate the myogenic potential of the muscle. Adjustments were made for patient age and lesion age. We found increased density of MyoD+ and myogenin+ cells in supraspinatus muscles compared to deltoid muscles (p < 0.001 and p = 0.003, respectively). Regression analyses that combined the density of positive nuclei with patient age showed a continuous increase in Pax7 with age but also a reduction of MyoD and myogenin in older patients. When combined with lesion age, there was a decline in the density of all myogenic markers after an initial rise. Pax7 density continued to be higher in supraspinatus compared to the deltoid muscle, but the density of MyoD and myogenin terminally dropped to a density lower than in the deltoid. Our findings suggest that the supraspinatus muscle in tear conditions showed signs of initial activation of muscle regeneration. When compared to the unaffected deltoid muscle, an apparent reduction in capacity to progress to full muscle fiber maturity was also demonstrated. This pattern of inhibited myogenesis seemed to increase with both patient age and lesion age. Our results on muscle regenerative capacity indicate that younger patients with rotator cuff tears have better chances of muscle recovery and may benefit from early surgical reconstruction.

Rotator Cuff Repair by All-Arthroscopic Versus Mini-Open Technique: A Comparison of Clinical and Functional Outcome.

Rotator cuff tears can lead to debilitating shoulder function and impairment. Rotator cuff repair aims to eliminate pain and improve function with increased shoulder strength and range of motion. This study evaluated the differences between all-arthroscopic (AA) and mini-open (MO) repair procedures for rotator cuff tendon tears regarding clinical and functional outcomes. This was a prospective study conducted at a tertiary care government Hospital in Kolkata, India, between March 2015 and September 2016 which evaluated 25 patients who had undergone all-arthroscopic surgery and 25 patients who underwent mini-open repair (total of 50 patients) for rotator cuff tear with a minimum one-year follow-up. The UCLA score was used to assess the functional outcome of these patients. The mean age of all patients included in this study was 45.32 years. 86% of patients were male. The two groups had similar demographic characteristics, pre-operative baseline parameters, and intra-op findings. The average UCLA score showed significant improvement from 13.92 pre-operatively to 29.76 at the final follow-up. The patients in the all-arthroscopic surgery group experienced a notable decrease in pain within the first three months compared to the mini-open group. However, at the time of the final follow-up, no significant difference was noted between both groups when comparing the University of California at Los Angeles (UCLA) score, Visual Analogue Scale (VAS) score for pain, and active or passive glenohumeral motion. The outcomes of all-arthroscopic and mini-open rotator cuff repair surgery are equivocal in terms of both clinical and functional results, with no significant difference in post-operative pain, shoulder joint strength range of motion, or patient satisfaction over the long term.

Establishing a rabbit model with massive supraspinatus tendon defect for investigating scaffold-assisted tendon repair

BackgroundShoulder pain and disability from rotator cuff tears remain challenging clinical problem despite advancements in surgical techniques and materials. To advance our understanding of injury progression and develop effective therapeutics using tissue engineering and regenerative medicine approaches, it is crucial to develop and utilize animal models that closely resemble the anatomy and display the pathophysiology of the human rotator cuff. Among various animal models, the rabbit shoulder defect model is particularly favored due to its similarity to human rotator cuff pathology. However, a standardized protocol for creating a massive rotator cuff defect in the rabbits is not well defined. Therefore, the objective of our study was to establish a robust and reproducible model of a rotator cuff defect to evaluate the regenerative efficacy of scaffolds.ResultsIn our study, we successfully developed a rabbit model with a massive supraspinatus tendon defect that closely resembles the common rotator cuff injuries observed in humans. This defect involved a complete transection of the tendon, spanning 10 mm in length and encompassing its full thickness and width. To ensure stable scaffolding, we employed an innovative bridging suture technique that utilized a modified Mason-Allen suture as a structural support. Moreover, to assess the therapeutic effectiveness of the model, we utilized different scaffolds, including a bovine tendon extracellular matrix (ECM) scaffold and a commercial acellular dermal matrix (ADM) scaffold. Throughout the observation period, no scaffold damage was observed. Notably, comprehensive histological analysis demonstrated that the regenerative tissue in the tendon ECM scaffold group exhibited an organized and aligned fiber structure, indicating tendon-like tissue regeneration while the tissue in the ADM group showed comparatively less organization.ConclusionsThis study presents a comprehensive description of the implemented procedures for the development of a highly reproducible animal model that induces massive segmental defects in rotator cuff tendons. This protocol can be universally implemented with alternative scaffolds to investigate extensive tendon defects and evaluate the efficacy of regenerative treatments. The application of our animal model offers a standardized and reproducible platform, enabling researchers to systematically evaluate, compare, and optimize scaffold designs. This approach holds significant importance in advancing the development of tissue engineering strategies for effectively repairing extensive tendon defects.

