Association between Low Back Pain and Neck Pain: A 3-Year Longitudinal Study Using the Data of the People after the Great East Japan Earthquake.

Low back pain (LBP) and neck pain (NP) are common health problems worldwide. LBP often coexists with NP; however, the association between these pains remains unclear. The purpose of this study was to clarify the association between LBP and NP, focusing on dose-dependent effects. This study used a 3-year longitudinal cohort data of people living in disaster-stricken areas after the Great East Japan Earthquake (n = 2,118). LBP and NP were assessed at 4, 5, 6, and 7 years after the disaster. LBP was categorized according to its frequency. Multivariate logistic regression analyses were performed to assess the association between LBP and NP, and the effect of preceding LBP on the subsequent onset of NP, according to the frequency of LBP. LBP was significantly associated with NP, and the association was stronger with increased frequency of LBP. Adjusted odds ratios (95% confidence intervals) were 2.40 (1.71-3.37) for "1", 3.99 (2.82-5.66) for "2", and 6.08 (4.40-8.41) for "≥ 3" in frequency when the absence of LBP was used as a reference (p for trend < 0.001). Furthermore, preceding LBP was significantly associated with subsequent onset of NP, and the effect was stronger with increased frequency of LBP. Adjusted odds ratios (95% confidence intervals) were 2.44 (1.62-3.68) for "1" and 2.68 (1.77-4.05) for "≥ 2" in frequency when the absence of LBP was used as a reference (p for trend < 0.001). LBP is associated with NP in a dose-dependent manner. The association between LBP and NP should be considered to effectively treat these pains.

Effect of the decreased frequency of going out on the association between anxiety and sleep disorder during the COVID-19 pandemic: a mediation analysis.

PURPOSE: The objective of the present study was to examine the relationship between anxiety and sleep disorder during the COVID-19 pandemic and to evaluate whether sleep disorder is mediated by the decreased frequency of going out. METHODS: The data of a total of 1976 residents aged 18 years and over who had responded to a self-reported questionnaires at a health survey in 2020 were analyzed. The subjects were divided into four groups based on their response to the questionnaire on anxiety about the COVID-19 pandemic. Sleep disorder was measured using the Athens Insomnia Scale (AIS). A cross-sectional analysis was performed to examine the association between anxiety about the COVID-19 pandemic and AIS scores. Mediation analysis was used to calculate the association between anxiety and AIS scores during the COVID-19 pandemic, with decreased frequency of going out as a potential mediating variable. RESULTS: In the cross-sectional study, the level of anxiety about the COVID-19 pandemic was significantly associated with the AIS score (p < 0.001). On mediation analysis, the direct effect of the relationship showed that anxiety positively influenced AIS scores (ß = 0.283, p < 0.01). The indirect effect of the relationship showed that the decreased frequency of going out positively mediated the relationship between anxiety and AIS scores (ß = 0.342, p < 0.05). The decreased frequency of going out accounted for almost 10% of the AIS score. CONCLUSION: The present study found that anxiety about the COVID-19 pandemic was significantly associated with sleep disorder, with the decreased frequency of going out mediating this association.

Knee pain in young sports players aged 6-15 years: a cross-sectional study in Japan.

