Toshihisa Osawa

Prevalence and risk factors of a rotator cuff tear in the general population.

BACKGROUND Little information is available about the epidemiology of rotator cuff tears in a population-based study. The purpose of this study was to elucidate the true prevalence of rotator cuff tears regardless of the presence or absence of symptoms in the general population and to assess the relationship between tears and their backgrounds. MATERIAL AND METHODS A medical check-up was conducted for residents of a mountain village in Japan. The subjects consisted of 683 people (total of 1,366 shoulders), including 229 males and 454 females with a mean age of 57.9 years (range, 22-87). We examined their background factors, physical examinations and ultrasonographic examinations on both shoulders. RESULTS Rotator cuff tears were present in 20.7% and the prevalence increased with age. Thirty-six percent of the subjects with current symptoms had rotator cuff tears, while 16.9% of the subjects without symptoms also had rotator cuff tears. Rotator cuff tears in the general population were most commonly associated with elderly patients, males, affected the dominant arm, engaged in heavy labor, having a history of trauma, positive for impingement sign, showed lesser active forward elevation and weaker muscle strength in abduction and external rotation. A logistic regression analysis revealed the risk factors for a rotator cuff tear to be a history of trauma, dominant arm and age. CONCLUSION 20.7% of 1,366 shoulders had full-thickness rotator cuff tears in the general population. The risk factors for rotator cuff tear included a history of trauma, dominant arm and age. LEVEL OF EVIDENCE Level 3.

Multivariate analysis of biochemical markers in synovial fluid from the shoulder joint for diagnosis of rotator cuff tears

Multivariate discriminant analysis allowed definition of cytokine, matrix metalloproteinases (MMP), and tissue inhibitors of metalloproteinases (TIMP) levels in synovial fluid (SF) of patients with rotator cuff tears and other shoulder lesions. We analyzed SF aspirated from the glenohumeral joints of 17 patients with rotator cuff tears; SF from nine patients with other shoulder lesions was used to characterize a non-rotator-cuff-tear (NRCT) group. Discriminant analysis demonstrated statistically significant differences in (1) the determination of whether rotator cuff tear patients are separable from the NRCT group using the influential functions, the most influential of which were interleukin 1-beta, MMP-2, and MMP-13, and (2) the assessment of whether full-thickness rotator cuff tears are distinguishable from partial tears using identical influential functions. The most influential function in the latter analysis was MMP-13. Both interleukin 1-beta and MMP-13 might be biochemical markers of impending rotator cuff tears.

Characteristics of neck and shoulder pain (called katakori in Japanese) among members of the nursing staff

BackgroundThe characteristics of neck and shoulder pain (NSP), called katakori in Japanese, have not been well documented to date. The aim of this study was to clarify the characteristics of NSP through a questionnaire survey of members of the nursing staff.MethodsThe study population consisted of 484 nursing staff members of Gunma University Hospital in Japan. The questionnaire involved information on age, body mass index (BMI), gender, psychological stress at work, musculoskeletal pain at other anatomic sites (elbow/wrist, lumbar and knee), smoking history, and hypertension. If subjects had NSP, they were asked about any coexisting symptoms, the utilization of health services, and the precise location of NSP.ResultsThe total study population included 393 persons after 91 persons were excluded for various reasons. The point prevalence of NSP was 68.1% (268 of 393). Age, BMI, smoking history, and hypertension showed no significant trend for the prevalence of NSP in the univariate analyses. The occurrence of NSP was significantly higher in subjects with psychological stress, elbow/wrist pain, lumbar pain, and knee pain, respectively. A multivariate logistic regression analysis showed that gender, psychological stress, elbow/wrist pain, and lumbar pain were significantly associated with the occurrence of NSP. One hundred fifty-eight of those with NSP (58.9%) reported coexisting symptoms, and the most common was headache. Fifty-seven (21.2%) of the subjects with NSP had consulted medical or health practitioners, and bone setting was the most common service provider. The most common area of NSP was the superior part of the trapezius.ConclusionsThis study confirmed that NSP, katakori in Japanese, is a prevalent problem in a nursing staff, and several factors associated with NSP were identified.