Acute and cumulative increases in rotator cuff tendon thickness’ in elite swimmers

Acute and cumulative increases in rotator cuff tendon thickness’ in elite swimmers

Magnetic resonance imaging of the shoulder in symptomatic professional rugby players: a retrospective analysis.

Shoulder injuries in rugby players are common due to frequent high-impact collisions and tackles. This study aimed to describe the spectrum and pattern of shoulder MRI findings in professional rugby players. Single-center retrospective study of shoulder MRI was carried out between 2012 and 2016 in symptomatic professional male rugby league and rugby union players. One hundred ten shoulder MRIs were scored for rotator cuff and long head of biceps tendons, labral, bursal, joint, and osseous abnormalities. MRI features were compared using the chi-square or Fisher's exact tests for categorical variables. There were a total of one hundred ten professional male rugby players (80 rugby league and 30 rugby union), with a mean age of 24.6 (range 17-38) and 23.7 (range 17-33) years old, respectively. Rotator cuff or long head biceps abnormality was found in 36 (33%) players, of which 22 (20%) were either partial or full-thickness tears. Glenoid labral tears were present in 63 (57%) players. There was no significant difference (p > 0.05) in the frequency of tears of the superior (24%), anterior inferior (25%), posterior superior (25%), and posterior inferior (32%) labrum. Forty-seven percent of players presented with two or more abnormalities of the rotator cuff tendons and glenoid labrum. There were significantly more osseous abnormalities in backs compared to forwards (48% vs. 21%; p = 0.01). There is a wide spectrum of shoulder abnormalities on MRI in professional rugby players, and many have two or more abnormalities. In common with other contact sports, posterior labral injury was a common finding and may relate to sub-clinical trauma, without an association with instability.

Tenascin C Deletion Impairs Tendon Healing and Functional Recovery After Rotator Cuff Repair.

The biological factors that affect healing after rotator cuff repair (RCR) are not well understood. Genetic variants in the extracellular matrix protein Tenascin C (TNC) are associated with impaired tendon healing and it is expressed in rotator cuff tendon tissue after injury, suggesting it may have a role in the repair process. The purpose of the current study was to determine the role of TNC on tendon healing after RCR in a murine model. The supraspinatus tendon was transected and repaired on the left shoulder of Wild-Type (WT-RCR), Tenascin C null (Tnc --RCR) and Tnc heterozygous (Tnc +/--RCR) mice. Controls included the unoperated, contralateral shoulder of WT-RCR, Tnc - RCR, Tnc +/--RCR mice and unoperated shoulders from age and genotype matched controls. We performed histologic, activity testing, RNA-seq, and biomechanical analyses. At 8-weeks post-RCR, Tnc - and Tnc +/- mice had severe bone and tendon defects following rotator cuff repair. Tnc --RCR mice had reduced activity after rotator cuff repair including reduced wheel rotations, wheel duration, and wheel episode average velocity compared with WT-RCR. Loss of Tnc following RCR altered gene expression in the shoulder, including upregulation of sex hormone and WNT pathways and a downregulation of inflammation and cell cycle pathways. Tnc - mice had similar biomechanical properties after repair as WT. Further research is required to evaluate tissue specific alterations of Tnc, the interactions of Tnc and sex hormone and inflammation pathways as well as possible adjuvants to improve enthesis healing in the setting of reduced TNC function.

