Background Partial-thickness rotator cuff tears are a common cause of shoulder pain and disability. There are few large prospective cohort studies evaluating outcomes following arthroscopic repair and reported structural failure rates vary widely across techniques. Purpose To (1) evaluate the structural and clinical outcomes of an arthroscopic undersurface knotless inverted mattress repair for partial-thickness rotator cuff tears, (2) assess the effect of surgical experience on outcomes, and (3) place these outcomes in the context of published series of alternative techniques Methods A prospectively collected cohort of 1000 consecutive patients with articular- or bursal-sided partial-thickness supraspinatus tears >50% thickness underwent arthroscopic repair using the Opus knotless system (Smith & Nephew) with an undersurface knotless inverted mattress technique. Structural integrity was assessed using ultrasound at a minimum of 6 months. Pain, range of motion, and strength were assessed preoperatively and at 6 weeks, 12 weeks, and 6 months. Results The cohort comprised 570 males and 430 females with a mean (± SD) age of 56 ± 11 years (range 18–87). Tear area was 1.5 ± 1.0 cm2 and median anchor number was one (range one to five). Repairs were intact in 986 patients 6 months, with retear rate of 1.4% (95% CI 0.8–2.3%). Seven patients (0.7%) underwent revision rotator cuff repair, and no patients required reoperation for infection or postoperative stiffness. Significant improvements were observed across pain, range of motion, strength, and functional outcomes (p<0.01). A learning curve was identified, with retear rates peaking at 5% between cases 100–200 and declining to ≤1% after approximately 200 cases. Conclusion Arthroscopic undersurface knotless inverted mattress repair of partial-thickness rotator cuff tears achieved a retear rate of 1.4%, with no reoperations for infection or postoperative stiffness and consistent improvements across all clinical outcome measures. Retear rates declined after approximately 200 cases, a pattern consistent with a learning-curve effect, although this descriptive moving-average analysis is exploratory and was not subjected to formal change-point modelling. The favourable structural outcomes and short operative time observed with this technique may relate, in part, to minimal disruption of the remaining tendon and subacromial bursa, and the direct intra-articular visualisation afforded by this undersurface approach. Level of evidence Level IV, Case Series, Treatment Study

Background:Despite many patients not returning to their preoperative levels of work and sports after primary rotator cuff repair, few studies have investigated the association between findings on postoperative imaging and patients returning to work and sports. Shear wave elastography ultrasound (SWEUS) is a recent technology that quantifies the stiffness of healing repaired cuff tendons. Hypothesis:Stiffer repaired cuff tendons that reflect improved healing would be associated with improved return to work and sports. Study Design:Cohort study; Level of evidence, 2. Methods:This was a prospective cohort study of 50 patients undergoing primary arthroscopic rotator cuff repair. Preoperatively, all patients completed a questionnaire ranking their level of sports and work activity on a 4-point Likert scale. At 8 days, 6 weeks, 12 weeks, 6 months, and 1 year postoperatively, patients reported their current levels of sports and work on the same scale and had SWEUS stiffness measurements taken at 3 points along their repaired tendons. Results:The elastographic stiffness of supraspinatus tendons at their repaired insertion sites increased by a mean of 22% over 12 months (P = .0001). Elevated supraspinatus tendon stiffness at 6 weeks and 12 weeks was associated with return to sports at 12 months (r = 0.46; P = .003 and r = 0.39; P = .01), and tendon stiffness at 12 weeks and 6 months was associated with return to work at 12 months (r = 0.49; P = .001 and r = 0.46; P = .003). Patients returning to sports (r = 0.46; P = .003) and work (r = 0.49; P = .001) were most strongly associated with SWEUS stiffness 12 weeks after cuff repair. Conclusion:The elastographic stiffness of a healing repaired supraspinatus tendon is moderately associated with improved return to work and sports 12 months after rotator cuff repair. Tendon stiffness at 12 weeks postrepair was the most critical timepoint in predicting both return to work and sports at 12 months postrepair.

