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Background The effect of the thumb test for assessing the cancellous bone quality at the resection plane of the proximal humerus on determining the application of a stemless shoulder prosthesis remains unclear. This study was conducted to survey the current utilization of the thumb test among surgeons and to investigate biomechanical features of the thumb test. Method A survey among shoulder surgeons who had experience with stemless prostheses was conducted to investigate the current utilization of preoperative assessments and intraoperative thumb test when applying stemless prosthesis. Biomechanical experiments for the thumb test using artificial bone models were performed to assess the compression force, contact pressure and area. According to the preliminary survey, three compression techniques were assessed: compression perpendicular to the surface with thumb pad (P-pad technique) or tip of the thumb (P-tip technique), or compression in the vertical direction simulating compression along the longitudinal axis of the humeral shaft with tip-pad of the thumb (H-axis technique). The contact area was separated into three subregions (proximal, middle and distal) to assess the distribution of contact pressure. Results Among 38 surgeons, 66% utilized the thumb test intraoperatively. The P-pad technique was more frequently applied than the P-tip or H-axis techniques (80%, 4% and 16%, respectively). Although with wide variation among the examiners, biomechanical assessments revealed the P-pad technique showed larger contact area and less compression force than the P-tip technique. The P-pad technique provided no significant localized differences in the mean contact pressure on the compressed plane, whereas the P-tip and H-axis techniques showed significant differences among subregions. Conclusion This survey demonstrated relatively frequent application of the thumb test on applying the stemless shoulder prosthesis. Biomechanical assessment revealed the thumb test can hinder objective reproducibility among examiners; therefore, further investigations to identify feasible assessments of the bone quality is required.

Abstract 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.

Key Clinical Message If you suspect cerebral fat embolism (CFE) of the diagnosis for the patients who present with impaired consciousness and hypoxia following a fracture, susceptibility‐weighted imaging should be included of head MRI imaging. Abstract We report a case of cerebral fat embolism (CFE) that could be identified only by susceptibility‐weighted imaging (SWI). Collection and analysis of previous case reports of CFE revealed utilization of SWI in less than one third of suspected cases, despite its known diagnostic ability for CFE.

Background: The Simple Shoulder Test (SST) is a widely used patient-reported outcome assessment. The purpose of this study was to develop and validate a Japanese version of the SST (SST-Jp). Methods: A two-stage observational study was conducted to validate the cross-cultural adaptation of the SST. A total of 100 patients with shoulder disorders completed the SST-Jp; the Disability of Arm, Shoulder, and Hand assessment; and the Medical Outcomes Short-Form 36 (SF-36) at an initial visit. Thirty-four of the patients repeated the SST-Jp one week after the first examination. The test-retest reliability was quantified using the interclass correlation coefficient, and Cronbach’s alpha (α) was calculated to assess internal consistency. Construct validity was assessed using Spearman’s rank correlation coefficient. Results: The internal consistency of the SST-Jp was very high (α = 0.826). The interclass correlation coefficient of the SST-Jp was also high (0.859). There was a strong, positive correlation between the Disability of Arm, Shoulder, and Hand and the SST-Jp (r = 0.717, P < .001). The SST-Jp was significantly correlated with most of the SF-36 subscales. The correlations of the SST-Jp with physical subscales of the SF-36 were stronger than those with the other subscales. Conclusions: The SST-Jp was found to be a valid and reliable measurement for shoulder joint pain and function assessment among the Japanese population.