Identification of age-related genes in rotator cuff tendon.

Rotator cuff tear (RCT) is the leading cause of shoulder pain, primarily associated with age-related tendon degeneration. This study aimed to elucidate the potential differential gene expressions in tendons across different age groups, and to investigate their roles in tendon degeneration. Linear regression and differential expression (DE) analyses were performed on two transcriptome profiling datasets of torn supraspinatus tendons to identify age-related genes. Subsequent functional analyses were conducted on these candidate genes to explore their potential roles in tendon ageing. Additionally, a secondary DE analysis was performed on candidate genes by comparing their expressions between lesioned and normal tendons to explore their correlations with RCTs. We identified 49 genes in torn supraspinatus tendons associated with advancing age. Among them, five age-related genes showed DE in lesioned tendons compared to normal tendons. Functional analyses and previous studies have highlighted their specific enrichments in biological functions, such as muscle development (e.g. myosin heavy chain 3 (MYH3)), transcription regulation (e.g. CCAAT enhancer binding brotein delta (CEBPD)), and metal ion homeostasis (e.g. metallothionein 1X (MT1X)). This study uncovered molecular aspects of tendon ageing and their potential links to RCT development, offering insights for targeted interventions. These findings enhance our understanding of the mechanisms of tendon degeneration, allowing potential strategies to be made for reducing the incidence of RCT.

Periarticular Calcifications: Clinical Features and Treatment Options

Periarticular calcifications are a common condition for rheumatologists. They are characterized by deposition of carbonated apatite in tendons or connective tissues around joints. It most commonly affects patients between 30 and 60, and the main location is the shoulder (rotator cuff tendons), followed by the hip. Although the disease is frequent, factors associated with the appearance of the deposits or their spontaneous resorption remain unclear. In this review, we will summarize the available data about mechanisms underlying the constitution of the deposits and their resorption and describe the various affected sites and the associated symptoms. In the last part, we will discuss current treatment options.

Shoulder balloon spacer for massive irreparable rotator cuff tears results in significant improvements.

The aim of the present study was to assess the effectiveness of balloon implantation in patients with irreparable supraspinatus tears alone or in combination withother rotator cuff (RC) tendon tearsand the effect of several covariables, such as age, gender, status of the long head biceps, with or without tendon repair and regardless the number of tendon involved. Patients enrolled from 'San Carlo' Hospital of Potenza (Italy, IT), from January 2012 to September 2014, underwent arthroscopic implantation of shoulder balloon by a single surgeon, and followed for 3 years. The American Shoulder and Elbow Surgeons (ASES) and Constant score (CS) were administered pre-, post-operatively at 12 months, and then annually. Patients were classified on the basis of the number of tendons involved in the tears and treatment performed, considering the reparability of the tendons themselves. Gleno-humeral joint osteoarthrosis (OA) was evaluated through shoulder radiographs and classified according to the Samilson-Prieto classification, at the first examination and at the final follow-up. Statistical improvements were evaluated using a variance model (least-squares means)and a T distribution test for the evaluation between different treatment groups. A total of 61 procedures were performed, and eight patients were lost during follow-up. The mean baseline CS was 30.2 ± 15.4 with statistically significant improvement, respectively, at 1-, 2- and 3-year follow-up to 69.3 ± 4.2, 74.6 ± 3.6 and 69.7 ± 5.1 respectively. ASES score at baseline was 22.5 ± 10.9, with a statistically significant improvement to 69.7 ± 9.2, 68 ± 17.8 and 71.2 ± 16.6 at 1-, 2- and 3-year follow-up, respectively. Tenotomy or absence of long head biceps at presentation did not influence results (n.s.), with no difference according to gender and age. At final follow-up, 24 patients (43.9%) showed progression of glenohumeral OA. One patient required secondary surgery for shoulder replacement after 18 months for persistent pain and one patient required implant removal following post-operative laser treatment. Arthroscopic rotator cuff tears repair with subacromial spacer balloon implantation showed statistically significant clinical and functional improvement at 3-year follow-up. Patients treated with combined partial repair and subacromial spacer balloon implantation experienced good results independent of gender, age, type of tear and long-head biceps tendon status. The risks related to this procedure appear to be minimal. Level IV.