The study aimed to describe the changes in biomechanical properties of the supraspinatus tendon, deltoid muscle, and humeral head post arthroscopic rotator cuff repair using shear wave elastography. Shear wave velocity of the tendon, deltoid, and humeral head of 48 patients was measured at predetermined sites at 1 week, 6 weeks, 12 weeks, 6 months, and 12 months post repair. One-way ANOVA with Tukey’s correction and Spearman’s correlation were performed. Mean±SEM healing tendon stiffness, adjacent to tendon footprint, increased from 1 week (6.2±0.2 m/s) to 6 months (7.5±0.3 m/s) and 12 months (7.8±0.3 m/s) (P<0.001). Mean±SEM deltoid muscle stiffness was higher at 12 months (4.1±0.2 m/s) compared to 1 week (3.4±0.1 m/s) and 12 weeks (3.5±0.1 m/s) (P<0.05). Humeral head stiffness did not change. Following arthroscopic rotator cuff repair, supraspinatus tendon stiffness increased in a curvilinear fashion over 6 months. From 6 months, deltoid muscle stiffness increased, corresponding to when patients were instructed to return to normal activities.

Rotator cuff repair is usually successful, but retear is not uncommon. It has been previously identified that there is a higher incidence of apoptosis in the edges of the torn supraspinatus tendon. A prospective cohort study was conducted with 28 patients-14 rotator cuff tear patients, 5 instability patients, and 9 Anterior cruciate ligament reconstruction patients to determine whether there was any increase in several genes implicated in apoptosis, including Fas receptor (FasR), Fas ligand, Aifm-1, Bcl-2, Fadd, Bax, and caspase-3. There was a significant expression of Bax (P=0.2) and FasR (P=0.005) in the edges of torn supraspinatus tendons, and in intact subscapularis tendons, there was a significant expression of caspase-3 (P=0.02) compared with samples from the torn supraspinatus tendon (P=0.04). The cytochrome c pathway, with its subsequent activation of caspase-3, as well as the TRAIL-receptor signaling pathway involving FasR have both been implicated. The elevated expression of Bax supported the model that the Bax to Bcl-2 expression ratio represents a cell death switch. The elevated expression of Bax in the intact subscapularis tissue from rotator cuff tear patients also may confirm that tendinopathy is an ongoing molecular process.

Background: Treating massive and irreparable rotator cuff tears are problematic. Several studies have reported that polytetrafluoroethy-lene (PTFE) patches demonstrated excellent construct integrity and positive clinical and patient outcomes. However, these studies either had small sample sizes or short follow-up periods.Purpose: To determine the survivorship, efficacy, and medium-term (2-19 years) outcomes of PTFE patch repairs.Methods: This retrospective study used prospectively collected data to establish the medium-term outcomes of PTFE interposition patch repairs for massive rotator cuff tears that could not be repaired by the standard technique. Patients included those who met the >2-year follow-up criteria post repair. Standardized assessments of patient-ranked shoulder pain and function and shoulder strength and passive range of motion (ROM) were performed preoperatively and at follow-up visits. Radiographs and ultrasonography were used to evaluate repair integrity, measure proximal humeral head migration, and determine glenohumeral arthritis scores. Results: Forty-one shoulders formed the study cohort at a mean follow-up period of 5 years (range: 2-19 years). The mean age of this group was 72 (standard deviation: 10; range: 50-88) and had 14 cm2 tears at surgery. Twenty-five of 41 (61%) PTFE interposition patch repairs remained intact at an average of 5 years postrepair. Thirteen patches failed at the patch-tendon junction, 1 was removed, and 2 patients underwent reverse total shoulder replacement. Patient-ranked shoulder stiffness (P < .05), frequency of pain during activity and sleep (P < .001), pain levels during overhead activity and rest (P < .001), and overall shoulder function significantly improved from bad preoperatively to fair at the mean 5-year postoperative visit (P < .001). No significant improvements were demonstrated in dynamometer-measured shoulder strength maneuvers and passive ROM. All patients demonstrated proximal humeral head migration on shoulder radiographs regardless of repair integrity (mean Upper Migration Index = 1.2). Failed repairs were associated with higher mean preoperative glenohumeral arthritis grades compared with intact repairs (grade 2 in failed repairs compared with grade 1 in intact repairs) (P < .01). Conclusion: PTFE interposition patch repairs for massive and irreparable tears had good construct integrity and clinical outcomes at 2 years. These outcomes were not maintained. PTFE patch repairs often failed at the patch-tendon junction at 4 years and beyond and were ineffective in (1) preventing proximal humeral head migration, (2) stopping progression of glenohumeral arthritis, and (3) improving shoulder strength and ROM.

