Normal shoulder muscular activation and co‐ordination during a shoulder elevation task based on activities of daily living: An electromyographic study

Studies of normal shoulder function have often failed to consider the inter‐relationship between different muscle groups in activities relevant to daily life. Upper limb functional status was assessed in 12 healthy male volunteers using the Functional Impairment Test‐Hand, Neck, Shoulder and Arm test (FIT‐HaNSA). Electromyography was then used to study the activity and coordination of 13 muscles (10 by surface electrodes, 3 by fine‐wire intramuscular electrodes) around the shoulder during a dynamic movement task based on the shelf‐lifting task in FIT‐HaNSA. Muscles were grouped for analysis into deltoid (anterior, middle, and posterior divisions), adductors (latissimus dorsi and teres major), rotator cuff (supraspinatus, infraspinatus, and subscapularis), and elbow flexor (brachioradialis, biceps brachii) groups. There were no significant inter‐session effects. Using cross‐correlation analysis to investigate the whole time‐course of activation, there were highly significant positive correlations (p < 0.001) between the deltoid and rotator cuff, the deltoid and adductor and the adductor and rotator cuff groups, and a significant negative correlation between the deltoid and elbow flexor groups (p = 0.031). We conclude that the deltoid, adductor, and rotator cuff muscles all contribute to the muscular component of glenohumeral joint stability. Muscular stability can be adapted as required to meet task‐specific demands. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:53–60, 2012     

Effects of age and pathology on shear wave speed of the human rotator cuff

Rotator cuff tears are common and often repaired surgically, but post‐operative repair tissue healing, and shoulder function can be unpredictable. Tear chronicity is believed to influence clinical outcomes, but conventional clinical approaches for assessing tear chronicity are subjective. Shear wave elastography (SWE) is a promising technique for assessing soft tissue via estimates of shear wave speed (SWS), but this technique has not been used extensively on the rotator cuff. Specifically, the effects of age and pathology on rotator cuff SWS are not well known. The objectives of this study were to assess the association between SWS and age in healthy, asymptomatic subjects, and to compare measures of SWS between patients with a rotator cuff tear and healthy, asymptomatic subjects. SWE images of the supraspinatus muscle and intramuscular tendon were acquired from 19 asymptomatic subjects and 11 patients with a rotator cuff tear. Images were acquired with the supraspinatus under passive and active (i.e., minimal activation) conditions. Mean SWS was positively associated with age in the supraspinatus muscle and tendon under passive and active conditions (p ≤ 0.049). Compared to asymptomatic subjects, patients had a lower mean SWS in their muscle and tendon under active conditions (p ≤ 0.024), but no differences were detected under passive conditions (p ≥ 0.783). These findings identify the influences of age and pathology on SWS in the rotator cuff. These preliminary findings are an important step toward evaluating the clinical utility of SWE for assessing rotator cuff pathology. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:282–288, 2018.     

Rotator cuff muscle degeneration and tear severity related to myogenic,adipogenic, and atrophy genes in human muscle

Large rotator cuff tear size and advanced muscle degeneration can affect reparability of tears and compromise tendon healing. Clinicians often rely on direct measures of rotator cuff tear size and muscle degeneration from magnetic resonance imaging (MRI) to determine whether the rotator cuff tear is repairable. The objective of this study was to identify the relationship between gene expression changes in rotator cuff muscle degeneration to standard data available to clinicians. Radiographic assessment of preoperative rotator cuff tear severity was completed for 25 patients with varying magnitudes of rotator cuff tears. Tear width and retraction were measured using MRI, and Goutallier grade, tangent (tan) sign, and Thomazeau grade were determined. Expression of myogenic‐, adipogenic‐, atrophy‐, and metabolism‐related genes in biopsied muscles were correlated with tear width, tear retraction, Goutallier grade, tan sign, and Thomazeau grade. Tear width positively correlated with Goutallier grade in both the supraspinatus (r = 0.73) and infraspinatus (r = 0.77), along with tan sign (r = 0.71) and Thomazeau grade (r = 0.68). Decreased myogenesis (Myf5), increased adipogenesis (CEBPα, Lep, Wnt10b), and decreased metabolism (PPARα) correlated with radiographic assessments. Gene expression changes suggest that rotator cuff tears lead to a dramatic molecular response in an attempt to maintain normal muscle tissue, increase adipogenesis, and decrease metabolism. Fat accumulation and muscle atrophy appear to stem from endogenous changes rather than from changes mediated by infiltrating cells. Results suggest that chronic unloading of muscle, induced by rotator cuff tear, disrupts muscle homeostasis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2808–2814, 2017.

