Aims. Rotator cuff muscle atrophy and fatty infiltration affect the clinical outcomes of rotator cuff tear patients. However, there is no effective treatment for fatty infiltration at this time. High-intensity interval training (HIIT) helps to activate beige adipose tissue. The goal of this study was to test the role of HIIT in improving muscle quality in a rotator cuff tear model via the β3 adrenergic receptor (β3AR). Methods. Three-month-old C57BL/6 J mice underwent a unilateral rotator cuff injury procedure. Mice were forced to run on a treadmill with the HIIT programme during the first to sixth weeks or seventh to 12th weeks after tendon tear surgery. To study the role of β3AR, SR59230A, a selective β3AR antagonist, was administered to mice ten minutes before each exercise through intraperitoneal injection. Supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat were harvested at the end of the 12th week after tendon tear and analyzed biomechanically, histologically, and biochemically. Results. Histological analysis of supraspinatus muscle showed that HIIT improved muscle atrophy, fatty infiltration, and contractile force compared to the no exercise group. In the HIIT groups, supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat showed increased expression of tyrosine hydroxylase and uncoupling protein 1, and upregulated the β3AR thermogenesis pathway. However, the effect of HIIT was not present in mice injected with SR59230A, suggesting that HIIT affected muscles via β3AR. Conclusion. HIIT improved supraspinatus muscle quality and function after rotator cuff tears by activating systemic sympathetic nerve fibre near adipocytes and β3AR. Cite this article: Bone Joint Res 2023;12(8):455–466

We have studied cellular and vascular changes in different stages of full thickness tears of the rotator cuff. We examined biopsies from the supraspinatus tendon in 40 patients with chronic rotator cuff tears who were undergoing surgery and compared them with biopsies from four uninjured subscapularis tendons. Morphological and immunocytochemical methods using monoclonal antibodies directed against leucocytes, macrophages, mast cells, proliferative and vascular markers were used. Histological changes indicative of repair and inflammation were most evident in small sized rotator cuff tears with increased fibroblast cellularity and intimal hyperplasia, together with increased expression of leucocyte and vascular markers. These reparative and inflammatory changes diminished as the size of the rotator cuff tear increased. Marked oedema and degeneration was seen in large and massive tears, which more often showed chondroid metaplasia and amyloid deposition. There was no association between the age of the patient and the duration of symptoms. In contrast, large and massive tears showed no increase in the number of inflammatory cells and blood vessels. Small sized rotator cuff tears retained the greatest potential to heal, showing increased fibroblast cellularity, blood vessel proliferation and the presence of a significant inflammatory component. Tissue from large and massive tears is of such a degenerative nature that it may be a significant cause of re-rupture after surgical repair and could make healing improbable in this group

The aim of this study was to investigate genetic influences on the development and progression of tears of the rotator cuff. From a group of siblings of patients with a tear of the rotator cuff and of controls studied five years earlier, we determined the prevalence of tears of the rotator cuff with and without associated symptoms using ultrasound and the Oxford Shoulder Score. In the five years since the previous assessment, three of 62 (4.8%) of the sibling group and one of the 68 (1.5%) controls had undergone shoulder surgery. These subjects were excluded from the follow-up. Full-thickness tears were found in 39 of 62 (62.9%) siblings and in 15 of 68 (22.1%) controls (p = 0.0001). The relative risk of full-thickness tears in siblings as opposed to controls was 2.85 (95% confidence interval (CI) 1.75 to 4.64), compared to 2.42 (95% CI 1.77 to 3.31) five years earlier. Full-thickness tears associated with pain were found in 30 of 39 (76.9%) tears in the siblings and in eight of 15 (53.3%) tears in the controls (p = 0.045). The relative risk of pain associated with a full-thickness tear in the siblings as opposed to the controls was 1.44 (95% CI 2.04 to 8.28) (p = 0.045). In the siblings group ten of 62 (16.1%) had progressed in terms of tear size or development compared to one of 68 (1.5%) in the control group which had increased in size. Full-thickness rotator cuff tears in siblings are significantly more likely to progress over a period of five years than in a control population. This implies that genetic factors have a role, not only in the development but also in the progression of full-thickness tears of the rotator cuff