Background and Objective: Tendon retear is the most common complication following rotator cuff repair surgery. Understanding the factors that are associated with greater risks of retear is important so surgeons can provide accurate prognostic information to patients. Advanced age and larger tear size have been shown to be associated with greater risk of retear at 6 months using multiple logistic regression analysis. Stiffness is the second most common complication, however recent evidence suggests that early postoperative stiffness may be associated with a more robust healing response. Thus, this paper aims to critically review the independent predictors of retear in rotator cuff repair patients. Methods: Literature review was conducted using electronic databases from their dates of inception. Key Content and Findings: There are multiple factors that affect rotator cuff repair integrity detailed in the literature. Tear size appeared to be the most important predictor of retear following rotator cuff repair. Postoperative stiffness at 6 and 12 weeks after surgery appears to be a factor associated with more intact repairs at 6 months. Shoulder stiffness tends to resolve within 6 months following the operation. This protective effect persists up to 5 years postoperatively. Conclusions: Shoulder stiffness may be an important protective factor against rotator cuff retear which requires further investigation from future studies. It is important to determine the relative importance of stiffness when compared to known important factors such as tear size with regards to its effect on rotator cuff repair integrity.

Background: We have developed a novel technique for managing rotator cuff calcific tendonitis, involving arthroscopic debridement of calcific tendonitis with localization assistance from a breast biopsy needle under ultrasound guidance. While we have demonstrated encouraging results at six-month follow-up, the medium-term outcomes and the long-term outcomes of this technique at 2 years or beyond are unknown. The aim of this paper was to determine if this technique was successful in resolving symptoms after two years and beyond. Study Design: Retrospective Cohort Study. Methods: Patients who underwent arthroscopic debridement of calcific tendonitis with localization assistance from a breast biopsy needle under ultrasound guidance by a senior surgeon were evaluated using patient-rated pain scores and functional status with the use of the Likert scales and via examiner-rated shoulder range-of-motion and strength at the pre-operative visit, at 1, 6, 12, and 24 weeks post-operatively, and long-term at a mean of 249 weeks after surgery. Results: At a mean follow-up period of 4.8 years (range, 2-10 years), 31 patients (33 shoulders) experienced significant improvement in the severity of pain at rest, with overhead activities, and during sleep compared to their pre-operative presentation (p < 0.001). The patient experienced less frequent pain during activities and sleep, and a decreased frequency of extreme pain (p < 0.001). Passive range of abduction (p = 0.003), forward flexion (p < 0.001), and supraspinatus strength (p = 0.018) improved compared to the presurgical presentation. Out of 27 patients, 24 patients (89%) had complete resolution of calcific tendonitis, and 26 patients (96%) had an intact rotator cuff. Conclusion: Arthroscopic debridement of calcific tendonitis with localization assistance from a breast biopsy needle under ultrasound guidance was very effective. Patients had significant pain relief, improved range of motion, and a reduction in stiffness at a mean post-operative period of 4.8 years. Patients had a significant reduction in residual calcification, and rotator cuff integrity was largely preserved by long-term follow-up. What is known about this subject: Calcific tendonitis of the rotator cuff is one of the most painful and debilitating disorders of the shoulder. This condition is characterized by the deposition of calcium-phosphate crystals within the rotator cuff tendons. Arthroscopic debridement and excision of rotator cuff calcifications have proven to be efficacious treatments with regards to clinical and functional outcomes in the short and medium term. Identifying the calcific lesion intra-operatively, however, can prove to be challenging. Furthermore, inadequate excision of the calcific deposit has been shown to have poorer clinical outcomes. We designed a technique that utilizes the assistance of ultrasound to guide a localization-biopsy wire to the calcific lesion. This technique aids in precisely identifying the location of the lesion intra-operatively to optimize accuracy in removing the maximum amount of calcific deposit possible. A short-term follow-up study by us has demonstrated successful outcomes with regards to the return of function and relief of pain. However, there have been no studies evaluating the effectiveness of this particular technique beyond six months. What this study adds to current knowledge: At a mean of 4. 8 years, arthroscopic debridement of calcific tendonitis, using our technique, was successful in relieving the severity and frequency of pain with overhead activities, pain at rest, and pain during sleep, as well as improving range of motion.

