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

Aims. The gluteus minimus (GMin) and gluteus medius (GMed) have unique structural and functional segments that may be affected to varying degrees, by end-stage osteoarthritis (OA) and normal ageing. We used data from patients with end-stage OA and matched healthy controls to 1) quantify the atrophy of the GMin and GMed in the two groups and 2) describe the distinct patterns of the fatty infiltration in the different segments of the GMin and GMed in the two groups. Methods. A total of 39 patients with end-stage OA and 12 age- and sex frequency-matched healthy controls were prospectively enrolled in the study. Fatty infiltration within the different segments of the GMin and the GMed was assessed on MRI according to the semiquantitative classification system of Goutallier and normalized cross-sectional areas were measured. Results. The GMin was smaller in the OA-group (p < 0.001) compared to the control group, but there was no group difference in the size of the GMed (p = 0.101). Higher levels of fatty infiltration were identified in the anterior segment of the GMin (p = 0.006) and the anterior (p = 0.006) and middle (p = 0.047) segments of the GMed in the OA group. All subjects in the control group had fatty infiltration of the anterior segment of the GMin, but all except one had no fatty infiltration in the entire GMed. Conclusion. End-stage OA was associated with significant atrophy of the GMin and higher levels of fatty infiltration, particularly in the anterior segments of the GMin and GMed. Minor fatty infiltration of the anterior segment of GMin appears to be a normal part of ageing. Our study has demonstrated different patterns of atrophy and fatty infiltration between patients with end-stage OA and healthy matched peers. Cite this article: Bone Jt Open 2021;2(1):40–47

Purpose of the study: Fatty infiltration and atrophy of rotator cuff muscles is an important prognostic factor for anatomic healing and function after repair. The purpose of this study was to analyse factors influencing the development and progression of the supraspinatus muscle and to search for correlation between infiltration and atrophy. Material and method: Preoperative arthroscans and MRI series for 1688 patients with rotator cuff tears were reviewed. We searched for correlations between fatty infiltration of the supraspinatus muscle and gender, age at imaging, size of the tear, onset (trauma or not), and time from symptom onset to imaging. Fatty infiltration was noted according to the Goutallier classification and on the MRI using the classification adapted by Fuchs. For the statistical analysis, fatty infiltration was considered minor for grades 0 and 1, moderate for grade 2 and severe for grades 3 and 4. Muscle atrophy was assessed using the tangent sign. Results: Fatty infiltration of the supraspinatus increased significantly with the size of the tendon tear (p< 0.0005), time from symptom onset to imaging (lp< 0.0005) and patient age (p< 0.0005). Atrophy increased with number of torn tendons, positive tangent sign was correlated with the grade of fatty infiltration of the supraspinatus (p< 0.0005) and the infraspinatus (p< 0.0005). Moderate and severe fatty infiltration developed a mean 3 and 5 years, respectively, after symptom onset. Discussion: Surgical treatment should be undertaken before the appearance of moderate (grade 2) fatty infiltration and atrophy (positive tangent sign). Conclusion: Moderate fatty infiltration of the supraspinatus develops on average three years after onset of symptoms