     

Rabbit supraspinatus motor endplates are unaffected by a rotator cuff tear

Rotator cuff tears are a major cause of morbidity. Following rotator cuff tears, muscle atrophy and fatty infiltration begin in the tissue, limiting repair potential and leading to a higher re‐tear rate and a worse functional outcome. We evaluated whether fatty degeneration resulting from a complete supraspinatus tear with retraction is associated with an injury to the suprascapular nerve. Four skeletally mature New Zealand white rabbits were randomized to receive an index procedure on either their right or left shoulder with the opposite shoulder serving as a control. At the index procedure, the supraspinatus tendon was transected at its insertion and allowed to retract. At 3 months, the rabbits were euthanized, and both supraspinatus muscles were harvested. The specimens were then examined with confocal microscopy and histology. Atrophy was grossly visible in all four test muscles, and fatty infiltration was confirmed with osmium tetroxide staining. In all four rabbits, the degree of denervation (p = 0.71) and partial denervation (p = 0.91) was not significantly different between control and experimental muscle. Rotator cuff tear does not affect the motor endplate or innervation status of the supraspinatus. Fatty infiltration occurs independent of denervation of the supraspinatus. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:99–104, 2012     

Botulinum toxin is detrimental to repair of a chronic rotator cuff tear in a rabbit model

Re‐tear continues to be a problem after rotator cuff repair. Intramuscular botulinum toxin (Botox) injection can help optimize tension at the repair site to promote healing but could have an adverse effect on the degenerated muscle in a chronic tear. We hypothesized that Botox injection would improve repair characteristics without adverse effect on the muscle in a chronic rotator cuff tear model. The supraspinatus tendon of both shoulders in 14 rabbits underwent delayed repair 12 weeks after transection. One shoulder was treated with intramuscular Botox injection and the other with a saline control injection. Six weeks after repair, outcomes were based on biomechanics, histology, and magnetic resonance imaging. Botox‐treated repairs were significantly weaker (2.64 N) than control repairs (5.51 N, p = 0.03). Eighty percent of Botox‐treated repairs and 40% of control repairs healed with some partial defect. Fatty infiltration of the supraspinatus was present in all shoulders (Goutallier Grade 3 or 4) but was increased in the setting of Botox. This study provides additional support for the rabbit supraspinatus model of chronic cuff tear, showing consistent fatty infiltration. Contrary to our hypothesis, Botox had a negative effect on repair strength and might increase fatty infiltration. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1152–1157, 2015.     

Effect of tamoxifen on fatty degeneration and atrophy of rotator cuff muscles in chronic rotator cuff tear: An animal model study

Fatty degeneration of the rotator cuff muscles is an irreversible change resulting from chronic rotator cuff tear and is associated with poor clinical outcomes following rotator cuff repair. We evaluated the effect of Tamoxifen, a competitive estrogen receptor inhibitor, on fatty degeneration using a mouse model for chronic rotator cuff tear. Sixteen adult mice were divided into two diet groups (Tamoxifen vs. Regular) and subjected to surgical creation of a large rotator cuff tear and suprascapular nerve transection in their left shoulder with the right shoulder serving as a control. The rotator cuff muscles were harvested at 16 weeks and subjected to histology and RT‐PCR for adipogenic and myogenic markers. Histology showed substantially decreased atrophy and endomysial inflammation in Tamoxifen group, but no significant differences in the amount of intramuscular adipocytes and lipid droplets compared to the Regular group. With RT‐PCR, the operated shoulders showed significant upregulation of myogenin and PPAR‐γ, and downregulation of myostatin compared to the nonsurgical shoulder. No significant differences of gene expression were found between the two diet groups. Our study demonstrated that tamoxifen diet leads to decreased muscle atrophy and inflammatory changes following chronic rotator cuff tear, but has no apparent effect on adipogenesis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1846–1853, 2015.     