BACKGROUND: Knee is the most commonly injured part of the body in young athletes. Knee pain in several studies have been seen to be more prevalent in active adolescents compared to inactive, although common in both groups. Nevertheless, few studies with large sample size have been published reporting the difference of the prevalence of knee pain for each sport among young sports players. This study investigated the point prevalence of knee pain among young sports players aged 6-15 years old according to age, sex, and sports discipline. Furthermore, this study investigated the association between knee pain and sports discipline among young sports players. METHODS: A cross-sectional study was conducted using a self-reported questionnaire on young sports players aged 6-15 years from the Miyagi Amateur Sports Association. Multivariable logistic regression models were used to examine the association between knee pain and sports discipline and were adjusted for age, sex, body mass index (BMI), training days per week, and training hours per weekday and weekend. RESULTS: A total of 7234 young sports players were included. The point prevalence of knee pain was 10.9%. Females (13.3%) had more knee pain than males (9.8%). Young, 13-year-old sports players had the highest prevalence of knee pain (19.1%). The multivariable analysis showed that the highest odds ratio [95% confidence interval] was observed for handball players (2.42 [1.01-5.81]). In addition, hand ball, mini-basketball (odds ratio 1.85; 95% CI 1.38-2.47), and basketball (odds ratio 1.66; 95% CI 1.23-2.26) were significantly associated with knee pain, compared with football. The lowest odds ratio was observed for swimming (0.34 [0.05-2.54]), followed by karate (odds ratio 0.38; 95% CI 0.16-0.89) and baseball (odds ratio 0.47; 95% CI 0.35-0.64). CONCLUSION: The prevalence of knee pain among young athletes differed according to age, sex, and sports discipline. Their parents and clinicians should recognize this information to manage knee pain among young sports players.

Extracorporeal shockwave therapy in an immobilized knee model in rats prevents progression of joint contracture.

Joint immobilization, which ensures rest and accelerates tissue recovery in musculoskeletal disorders, often causes joint contracture, for which there is still no effective prevention. To address this, we investigated the effects of extracorporeal shockwave therapy (ESWT) in preventing joint contracture, in a unilaterally immobilized knee rat model. Under general anesthesia, ESWT (0.25 mJ/mm2 , 3000 shot, 4 Hz, 3 days/week) was administered from 1 day after immobilization up to 2, 4, and 6 weeks. The immobilized control group received general anesthesia without ESWT. We evaluated joint angle, tissue elasticity, and gene and protein expression related to fibrosis, inflammation, and angiogenesis in the joint capsule. Relative to the control, the ESWT group had greater joint angle at 4 and 6 weeks, and lower posterior-capsule elasticity at 6 weeks. In the ESWT group, at 6 weeks, gene expression of collagen type I (col1α1), connective tissue growth factor (CTGF), and α-smooth muscle actin (α-SMA) was significantly downregulated, whereas interleukin-6 (IL-6) and hypoxia-inducible factor-1α (HIF-1α) gene expression was upregulated, relative to that in the control. Compared with that in the control, at 4 and 6 weeks, the ratio of CTGF+ cells was significantly lower in the ESWT group; at 4 weeks, the ESWT group had significantly fewer CD68+ cells in the adhesion area, and at 6 weeks, significantly more blood vessels. Statement of Clinical Significance: In a rat model, ESWT counteracted fibrosis, suppressed macrophage infiltration, and promoted neovascularization, reducing elasticity, and increasing joint range-ofmotion. ESWT offers a potential new strategy to prevent progression in joint contracture.

Low back pain is associated with sleep disturbance: a 3-year longitudinal study after the Great East Japan Earthquake.

BACKGROUND: Low back pain and sleep disturbance are common health problems worldwide which are also commonly observed among people after natural disasters. These symptoms are well known to coexist, and recent reports have indicated that sleep disturbance is a risk factor for low back pain. However, the influence of low back pain on sleep disturbance has rarely been assessed; therefore, this study aimed to clarify the association of low back pain with sleep disturbance, especially focusing on the frequency of low back pain, using 3-year cohort data after the Great East Japan Earthquake. METHODS: This study used the data obtained from people living in the disaster-affected areas after the Great East Japan Earthquake (n = 2,097). Low back pain and sleep disturbance were assessed at 4, 5, 6, and 7 years after the disaster. The frequency of low back pain was defined as the number of low back pain episodes at and before the evaluation time point and categorized into five groups such as absence, 1, 2, 3, and 4 at the fourth time point and four groups such as absence, 1, 2, and 3 at the third time point. Multivariate logistic regression analyses were conducted to assess the association of low back pain with sleep disturbance. RESULTS: Low back pain was significantly associated with sleep disturbance, and the association was stronger in participants with more frequent low back pain (adjusted odds ratios [95% confidence intervals],1.46 [1.10-1.95] in "1"; 2.02 [1.49-2.74] in "2"; 2.38 [1.67-3.40] in "3"; and 4.08 [2.74-6.06] in "4" in the frequency of low back pain) (P for trend < 0.001). Furthermore, antecedent low back pain was significantly associated with new-onset sleep disturbance, and the association was robust in more frequent low back pain (adjusted odds ratios [95% confidence intervals],1.60 [1.05-2.44] in "1"; 1.96 [1.20-3.21] in "2"; and 2.17 [1.14-4.14] in "3" in the frequency of low back pain) (P for trend = 0.007). CONCLUSION: Our study showed that low back pain is strongly associated with sleep disturbance. Attention should be paid to low back pain to prevent and treat sleep disturbance, especially focusing on chronicity of low back pain.