OBJECTIVES:How the material properties of the human supraspinatus tendon change following arthroscopic rotator cuff repair is undetermined. Shear wave elastography ultrasound is a relatively new, noninvasive measure of tissue stiffness. We aimed to evaluate any temporal changes in stiffness and/or thickness of supraspinatus tendons in humans following primary arthroscopic rotator cuff repair.METHODS:Shear wave elastography was performed at three predetermined regions by a single sonographer at 1-, 6-, 12-, 24-, and 52 weeks postoperatively in 50 consecutive single-row inverted mattress primary arthroscopic rotator cuff repairs. One-way ANOVA with Tukey's correction and Spearman's correlation tests was performed.RESULTS:Of 50 patients, two retore by 1-week and were excluded. Two patients retore at 6 weeks, two at 12 weeks, and one at 24 weeks. The mean tendon stiffness in 48 patients at the tendon footprint increased by 21% (1.32 m/s) at 6 months (P < .001), with the lateral tendon stiffening before the medial tendon. Tendon thickness decreased by 11% (0.6 mm) at 6 weeks (P = .008), then stabilized to 24 weeks. Tendons that were less elastographically stiff at 1 week were more likely to be thinner at 6-weeks (r = .38, P = .010).CONCLUSIONS:The data supports the hypothesis that rotator cuff tendons repaired using the single-row inverted-mattress technique take 6 weeks to heal to bone. Unlike in other tendons, there was no hypertrophic healing response. Prior to 6 weeks, the tendon may stretch/thin-out, particularly if its material properties, as assessed by shear wave elastography, are inferior. The material properties of the tendon improved at the tendon insertion site first, then medially out to 12 months post-repair.

Background: Ultrasound is commonly used to assess rotator cuff repair (RCR), but no standardized criterion exists to characterize the tendon.Purpose: The aims of this study were to (1) develop content validity for ultrasound specific criteria to grade the postoperative appear-ance of a tendon after RCR, (2) assess the reliability of the criteria, and (3) assess the feasibility to use these assessments.Methodology: Following expert consultation and literature review for content validity, 2 scales were created: 1) the Fibrillar matrix, Echogenicity, Contour, Thickness, and Suture (FECTS) scale and 2) the Rotator Cuff Repair-Investigator Global Assessment (RCR-IGA). A prospective cohort study was undertaken on patients who had received a RCR and serial B-mode ultrasound images. Four raters assessed the 64-ultrasound images using the scales created in a blinded fashion using intraclass correlation coefficients.Results: The FECTS scale was a composite score with 5 key parameters and the RCR-IGA scale was a 5-point global score. The intra-rater reliability for the FECTS scale was excellent for the most experienced rater (0.92) and fair for the rater with no experience (0.72). The intrarater reliability for the RCR-IGA scale was excellent for 3 of the 4 raters (0.80-0.87) and fair when used by the least experi-enced rater (0.56). Inter-rater testing for all the FECTS scale parameters had excellent reliability (0.82-0.92) except for Fibrillar matrix (0.73). The average time to complete the FECTS scale per image was 23 seconds and 11 seconds for the RCR-IGA scale.Conclusion: The FECTS scale and the RCR-IGA scale are reliable tools to assess the ultrasonic appearance of the repaired rotator cuff tendon. The FECTS scale was more reliable for less experienced assessors. The RCR-IGA scale was easier, more time efficient and reliable for those with experience.Level of evidence: Basic Science Study; Development and Validation of Classification System (c) 2022 Journal of Shoulder and Elbow Board of Trustees. All reserved.