Fixation of the rotator cuff tendons for the greater tuberosity fracture of the humerus

Introduction Strategical approaches to managing patients with a greater tuberosity fracture of the humerus are controversial and there are discussions about surgical treatment options. Nondisplaced fractures require no surgical management. Shoulder replacement can be indicated for the surgical treatment of proximal humeral fractures with limited function of the upper limb and difficulties in refixation of the rotator cuff tendons due to the peculiar anatomical location of the tendon fixation. Solution to this problem can improve the quality of life of patients with greater tuberosity fracture of the humerus.The objective was to evaluate the treatment outcome of a patient with a greater tuberosity fracture of the humerus repaired with open refixation of the rotator cuff tendons and medialization of the border of the articular surface of the humerus.Material and methods A 46-year-old patient presented with limited movements and severe pain in the left shoulder after humerus dislocation and a greater tuberosity fracture.Results The condition was repaired with an open repair of the rotator cuff tendons and medialization of the border of the articular surface of the humerus. The patient reported neither pain nor limited movements in the left shoulder at the one-year follow-up.Discussion Treatment options for patients with a greater tuberosity injury remains controversial. The effectiveness and results of organ-saving surgery have not been explored and require scientific evaluation using a larger cohort of patients.Conclusion Excellent functional results were achieved in a patient with injury to the greater tuberosity using surgical refixation of the rotator cuff tendons and medialization of the cartilaginous surface.

Critical shoulder angle and acromial index do not influence functional outcomes after repair of massive rotator cuff tears

ObjectivesCritical shoulder angle (CSA) and acromial index (AI) are two radiographic signs that can influence the risk of rotator cuff tears and the outcomes of repair. The purpose of this study was to determine the influence of CSA and AI on massive cuff tears and on the functional outcomes after repair. The hypothesis was that CSA and AI would be higher in posterosuperior compared to anterosuperior tears. MethodsCSA and AI were retrospectively measured on radiographs of patients who underwent repair of two rotator cuff tendons. Functional outcomes were evaluated using the American Shoulder and Elbow Surgeons (ASES) score and Simple Shoulder Test (SST) at least six months postoperatively. Patients were divided according to the tendons repaired into anterosuperior group and posterosuperior group. Radiographic measurements and functional outcomes were compared. Patients in the posterosuperior group were subdivided into low or high CSA (cut-off value ​= ​39), and into low or high AI (cut-off value ​= ​0.75). All available preoperative magnetic resonance images were reviewed and graded according to Goutallier classification. Multivariate analysis was used to determine the influence of CSA, AI and Goutallier grade on functional outcomes. ResultsEighty six patients were included. Both CSA and AI were statistically significantly higher in the posterosuperior group (p ​= ​0.0143 and 0.0052, respectively). After a mean follow-up of 33 months, ASES and SST were significantly better in patients with Goutallier grades 0–1 than grades>1 (multivariate p ​= ​0.03 and 0.009, respectively). No statistically significant differences were found between low and high CSA and AI groups in terms of functional outcomes of the posterosuperior group after repair (multivariate p ​= ​0.9). ConclusionHigher CSA and AI seem to increase the risk of posterosuperior more than anterosuperior rotator cuff tears. Neither of these radiographic parameters influenced the functional outcomes of massive posterosuperior tears after repair. Level of evidenceLevel III.

