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Background: A torn rotator cuff muscle deteriorates over time leading with an increase in muscle atrophy and fatty infiltration. There are several clinical assessments for evaluating the atrophy of the torn supraspinatus muscle. However, it is unclear which approach can more accurately estimate the activity of the torn supraspinatus muscle. The purpose of this study was to determine which magnetic resonance imaging-based muscle atrophy imaging assessment currently implemented in the clinical setting accurately estimates the activity of the torn supraspinatus muscle., Methods: Forty patients who were diagnosed with a rotator cuff tear and were candidates for repairs were selected for this study. Cross-sectional area, occupation ratio, and tangent sign were analyzed on T1-weighted oblique sagittal plane magnetic resonance images in which the scapular spine leads to the Y-section. Muscle belly ratio of the supraspinatus muscle was analyzed by calculating the ratio of the width of the muscle belly to the distance from the greater tubercle to the proximal end of the muscle on T1-weighted coronal plane magnetic resonance imaging images. Fatty infiltration was evaluated using the Goutallier classification system. Tear size was obtained intraoperatively by measuring the width and length of the tear and classified based on the Cofield's classification. To assess activity of the torn supraspinatus muscle, participants were first instructed to sit on a chair with the affected arm resting on a table and the shoulder abducted to 60° in the scapular plane with neutral rotation. Elasticity of the supraspinatus muscle belly was then obtained at rest and during isometric contraction using with real-time tissue elastography. Muscle activity, a surrogate for contractility, was defined as the difference between the elasticities measured at rest and during isometric contraction. A stepwise multiple regression analysis was used to investigate independent factors, such as sex, tear width, cross-sectional area, occupation ratio, tangent sign, and muscle belly ratio, related to muscle activity., Results: Stepwise multiple regression analysis ( R 2  = 0.522, P  < .001) revealed that supraspinatus muscle activity was significantly correlated with muscle belly ratio ( β  = 0.306, P  = .044) and Goutallier stage ( β  = -0.490, P  = .002)., Conclusion: Estimations of muscle belly ratio are most suitable for assessing the activity of a torn supraspinatus muscle compared to other clinical measurements., (© 2023 The Authors.)

Background: This study aimed to investigate the prognosticator of the contralateral rotator cuff in patients who underwent arthroscopic rotator cuff repair (ARCR) for symptomatic rotator cuff tear (RCT)., Methods: A total of 104 patients with a mean age of 64.7 years (range, 40-83 years) underwent ARCR and were checked for the presence of a contralateral RCT using preoperative ultrasonography. Preoperative demographic data, including patients' occupations and sports activities, were also evaluated., Results: The mean follow-up period for the operated shoulder was 25.0 months (range, 12-72 months). An RCT of the contralateral shoulder was observed in 40 of the 104 (38.5%) patients. Contralateral shoulder pain was observed in 16 (40%) and 15 (23.1%) patients in the RCT group preoperatively and the non-tear group, respectively. Of the 31 patients with shoulder pain, a poor prognosis was seen in 17 (54.8%). Statistical significance was observed between the active and sedentary groups in the RCT group, with eight patients (30.8%) in the active group and none in the sedentary group having a poor prognosis ( P  = .02). In contrast, in the non-tear group, a poor prognosis was observed in four patients (10.5%) in the active group, which was not significantly different compared to the five patients (19.2%) in the sedentary group ( P  = .33)., Conclusions: For patients in the active group, RCTs are a risk factor for poor prognosis in the contralateral shoulder of ARCR., (© 2023 The Authors.)

Background: Knowledge of the morphological and functional differences in the anatomic subregions of the supraspinatus (SSP) and infraspinatus (ISP) muscles during forward flexion will provide useful information in the management of shoulder joint disorders. The purpose of this study was to investigate whether the SSP and ISP muscle subregions exhibit independent roles during forward flexion of the shoulder joint., Methods: Eight healthy male volunteers without any restriction in their shoulder joints were recruited for this study. Participants were instructed to sit on a chair with their back against the backrest. Shear modulus (kPa) was measured as a surrogate for muscle stiffness using shear wave elastography on the SSP and ISP muscle subregions. Active measurements of the nondominant arm were obtained during isometric contraction at a neutral position and every 15° intervals from 30° to 150° during forward flexion. Friedman test and Dunn's post hoc test were used to evaluate differences in measurement outcomes among angles during forward flexion in each muscle subregion., Results: Active stiffness outcomes of the anterior-middle subregion of the SSP muscle during forward flexion increased from 30° up to 45°, reaching a value of 182.4 ± 32.1 kPa ( P  < .001). Stiffness of the anterior-superficial subregion of the SSP muscle was highest at 30° (125.0 ± 20.6 kPa; P  < .019) and linearly decreased up to 105° with increasing shoulder angle position. Stiffness of the superior, middle, and inferior subregions of ISP muscle presented a mountain-shaped trend, with peaks of 99.9 ± 23.5 kPa at 90° ( P  < .013), 144.2 ± 11.2 kPa at 90° ( P  < .013), and 122.9 ± 27.9 kPa at 105° ( P  < .007), respectively. Finally, the stiffness outcomes of the pectoralis major and anterior region of the deltoid muscles showed a mountain-shaped trend with peaks of 89.4 ± 23.5 kPa at 60° ( P  < .007) and 176.7 ± 22.9 kPa at 90° ( P  < .026), respectively., Conclusions: The SSP and ISP muscle subregions play a significant role during active forward flexion motion. While closely overlapped, the activity of the muscle subregions changed during the forward flexion motion range, starting with an active anterior-superficial subregion of the SSP muscle at the initial range of motion and an active inferior subregion of the ISP muscle toward midrange of motion. The SSP and ISP subregions did not demonstrate independent functional behavior during forward flexion., (© 2022 The Authors.)