Background:The most common complication of arthroscopic rotator cuff repair is retear, which is more common in larger tears and older patients. We hypothesized that the quality of the torn tendon is important in protecting against retear. Surgeons have traditionally assessed the quality of repaired tendons with a four-point Likert scale. Shear Wave Elastography Ultrasound (SWEUS) is a recent technological advancement that can quantify soft-tissue stiffness. This study aimed to determine how closely a surgeon's intraoperative ranking of tissue quality during rotator cuff repair correlated to postoperative supraspinatus tendon stiffness measured by SWEUS.Methods:This was a prospective case series on 50 patients undergoing arthroscopic rotator cuff repair, involving SWEUS measurements of each patient's supraspinatus tendon at 8 days, 6 weeks, 12 weeks, 6 months, and 12 months. The intraoperative surgeon score of tissue quality for each patient was ranked on a four-point Likert scale. Each patient's scores were compared to postoperative SWEUS velocity measurements of the supraspinatus tendon postrepair.Results:The SWEUS determined stiffness of supraspinatus tendons at their repaired insertion site postrepair increased by 22% from 6.3 ± 0.2 m/s to 7.7 ± 0.3 m/s over 12 months as the tendons healed (P = .0001). Supraspinatus tendon stiffness was greater in patients with smaller tears (r = -0.50, P = .001) and of younger age (r = -0.58, P = .00001). Surgeons also consistently rated younger patients (rs = -0.49, P = .0001) and smaller tears (rs = -0.56, P = .00001) as having superior intraoperative tendon quality. The correlations between SWEUS velocity and surgeon tissue quality rankings were modest at best and strongest at 12 weeks (rs = 0.27, P = .04). There were modest associations between SWEUS tendon stiffness and surgeon tendon mobility rankings at 6 weeks (rs = 0.26, P = .04) and repair quality rankings at 12 months (rs = 0.36, P = .02).Conclusions:These data support the finding that machines (SWEUS) are better at assessing torn rotator cuff tendon quality and whether that tendon will heal after repair than the 'person' performing the surgery. Supraspinatus tendons lose stiffness as they get older and when the tear is larger, likely explaining why retear post-cuff repair is more common with advanced age and larger tears.

Background: Shear wave elastography (SWE) is an emerging ultrasound-based technology that provides a quantitative assessment of musculoskeletal tissue integrity. This systematic review investigates the use of SWE in the evaluation of rotator cuff tears. Methods: PubMed, Embase, Web of Science, Google Scholar, and the Cochrane Library databases were searched for relevant studies from 1901 up to June 2022. Articles utilizing SWE in rotator cuff tears were selected based on inclusion and exclusion criteria. The studies included involved the assessment of shear wave velocity, tendon thickness and stiffness after healing, and fatty infiltrates evaluation using SWE. The Newcastle-Ottawa Scale was used to evaluate the risk of bias in included observational studies. Double-sided P value < .05 was considered statistically significant. Results: Sixteen studies comprising 520 patients were included in the systematic review. SWE demonstrated that shear wave velocities in torn supraspinatus tendons were lower than in healthy supraspinatus tendons. A decrease in tendon SWE modulus elasticity was observed in tendinopathic tendons. Shear wave velocity decreased with increasing fat content and muscle atrophy. The velocity of SWE in muscle in re-tear groups was greater than in the healed group at 1 month after surgery (P < .05). Conclusion: SWE ultrasound of the supraspinatus tendon can be a useful diagnostic tool for orthopedic surgeons that provide quantitative information on tendinopathic stiffness, velocity, fatty infiltrate, and elasticity characteristics. Decreased tendon velocity of SWE may predict recurrent rotator cuff tears and be useful in postoperative evaluations for muscle healing to plan for future management.