Preoperative Increases in T2-Weighted Fat-Suppressed Magnetic Resonance Imaging Signal Intensities Associated With Advanced Tissue Degeneration and Mitochondrial Dysfunction in Rotator Cuff Tears

PurposeThe purpose of this study was to investigate the relationship between magnetic resonance imaging (MRI) signal intensities and mitochondrial function in patients undergoing arthroscopic rotator cuff repair, assessed through histological and genetic profiling of tendon tissue. MethodsThis study, conducted between April 2022 and January 2023, included 20 patients undergoing rotator cuff repair for atraumatic/degenerative tears. Rotator cuff tendon edge samples were obtained during arthroscopic rotator cuff repair. Patients were classified based on signal intensity from preoperative T2-weighted fat suppressed MRI. Specifically, they were categorized as having either high or low signal intensity at the rotator cuff tendon edge, with the deltoid muscle serving as a reference. Comparative analyses specifically compared the histological features and genetic profiles of the tendon tissue at the rotator cuff tendon edge. Histological evaluation of harvested tendon specimens during arthroscopic rotator cuff repair employed the modified Bonar score. Real-time polymerase chain reaction was used to assess expression of various mitochondrial and apoptosis-related genes. The mitochondrial morphology of the rotator cuff torn site was examined using electron microscopy. ResultsThe higher signal intensity group showed significantly higher modified Bonar scores (p=0.0068), decreased mitochondrial gene expression, increased TUNEL-positive cells (p=0.032), lower SOD activity (p=0.011), reduced ATP5A (p=0.031), and increased cleaved caspase-9 activity (p=0.026) when compared to the lower signal intensity group. Electron microscopy revealed fewer mitochondrial cristae in the higher signal intensity group. ConclusionOur results suggest correlations between high MRI signal intensities and the presence of degeneration, mitochondrial dysfunction, and increased apoptosis in rotator cuff tissues. This underscores the utility of MRI signal intensity as an indicator of tissue condition. Clinical RelevanceBuilding on the established premise that elevated preoperative MRI signal intensities may indicate higher rates of postoperative rotator cuff re-tears, the current study substantiates these findings from a mitochondrial function perspective.

Development of a deep learning-based fully automated segmentation of rotator cuff muscles from clinical MR scans.

The fatty infiltration and atrophy in the muscle after a rotator cuff (RC) tear are important in surgical decision-making and are linked to poor clinical outcomes after rotator cuff repair. An accurate and reliable quantitative method should be developed to assess the entire RC muscles. To develop a fully automated approach based on a deep neural network to segment RC muscles from clinical magnetic resonance imaging (MRI) scans. In total, 94 shoulder MRI scans (mean age = 62.3 years) were utilized for the training and internal validation datasets, while an additional 20 MRI scans (mean age = 62.6 years) were collected from another institution for external validation. An orthopedic surgeon and a radiologist manually segmented muscles and bones as reference masks. Segmentation performance was evaluated using the Dice score, sensitivities, precision, and percent difference in muscle volume (%). In addition, the segmentation performance was assessed based on sex, age, and the presence of a RC tendon tear. The average Dice score, sensitivities, precision, and percentage difference in muscle volume of the developed algorithm were 0.920, 0.933, 0.912, and 4.58%, respectively, in external validation. There was no difference in the prediction of shoulder muscles, with the exception of teres minor, where significant prediction errors were observed (0.831, 0.854, 0.835, and 10.88%, respectively). The segmentation performance of the algorithm was generally unaffected by age, sex, and the presence of RC tears. We developed a fully automated deep neural network for RC muscle and bone segmentation with excellent performance from clinical MRI scans.

Nanofiber Graft Therapy to Prevent Shoulder Stiffness and Adhesions after Rotator Cuff Tendon Repair: A Comprehensive Review.

Stiffness and adhesions following rotator cuff tears (RCTs) are common complications that negatively affect surgical outcomes and impede healing, thereby increasing the risk of morbidity and failure of surgical interventions. Tissue engineering, particularly through the use of nanofiber scaffolds, has emerged as a promising regenerative medicine strategy to address these complications. This review critically assesses the efficacy and limitations of nanofiber-based methods in promoting rotator cuff (RC) regeneration and managing postrepair stiffness and adhesions. It also discusses the need for a multidisciplinary approach to advance this field and highlights important considerations for future clinical trials.

Combination of Anatomical Plates and Rotator Cuff Reinforcement for Minimally Invasive Treatment of Greater Tuberosity Fractures of the Humerus.