Four‐week exercise program does not change rotator cuff muscle activation and scapular kinematics in healthy subjects

Rotator cuff and scapular muscle strengthening exercises are an essential part of shoulder rehabilitation and sports training. Although the effect of exercise training on pain and function have been widely investigated, few studies have focused on the changes in shoulder kinematics and muscle activity after exercise training. Therefore, the purpose of the present study was to investigate the effect of rotator cuff and scapular strengthening exercises on shoulder kinematics and the activation of rotator cuff and scapular muscles in healthy subjects. Thirty‐six healthy subjects were recruited and randomly assigned into either a training or control group. Subjects in the training group were trained with rotator cuff and scapular strengthening exercises for 4 weeks. Scapular kinematics and shoulder muscle activity during arm elevation were measured before and after exercise training. After the 4‐week training protocol, there was an increase in strength and a decrease in upper trapezius activation in the training group, which is consistent with previous studies. However, no difference was found in scapular kinematics and activation of rotator cuff muscles between the control and training groups after the training protocol. Although the exercise protocol resulted in strength gains for the rotator cuff, these gains did not transfer to an increase in muscle activation during motion. These results demonstrate the difficulty in changing activation patterns of the rotator cuff muscles. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2079–2088, 2016.     

Moment arms of the shoulder muscles during axial rotation

The objective of the present study was to determine the instantaneous moment arms of 18 major muscle sub‐regions crossing the glenohumeral joint in axial rotation of the humerus during coronal‐plane abduction and sagittal‐plane flexion. The tendon‐excursion method was used to measure instantaneous muscle moment arms in eight entire upper‐extremity cadaver specimens. The results showed that the inferior subscapularis was the largest internal rotator; its rotation moment arm peaks were 24.4 and 27.0 mm during abduction and flexion, respectively. The inferior infraspinatus and teres minor were the greatest external rotators; their respective rotation moment arms peaked at 28.3 and 26.5 mm during abduction, and 23.3 and 22.1 mm during flexion. The two supraspinatus sub‐regions were external rotators during abduction and internal rotators during flexion. The latissimus dorsi and pectoralis major behaved as internal rotators throughout both abduction and flexion, with the three pectoralis major sub‐regions and middle and inferior latissimus dorsi displaying significantly larger internal rotation moment arms with the humerus adducted or flexed than when abducted or extended (p < 0.001). The deltoid behaved either as an internal rotator or an external rotator, depending on the degree of humeral abduction and axial rotation. Knowledge of moment arm differences between muscle sub‐regions may assist in identifying the functional effects of muscle sub‐region tears, assist surgeons in planning tendon transfer surgery, and aid in the development and validation of biomechanical computer models. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:658–667, 2011     

A Spectral Analysis of Rotator Cuff Musculature Electromyographic Activity: Surface and Indwelling

Electromyography (EMG) of the shoulder girdle is commonly performed; however, EMG spectral properties of shoulder muscles have not been clearly defined. The purpose of this study was to determine the maximum power frequency, Nyquist rate, and minimum sampling rate for indwelling and surface EMG of the normal shoulder girdle musculature. EMG signals were recorded using indwelling electrodes for the rotator cuff muscles and surface electrodes for ten additional shoulder muscles in ten healthy volunteers. A fast Fourier transform was performed on the raw EMG signal collected during maximal isometric contractions to derive the power spectral density. The 95% power frequency was calculated during the ramp and plateau subphase of each contraction. Data were analyzed with analysis of variance (ANOVA) and paired t tests. Indwelling EMG signals had more than twice the frequency content of surface EMG signals (p < .001). Mean 95% power frequencies ranged from 495 to 560 Hz for indwelling electrodes and from 152 to 260 Hz for surface electrodes. Significant differences in the mean 95% power frequencies existed among muscles monitored with surface electrodes (p = .002), but not among muscles monitored with indwelling electrodes (p = .961). No significant differences in the 95% power frequencies existed among contraction subphases for any of the muscle–electrode combinations. Maximum Nyquist rate was 893 Hz for surface electrodes and 1,764 Hz for indwelling electrodes. Our results suggest that when recording EMG of shoulder muscles, the minimum sampling frequency is 1,340 Hz for surface electrodes and 2,650 Hz for indwelling electrodes. The minimum sampling recommendations are higher than the 1,000 Hz reported in many studies involving EMG of the shoulder.     