BACKGROUND:The main complication of rotator cuff repair is retear, which is most common in older patients and patients with greater tear sizes. However, it is unknown why these factors are associated with increased rates of retear. The aim of this study was to determine whether the factors associated with rotator cuff retear (age, tear size, sex, history of trauma, and duration of symptoms) are also associated with decreased mechanical stiffness of the supraspinatus tendon after repair, as assessed by shear wave elastography. METHODS:This was a prospective study of 50 patients undergoing primary rotator cuff repair. A sonographer conducted shear wave elastography ultrasound in all patients at 1, 6, 12, 26, and 52 weeks after repair. The shear wave velocity of the supraspinatus tendon was measured at the tendon-bone interface, 3 mm medial to the interface, and 6 mm medial to the interface. A multiple linear regression analysis was performed with calculation of Cohen F2 values to determine the factors that independently affected supraspinatus tendon stiffness postoperatively. RESULTS:For every decade increase in age, the shear wave velocity of the supraspinatus tendon decreased by 0.5 m/s (P = .004). Greater tear size correlated with reduced supraspinatus shear wave velocity (P < .03 at 6 weeks). Male patients had greater supraspinatus tendon stiffness than female patients (8.2 m/s vs. 6.9 m/s, P = .04). Tendons in patients with a history of trauma were approximately 16% stiffer postoperatively than those in patients with no trauma history (P < .001). Duration of symptoms had no impact on the mechanical stiffness of the supraspinatus tendon. CONCLUSION:Older age, larger tear size, female sex, and nontraumatic tear causation were independently associated with reduced shear wave velocity of the supraspinatus tendon postoperatively. The findings of our study correlate with the results of cohort studies assessing the influence of these variables on rotator cuff retear rates, suggesting that the mechanical stiffness of the supraspinatus tendon, as assessed by shear wave elastography, may have an important association with a successful repair.

BACKGROUND:Superior capsular reconstruction (SCR) for massive, irreparable rotator cuff tears involves anchoring a graft between the superior glenoid and the greater tuberosity of the humerus. Optimizing the graft size is important. We aimed (1) to evaluate the reliability of plain film radiography in determining graft size for SCR and (2) to create a database to help predict future graft sizes.METHODS:An inter- and intra-rater reliability trial was conducted on 10 and 6 subjects with healthy shoulders, respectively, using plain film radiography to measure the distance between the superior glenoid and the supraspinatus footprint. The subjects were positioned upright with an abduction pillow modified to hold the shoulder at 30° abduction and 45° external rotation, afterwhich a true antero-posterior shoulder radiograph was captured. Thirty subjects were recruited for the database and grouped using the aforementioned protocol.RESULTS:The inter-rater and intra-rater trial agreement was excellent, with intraclass correlation coefficients of 0.94 (95% CI) and 0.76 (95% CI), respectively. Three medio-lateral patch sizes, of 33 mm, 38 mm, and 47 mm, were proposed based on the protocol in 30 subjects.CONCLUSIONS:Plain film radiography demonstrated excellent reliability in measuring the distance between the superior glenoid and the supraspinatus footprint. Three ordinal patch sizes are proposed.

Background:The addition of onlay biological grafts to augment difficult rotator cuff repairs has shown encouraging results in a case series. Purpose/Hypothesis:The purpose of this study was to determine whether the addition of an onlay bioinductive implant would improve repair integrity, shear wave elastographic appearance of the repaired tendon and patch, and patient-rated and/or surgeon-measured shoulder function when used in workers' compensation patients undergoing revision arthroscopic rotator cuff repair. We hypothesized that the addition of the bioinductive implant would enhance repair integrity and clinical outcomes compared with standard repair. Study Design:Cohort study; Level of evidence, 3. Methods:A post hoc matched-cohort study was conducted on prospectively recruited workers' compensation patients who received a bioinductive implant for revision rotator cuff repair (n = 19). The control group was selected from consecutive workers' compensation revision rotator cuff repair patients before the introduction of bioinductive implants. Then, they were matched for age and tear size (n = 32). Kaplan-Meier curves were generated to compare the primary outcome of repair integrity between groups. The secondary outcomes were to evaluate the elastographic appearance of the tendon and patch in the bioinductive implant group and to compare patient-rated and surgeon-measured shoulder function between groups preoperatively and at 1 week, 6 weeks, 3 months, and 6 months postoperatively. Results:No major complications associated with the bioinductive implants were identified. Six months after the revision rotator cuff repair, the retear rate in the bioinductive implant group was 16% (3/19), compared with 19% (6/32) in the age- and tear size-matched control group (P = .458). At the final follow-up, the retear rate in the bioinductive implant group was 47% (9/19) at a mean of 14 months compared with 38% (12/32) at a mean of 29 months in the control group (P = .489). The shear wave elastographic stiffness of repaired tendons augmented with the bioinductive implant remained unchanged at 6 m/s from 1 week to 6 months postoperatively, which is lower than the stiffness of 10 m/s in healthy tendons. There were no significant differences in patient-rated or surgeon-measured outcomes between groups 6 months postoperatively. Conclusion:There were no differences in repair integrity or clinical outcomes between workers' compensation patients who underwent revision arthroscopic rotator cuff repair with an onlay bioinductive implant compared to those who underwent standard revision rotator cuff repair.