Greater tuberosity fractures of the humerus can be challenging to manage due to their complex anatomy and the potential for compromised shoulder function. We present a novel technique for treating greater tuberosity fractures utilizing specialized anatomical plates and rotator cuff reinforcement. The technique involves the use of an anatomically T-shaped plate designed specifically for the greater tuberosity region of the humerus, allowing for precise fixation and stability. Additionally, rotator cuff reinforcement is performed using sutures to enhance structural integrity and promote early mobilization. The simplified process is as follows: After administering anesthesia, a 3 cm incision is made along the lateral aspect of the shoulder to precisely expose the fracture site of the greater tuberosity. A suture of size 5 is skillfully threaded through the tough rotator cuff tendon to securely attach the proximal humerus to the anatomical plate after the greater tuberosity has been reduced. Intraoperative fluoroscopy is utilized to verify the accurate positioning of plates and screws. After ensuring everything is correct, the surgery concludes.

Integrating Tendinous Pathophysiology Into Rotator Cuff Tears And Greater Trochanteric Pain Syndrome: A Narrative Review

This narrative review aims to use the similarities between the shoulder and hip joints to better understand why rotator cuff (RC) tendinopathy and hip abductor tendinopathy occur and inform about diagnosis and treatment of both orthopedic complaints. A search of the literature was conducted using GoogleScholar and Pubmed and initially followed a systematic review protocol, but the nature of the topic, current literature and data necessitated a narrative review. Reports that discussed pathomechanics of RC and gluteal tendinopathy individually, together and with other muscles groups were reviewed. It was found that the methods measuring and describing the processes of tendinopathy differ significantly, for each individual joint and between all joints. A review of a large body of quantifiable measures and theoretical ideas regarding tendinopathy was performed to address this lack of consensus in current literature. Initial literature yielded 74 articles. After review, only 43 articles were used from a broad range of approaches and methodologies. The review found a body of evidence suggesting that fibrocartilage overgrowth and compressive forces over bony structures cause tendonous pathology of the RC and hip abductor tendons. These findings support the idea that tendinopathy is often caused by intrinsic factors rather than the traditional view of external factors. Earlier treatment and improved outcomes without surgery are possible using current imaging technology to identify these intrinsic factors that affect tendinous properties.

Poster 112: Toxicity of Chlorhexidine and Povidone-Iodine to Rotator Cuff Tendon

Objectives: Antimicrobial wound lavages containing chlorhexidine gluconate (CHG) or povidone-iodine (PI) are commonly used to prevent periprosthetic infection during shoulder arthroplasty. However, the potential toxicity of these solutions to the native surrounding rotator cuff tendon is not well understood. In total shoulder arthroplasty, the rotator cuff tendon is often concomitantly repaired, and any toxic effects from antimicrobial wound lavage during surgery may be detrimental to postoperative rotator cuff tendon healing. The purpose of this study was to determine the in vitro effects of a 1-minute CHG exposure and a 3-minute 0.35% PI exposure on the viability and biochemical content of rotator cuff tendon. Methods: Infraspinatus tendons (n=6 per group) were isolated from shoulders of Nubian goats (n=3; 2 female and 1 male). Tendons were submerged in Irrisept (0.05% CHG in sterile water) for 1 minute or 0.35% Betadine (PI) for 3 minutes per manufacturer guidelines, followed by phosphate-buffered saline wash and culture in tissue culture medium. Control tendon specimens were similarly exposed to tissue culture medium, followed by phosphate-buffered saline wash and culture in tissue culture medium. After seven days of culture, isolates from both the tendinous and enthesis portions of the rotator cuff were analyzed for viability, collagen content (hydroxyproline assay), and glycosaminoglycan (GAG) content (dimethylmethylene blue assay). Statistical analyses were performed via one-way ANOVA with post hoc Tukey’s test. Results: Within the tendinous portion of the rotator cuff, CHG-treated specimens demonstrated a decrease in mean tenocyte viability compared to controls (p=0.045) (Fig.1). While PI-treated specimens exhibited lower mean viability compared to controls, this difference was not statistically significant. Within the enthesis portion of the rotator cuff, tenocyte viability decreased in both CHG- and PI-treated groups; however, these decreases were not statistically significant (Fig. 2). There were no significant differences in mean collagen content/wet weight or GAG/wet weight among groups within the tendinous and enthesis portion of the rotator cuff (Fig. 3). Conclusions: Due to the potential catastrophic consequences associated with periprosthetic infection, CHG and PI antimicrobial lavages are commonly used to reduce the risk of periprosthetic infection during shoulder arthroplasty. However, in this study, brief 0.05% CHG and 0.35% PI exposures to rotator cuff tendon resulted in lower tenocyte viability 7 days after treatment. These results are consistent with the toxicity reported with exposure of CHG and PI to other musculoskeletal tissues, including articular cartilage. The toxicity of antimicrobial irrigation to the surrounding native rotator cuff tendon may be detrimental to the postoperative healing of concomitant rotator cuff repair in the setting of shoulder arthroplasty.