Background. Rotator cuff atrophy evaluated with computed tomography scans has been associated with asymmetric glenoid wear and humeral head subluxation in glenohumeral arthritis. Magnetic resonance imaging has increased sensitivity for identifying rotator cuff pathology and has not been used to investigate this relationship. The purpose of this study was to use MRI to assess the association of rotator cuff muscle atrophy and glenoid morphology in primary glenohumeral arthritis. Methods. 132 shoulders from 129 patients with primary GHOA were retrospectively reviewed and basic demographic information was collected. All patients had MRIs that included appropriate orthogonal imaging to assess glenoid morphology and rotator cuff pathology and were reviewed by two senior surgeons. All patients had intact rotator cuff tendons. Glenoid morphology was assigned using the modified-Walch classification system (types A1, A2, B1, B2, B3, C, and D) and rotator cuff fatty infiltration was assigned using Goutallier scores. Results. 46 (35%) of the shoulders had posterior wear patterns (23 type B2s, 23 type B3s). Both the infraspinatus and teres minor independently had significantly more fatty infiltration in B2 and B3 type glenoids compared to type A glenoids (p<0.001). There was a greater imbalance in posterior rotator cuff muscle fatty atrophy in B2 and B3 type glenoids compared to type A glenoids (p<0.001). However, there was no difference in axial plane imbalance between B2 and B3 glenoids (p=1.00). There was increased amount fatty infiltration of the infraspinatus among B2 and B3-type glenoids compared to type A glenoids on multivariate analysis controlling for age and gender (p<0.001). Conclusions. These results identify significant axial plane rotator cuff muscle imbalances in B2 and B3-type glenoids compared to concentrically worn glenoids, favoring a relative increase in fatty infiltration of the infraspinatus and teres minor compared to the subscapularis in glenoids with patterns of posterior wear. For any figures or tables, please contact authors directly

Disturbed muscular architecture, fatty infiltration and muscular atrophy remain irreversible in chronic rotator cuff tears (RCT) even after repair. Poly-[ADP-ribose]-polymerase 1 (PARP-1), a nuclear factor involved in DNA damage repair, has shown to be a key element in the up-regulation of early muscle inflammation, atrophy and fat deposition. We therefore hypothesized that the absence of PARP-1 would lead to a reduction in muscular architectural damage, early inflammation, atrophy and fatty infiltration subsequent to combined tenotomy and neurectomy in a PARP-1 knock-out mouse model. PARP-1 knock-out (KO group) and standard wild type C57BL/6 (WT group) mice were randomly allocated into three different time points (1, 6 and 12 weeks, total n=72). In all mice the supraspinatus (SSP) and infraspinatus (ISP) tendons of the left shoulder were detached and the SSP muscle was denervated according to a recently established model. Macroscopic muscle weight analysis, retraction documentation using macroscopic suture, magnetic resonance imaging, immunohistochemistry gene expression analysis using real time qPCR (RTqPCR) and histology were used to assess the differences in muscle architecture, early inflammation, fatty infiltration and atrophy between knock out and wild type mice in the supraspinatus muscle. The SSP did retract in both groups, however; the KO muscles and tendons retracted less than the WT muscles (2.1±21mm vs 3.4±0.41mm; p=0.02). Further assessment of muscle architecture demonstrated that the pennation angle was significantly higher in the KO groups at 6 and 12 weeks (28±5 vs 36±5 and 29±4 vs 34±3; p<0.0001). Combined Tenotomy and neurectomy resulted in a significant loss of muscle mass in both groups compared to the contralateral unoperated side (KO group 62±11% and WT group 52±11%, p=0.04) at 6 weeks. But at 12 weeks postoperatively, there was a significant increase in muscle mass to near normal levels in KO group compared to the WT group (14±6% and 42±7% lower muscle mass respectively; p<0.0001) and less fatty infiltration (12.5 ± 1.82% and 19.6 ± 1.96%, p=0.027). Immunohistochemistry revealed a significant decrease in the expression of inflammatory, apoptotic, adipogenic and muscular atrophy genes at both the 1 week and 6 weeks time points, but not at 12 weeks in the KO group compared to the WT group. This was confirmed by histology. Our study is the first to show that knocking out PARP-1 leads to decreased loss of muscle architecture, early inflammation, fatty infiltration and atrophy after combined tenotomy and neurectomy of the rotator cuff muscle. Although the macroscopic muscles reaction to injury is similar in the first 6 weeks, its ability to regenerate is much greater in the PARP-1 group leading to a near normalization of the muscle substance and muscle weight, less retraction, and less fatty infiltration after 12 weeks

1. Three cases of fatty infiltration of the median nerve are reported. 2. One patient had symptoms of median nerve compression. 3. The intimate association of fibro-fatty tissue within the nerve precludes enucleation of the swelling