Objectives: It is unclear if concomitant glenohumeral osteoarthritis is protective or detrimental with respect to rotator cuff integrity after arthroscopic repair surgery. We hypothesized that the associated stiffness might protect the repaired tendon. In the alternate, arthritis might reflect a gradual degeneration of the joint including a degenerative tendon and therefore predispose the repair to re-tear. Therefore, the purpose of this study was to investigate whether concomitant osteoarthritic changes found intra-operatively during arthroscopic rotator cuff repairs (RCR) have a beneficial or detrimental effect on post-operative repair integrity. Methods: This study is a post-hoc analysis of prospectively collected data of patients who underwent primary arthroscopic RCR between 2005 and 2019 by a single surgeon. Patients were divided into an osteoarthritic group and a control group based on the presence or absence of intra- operative osteoarthritic changes respectively. The primary outcome measure was cuff integrity detected by post-operative ultrasound at 6-months. The secondary outcomes were patient-reported outcomes including shoulder pain, stiffness, level of activity at work and level of sport, and physician-reported outcomes including shoulder range of motion and strength. Results: A total of 2155 consecutive patients met the inclusion criteria with a mean age of 59 years (SD=0.2) and there were more males as compared to females (56% vs. 44%). 28% of patients undergoing RCR had osteoarthritic changes detected intra- operatively. Intra-operatively, the osteoarthritic group had more full-thickness tears (64% vs. 59%) (p<.001), a larger mean anteroposterior tear length [20mm (SD=0.5) vs. 17mm (SD=0.4)] (p<.001) and a larger mean mediolateral tear length [17mm (SD=0.5) vs. 15mm (SD=0.4)] (p<.001). Ultrasonographic evaluation at 6-months post-surgery demonstrated that the osteoarthritic group had a higher incidence of cuff re-tear rate as compared to the control group (15% vs. 11%) (p=.016) ( Figure 1 ). However, after performing a multiple logistic regression analysis, osteoarthritis was not found to be an independent predictor of re-tear. There were very marginal differences in patient-reported outcomes at 6-months after surgery between the two groups ( Table 1 ). The osteoarthritic group reported lesser post-operative frequency of activity pain [2.0 (SD=1.46) vs. 2.2 (SD=1.43)] (p=.005), frequency of extreme pain [0.8 (SD=1.35) vs. 1.0 (SD=1.41)] (p=.035) and level of pain during overhead activity [1.7 (SD=1.30) vs. 1.9 (SD=1.30)] (p=.021) as compared to controls. As compared to controls, the osteoarthritic group also experienced lesser post-operative stiffness [1.5 (SD=1.32) vs. 1.6 (SD=1.31)] (p=.019) and reported lower intensities of work-related activities [1.1 (SD=0.88) vs. 1.2 (SD=0.85)] (p=.038) and lower level of sport activity [0.4 (SD=0.62) vs. 0.5 (SD=0.70)] (p=.004). In terms of physical examination at 6-months following surgery ( Table 2 ), the osteoarthritic group were found to have lesser range of motion in forward flexion [146° (SD=33.1) vs. 151° (SD=31.2)] (p=.009), abduction [127° (SD=38.8) vs. 131° (SD=38.1)] (p=.034), external rotation [50° (SD=21.4) vs. 52° (SD=21.0)] (p=.024) and internal rotation (L1 vertebrae (SD=4.2) vs. T12 vertebrae (SD=4.2)] (p=.004) as compared to controls. The osteoarthritic group as weaker internal rotation strength [68N (SD=30.5) vs. 73N (SD=32.9)] (p=.004), external rotation strength [57N (SD=25.3) vs. 60N (SD=27.2)] (p=.026), supraspinatus flexion strength [45N (SD=26.8) vs. 50N (SD=27.9)] (p<.001), lift-off [40N (SD=24.3) vs. 44N (SD=25.3)] (p<.001) and adduction strength [76N (SD=36.5) vs. 81N (SD=39.3)] (p=.008) as compared to the control group. Conclusions: Patients with concomitant glenohumeral osteoarthritis who underwent arthroscopic RCR had higher re-tear rates at 6-months after surgery. However, osteoarthritis is not an independent predictor of rotator cuff re-tear at 6-months. Therefore, arthroscopic RCR is a viable surgical option for these patients. Figure 1: Proportion of intract vs. torn rotator cuff repairs between the osteoarthritic group (n=1552) and control group (n=603) at 6-months post-operative follow-up (p=.016). Table 1: 6-month post-operative pain scares and shoulder function in the osteoarthritic group vs. control group. Table 2: 6-month post-operative shoulder range of motion and strength in the osteoarthritic group vs. control group.