The aim of this study was to define the microcirculation of the normal rotator cuff during arthroscopic surgery and investigate whether it is altered in diseased cuff tissue. Blood flow was measured intra-operatively by laser Doppler flowmetry. We investigated six different zones of each rotator cuff during the arthroscopic examination of 56 consecutive patients undergoing investigation for impingement, cuff tears or instability; there were 336 measurements overall. The mean laser Doppler flowmetry flux was significantly higher at the edges of the tear in torn cuffs (43.1, 95% confidence interval (CI) 37.8 to 48.4) compared with normal cuffs (32.8, 95% CI 27.4 to 38.1; p = 0.0089). It was significantly lower across all anatomical locations in cuffs with impingement (25.4, 95% CI 22.4 to 28.5) compared with normal cuffs (p = 0.0196), and significantly lower in cuffs with impingement compared with torn cuffs (p < 0.0001). Laser Doppler flowmetry analysis of the rotator cuff blood supply indicated a significant difference between the vascularity of the normal and the pathological rotator cuff. We were unable to demonstrate a functional hypoperfusion area or so-called ‘critical zone’ in the normal cuff. The measured flux decreases with advancing impingement, but there is a substantial increase at the edges of rotator cuff tears. This might reflect an attempt at repair

We undertook clinical and ultrasonographic examination of the shoulders of 420 asymptomatic volunteers aged between 50 and 79 years. MRI was performed in selected cases. Full-thickness tears of the rotator cuff were detected in 32 subjects (7.6%). The prevalence increased with age as follows: 50 to 59 years, 2.1%; 60 to 69 years, 5.7%; and 70 to 79 years, 15%. The mean size of the tear was less than 3 cm and tear localisation was limited to the supraspinatus tendon in most cases (78%). The strength of flexion was reduced significantly in the group with tears (p = 0.01). Asymptomatic tears of the rotator cuff should be regarded as part of the normal ageing process in the elderly but may be less common than hitherto believed

We have conducted a prospective study to assess the mid-term clinical results following arthroscopic repair of the rotator cuff. Patients were evaluated using the Constant score, subjective satisfaction levels and post-operative ultrasound scans. Of 115 consecutive patients who underwent arthroscopic repair of the rotator cuff at our institution, 102 were available for follow-up. The mean period of follow-up was for 35.8 months (24 to 73). The mean age of the patients was 57.3 years (23 to 78). There were 18 small (≤ 1 cm in diameter), 44 medium (1 cm to 3 cm in diameter), 34 large (3 cm to 5 cm in diameter) and six massive (> 5 cm in diameter) tears. There was a statistically significant increase in the size of the tear with increasing age (p = 0.0048). The mean pre-operative Constant score was 41.4 points (95% confidence interval, 37.9 to 44.9), which improved to 84.5 (95% confidence interval, 82.2 to 86.9). A significant inverse association (p = 0.0074), was observed between the size of the tear and the post-operative Constant score, with patients having smaller tears attaining higher Constant scores after repair. Post-operatively, 80 patients (78.4%) were able to resume their occupations and 84 (82.4%) returned to their pre-injury leisure activities. Only eight (7.8%) of 102 patients were not satisfied with the outcome. Recurrent tears were detected by ultrasound in 19 (18.6%) patients, and were generally smaller than the original ones. Patients with recurrent tears experienced a mean improvement of 31.6 points (95% confidence interval, 23.6 to 39.6) in their post-operative Constant scores. Those with intact repairs had significantly improved (p < 0.0001) Constant scores (mean improvement 46.3 points, 95% confidence interval, 41.9 to 50.6). Patient satisfaction was high in 94 cases (92%), irrespective of the outcome of the Constant score. Recurrent tears appear to be linked to age-related degeneration. Arthroscopic repair of the rotator cuff leads to high rates of satisfaction (92%) and good functional results, albeit with a recurrence rate of 18.6% (19 of 102)

CT arthrography and arthroscopy were used to assess tears of the rotator cuff in 259 shoulders. Tear size was determined in the frontal and sagittal planes according to the classification of the French Arthroscopy Society. CT arthrography had a sensitivity of 99% and a specificity of 100% for the diagnosis of tears of supraspinatus. For infraspinatus these figures were 97.44% and 99.52%, respectively and, for subscapularis, 64.71% and 98.17%. For lesions of the long head of the biceps, the sensitivity was 45.76% and the specificity was 99.57%. Our study showed an excellent correlation between CT arthrography and arthroscopy when assessing the extent of a rotator cuff tear. CT arthrography should, therefore, be an indispensable part of pre-operative assessment. It allows determination of whether a tear is reparable (retraction of the tendon and fatty degeneration of the corresponding muscle) and whether this is possible by arthroscopy (degree of tendon retraction and extension to subscapularis)