Association between low back pain and functional disability in the elderly people: a 4-year longitudinal study after the great East Japan earthquake.

BACKGROUND: Functional disability is a major health issue in an aging population. Low back pain (LBP) is a common health concern that can lead to functional disability in the elderly; nonetheless, their association has not yet been clarified. This study aimed to examine the association between LBP and functional disability in the elderly, with a focus on its dose-dependent effects. METHODS: This study used the 4-year longitudinal data of people living in disaster-affected areas after the Great East Japan Earthquake (aged ≧65, n = 914). LBP and physical function were assessed at 2, 4, and 6 years after the disaster. Multivariate logistic regression analyses were performed to assess the association between LBP and low physical function, as well as the effect of preceding LBP on the onset of low physical function. RESULTS: LBP was significantly associated with low physical function, and the association became stronger as the duration of LBP increased. Adjusted odds ratios (95% confidence intervals) were 1.27 (0.79-2.06) in "< 2 years," 1.95 (1.01-3.77) in "≥2 years and <4 years," and 2.34 (1.35-4.06) in "≥4 years" (p for trend = 0.009). Additionally, preceding LBP was significantly associated with the onset of low physical function, and the effect became prominent as the duration of LBP increased. Adjusted odds ratios (95% confidence intervals) were 2.28 (1.19-4.37) in "< 2 years" and 2.82 (1.35-5.90) in "≥2 years" (p for trend = 0.003). CONCLUSIONS: LBP is associated with physical disability among the elderly in a dose-dependent manner. Therefore, prevention and treatment of LBP are important for preventing functional disability.

Sleep disturbance is associated with neck pain: a 3-year longitudinal study after the Great East Japan Earthquake.

BACKGROUND: Neck pain is a common health problem in the general population as well as in people after natural disasters. Sleep disturbances are gaining attention as risk factors for musculoskeletal pain; however, the association between sleep disturbance and neck pain has not been clarified. The present study aimed to clarify the association between sleep disturbance and neck pain, especially focusing on the effect of the duration of sleep disturbance, after the Great East Japan Earthquake. METHODS: This study used 3-year longitudinal data obtained from individuals (n = 2,059) living in disaster-affected areas after the Great East Japan Earthquake. Sleep disturbance and neck pain were investigated at 4, 5, 6, and 7 years after the disaster. Multivariate logistic regression analyses were used for the assessment. RESULTS: Sleep disturbance was significantly associated with neck pain, and the association was stronger as the duration of sleep disturbance increased (adjusted odds ratios [95% confidence intervals]: 1.84 [1.23-2.75] for " < 1 year"; 2.41 [1.53-3.81] for " ≥ 1 year and < 2 years"; 2.80 [2.09-3.76] for " ≥ 2 years"). Furthermore, preceding sleep disturbance was significantly associated with the onset of neck pain, and the association was stronger as the duration of sleep disturbance increased (adjusted odds ratios [95% confidence intervals]: 1.86 [1.08-3.20] for " < 1 year"; 2.39 [1.22-4.70] for " ≥ 1 year and < 2 years"; 3.00 [1.94-4.65] for " ≥ 2 years"). CONCLUSIONS: Sleep disturbance is associated with neck pain, and long-lasting sleep disturbance strengthens the association. Clinicians should consider this association to effectively treat patients with neck pain, especially those affected by natural disasters.