Tendon injuries are associated with the formation of inferior, disorganized scar tissue at the tendon bone insertion site and high failure rates. Two major processes are discussed being key players: the inflammatory reaction upon tear and the remodeling process of the tendon. In a previous study we demonstrated that the profile of MMPs and TIMPs, being key factors of tendon modeling and remodeling, is altered in tenocytes of rotator cuff tears from donors with higher age (>65 years) and degenerative status (high degree of muscle fatty infiltration)[1]. But do these cells also show different expression of inflammatory cytokines or react different upon cytokine stimulation? The aim of our project was to analyze the expression of inflammatory cytokines in human tenocyte-like cells (hTLCs) on mRNA-level and the responsiveness to cytokine stimulation regarding differences between varying donor characteristics such as age, sex and the degenerative status of the tendon. TLCs were isolated from SSP tendon biopsies from 16 male and 14 female donors undergoing arthroscopic or open shoulder surgery. Cells from each donor (passage 1 or 2) were seeded in a 6-well plate and RNA was isolated after 7 days of culture. Quantitative Real-Time PCR was performed to analyze the expression of IL-6, IL-1β, TNF-α, IL-10, IL-33, TGF-β1 and COX-2. Furthermore, hTLCs of 12 male donors were stimulated for 3 days with a combination of TNF-α and IFN-γ (10ng/ml). The effect of the cytokines was analyzed by flow cytometry regarding surface marker expression: ICAM (CD54), VCAM (CD106), and Major Histocompatibility Complex (MHC)-class I and MHC-class II. Statistics: Mann-Whitney-U-Test, Spearman´s-Rho-correlation, p≤0.05. Gene expression analysis revealed high levels of IL-6, TGF-β1 and COX-2 in hTLCs but low expression of TNF-α and IL-10. No differences in the expression of the inflammatory cytokines were found between low and high fatty infiltration or with respect to age. The stimulation of the hTLCs with TNF-α and IFN-γ increased the number of ICAM and VCAM positive cells up to 100% and 97±5%, respectively. MHC-class II was not expressed on unstimulated cells but 77±17% MHC-class II positive cells were present after stimulation. All unstimulated cells were positive for MHC-class I, but the MFI (Mean Fluorescent Intensity) increased after stimulation. No significant difference in the expression of surface markers was detected when comparing tenocytes of donors with low and high muscle fatty infiltration. In contrast to the significant changes in expression levels of MMPs and TIMPs in tenocytes of donors with different age and degenerative status[1], we could not detect any significant changes in the expression of inflammatory cytokines or in the responsiveness of these tenocytes upon cytokine stimulation. All tenocytes showed the potential to respond to inflammatory processes. This indicates that the response of the tenocytes to inflammatory stimuli seems to be independent of donor characteristics, whereas the tendon remodeling might depend on age and degenerative status of the donor

Purpose. Chronic massive rotator cuff tears are challenging to repair completely because of the development of tendon retraction with inelasticity, muscle atrophy and fatty infiltration. The objective of this study was to investigate the clinical outcome and MRI findings after arthroscopic superior capsule reconstruction (ASCR) for symptomatic irreparable rotator cuff tears. Methods. From 2011 to 2013, 12 shoulders in 12 consecutive patients (mean, 70.8 years) with irreparable massive rotator cuff tears underwent ASCR using fascia lata. We used suture anchors to attach the graft medially to the glenoid superior tubercle and laterally to the greater tuberosity as same technique by Mihata et al. We added side-to-side sutures between the graft and infraspinatus tendon and between the graft and residual anterior supraspinatus/subscapularis tendon to improve force coupling. Physical examination, clinical rating system, and magnetic resonance imaging (MRI) were performed before surgery; at 6 and 12 months after surgery; and 6 months thereafter. Average follow-up was 19.1 months (12 to 28 months) after surgery. We assessed patients preoperatively by using the scoring systems of the shoulder index of the American Shoulder and Elbow Surgeons (ASES), the Japanese Orthopaedic Association, and the University of California, Los Angeles. Results. Mean active elevation increased from 59° to 111° significantly and external rotation increased from 28 to 33. The average preoperative scores were 16.0 points by ASES, 48.0 points by JOA, and 10.8 points by UCLA. Average clinical outcome scores all improved significantly after ASCR at the final follow-up (ASES, 73.3 points; JOA, 73.7 points; UCLA, 22.7 points). There was surgical complication as infection. Although infection was controlled by arthroscopic irrigation, the transplanted tendon was absorbed, and preoperative conditions did not functionally improve. Five patients had graft tear during follow-up. Postoperative active range of motion in the healed patients was significantly greater than in the unhealed patients who had graft tears. Conclusions. ASCR restored superior glenohumeral stability and function of the shoulder joint with irreparable rotator cuff tears compared to preoperative function in the cases without postoperative complications. However ratio of graft tears were 50% and clinical results of these cases were not improved sufficiently