In a prospective, randomised study on the repair of tears of the rotator cuff we compared the clinical results of two suture techniques for which different suture materials were used. We prospectively randomised 100 patients with tears of the rotator cuff into two groups. Group 1 had transosseous repair with No. 3 Ethibond using modified Mason-Allen sutures and group 2 had transosseous repair with 1.0 mm polydioxanone cord using modified Kessler sutures. After 24 to 30 months the patients were evaluated clinically using the Constant score and by ultrasonography. Of the 100 patients, 92 completed the study. No significant statistical difference was seen between the two groups: Constant score, 91% vs 92%; rate of further tear, 18% vs 22%; and revision, 4% vs 4%. In cases of further tear the outcome in group 2 did not differ from that for the intact repairs (91% vs 91%), but in group 1 it was significantly worse (94% vs 77%, p = 0.005). Overall, seven patients had complications which required revision surgery, in four for pain (two in each group) and in three for infection (two in group 1 and one in group 2)

In a prospective randomised trial of calcifying tendinitis of the rotator cuff, we compared the efficacy of dual treatment sessions delivering 2500 extracorporeal shock waves at either high- or low-energy, via an electromagnetic generator under fluoroscopic guidance. Patients were eligible for the study if they had more than a three-month history of calcifying tendinitis of the rotator cuff, with calcification measuring 10 mm or more in maximum dimension. The primary outcome measure was the change in the Constant and Murley Score. A total of 80 patients were enrolled (40 in each group), and were re-evaluated at a mean of 110 (41 to 255) days after treatment when the increase in Constant and Murley score was significantly greater (t-test, p = 0.026) in the high-energy treatment group than in the low-energy group. The improvement from the baseline level was significant in the high-energy group, with a mean gain of 12.5 (−20.7 to 47.5) points (p < 0.0001). The improvement was not significant in the low-energy group. Total or subtotal resorption of the calcification occurred in six patients (15%) in the high-energy group and in two patients (5%) in the low-energy group. High-energy shock-wave therapy significantly improves symptoms in refractory calcifying tendinitis of the shoulder after three months of follow-up, but the calcific deposit remains unchanged in size in the majority of patients

This study reports the application of a novel method for quantitatively determining differences in the mechanical properties of healthy and torn rotator cuff tissues. In order to overcome problems of stress risers at the grip-tendon interface that can obscure mechanical measurements of small tendons, we conducted our investigation using dynamic shear analysis. Rotator cuff tendon specimens were obtained from 100 patients during shoulder surgery. They included 82 differently sized tears and 18 matched controls. We subjected biopsy samples of 3 mm in diameter to oscillatory deformation under compression using dynamic shear analysis. The storage modulus (G’) was calculated as an indicator of mechanical integrity. Normal tendons had a significantly higher storage modulus than torn tendons, indicating that torn tendons are mechanically weaker than normal tendons (p = 0.003). Normal tendons had a significantly higher mean shear modulus than tendons with massive tears (p < 0.01). Dynamic shear analysis allows the determination of shear mechanical properties of small tissue specimens obtained intra-operatively that could not be studied by conventional methods of tensile testing. These methods could be employed to investigate other musculoskeletal tissues. This pilot study provides some insight into mechanisms that might contribute to the failure of repair surgery, and with future application could help direct the most appropriate treatment for specific rotator cuff tears

Age-related localised deposition of amyloid in connective tissue has been found in degenerative articular and periarticular tissue. Biopsies of the supraspinatus tendon of 28 patients undergoing repair of the rotator cuff were analysed histologically for the presence of localised deposition of amyloid. There was a long history of impingement in 20 patients, and eight patients had suffered an acute traumatic tear with no preceding symptoms. Localised deposition of amyloid identified by Congo Red staining was detected in 16 samples (57%). Amyloid was present in 14 (70%) of the degenerative tears, but in only two (25%) of the acute tears. Immunohistochemical staining showed that the amyloid deposits were positive for P component, but negative for κ and λ light chains, prealbumin, and β2 microglobulin. Critical electrolyte staining revealed highly-sulphated glycosaminoglycans at sites of deposition of amyloid. The presence of localised deposition of amyloid in tears of the rotator cuff is likely to represent irreversible structural changes. These findings support the theory that impingement and tears are due to intrinsic degenerative changes within the tendons of the rotator cuff