Association between Prior and Later Occurrence of Shoulder Pain Episodes: A 5-Year Longitudinal Study after the Great East Japan Earthquake.

Shoulder pain is more common among survivors of natural disasters than the general population. This study aimed to examine the occurrence of shoulder pain, especially the association between prior and later shoulder pain episodes, in survivors living in coastal areas severely damaged by the Great East Japan Earthquake (GEJE) (n = 1,821) over a period of 5 years. The presence of shoulder pain was assessed at 2 (first period), 4 (second period), and 7 (third period) years after the disaster. Multiple logistic regression analyses were performed to assess the association between shoulder pain during the first and second periods and shoulder pain during the third period. Shoulder pain in the first period was significantly associated with shoulder pain in the third period [adjusted odds ratio (OR) 5.93; 95% confidence interval (CI) 4.06-8.66]. Furthermore, shoulder pain in the first and second periods was significantly associated with shoulder pain in the third period. With the absence of shoulder pain in both the first and second periods used as the reference, adjusted ORs for the presence of shoulder pain during each period and both periods were 4.58 (95% CI 3.17-6.62) and 15.54 (95% CI 8.38-28.84), respectively (P for trend < 0.001). Thus, prior shoulder pain was significantly associated with shoulder pain after 5 years among GEJE survivors, and the association was stronger as the number of prior shoulder pain episodes increased. This expertise should be shared with other expert teams to address the affected people and prepare for future disasters.

Tissue accumulation of neutrophil extracellular traps mediates muscle hyperalgesia in a mouse model.

Accumulation of uric acid (UA) during muscular trauma is a factor involved in the development of muscle hyperalgesia. Neutrophil extracellular traps (NETs), DNA-based reticular structures to capture UA, play a central role in the pain onset of gout attacks; however, the involvement of NETs via the elevation of local UA level in muscle hyperalgesia due to injuries from muscle overuse remains unknown. The triceps surae muscles (TSMs) in the unilateral hindlimb of mice were electrically stimulated to induce excessive muscle contraction. Mechanical withdrawal thresholds, tissue UA levels, neutrophil recruitment, and protein amount of citrullinated histone 3 (citH3), a major marker of NETs, were investigated. Furthermore, whether neutrophil depletion, extracellular DNA cleavage, and administration of the urate-lowering agent febuxostat improved muscle hyperalgesia caused by NET formation was examined. CitH3 expression upon neutrophil recruitment was significantly increased in the stimulated TSMs with increased tissue UA levels, whereas febuxostat administration improved muscle hyperalgesia with decreased citH3 and tissue UA levels, as observed in neutrophil depletion and extracellular DNA digestion. The underlying mechanism of muscle hyperalgesia associated with locally recruited neutrophils forming NETs due to increased tissue UA levels potentially plays a significant role in creating a vicious circle of muscle pain.

Factors Associated with Thickening of the Ligamentum Flavum on Magnetic Resonance Imaging in Patients with Lumbar Spinal Canal Stenosis.