Introduction: Magnetic Resonance Imaging (MRI) is the gold standard for imaging muscle and fatty infiltrate has featured in low back pain. However, there is little knowledge about in vivo features of neck muscles in chronic WAD. The purpose of this study was to quantitatively compare fatty infiltrate in the cervical extensors in patients with chronic WAD and controls across muscle and segmental level. Methods: Volunteer subjects were gained through referral from local practitioners and the local university fraternity. A previously established MRI measure was performed in 113 female subjects (79- WAD & 34 healthy controls). Subjects with chronic WAD (> three months – < three years) were included if, classifiable as WAD II per the Quebec Task Force. The cohort was restricted to females (18–45 years) as they best represent those with chronic WAD. Volunteers were excluded when. classified as WAD I, III or IV. lost consciousness as a result of a motor vehicle crash (MVC). previous history of MVC. previous non-traumatic neck pain. diagnosed with any neurological, metabolic or inflammatory conditions or. were pregnant. The measure was performed for the rectus capitis minor/major, multifidus, semispinalis cervicis/capitis, splenius capitis and upper trapezius. The values for all muscles were plotted for level and side and linear regression analysis was used to determine segmental trends (C3-7). A multi-factorial analysis of variance (MANOVA) was applied to investigate group means of whiplash and controls for fat indices across muscle, side and level. Bonferroni post-hoc comparisons were used to compare group by muscle interactions at each level. Multiple regression analyses were performed to determine if the score on the Neck Disability Index (NDI), age, Body Mass Index (BMI), compensation status and duration influenced fatty infiltrate. Significance was set at p < 0.05. Data presented as mean ± SD. Results: The demographic characteristics of the two groups are: WAD (n = 79): age: 29.7 ± 7.8 years, BMI (kg/m2): 25.1 ± 5.7; duration: 20.3 ± 9.6 months and NDI: 45.5 ± 15.9. Healthy Controls (n = 34): Age: 27.0 ± 5.6 years, BMI: 23.0 ± 4.4.. NDI was not collected in controls. MANOVA revealed significant main effects for group, muscle, segmental level and side (p < 0.0001), and significant interactions between Group:Muscle, Group:Level, Muscle:Level and Group:side (p < 0.0001). Sides were averaged for each muscle and level for post-hoc analysis. There was a linear decrease in the fat indices from C3 – C7 for each muscle in both groups. No significant differences in fat indices across muscle, levels and side were noted in controls (p = 0.09). For the WAD subjects, the multifidus muscle had significantly higher fat content at each level compared to the other segmental muscles (p < 0.0001) and was highest at C3 (p < 0.0001). There were higher fat indices in the whiplash group compared to the controls for the rcpmin and rcpmaj muscles (p < 0.0001). No relationship was found for fat indices in all WAD muscles and NDI scores (p = 0.81), age (p = 0.14), duration (p = 0.99), compensation (p = 0.37) or BMI (p = 0.74). Discussion: There is significantly greater fatty infiltration in neck extensors, especially in the deeper muscles, in females with chronic WAD when compared with controls. Future studies are required to investigate relationships between muscular degeneration and symptoms