The aim of this study was to determine the functional outcome and rate of re-tears following mini-open repair of symptomatic large and massive tears of the rotator cuff using a two-row technique. The 24 patients included in the study were assessed prospectively before and at a mean of 27 months (18 to 53) after surgery using the Constant and the Oxford Shoulder scores. Ultrasound examination was carried out at follow-up to determine the integrity of the repair. Patient satisfaction was assessed using a simple questionnaire. The mean Constant score improved significantly from 36 before to 68 after operation (p < 0.0001) and the mean Oxford Shoulder score from 39 to 20 (p < 0.0001). Four of the 24 patients (17%) had a re-tear diagnosed by ultrasound. A total of 21 patients (87.5%) were satisfied with the outcome of their surgery. The repair remained intact in 20 patients (83%). However, the small number of re-tears (four patients) in the study did not allow sufficient analysis to show a difference in outcome in relation to the integrity of the repair

The diagnosis of chronic lesions of the rotator cuff is challenging. We have developed a new index to improve the sonographic diagnosis of chronic tears of the cuff. In a pilot study, we examined 50 asymptomatic healthy volunteers by ultrasound to establish the diameter of the rotator cuff in relation to the tendon of the long head of biceps. Subsequently, the index was calculated in 64 patients who had had shoulder pain for more than three months caused by clinically diagnosed lesions of the rotator cuff. The compensatory hypertrophy of the biceps tendon was quantified sonographically in relation to the diameter of the cuff. Comparison with the contralateral shoulder revealed a significantly higher biceps rotator-cuff ratio (p < 0.05) for patients with torn rotator cuffs. A ratio greater than 0.8 was considered pathological (index positive); the mean ratio in the control group was 0.43. The sensitivity of a positive index was 97.8%, the specificity 63.2%, the positive predictive value 86.3%, and the negative predictive value 92.4% in comparison with surgical findings. Use of the index improves sensitivity in the diagnosis of chronic tears of the cuff by ultrasound

A consecutive series of 372 patients who underwent surgery for disorders of the rotator cuff involving arthroscopic subacromial decompression and open or arthroscopic repairs of the cuff were prospectively investigated as to the comparability of subjective and objective assessment scores of shoulder function. Assessments were made before operation and at 3, 6, 12, 18 and 24 months after surgery using the Disabilities of the Arm, Shoulder, and Hand score, the Oxford shoulder score and the Constant-Murley score, which was used as a reference. All scores were standardised to a scale of 0 to 100 for comparison. Statistical analysis compared the post-operative course and the mean score for the subjective Disabilities to the Arm, Shoulder and Hand score and Oxford shoulder score, with the objective Constant score at each interval. A strong correlation was evident between both subjective scores and the Constant score. We concluded that both the subjective scores would be useful substitutes for the Constant score, obviating the need for a trained investigator and the specialist equipment required to perform the Constant score

From a retrospective, cohort study of 205 patients diagnosed with full-thickness tears of the rotator cuff, we determined, using ultrasound, the prevalence of such tears in their 129 siblings. Using 150 spouses as controls, the relative risk of full-thickness tears in siblings versus controls was 2.42 (95% CI 1.77 to 3.31). The relative risk of symptomatic full-thickness tears in siblings versus controls was 4.65 (95% CI 2.42 to 8.63). The significantly increased risk for tears in siblings implies that genetic factors play a major role in the development of full-thickness tears of the rotator cuff