STUDY DESIGN: Experimental study of the ligamentum flavum (LF) thickness among patients with lumbar spinal canal stenosis (LSCS). OBJECTIVES: To elucidate the factors associated with thickening of the LF on magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA: Thickening of the LF is a major contributor to LSCS. This thickening is attributed to tissue hypertrophy or buckling of the ligament, and there may be several associated factors on MRI; however, these factors remain unclear. METHODS: We studied the LF in 56 patients (a total of 106 ligaments) with LSCS, who underwent decompressive surgery; among them, 23 were receiving haemodialysis. The Pearson correlation coefficient was used to assess relationships between the thickness of the LF on MRI and the thickness of the LF tissue, age, disc height, disc degeneration, and disc level. Patients were also categorised into 2 groups based on whether they were undergoing haemodialysis, and the relationships were assessed similarly. RESULTS: Among patients with LSCS, the thickness of the LF on MRI showed a significant positive linear relationship with the thickness of the LF tissue, and no association with disc height. Except for in those receiving haemodialysis, the thickness of the LF on MRI showed a significant positive relationship with age, disc degeneration, and disc level among patients with LSCS. CONCLUSION: In patients with LSCS, thickening of the LF on MRI appears to represent tissue hypertrophy. The association between the thickness of the LF on MRI and age, disc degeneration, and disc level may indicate simultaneous alterations of spine components along with aging that was cancelled by the effects of haemodialysis.

Comparative proteome analysis of the ligamentum flavum of patients with lumbar spinal canal stenosis.

Background: Thickening of the ligamentum flavum is considered to be the main factor for lumbar spinal canal stenosis (LSCS). Although some mechanisms have been speculated in the thickening of the ligamentum flavum, there are only a few comprehensive approaches to investigate its pathology. The objective of this study was to investigate the pathology of thickened ligamentum flavum in patients with LSCS based on protein expression levels using shotgun proteome analysis. Methods: Ligamentum flavum samples were collected from four patients with LSCS (LSCS group) and four patients with lumbar disc herniation (LDH) as controls (LDH group). Protein mixtures were digested and analyzed by liquid chromatography/mass spectrometry analysis. To compare protein expression levels between the LSCS and LDH groups, the mean Mascot score was compared. Biological processes were assessed using Gene Ontology analysis. Results: A total of 1151 proteins were identified in some samples of ligamentum flavum. Among these, 145 proteins were detected only in the LSCS group, 315 in the LDH group, and 691 in both groups. The demonstrated biological processes occurring in the LSCS group included: extracellular matrix organization, regulation of peptidase activity, extracellular matrix disassembly, and negative regulation of cell growth. Proteins related to fibrosis, chondrometaplasia, and amyloid deposition were found highly expressed in the LSCS group compared with those in the LDH group. Conclusions: Tissue repair via fibrosis, chondrometaplasia, and amyloid deposits may be important pathologies that occur in the thickened ligamentum flavum of patients with LSCS.

Association Between Sleep Disturbance and Low Back Pain: A 3-Year Longitudinal Study After the Great East Japan Earthquake.

STUDY DESIGN: A longitudinal study. OBJECTIVE: The aim of this study was to clarify the association between sleep disturbance and low back pain (LBP) using 3-year longitudinal data after the Great East Japan Earthquake, with a focus on the duration or frequency of sleep disturbance and the effect of sleep disturbance on LBP. SUMMARY OF BACKGROUND DATA: Sleep disturbance and LBP are common health problems in the general population and natural disaster survivors. However, a longitudinal study in this field is rare, and the association between sleep disturbance and LBP has not been clarified. METHODS: A 3-year longitudinal study was conducted among people living in disaster-stricken areas after the Great East Japan Earthquake (n = 2059). Sleep disturbance and LBP were assessed at 4, 5, 6, and 7 years after the disaster. Multiple logistic regression analysis was performed to assess the association between the duration or frequency of sleep disturbance and LBP, and the effect of preceding sleep disturbance on the onset of LBP. The χ2 test and crude and multiple logistic regression models were used in data analysis. RESULTS: The duration and frequency of sleep disturbance were significantly associated with LBP, and the effect was stronger with longer duration and increased frequency of sleep disturbance. Furthermore, the duration and frequency of preceding sleep disturbance were significantly associated with the onset of LBP, and the effect was stronger with an increase in the duration and frequency of sleep disturbance. CONCLUSION: Sleep disturbance is associated with LBP in a dose-dependent manner. Attention should be paid to sleep disturbance for the treatment and prevention of LBP, especially with regard to the duration and frequency of sleep disturbance.Level of Evidence: 3.