Background: We aimed to retrospectively determine the effects of arthroscopic pan-capsular release with or without entire coracohumeral ligament (CHL) release and diabetes mellitus (DM) in patients with frozen shoulder (FS). Methods: The study included 34 patients (20 male and 14 female patients) who underwent arthroscopic pan-capsular release without entire CHL release (group 1) and 26 patients (6 male and 20 female patients) who underwent entire CHL release for FS (group 2). Patients with a minimum of 12 months of follow-up were included, and range of motion (ROM) and the shoulder rating scale of the University of California at Los Angeles (UCLA) scoring system were evaluated. Results: In group 2, external rotation and hand-behind-the-back (HBB) ROMs were significantly increased compared with group 1 at the final follow-up (external rotation, 53.1° ± 15.2° vs. 41.3° ± 20.5° [P = .044]; HBB level, T6 [interquartile range, T5-T9] vs. T11 [interquartile range, T8-L4] [P < .001]). Total UCLA scores and UCLA scores for pain (9.2 ± 1.5 vs. 10.0, P = .003), function (8.5 ± 1.4 vs. 10.0, P < .001), and active forward flexion (4.6 ± 0.6 vs. 4.9 ± 0.2, P < .011) were significantly greater in group 2 at the final follow-up. Patients without DM tended to have greater recovery of forward flexion and HBB ROMs and better total, pain, and function UCLA scores compared with those with DM. In group 2, there were no significant differences in ROMs and UCLA scores between the patients with DM and those without DM. Conclusion: Arthroscopic entire CHL release is an essential treatment option for FS patients to regain ROMs and function and to reduce pain.

Background: Proximal humeral fractures are one of the most common fractures in adults. Some patients treated operatively have restriction in range of motion (ROM) after surgery. This study aimed to evaluate arthroscopic pancapsular release in patients with severe stiffness after treatment with intramedullary nailing for proximal humeral fractures. Methods: This study included 12 patients (7 women and 5 men) who underwent arthroscopic pancapsular release in the beach-chair position between May 2015 and February 2018. Intraoperative findings were recorded, and ordinary (with scapulothoracic motion) and true (without scapulothoracic motion) glenohumeral ROMs were measured with a goniometer. The American Shoulder and Elbow Surgeons shoulder score, Shoulder Rating Scale score of the University of California, Los Angeles scoring system, and Constant score were compared before and after the release. The Wilcoxon signed rank and Mann-Whitney U tests were used to analyze data. Results: The average age of the patients was 65.1 years (standard deviation, 9.5 years), and the mean follow-up period after the release was 30.6 months (standard deviation, 11.7 months). All ROMs on the affected side after surgery were significantly greater than those before surgery in all directions. However, ROMs in forward flexion, lateral elevation, and external rotation with the arm at the side and at 90° of forward flexion on the affected side postoperatively were significantly lower than those on the unaffected side. All scores were significantly greater after surgery than before surgery. Conclusion: Arthroscopic pancapsular release is effective for patients with proximal humeral fractures treated with intramedullary nailing.

Abstract Background Low back pain (LBP) is a common problem among young basketball players in addition to lower extremity injuries. However, studies that focus on LBP with lower extremity pain are limited. From the perspective of the kinematic chain, disrupted lower extremity function can lead to LBP. The association between these two symptoms in basketball players, however, has not been reported. Therefore, this study aimed to clarify the association between lower extremity pain and LBP among young basketball players. Methods This cross-sectional study was conducted on school-aged basketball players (n = 592). Information regarding their sporting activities was collected using a self-reported questionnaire. Musculoskeletal pain such as low back, knee, and ankle pain was assessed. The sports players with knee and/or ankle pain were defined as having lower extremity pain. Multivariate logistic regression analysis was used to assess the association between lower extremity pain and LBP. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated. The associations of knee or ankle pain with LBP were similarly assessed. Results School-aged basketball players had a point prevalence of 12.8% for LBP. Compared with the players without lower extremity pain, the players with lower extremity pain had higher rates of LBP, with an adjusted OR (95% CI) of 6.21 (3.57–10.80). There was also a significant association of knee and ankle pain with LBP. Compared with the players without knee or ankle pain, the adjusted ORs (95% CI) for LBP were 4.25 (2.55–7.07) in the players with knee pain and 3.79 (2.26–6.36) in the players with ankle pain. Conclusions Lower extremity pain was associated with LBP among school-aged basketball players. Further research is needed to clarify the mechanism of this association, which will provide useful information for prevention and treatment of LBP among young basketball players.