We have undertaken an in vivo assessment of the tissue metabolism and cellular activity in torn tendons of the rotator cuff. Cellular oxygen consumption was measured in 13 patients undergoing mini-open repair of small, medium, large and massive full-thickness tears. Measurements were also taken from three control patients who were undergoing open stabilisation of the shoulder with grossly normal tendons. The level of oxygen and nitrous oxide was measured amperometrically using silver needle microelectrodes at the apex of the tear and 1.5 cm from its edge. With nitrous oxide indicating the degree of perfusion, oxygen consumption was calculated at each location to reflect cellular activity. All of the torn tendons had lower levels of cellular activity than the control group. This activity was lower still in the tissue nearest to the edge of the tear with the larger tears showing the lowest activity. This indicated reduced levels of tissue metabolism and infers a reduction in tendon viability. Our findings suggest that surgical repair of torn tendons of the rotator-cuff should include the more proximal, viable tissue, and may help to explain the high rate of re-rupture seen in larger tears

Introduction. The pathogenesis of rotator cuff disease (RCD) is complex and not fully understood. This systematic review set out to summarise the histological and molecular changes that occur throughout the spectrum of RCD. Methods. We conducted a systematic review of the scientific literature with specific inclusion and exclusion criteria. Results. A total of 101 studies met the inclusion criteria: 92 studies used human subjects exclusively, seven used animal overuse models, and the remaining two studies involved both humans and an animal overuse model. A total of 58 studies analysed supraspinatus tendon exclusively, 16 analysed subacromial bursal tissue exclusively, while the other studies analysed other tissue or varying combinations of tissue types including joint fluid and muscle. The molecular biomarkers that were altered in RCD included matrix substances, growth factors, enzymes and other proteins including certain neuropeptides. Conclusions. The pathogenesis of RCD is being slowly unravelled as a result of the significant recent advances in molecular medicine. Future research aimed at further unlocking these key molecular processes will be pivotal in developing new surgical interventions both in terms of the diagnosis and treatment of RCD

We report the use of the reverse shoulder prosthesis in the revision of a failed shoulder hemiarthroplasty in 19 shoulders in 18 patients (7 men, 11 women) with severe pain and loss of function. The primary procedure had been undertaken for glenohumeral arthritis associated with severe rotator cuff deficiency. Statistically significant improvements were seen in pain and functional outcome. After a mean follow-up of 44 months (24 to 89), mean forward flexion improved by 26.4° and mean abduction improved by 35°. There were six prosthesis-related complications in six shoulders (32%), five of which had severe bone loss of the glenoid, proximal humerus or both. Three shoulders (16%) had non-prosthesis related complications. The use of the reverse shoulder prosthesis provides improvement in pain and function for patients with failure of a hemiarthroplasty for glenohumeral arthritis and rotator cuff deficiency. However, high rates of complications were associated with glenoid and proximal humeral bone loss

We compared the outcome of arthroscopic repair of the rotator cuff in 32 diabetic patients with the outcome in 32 non-diabetic patients matched for age, gender, size of tear and comorbidities. The Constant-Murley score improved from a mean of 49.2 (24 to 80) pre-operatively to 60.8 (34 to 95) post-operatively (p = 0.0006) in the diabetic patients, and from 46.4 (23 to 90) pre-operatively to 65.2 (25 to 100) post-operatively (p = 0.0003) in the non-diabetic patients at six months. This was significantly greater (p = 0.0002) in non-diabetic patients (18.8) than in diabetics (11.6). There was no significant change in the mean mental component of the Short-Form 12, but the mean physical component increased from 35 to 41 in non-diabetics (p = 0.0001), and from 37 to 39 (p = 0.15) in diabetics. These trends were observed at one year. Patients with diabetes showed improvement of pain and function following arthroscopic rotator cuff repair in the short term, but less than their non-diabetic counterparts

Os acromiale is a rare anatomical abnormality and treatment is controversial. Our retrospective study analyses the outcome of excision, acromioplasty and bony fusion of the os acromiale when it is associated with a tear of the rotator cuff. After a mean follow-up of 41 months, 33 patients were radiologically and clinically assessed using the Constant score. The surgical procedure was to repair the rotator cuff together with excision of the os acromiale in six patients, acromioplasty in five, and fusion in 22. Of the 22 attempted fusions seven failed radiologically. The Constant scores were 82%, 81%, 81% and 84% for patients who had excision, acromioplasty, successful fusion and unsuccessful fusion respectively. There were no statistically significant differences. We conclude that a small mobile os acromiale can be resected, a large stable os acromiale treated by acromioplasty and a large unstable os acromiale by fusion to the acromion. Even without radiological fusion the clinical outcome can be good