Influence of rotator cuff tears on glenohumeral stability during abduction tasks

One of the main goals in reconstructing rotator cuff tears is the restoration of glenohumeral joint stability, which is subsequently of utmost importance in order to prevent degenerative damage such as superior labral anterior posterior (SLAP) lesion, arthrosis, and malfunction. The goal of the current study was to facilitate musculoskeletal models in order to estimate glenohumeral instability introduced by muscle weakness due to cuff lesions. Inverse dynamics simulations were used to compute joint reaction forces for several static abduction tasks with different muscle weakness. Results were compared with the existing literature in order to ensure the model validity. Further arm positions taken from activities of daily living, requiring the rotator cuff muscles were modeled and their contribution to joint kinetics computed. Weakness of the superior rotator cuff muscles (supraspinatus; infraspinatus) leads to a deviation of the joint reaction force to the cranial dorsal rim of the glenoid. Massive rotator cuff defects showed higher potential for glenohumeral instability in contrast to single muscle ruptures. The teres minor muscle seems to substitute lost joint torque during several simulated muscle tears to maintain joint stability. Joint instability increases with cuff tear size. Weakness of the upper part of the rotator cuff leads to a joint reaction force closer to the upper glenoid rim. This indicates the comorbidity of cuff tears with SLAP lesions. The teres minor is crucial for maintaining joint stability in case of massive cuff defects and should be uprated in clinical decision‐making. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1628–1635, 2016.     

Long-term outcome and structural integrity following open repair of massive rotator cuff tears

Background:

Surgical repair of massive rotator cuff tears is associated with less favorable clinical results and a higher retear rate than repair of smaller tears, which is attributed to irreversible degenerative changes of the musculotendinous unit.

Materials and Methods:

During the study period, 25 consecutive patients with a massive rotator cuff tear were enrolled in the study and the tears were repaired with an open suture anchor repair technique. Preoperative and postoperative clinical assessments were performed with the Constant score, the simple shoulder test (SST) and a pain visual analog scale (VAS). At the final follow-up, rotator cuff strength measurement was evaluated and assessment of tendon integrity, fatty degeneration and muscle atrophy was done using a standardized magnetic resonance imaging protocol.

Results:

The mean follow-up period was 70 months. The mean constant score improved significantly from 42.3 to 73.1 points at the final follow-up. Both the SST and the pain VAS improved significantly from 5.3 to 10.2 points and from 6.3 to 2.1, respectively. The overall retear rate was 44% after 6 years. Patients with an intact repair had better shoulder scores and rotator cuff strength than those with a failed repair, and also the retear group showed a significant clinical improvement (each P<0.05). Rotator cuff strength in all testing positions was significantly reduced for the operated compared to the contralateral shoulder. Muscle atrophy and fatty infiltration of the rotator cuff muscles did not recover in intact repairs, whereas both parameters progressed in retorn cuffs.

Conclusions:

Open repair of massive rotator tears achieved high patient satisfaction and a good clinical outcome at the long-term follow-up despite a high retear rate. Also, shoulders with retorn cuffs were significantly improved by the procedure. Muscle atrophy and fatty muscle degeneration could not be reversed after repair and rotator cuff strength still did not equal that of the contralateral shoulder after 6 years.