The impact of faulty posture on rotator cuff tears with and without symptoms

HYPOTHESIS We hypothesized that the prevalence of rotator cuff tears would be higher among individuals with poor posture, regardless of the presence of symptoms. METHODS The study initially comprised 525 residents of a mountain village who participated in an annual health check. Participants completed a background questionnaire, and physical examinations were performed to evaluate shoulder function. Ultrasonographic examinations were also performed to identify rotator cuff tears, and participants were grouped according to the presence or absence of tears. Posture was classified by 2 observers into 4 types according to the classification of Kendall, as follows: ideal alignment, kyphotic-lordotic posture, flat-back posture, and sway-back posture. Univariate analyses were performed to compare differences in background characteristics between groups, then multivariate analysis was performed to identify those factors associated with rotator cuff tears. RESULTS Final analysis was performed for 379 participants (135 men, 244 women; mean age, 62.0 years; range, 31-94 years) showing the same posture classification from both observers. Of these, 93 (24.5%) showed rotator cuff tear in one shoulder and 45 (11.9%) showed tears in both. Prevalence of rotator cuff tears was 2.9% with ideal alignment, 65.8% with kyphotic-lordotic posture, 54.3% with flat-back posture, and 48.9% with sway-back posture. Logistic regression analysis identified increased age, abnormal posture, and past pain as factors associated with rotator cuff tears. CONCLUSIONS Postural abnormality represented an independent predictor of both symptomatic and asymptomatic rotator cuff tears. These results may help define preventive measures for rotator cuff tears and in design ing rehabilitation therapies for shoulder disease.

The Neural Correlates of Shoulder Apprehension: A Functional MRI Study.

Although shoulder apprehension is an established clinical finding and is important for the prevention of shoulder dislocation, how this subjective perception is evoked remains unclear. We elucidated the functional neuroplasticity associated with apprehension in patients with recurrent anterior shoulder instability (RSI) using functional magnetic resonance imaging (fMRI). Twelve healthy volunteers and 14 patients with right-sided RSI performed a motor imagery task and a passive shoulder motion task. Brain activity was compared between healthy participants and those with RSI and was correlated with the apprehension intensity reported by participants after each task. Compared to healthy volunteers, participants with RSI exhibited decreased brain activity in the motor network, but increased activity in the hippocampus and amygdala. During the passive motion task, participants with RSI exhibited decreased activity in the left premotor and primary motor/somatosensory areas. Furthermore, brain activity was correlated with apprehension intensity in the left amygdala and left thalamus during the motor imagery task (memory-induced), while a correlation between apprehension intensity and brain activity was found in the left prefrontal cortex during the passive motion task (instability-induced). Our findings provide insight into the pathophysiology of RSI by identifying its associated neural alterations. We elucidated that shoulder apprehension was induced by two different factors, namely instability and memory.

Shoulder pain and intra-articular interleukin-8 levels in patients with rotator cuff tears.

Rotator cuff disease (RCD) is one of the most common disorders in the shoulder joint and causes joint pain and functional disability. In this study, we investigated the associations among cytokine levels and clinical symptoms in patients with RCD.

What Is the Appropriate Reference for Evaluating the Recovery of Supraspinatus Muscle Atrophy After Arthroscopic Rotator Cuff Repair? The Occupation Ratio of the Supraspinatus May Change After Rotator Cuff Repair Without Volumetric Improvement:

Background: Supraspinatus muscle atrophy is typically assessed by the occupation ratio of the cross-sectional area of the muscle belly to the supraspinatus fossa at the medial border of the coracoid process in a slice along the oblique-sagittal plane on MRI. Previous studies have shown that the occupation ratio of the supraspinatus changed soon after rotator cuff repair compared with before surgery. However, no studies have examined the perioperative change in the muscle volume assessed with 3-dimensional measurement. Purpose: To compare the volume of the supraspinatus muscle before and soon after surgery by using 3-dimensional imaging and to elucidate whether the changes in the occupation ratio represent corresponding changes in the muscle volume. Study Design: Cohort study; Level of evidence, 3. Methods: Thirty shoulders of patients who underwent arthroscopic rotator cuff repair were evaluated. T2-weighted images were obtained before surgery and 2 weeks after surgery. After the muscle and its tendon borders were plotted, the supraspinatus and its tendon were segmented with interactive thresholding in all slices. The 3-dimensional images were then reconstructed and the volumes calculated. Changes in the muscle volume and the occupation ratio were evaluated via 3-dimensional and 2-dimensional image assessments. The 3-dimensional and 2-dimensional findings before and after surgery were compared by use of paired t tests. Results: The mean muscle volume did not change significantly at a time point soon after surgery in any group. In patients with little medial retraction (n = 7) or isolated detachment at the superior facet (n = 17), no significant differences were noted in the occupation ratio after surgery compared with before surgery. In contrast, in patients with moderate medial retraction (n = 23) or extended tearing in the transverse direction (n = 13), the occupation ratio increased significantly. Conclusion: Although the muscle volume did not change soon after surgery compared with the preoperative values, in patients with moderate medial retraction or extended tearing in the transverse direction, the occupation ratio increased, probably due to lateral traction of the supraspinatus muscle. We recommend that MRI findings obtained soon after surgery be used as the time-zero reference for evaluating the postoperative changes in the supraspinatus.

Clinical Outcome of Arthroscopic Remplissage as Augmentation During Arthroscopic Bankart Repair for Recurrent Anterior Shoulder Instability

Purpose: We aimed to assess functional outcomes and postoperative recurrence rate associated with the remplissage procedure used for bone augmentation with Bankart repair in patients with Hill-Sachs lesions after shoulder dislocation. Methods: Preoperative computed tomography was performed to check for bony Bankart lesions,calculate the bone defect rate, and estimate the risk for re-dislocation. Functional and clinical scores were assessed preoperatively and at three months, six months, and one year postoperatively. Results: Between 2011 and 2014, 18 patients (17 male; age at surgery, 29.0±10.4 years; 18 affected shoulders) underwent arthroscopic Bankart repair with arthroscopic remplissage (remplissage group), and 18 sex- and age-matched controls underwent arthroscopic Bankart repair alone (control group). The incidence of bony Bankart lesion and glenoid bone defect was significantly higher in the remplissage group. No complications, re-dislocation, or re-subluxation was noted during or after the operation. Postoperatively, the range of motion and muscular weakness alleviated with time, and the clinical scores improved significantly from the preoperative values. However, the remplissage group showed significantly restricted shoulder flexion, abduction, internal rotation and external rotation even at one year postoperatively. Compared to the control group, the remplissage group showed significantly lower Rowe scores preoperatively, and both Rowe scores and University of California-Los Angeles scale scores remained significantly lower throughout the one-year follow-up. Conclusion: Despite some restriction of external rotation, remplissage leads to better clinical scores and no recurrence, providing a valid means of augmentation for Bankart repair in high-risk patients with engaged Hill-Sachs lesion.

Shoulder Stretching Intervention Reduces the Incidence of Shoulder and Elbow Injuries in High School Baseball Players: a Time-to-Event Analysis

We prospectively evaluated the effects of a prevention program on the incidence of shoulder and elbow injuries in high school baseball pitchers. Ninety-two pitchers participated in this study and were taught to perform stretching and strength exercises aimed at improving shoulder external rotation strength in the preseason. The pitchers freely chose to participate in one of four groups [SM-group: performed both exercises, S-group: performed stretching exercise only, M-group: performed strength training only, and N-group: performed neither intervention]. Injury was defined as inability to play for ≥8 days because of shoulder/elbow symptoms. Kaplan-Meier survival curves were generated and hazard ratios (HRs) for injury occurrence were calculated using multivariate Cox regression. Log-rank test was used for between-group comparisons of survival distributions. The injuries occurred in 25, 35, and 57% of participants and median times to injury were 89, 92, and 29.5 days in the S- (n = 32), SM- (n = 46), and N- (n = 14) group, respectively. Nobody chose M-group. HRs were 0.36 and 0.47 for the S- and SM-group, respectively, based on the N-group. The incidence of injury was significantly lower in the S-group than in the N-group (p = 0.04). Daily posterior shoulder stretching may reduce the incidence of the injuries in high school baseball pitchers.