Aims. Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells. Methods. HDACis were added to FAPs and satellite cell cultures isolated from mice. The HDACi vorinostat was additionally administered into a RC injury animal model. Histological analysis was carried out on the isolated supra- and infraspinatus muscles to assess vorinostat anti-muscle degeneration potential. Results. Vorinostat, a HDACi compound, blocked the adipogenic transformation of muscle-associated FAPs in culture, promoting myogenic progression of the satellite cells. Furthermore, it protected muscle from degeneration after acute RC in mice in the earlier muscle degenerative stage after tenotomy. Conclusion. The HDACi vorinostat may be a candidate to prevent early muscular degeneration after RC injury. Cite this article: Bone Joint Res 2024;13(4):169–183

Aims

The aim of this study was to analyse human muscle tissue before and after rotator cuff repair to look for evidence of regeneration, and to characterise the changes seen in the type of muscle fibre.

The direct anterior approach (DAA) is a popular minimally invasive approach for total hip arthroplasty (THA). It usually involves ligation of the lateral femoral circumflex artery's ascending branch (a-LFCA), which contributes to the perfusion of the tensor fasciae latae (TFL) muscle. Periarticular muscle status and clinical outcome were assessed after DAA-THA after a-LFCA preservation versus ligation. We evaluated surgical records of 161 patients undergoing DAA-THA with tentative preservation of the a-LFCA by the senior author between May and November 2021. Among 92 eligible patients, 33 (35 hips) featured successful preservation, of which 20 (22 hips, 13 female) participated in the study. From 59 patients with ligated a-LFCA, 26 (27 hips, 15 female) were enrolled, constituting the control group. MRI and clinical examinations were performed at 17–26 months to analyze volume and fatty infiltration of the TFL, gluteus medius and gluteus minimus muscles relative to the contralateral non-THA hip (15 preserved, 18 ligated). Clinical and radiographic data was retrospectively extracted from patient files. Patient-reported outcomes (PROMs) were added from the THA registry. There was a relative difference in TFL muscle volume of -6.27 cm. 3. (−9.89%, p=0.018) after a-LFCA preservation versus -8.6 cm. 3. (=11.62%, p=0.002) after ligation, without group differences (p>0.340). a-LFCA preservation showed lower relative TFL fatty infiltration (p=0.10). Gluteal muscle status was similar between sides and groups. Coxa valga morphology was more frequent in a-LFCA preservation (83%) than ligation (17%). Clinical outcomes showed high patient satisfaction in both groups, without difference in PROMs, but less anterolateral soft-tissue swelling after a-LFCA preservation (p<0.001). Despite excellent clinical results in both groups, preservation of the a-LFCA was associated with less TFL fatty infiltration and soft tissue swelling. Provided there is no compromise of intraoperative access we recommend a-LFCA preservation for DAA-THA

The April 2024 Shoulder & Elbow Roundup. 360. looks at: Acute rehabilitation following traumatic anterior shoulder dislocation (ARTISAN): pragmatic, multicentre, randomized controlled trial; Prevalence and predisposing factors of neuropathic pain in patients with rotator cuff tears; Are two plates better than one? The clavicle fracture reimagined; A single cell atlas of frozen shoulder capsule identifies features associated with inflammatory fibrosis resolution; Complication rates and deprivation go hand in hand with total shoulder arthroplasty; Longitudinal instability injuries of the forearm; A better than “best-fit circle” method for glenoid bone loss assessment; 3D supraspinatus muscle volume and intramuscular fatty infiltration after arthroscopic rotator cuff repair