Level of evidence:

Level IV     

Compensatory Movement Patterns Are Based on Abnormal Activity of the Biceps Brachii and Posterior Deltoid Muscles in Patients with Symptomatic Rotator Cuff Tears

BackgroundAbnormal movement patterns due to compensatory mechanisms have been reported in patients with rotator cuff tears. The long head of the biceps tendon may especially be overactive and a source of pain and could induce abnormal muscle activation in these patients. It is still unknown why some patients with a rotator cuff tear develop complaints and others do not.Questions/purposes(1) Which shoulder muscles show a different activation pattern on electromyography (EMG) while performing the Functional Impairment Test-Hand and Neck/Shoulder/Arm (FIT-HaNSA) in patients with a symptomatic rotator cuff tear compared with age-matched controls with an intact rotator cuff? (2) Which shoulder muscles are coactivated on EMG while performing the FIT-HaNSA?MethodsThis comparative study included two groups of people aged 50 years and older: a group of patients with chronic symptomatic rotator cuff tears (confirmed by MRI or ultrasound with the exclusion of Patte stage 3 and massive rotator cuff tears) and a control group of volunteers without shoulder conditions. Starting January 2019, 12 patients with a chronic rotator cuff tear were consecutively recruited at the outpatient orthopaedic clinic. Eleven age-matched controls (randomly recruited by posters in the hospital) were included after assuring the absence of shoulder complaints and an intact rotator cuff on ultrasound imaging. The upper limb was examined using the FIT-HaNSA (score: 0 [worst] to 300 seconds [best]), shoulder-specific instruments, health-related quality of life, and EMG recordings of 10 shoulder girdle muscles while performing a tailored FIT-HaNSA.ResultsEMG (normalized root mean square amplitudes) revealed hyperactivity of the posterior deltoid and biceps brachii muscles during the upward phase in patients with rotator cuff tears compared with controls (posterior deltoid: 111% ± 6% versus 102% ± 10%, mean difference -9 [95% confidence interval -17 to -1]; p = 0.03; biceps brachii: 118% ± 7% versus 111% ± 6%, mean difference -7 [95% CI -13 to 0]; p = 0.04), and there was decreased activity during the downward phase in patients with rotator cuff tears compared with controls (posterior deltoid: 89% ± 6% versus 98% ± 10%, mean difference 9 [95% CI 1 to 17]; p = 0.03; biceps brachii: 82% ± 7% versus 89% ± 6%, mean difference 7 [95% CI 0 to 14]; p = 0.03). The posterior deltoid functioned less in conjunction with the other deltoid muscles, and lower coactivation was seen in the remaining intact rotator cuff muscles in the rotator cuff tear group than in the control group.ConclusionPatients with a symptomatic rotator cuff tear show compensatory movement patterns based on abnormal activity of the biceps brachii and posterior deltoid muscles when compared with age-matched controls. The posterior deltoid functions less in conjunction with the other deltoid muscles, and lower coactivation was seen in the remaining intact rotator cuff muscles in the rotator cuff tear group than the control group.Clinical RelevanceThis study supports the potential benefit of addressing the long head biceps tendon in the treatment of patients with a symptomatic rotator cuff tear. Moreover, clinicians might use these findings for conservative treatment; the posterior deltoid can be specifically trained to help compensate for the deficient rotator cuff.     

Biomechanical comparison of single‐row,double‐row,and transosseous‐equivalent repair techniques after healing in an animal rotator cuff tear model

The transosseous‐equivalent (TOE) rotator cuff repair technique increases failure loads and contact pressure and area between tendon and bone compared to single‐row (SR) and double‐row (DR) repairs, but no study has investigated if this translates into improved healing in vivo. We hypothesized that a TOE repair in a rabbit chronic rotator cuff tear model would demonstrate a better biomechanical profile than SR and DR repairs after 12 weeks of healing. A two‐stage surgical procedure was performed on 21 New Zealand White Rabbits. The right subscapularis tendon was transected and allowed to retract for 6 weeks to simulate a chronic tear. Repair was done with the SR, DR, or TOE technique and allowed to heal for 12 weeks. Cyclic loading and load to failure biomechanical testing was then performed. The TOE repair showed greater biomechanical characteristics than DR, which in turn were greater than SR. These included yield load (p < 0.05), energy absorbed to yield (p < 0.05), and ultimate load (p < 0.05). For repair of a chronic, retracted rotator cuff tear, the TOE technique was the strongest biomechanical construct after healing followed by DR with SR being the weakest. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1254–1260, 2013     