Hypothesis/background: Complications involving the fingers and hand after arthroscopic rotator cuff repair (ARCR) include complex regional pain syndrome, carpal tunnel syndrome (CTS), and flexor tenosynovitis (TS). The aims of this study were to diagnose the complications after ARCR and investigate the risk factors that could predispose individuals to these finger and hand complications., Methods: Fifty patients (50 shoulders) who underwent ARCR participated in this study. The patients' ages ranged from 36 to 84 years (mean, 63 years). Before ARCR, we determined the disease history of the fingers and hand (CTS or TS) and subjectively assessed their symptoms using a questionnaire that included a scale ranging from 1 (no symptoms or no disability) to 5 (the worst symptoms or severest disability). ARCR was performed in all patients using suture anchors. The mean observation period after surgery was 15.5 months (range, 12-48 months). We diagnosed complications involving the fingers and hand after ARCR and investigated the preoperative, intraoperative, and postoperative risk factors that could predispose patients to these complications using univariable and multivariable analyses., Results: After ARCR, 20 patients (20 hands) (40%) had complications of the fingers and hand. Among them, the diagnosis was CTS in 2 hands, TS in 15 hands, and both CTS and TS in 3 hands. None of the hands exhibited complex regional pain syndrome. These complications occurred at an average of 1.8 months (range, 0.1-4 months) after ARCR. In the 47 patients who did not have symptoms just before the operation, both univariable and multivariable analyses between the complication group (n = 17) and the no-complications group (n = 30) showed a significant difference in the presence of a past history of CTS or TS (complication frequency: past history: 88%, no past history: 25%) ( P  < .05) and the preoperative subjective assessment for edema of the fingers and hand (complication frequency: edema ≥ 2 points: 89%, edema < 2 points: 24%) ( P  < .05). There were no relationships between the other candidate intraoperative and postoperative factors and complications., Conclusion: In all 20 hands with complications of the fingers and hand after ARCR, the diagnosis was CTS or TS. Complications of the fingers and hand after ARCR easily occurred in patients with a past history of CTS or TS and in patients with edema as per a subjective assessment. We speculate that the ARCR triggered the occurrence of CTS and TS postoperatively in patients who had subclinical CTS or TS before surgery., (© 2021 The Author(s).)

Background: Complications in the fingers and hand after arthroscopic rotator cuff repair (ARCR) have been reported to include carpal tunnel syndrome (CTS), flexor tenosynovitis (TS), and complex regional pain syndrome. These studies were conducted retrospectively; however, the reported complications have not been examined prospectively. The aim of this study was to evaluate the outcomes of early detection and treatment of the complications after ARCR., Methods: Forty-six patients (48 shoulders) who underwent ARCR were prospectively examined to investigate complications in the fingers and hand after ARCR. We attempted to immediately detect and proactively treat these complications. We evaluated the outcomes of the early detection and treatment of the complications., Results: Complications were observed in 17 hands (35%) and occurred an average of 1.5 months after ARCR. The symptoms in 3 hands resolved spontaneously, 2 hands were diagnosed with CTS, and 12 hands were diagnosed with TS. Of the 12 hands with TS, 11 exhibited no triggering of the fingers. Among the 14 hands diagnosed with CTS or TS, 13 hands (CTS: 2 hands, TS: 11 hands) were treated with corticosteroid injections; the mean interval between treatment initiation and symptom resolution was 1.0 months (0.5-3.0 months). None exhibited complex regional pain syndrome., Conclusions: When symptoms occur in the fingers and hand after ARCR, CTS or TS should be primarily suspected. The diagnosis of TS must be made carefully because most patients with TS have no triggering. For patients with CTS or TS after ARCR, rapid corticosteroid injection administration can lead to improvement in these symptoms., (© 2020 The Author(s).)