The June 2024 Shoulder & Elbow Roundup. 360. looks at: Reverse versus anatomical total shoulder replacement for osteoarthritis? A UK national picture; Acute rehabilitation following traumatic anterior shoulder dislocation (ARTISAN): pragmatic, multicentre, randomized controlled trial; acid for rotator cuff repair: a systematic review and meta-analysis of randomized controlled trials; Metal or ceramic humeral head total shoulder arthroplasty: an analysis of data from the National Joint Registry; Platelet-rich plasma has better results for long-term functional improvement and pain relief for lateral epicondylitis: a systematic review and meta-analysis of randomized controlled trials; Quantitative fatty infiltration and 3D muscle volume after nonoperative treatment of symptomatic rotator cuff tears: a prospective MRI study of 79 patients; Locking plates for non-osteoporotic proximal humeral fractures in the long term; A systematic review of the treatment of primary acromioclavicular joint osteoarthritis

Aims. This study compared patients who underwent arthroscopic repair of large to massive rotator cuff tears (LMRCTs) with isolated incomplete repair of the tear and patients with incomplete repair with biceps tendon augmentation. We aimed to evaluate the additional benefit on clinical outcomes and the capacity to lower the re-tear rate. Methods. We retrospectively reviewed 1,115 patients who underwent arthroscopic rotator cuff repair for full-thickness tears between October 2011 and May 2019. From this series, we identified 77 patients (28 male, 49 female) with a mean age of 64.1 years (50 to 80). Patients were classified into groups A (n = 47 incomplete) and B (n = 30 with biceps augmentation) according to the nature of their reconstruction. Clinical scores were checked preoperatively and at six months, one year, and two years postoperatively. In preoperative MRI, we measured the tear size, the degree of fatty infiltration, and muscle volume ratio of the supraspinatus. In postoperative MRI, the integrity of the repaired rotator cuff tendon was assessed using the Sugaya classification. Tendon thickness at the footprint was evaluated on T2-weighted oblique coronal view. Results. There were no significant differences in the initial preoperative demographic characteristics. In both groups, there were significant improvements in postoperative clinical scores (p < 0.001). However, most clinical outcomes, including range of motion measurements (forward elevation, external rotation, internal rotation, and abduction), showed no differences between the pre- and postoperative values. Comparing the postoperative outcomes of both groups, no further improvement from biceps augmentation was found. Group B, although not reaching statistical significance, had more re-tears than group A (30% vs 15%; p = 0.117). Conclusion. In LMRCTs, biceps augmentation provided no significant improvement of an incomplete repair. Therefore, biceps augmentation is not recommended in the treatment of LMRCTs. Cite this article: Bone Joint J 2022;104-B(11):1234–1241

Background: Progression of fatty infiltration of the suscapularis muscle subsequent to total shoulder arthroplasty is frequent and may be an underestimated problem. The approach with osteotomy of the lesser tuberosity led to consistent bone to bone healing with neither retraction nor overtensioning of the musculotendinous unit. However, in a previous study, fatty infiltration of the subscapular muscle had progressed at least by one stage in 45% of the patients’ shoulders. We hypothesized that anterior approach to the shoulder joint with release of the subscapularis muscle would lead to a direct or indirect subclinical damage of the subscapular nerve and would be an explanation for the progression of fatty infiltration of the muscle. Methods: Nine Shoulders in eight consecutive patients had received a total shoulder arthroplasty using an anterior approach with osteotomy of the lesser tuberosity. The mean age at time of operation was 67 years. Patients were followed clinically including the Constant score and a detailed neurological examination, as well as radiographically with pre–and postoperative MRI’s, CT’s and standard radiographs at 6–and 12 months thereafter. Neurophysiological assessment was performed using a new pre–intra–and postoperative electromyographic technique for the subscapular muscle. Fibrillation and sharp waves as spontaneuous activities of the motor unit potentials (MUP) indicated direct signs of denervation. Incomplete interference patterns (IP’s) indicated an incomplete innervation pattern as an indirect sign of denervation. Results: After a one year follow up, 89% of the patients were very satisfied or satisfied with the result. The relative Constant Score improved from an average of 50 percent preoperatively to an average of 96 percent postoperatively (p=0,008). That corresponds to a postoperative subjective Shoulder value of 89 percent. From preoperative to 6–and 12-months postoperative, the average degree of fatty infiltration of the subscapular muscle progressed in an almost significant extent (0.6, 1.1, and 1.6 respectively; p=0.056). Intra–and postoperatively, there were neither fibrillations and sharp waves of the MUP’s as direct signs, nor incomplete (IP’s) of the motor unit of the subscapular nerve as indirect signs of denervation. Conclusion: Total Shoulder Arthroplasties perfomed by an anterior approach using an osteotomy of the lesser tuberosity yields good results with a high satisfaction rate. Comparable to our previous study, there are signs of progression of fatty infiltration of the subscapularis muscle within the first year subsequent to total shoulder arthroplasty. However, there were no signs of direct or indirect subclinical damage of the subscapular nerve during total shoulder arthroplasty