Treatment options for irreparable postero-superior cuff tears in young patients

Rotator cuff tears (RCTs) occur more commonly with advanced age, with most rotator cuff abnormalities in patients less than 30 years old being painful tendinoses or partial-thickness RCTs. Irreparable postero-superior cuff tears has been reported as frequent as 7% to 10% in the general population, and the incidence of irreparable RCTs in young patients is still unknown. Several surgical procedures have been proposed for young patients with irreparable postero-superior RCTs, such as rotator cuff debridement, partial rotator cuff repair, biceps tenotomy/tenodesis, rotator cuff grafting, latissimus dorsi tendon transfer, and reverse shoulder arthroplasty. After being thoroughly investigated in open surgery, arthroscopic techniques for latissimus dorsi tendon transfer have been recently described. They have been shown to be an adequate option to open surgery for managing irreparable postero-superior RCTs refractory to conservative management.     

两种不同术式治疗合并肩胛上神经损伤的巨大肩袖撕裂后神经恢复的临床对比研究

目的对比传统双排修复术与阔筋膜移植术两种术式治疗合并肩胛上神经损伤的巨大肩袖撕裂患者的功能恢复情况。 方法回顾性分析2013年1月至2018年1月因巨大肩袖撕裂损伤于本院行关节镜肩袖损伤修复术患者20例,其中传统双排缝合组（A组）10例,阔筋膜移植组（B组）10例。所有患者术前均经肩关节MRI及肌电图诊断为巨大肩袖损伤合并神经损伤。术后1个月、6个月定期随访患者。比较手术前后两组患者的疼痛视觉模拟评分（visual analogue scale,VAS）、美国加州大学洛杉矶分校（University of California at Los Angeles,UCLA）评分、Constant-Murely肩关节功能评分的变化情况。术后6个月复查肌电图及MRI评估肩袖愈合及神经恢复情况。 结果20例患者均获得随访,随访时间6~18个月。术后6个月A组VAS评分从术前（7.4±0.8）分下降到（2.3±1.7）分,差异有统计学意义（P<0.01）,UCLA评分从术前（11.5±1.4）分上升到（28.3±5.8）分,差异有统计学意义（P<0.01）,Constant-Murely评分从术前（45.6±6.2）分上升到（79.0±11.7）分,差异有统计学意义（P<0.01）。B组VAS评分从术前（7.9±0.6）分下降到（2.7±1.8）分,差异有统计学意义（P<0.01）,UCLA评分从术前（10.1±1.4）分上升到（26.9±6.9）分,差异有统计学意义（P<0.01）,Constant-Murely评分从术前（39.0±3.4）分上升到（72.9±9.4）分,差异有统计学意义（P<0.01）。术后6个月时两组患者VAS评分比较差异无统计学意义（P>0.05）,两组患者UCLA评分比较差异无统计学意义（P>0.05）,两组患者Constant-Murely评分比较差异无统计学意义（P>0.05）。术后6个月复查肌电图,A组患者无肩胛上神经损伤,B组患者中有5例患者仍有肩胛上神经损伤（P<0.01）。 结论关节镜下巨大肩袖损伤传统双排修复术及阔筋膜移植术均能改善患者肩关节功能,双排缝合对于肩胛上神经功能恢复的短期效果要比阔筋膜移植组好,但再撕裂可能性大。     

MRI quantification of fatty infiltration and muscle atrophy in a mouse model of rotator cuff tears