Poster 141: In Vitro Inflammatory Response to Surgical Scaffolds for Rotator Cuff Repair

Objectives: Surgical scaffolds are used to augment rotator cuff tendon repairs. Interactions between recruited immune cells and tendon-resident stromal cells influence whether the scaffold is integrated or rejected by the body. The primary aim of this in vitro study was to compare the inflammatory response of human monocytes to different surgical scaffolds. The secondary aim was to determine how this monocyte response affects the behavior of human rotator cuff tendon-derived stromal cells in vitro. Methods: Primary human monocytes were cultured on four commercially available scaffolds: LARS ligament (synthetic); GraftJacket (allograft), Permacol (xenograft, cross-linked), and Conexa (xenograft, noncross-linked). Secreted inflammatory proteins were measured after 1 and 10 days. Foreign body giant cell formation was assessed after 10 days. Proliferation and gene expression of tendon stromal cells were assessed after being grown in a conditioned medium from monocyte-scaffold cultures. Results: After 10 days, monocytes cultured on the Conexa scaffold secreted the highest levels of the pro-inflammatory markers GM-CSF, IL-8, and IL-10 (fig. 1). After 1 day, tendon stromal cells incubated in conditioned media from Conexa-monocyte cultures expressed lower Collagen Type VI and increased MMP3 and MMP6 mRNA (fig. 2). Foreign Body Giant Cell formation was most prominent in monocytes cultured on the Permacol scaffold (Figure 3). Conclusions: In vitro experiments demonstrated that xenograft scaffolds elicited a more pronounced pro-inflammatory response in human monocytes compared to synthetic and allograft scaffolds. Inflammatory cytokines secreted by monocytes in response to xenografts may modulate scaffold integration through paracrine signaling to tendon stromal cells. These findings may help explain the clinical performance of xenograft scaffolds for tendon repair and inform future scaffold design.

Morphologic changes in the posterior glenoid rim is independently associated with rotator cuff impingement in baseball players

BackgroundThe morphological changes in the posterior glenoid rim are unknown in relation to the area of rotator cuff tendons pinched within the glenohumeral joint in the throwing shoulders of baseball players. Therefore, this study aimed to clarify whether these changes are associated with the area of impingement in baseball players. MethodsOverall, 25 asymptomatic male college baseball players (average age19.8 years, 11.6 years of competing, and 50 shoulders) participated in this study. The area of impingement (AOI, mm2) and posterior glenohumeral distance (PGHD, mm) were measured using magnetic resonance imaging to quantitatively assess the impingement area of the rotator cuff tendon within the glenohumeral joint and the morphologic change in the posterior glenoid rim. These magnetic resonance imaging assessments were measured at 90° shoulder abduction with 90° and 100° external rotation. Multiple linear regression analysis was performed to determine whether AOI is predicted by PGHD. FindingsMultiple linear regression analysis showed that the PGHD was a predictor of the AOI at external rotation 90° (β-coefficient = 0.738, R2 = 0.77, P < 0.001) and external rotation 100° position (β-coefficient = 0.879, R2 = 0.76, P < 0.001). InterpretationThis study found that the area of impingement was associated with posterior glenohumeral distance. Therefore, these findings may indicate that complex shoulder joint morphologic changes result in a disabled throwing shoulder.