INTRODUCTION: Chronic experimental rotator cuff tears are associated with muscle retraction, atrophy, fatty infiltration, a pronounced change in the pennation angle of the muscle and consequent shortening of muscle fibres. It was the purpose of this investigation to study whether slow, continuous elongation of the musculotendinous unit can revert the pennation angle and elongate the shortened muscle fibres. MATERIAL AND METHODS: The infraspinatus tendons of twelve sheep were released. After retraction of the tenotomised musculotendinous unit, the infra-spinatus was elongated one mm per day using a new elongation-apparatus. After restoring the approximate original length, the tendon was repaired back. Muscular architecture (retraction and pennation angle), fatty infiltration (in Hounsfield units=HU) and muscular cross sectional area (in % of the mean control side) were analyzed at start, at the time before elongation, at the time of repair and six and eighteen weeks thereafter. RESULTS: In four sheep the elongation failed technically. In the other eight sheep, elongation could be achieved as planned. After retraction of 29mm ± 6 mm after 16 weeks (14% of original length, p=0.008), the mean traction time was 24 days ± 6 days with a mean traction distance of 19 mm ± 4 mm. At sacrifice the mean pennation angle increased in the failed sheep from 30° ± 6° up to 55° ± 14° (p=0.035). In those sheep in which traction was applied, the mean pennation angle was not different to the control side (29.8° ± 7.5° vs. 30° ± 6°, p=0.575). Compared to preoperative, there was a significant increase in fatty infiltration (36 HU, p=0.0001) and decrease of the muscular cross sectional area of 43 % (range 21% to 67%, p=0.0001) at 4 months. In the sheep in which traction could be achieved, fatty infiltration remain unchanged (36 HU ± 6 HU vs 38 HU ± 4 HU, p=0.438) and atrophy decreased by 22% (range 10% to 33%) after 6 weeks of continuous traction (p=0.008). CONCLUSION: Continuous experimental elongation of a retracted musculotendinous unit is technically feasible and might lead to recovery of the muscle architecture, partial reversibility of atrophy and, arrest of progression of fatty infiltration

Our aim was to accurately determine whether muscle atrophy and fatty infiltration are reversible following cuff repair. Patients with a repairable cuff-tear were recruited and assessed clinically and radiologically (Magnetic Resonance Imaging). At surgery, supraspinatus was biopsied. Post-operatively, patients underwent clinical evaluation at standardised intervals, with further MRI and an ultrasound guided biopsy of supraspinatus at 12 months. MRI was used to characterize cuff-tears and determine the degree of muscle atrophy and fatty infiltration. Biopsy samples were fixed on-site and transported for processing. Morphometric assessments of myofibres were made and mean cross-sectional areas calculated using validated techniques. The pathologist was blinded to sample details. Statistical analysis was performed to assess differences in mean myofibre area following cuff repair and correlated with radiological findings. Eight patients were available for completed histological and radiological analysis. Six (two re-tears) demonstrated sizeable and highly statistically significant improvements in mean myofibre cross-sectional area (P=0.000–0.0253). Of the two not showing any increase in myofibre area, neither result was statistically significant (P=0.06, 0.2); one was a re-tear and one was a repair of a partial-thickness tear. Radiologically, the muscle and fatty changes had not demonstrably changed. Our finding that myofibre cross-sectional area increases following cuff repair suggests muscle atrophy is a potentially reversible process. Even with re-tears, improvements were seen. MRI features of fatty infiltration and muscle atrophy were not seen to improve however. It is likely that radiological assessment is not sensitive enough to demonstrate the reversibility of muscle atrophy seen on histological analysis at one year