The 5-Year Course of Neck Pain Among Natural Disaster Survivors: The Association of Prior Neck Pain with New Episodes of Neck Pain.

OBJECTIVE: Neck pain is a common health problem among both the general population and natural disaster survivors. However, the long-term course of neck pain has rarely been reported. The aim of this study was to elucidate the 5-year course of neck pain among survivors of the Great East Japan Earthquake (GEJE) by assessing the association of neck pain 2 and 4 years after the disaster with that at 7 years. STUDY DESIGN: Longitudinal study. METHODS: A panel study was conducted on GEJE survivors (n = 1,821) through the administration of a self-reported questionnaire at 2 (first time point), 4 (second time point), and 7 years (third time point) after the disaster. Multivariate logistic regression analyses were performed to assess the association between prior neck pain and subsequent neck pain. RESULTS: The rates of neck pain at the first, second, and third time points were 20.7%, 21.1%, and 20.1%, respectively. Neck pain at the first time point was significantly associated with neck pain at the third time point (adjusted odds ratio [95% confidence interval]: 5.96 [4.53-7.83]). Furthermore, neck pain at the first and second time points was significantly associated with neck pain at the third time point (adjusted odds ratio [95% confidence interval]: 5.71 [4.19-7.78] for neck pain at either time point; 15.94 [10.99-23.12] for neck pain at both time points; P for trend <0.001). CONCLUSIONS: Prior neck pain was significantly associated with neck pain 5 years later, and the effect was stronger with an increase of prior neck pain episodes. Clinicians should base their selection of treatment method on an individual's history of neck pain.

Low Back Pain in Young Sports Players: A Cross-sectional Study in Japan.

STUDY DESIGN: A cross-sectional study. OBJECTIVE: The purpose of this large cohort study was to assess the prevalence of low back pain (LBP) among young players participating in several types of sports. SUMMARY OF BACKGROUND DATA: LBP is a significant problem among young sports players. Sport discipline among young players is thought to be associated with LBP. However, similar previous studies did not specifically analyze LBP by age and sex. METHODS: A cross-sectional study was conducted with young sports players (ages 6-15 years, n = 7277) using a self-reported questionnaire. The prevalence of LBP was assessed using the variables of age, sex, and sport discipline. RESULTS: The point prevalence of LBP among young sports players was 5.0%. The participants between 6 and 8 years' old had the lowest prevalence of LBP (0.4%-1.3%), which increased with aging and reached the highest proportion of 13.5% to 14.8% at 13 to 14 years. Furthermore, female players had significantly higher proportions of LBP than male players (8.1% vs. 3.7%). Regarding sport discipline, the prevalence of LBP was higher in basketball, handball, and volleyball. CONCLUSION: The prevalence of LBP among young sports players was different for age, sex, and sport discipline. Further studies are needed to clarify the association of sport-specific movements to LBP in each sport discipline. This may assist in developing programs or strategies for preventing LBP among young sports players.Level of Evidence: 3.

Association of decreased physical activity due to the COVID-19 pandemic with new-onset neck pain in survivors of the Great East Japan Earthquake: a prospective cohort study.