Rotator cuff pathology is the most common shoulder problem seen by orthopedic surgeons. Rotator cuff muscle fatty infiltration and muscle atrophy are common in larger tears and are considered predicting factors for the prognosis of cuff repair. Clinically, MRI is the gold standard in determining fatty infiltration and muscle atrophy; however, analysis for MRI imaging is primarily qualitative in nature with the results lacking further validation. We have recently developed a mouse model of rotator cuff tears. The goal of this study is to quantify and verify rotator cuff muscle atrophy and fatty infiltration using high‐resolution MRI in our mouse model. The rotator cuff muscles were analyzed for fat using a triglyceride quantification assay (TQA), muscle volume was measured through water displacement (WD), and histology. The study revealed that MRI had a high correlation with fat as measured with histology and TQA (R² = 098). MRI also correlated well with atrophy measured with WD and wet weight. This suggests that MRI is a reliable modality in evaluating the progression of fatty infiltration and muscle atrophy following rotator cuff tears in a small animal model. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 421–426, 2013     

反式全肩关节假体置换治疗巨大不可修复肩袖撕裂

目的探讨反式全肩关节置换术（reverse total shoulder arthroplasty,RTSA）治疗巨大不可修复肩袖撕裂的临床治疗效果。 方法对南京中医药大学附属医院2018年5月至2020年1月收治的采取RTSA治疗的13例巨大不可修复肩袖撕裂患者的临床资料进行回顾性分析。记录术前及最后一次随访时患者的肩关节前屈、外展、外旋活动,美国肩肘外科协会评分（American shoulder and elbow surgeons score,ASES）及美国加州大学洛杉矶分校（University of California at Los Angeles,UCLA）评分评估患者肩关节功能。并记录患者发生并发症的情况及影像学检查结果。术前行MR确定肩袖脂肪浸润程度,CT评价肩胛盂骨质情况及有无缺损,术后使用X线评估假体情况。 结果13例患者均随访至少12个月以上。统计术前与术后12个月数据之间的关系,术后12个月肩关节前屈、外展、外旋活动,ASES评分和UCLA评分较术前明显提高,差异具有统计学意义（P<0.01）。随访期内13例患者中有1例患者因局部血肿在术后1周行切开血肿清除引流术,所有患者功能恢复良好。 结论RTSA治疗巨大不可修复肩袖撕裂临床效果良好。     

Central neuromuscular dysfunction of the deltoid muscle in patients with chronic rotator cuff tears

Background  

Previous surface electromyogram (EMG) studies have shown that chronic rotator cuff tears (RCT) may be associated with a altered activation of adjacent shoulder muscles. The effect of RCT on central neuromuscular control mechanisms of the shoulder girdle muscles such as the deltoideus muscle (DM), a key muscle of shoulder function, has as not yet been studied in detail.     

Increased IL‐1β expression and myofibroblast recruitment in subacromial bursa is associated with rotator cuff lesions with shoulder stiffness

We evaluated whether proinflammatory cytokine expression and myofibroblast recruitment in subacromial bursa was linked to rotator cuff lesions with shoulder stiffness. We analyzed expressions of IL‐1β, IL‐6, and TNF‐α in subacromial bursa and joint fluid collected from 14 patients with cuff tears with stiffness as a study group (Group I) and 14 patients with rotator cuff tears without shoulder stiffness as a control group (Group II) using real‐time RT‐PCR, immunohistochemistry, and ELISA. Myofibroblast apoptosis in subacromial bursa was analyzed using terminal deoxynucleotidyl transferase ‐mediated deoxyuridine triphosphate‐biotin nick end‐labeling (TUNEL) and α‐smooth muscle actin immunofluorescence staining. Shoulder function was evaluated using the Constant score. Group I had higher mRNA expression (p < 0.001) and immunoreactivities (p < 0.001) of IL‐1β. They also had higher levels of IL‐1β, IL‐6, and TNF‐α in joint fluid. Increased IL‐1β mRNA expression in the subacromial bursa and IL‐1β levels in joint fluid were correlated with a preoperative deficit in shoulder motion (p < 0.001) and preoperative Constant scores (p < 0.001). Immunofluorescence observations showed that Group I subjects had more myofibroblasts (p < 0.001) than Group II. In Group II, a significant correlation was found between apoptotic myofibroblasts and total myofibroblasts (p = 0.002), but not in Group I (p = 0.510). Increased expression of IL‐1β and myofibroblast recruitment in the subacromial bursa in rotator cuff lesions are linked to shoulder stiffness. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1090–1097, 2008