Aims. The Walch Type C dysplastic glenoid is characterized by excessive retroversion. This anatomical study describes its morphology. Patients and Methods. A total of 29 shoulders with a dysplastic glenoid were analyzed. CT was used to measure retroversion, inclination, height, width, radius-of-curvature, surface area, depth, subluxation of the humeral head and the Goutallier classification of fatty infiltration. The severity of dysplasia and deficiency of the posterior rim of the glenoid were recorded. Results. A type C glenoid occurred in 1.8% of shoulders referred to our tertiary centres. The mean retroversion, inclination, height, width, radius-of-curvature, surface area, and depth of the glenoid were 37°, 3°, 46 mm, 30 mm, 37°, 1284 mm. 3. , and 16 mm, respectively. The mean posterior subluxation was 90%. The Goutallier class was < 2 in 25 shoulders (86%). Glenoid dysplasia was mild in four, moderate in 14, and severe in 11 shoulders. The typical appearance of the posterior glenoid rim had a rounded or ‘lazy J’ morphology. The glenoid neck was deficient in 18 shoulders (62%). Conclusion. A dysplastic Type C glenoid characteristically has a uniconcave retroverted morphology, a deficient posteroinferior rim and scapular neck, and a reduced depth. These findings help to define the unique anatomical variations and may aid the planning of surgery and the development of components for these patients. Cite this article: Bone Joint J 2018;100-B:1074–9

Aim:. To assess the long term MRI pathoanatomical changes of unrepaired, isolated full thickness supraspinatus tears in a population of patients that had acromioplasty done for symptomatic impingement syndrome. Background:. To date there are no studies assessing the effect of acromioplasty on rotator cuff tear progression in impingement syndrome. The natural evolution of unrepaired tears suggests that small isolated tears may heal, and not all tears progress onto significant fatty change and atrophy. Which tears heal and which tears progress and the effect of acromioplasty on tear progression is still not known. Results:. There were 17 shoulders examined. Average age of our patients was 65 years at time of surgery and 73 years at follow up. The patients were divided into three groups depending on the size of the tear at the time of surgery: C1 tears (< 1cm) n = 5, C2 tears (1–2 cm) n = 8, C3 tears (2–3 cm) n = 4. The C1 tear group did the best clinically with a Constant score mean 86, 4(range 83–96) and mean Oxford score of 47 (range 46–48). The MRI findings in this group showed only one patient (20%) with significant fatty infiltration and atrophy. The C2 group had mean Constant scores of 72(range 65–98), mean Oxford score 45(range 42–48). On MRI evaluation there were 2 patients (11.8%) that had tears that had regressed in size (CI 1.4‐36.4). In the C3 group the mean Constant score was 75(range 65–85) and Oxford score 45(range 42–48). MRI evaluation revealed that all (100%) the rotator cuff tears went on to significant degeneration and atrophy in this group. No statistical difference was found between these groups when assessing Oxford score (p=0.75) and Constant scores(p=0.69). Significant associations were found between tear size and fatty infiltration (p=0.028), and tear size and atrophy (p=0.054. Conclusion:. Acromioplasty in the management of impingement syndrome may be protective when small isolated tears are noted during surgery as two tears regressed in size. Large tears all progress onto fatty infiltration and atrophy, but all three groups despite tear size had good clinical and functional outcomes. More research is needed to further understand the evolution of tears in impingement syndrome