Introduction: The most common complication of arthroscopic rotator cuff repair is retear, and retear or failure to heal is more common in larger tears in older patients. We hypothesised that the quality of the torn tendon is important in protecting against retear. Surgeons have traditionally assessed the quality of repaired tissue with a four-point Likert scale. Shear Wave Elastography Ultrasound (SWEUS) is a recent technological advancement which can quantify soft tissue stiffness. The aim of this study was to determine how closely a surgeon’s intraoperative rankings of tissue quality correlate to postoperative supraspinatus tendon stiffness as measured by SWEUS. Methods: A prospective cohort study was conducted on 50 patients undergoing arthroscopic rotator cuff repair, taking SWEUS images of each patient’s supraspinatus tendon at 8-days, 6-weeks, 12-weeks, 6-months and 12-months. The intraoperative surgeon-score of tissue quality for each patient was ranked on a four-point Likert scale. Each patient’s scores were compared to postoperative SWEUS velocity (m/s) measurements of the supraspinatus tendon post-repair using spearman’s correlation coefficients, with repeated measures ANOVAs and Pearson’s correlation coefficients for parametric data. Results: The SWEUS determined stiffness of supraspinatus tendons at their repaired insertion site increased by 22% from 6.2±1.5m/s to 7.8±1.7m/s over 12-months as tendons healed (p=0.0001). There were significant differences in the stiffness of the supraspinatus tendon along the tendon insertion site itself, with the lateral portion becoming stiffest early on (8-days and 6-weeks) and the medial area later on (52-weeks). SWEUS tendon stiffness was greater in patients with smaller tears (r=-0.50) of younger age and of male sex (p=0.04). Surgeons also consistently rated younger patients (rs=-0.49, p=0.0001) and smaller tears (rs=-0.56, p=0.00001) as having superior intraoperative tendon quality. The correlations between SWEUS velocity and surgeon tissue quality rankings were modest at best, and strongest at 12 weeks (r=0.27). There were also modest associations between surgeon ranked tendon mobility scores and SWEUS tendon stiffness at 6 weeks (r=0.25) and repair quality rankings at 1 week (r=0.32). Discussion: This data supports the hypothesis that machines (via shear wave elastography) are better at assessing the quality of a torn rotator cuff tendon and whether that tendon will heal after a repair, than the ‘man’ performing the surgery. Impact and Application to the field: Knowledge•Shear Wave Elastography Ultrasound (SWEUS) Velocity measurements are useful for assessing the quality of a tendon.•Tendons lose SWEUS stiffness as they get older and when the tear is larger. This reduction in mechanical integrity likely explains, in part at least, why age and tear size affect re-tear rates post rotator cuff repair.•The supraspinatus tendon as it heals becomes stiffer laterally faster than it does medially. My co-authors and I acknowledge that we have no conflict of interest or relevance to the submission of this abstract.

Supraspinatus tendinopathy is a common cause of shoulder pain and tendon degeneration in individuals who participate in repetitive overhead activities, such as tennis players or tradespeople. Early diagnosis and treatment of tendinopathies is necessary to prevent chronic sequelae and tendon rupture, which is especially important for groups such as professional athletes and manual workers for avoidance of prolonged downtime.