OBJECTIVES: The COVID-19 pandemic has forced many people to stay at home and to maintain social distancing. This study aimed to assess the association of reduced physical activity during the COVID-19 pandemic with new onset of neck pain (katakori) among a rural Japanese population living in areas damaged by the Great East Japan Earthquake (GEJE). DESIGN, SETTING AND PARTICIPANTS: This prospective cohort study has been conducted continuously since 2011 after the GEJE. This study used longitudinal data from 1608 adults who responded to the self-reported questionnaire before and during the COVID-19 pandemic. Changes in physical activity due to the COVID-19 pandemic were categorised into four groups: 'no change', 'decreased by 20%-30%', 'decreased by half' and 'almost never go out'. Multiple logistic regression analysis was used to estimate the OR and 95% CI of the association between COVID-19 pandemic-related physical inactivity and new-onset neck pain. RESULTS: In total, 'no change', 'decreased by 20%-30%', 'decreased by half', and 'almost never go out' were reported by 9.2%, 27.7%, 31.2% and 21.9% of respondents, respectively. Among them, 9.8% reported new-onset neck pain. A significantly higher rate of new-onset neck pain was observed in participants who reported 'decreased by half' (adjusted OR 1.85, 95% CI 1.04 to 3.30) and who 'almost never go out' (adjusted OR 2.13, 95% CI 1.16 to 3.91), compared with those who reported 'no change.' CONCLUSIONS: Decreased physical activity has increased due to the COVID-19 pandemic and was significantly associated with new-onset neck pain among GEJE survivors.

Contracted joint capsule affects labral and chondral lesions in patients with frozen shoulder.

PURPOSE: Intra-articular pathologies, such as labral and chondral lesions, are common in patients with frozen shoulder. This study evaluated the correlations between the range of motion and labral and chondral lesions in patients with frozen shoulder and investigated their pathophysiologies. METHODS: In total, 125 individuals (53 men and 72 women) who underwent arthroscopic pan-capsular release between 2014 and 2020 were included in the study. The range of motion was measured using scapular fixation and true glenohumeral motion under general anaesthesia. The American Shoulder and Elbow Surgeons Shoulder score and the Shoulder Rating Scale score of the University of California, Los Angeles were used to compare intra-articular pathologies. RESULTS: More than 80% of patients with frozen shoulder had labral pathologies, and nearly half of them had chondral pathologies. Labral lesions extending to the anterior rim of the glenoid had a greater range of motion and the greatest total American Shoulder and Elbow Surgeons Shoulder score. More severe chondral lesions had a lesser range of motion, but presented the greatest function scores and the lowest strength scores according to the Shoulder Rating Scale of the University of California, Los Angeles. The pain scores of the American Shoulder and Elbow Surgeons Shoulder score and the Shoulder Rating Scale of the University of California, Los Angeles were not correlated with the degree of these pathologies. The traction force affected the labrum during true range of motion, and the compression force occurred on the articular cartilage during internal rotation at 90° of forward flexion during diagnostic arthroscopy. CONCLUSION: Labral and chondral lesions are common in patients with frozen shoulder. Adherence to the capsulolabral complex induced a limited range of motion and labral and chondral pathologies. Diagnostic arthroscopy with motion is an important method of reproducing the pathogenesis of intra-articular structures for patients with frozen shoulder. LEVEL OF EVIDENCE: Level III.

Skeletal muscle-specific Keap1 disruption modulates fatty acid utilization and enhances exercise capacity in female mice.

Skeletal muscle health is important for the prevention of various age-related diseases. The loss of skeletal muscle mass, which is known as sarcopenia, underlies physical disability, poor quality of life and chronic diseases in elderly people. The transcription factor NRF2 plays important roles in the regulation of the cellular defense against oxidative stress, as well as the metabolism and mitochondrial activity. To determine the contribution of skeletal muscle NRF2 to exercise capacity, we conducted skeletal muscle-specific inhibition of KEAP1, which is a negative regulator of NRF2, and examined the cell-autonomous and non-cell-autonomous effects of NRF2 pathway activation in skeletal muscles. We found that NRF2 activation in skeletal muscles increased slow oxidative muscle fiber type and improved exercise endurance capacity in female mice. We also observed that female mice with NRF2 pathway activation in their skeletal muscles exhibited enhanced exercise-induced mobilization and ß-oxidation of fatty acids. These results indicate that NRF2 activation in skeletal muscles promotes communication with adipose tissues via humoral and/or neuronal signaling and facilitates the utilization of fatty acids as an energy source, resulting in increased mitochondrial activity and efficient energy production during exercise, which leads to improved exercise endurance.