Antimony tin oxide (ATO) nanoparticle-based porous electrodes have been investigated for use in fast-response electrochromic devices. However, despite their low resistivity, the electrochemical response characteristics of these electrodes are inferior to those of TiO2, which was attributed to the effect of small particle and pore size based on structural simulation. Therefore, we investigated the electrochemical response characteristics of ATO porous electrodes with different nanoparticle sizes, to clarify the effect of the porous electrode structure on response characteristics. The time required for charging an electric double layer (EDL) on the surface of a porous electrode increased as the particle size decreased. The ratios of the time constants of the EDL charging current between each porous electrode were larger than the ratios of the effective surface areas although the porous electrodes had almost the same resistivity. When the particle diameter was small (around 20 nm), the electrochromic reaction of dye modification on the porous electrode started 10 s after the application of a potential, because of the extremely low EDL formation rate. It was confirmed that the delay in EDL formation was induced by a lack of electrolyte ions inside the porous electrode. Therefore, to achieve ideal fast-response electrochemical reactions in low-resistivity nanoparticle-based porous electrodes, it is important to optimize the relationship between the electrode structure and the electrolyte ion concentration.

Abstract Background Soccer is a high-intensity sport with a high injury rate. Among youth soccer players, lower extremity pain is a major problem that could be associated with trunk function. This study investigated the association between lower extremity pain and trunk pain among youth soccer players. Methods A cross-sectional study involving youth soccer players participating in the Miyagi Amateur Sports Association was conducted using a self-reported questionnaire. A multiple logistic regression analysis was used to examine the association between trunk pain and lower extremity pain. Covariates were sex, age, body mass index, height increase, number of days of training per week, practice time per day on weekdays or weekends, competition levels, frequency of participation in games, and previous injuries. Results The final study population comprised 1139 youth soccer players (age, 6–15 years; male, 94.2%). Lower extremity pain with concomitant trunk pain occurred in 61.8% (42/68). Trunk pain was significantly associated with lower extremity pain (adjusted odds ratio [OR], 6.82; 95% confidence interval [CI], 3.99–11.67). Back pain and hip pain were significantly associated with knee pain (adjusted OR [95% CI]: 7.63 [3.70–15.76] and 3.84 [1.89–7.83], respectively), ankle pain (adjusted OR [95% CI]: 9.03 [4.42–18.44] and 5.43 [2.77–10.62], respectively), and both knee and ankle pain (adjusted OR [95% CI]: 13.67 [6.01–31.09] and 5.98 [2.56–13.97], respectively). Conclusions Trunk pain was associated with lower extremity pain among youth soccer players. Clinicians and coaches should consider comorbidities while treating those players.

Abstract Background Sports-related dental injuries, such as tooth fracture, loosening, and avulsion, are a major concern among young athletes because they directly impair oral function. Although the preventive efficacy of mouthguards has been well established, the prevalence of sports-related dental injuries remains high among young athletes. The aim of this study is to identify the variables contributing to the risk of sports-related dental injuries by conducting a survey on large population of young athletes in Miyagi prefecture. Methods A cross-sectional study was conducted with school-aged athletes (aged 6–15 years, n = 5735) using a self-reported questionnaire. The questionnaire examined general variables, including sex, age, and body mass index; sports-related variables, including sports-type, team level, activity schedule, break time, and verbal/physical abuse by coaches; and lifestyle variables related to free time, including screen-time and sleep duration. Their associations with sports-related dental injuries were examined using multivariate logistic regression models. Results The prevalence of sports-related dental injuries was 13.3% (763 of 5735 young athletes) and was higher in males (14.3%, 592 of 4132) than in females (10.7%, 171 of 1603; adjusted odds ratios [ORs] and 95% confidence intervals [CIs]: 1.48 [1.22–1.79], p

Arthroscopic pancapsular release has been recommended for recalcitrant frozen shoulder, but regaining range of motion has not been sufficient compared with the unaffected side. There is no consensus about the reasons for these remaining restrictions in range of motion, but residual capsular or connective tissue must be considered a candidate. A thickened coracohumeral ligament at the rotator interval has been reported as one of the most specific manifestations of frozen shoulder. It covers wider portions of the subscapularis tendon, supraspinatus tendon, and infraspinatus tendon than previously reported. We describe an arthroscopic surgical technique for the release of the entire coracohumeral ligament including the subscapularis and supraspinatus portions and the release of the inferior and posterior parts of the glenohumeral ligament using the 7-o'clock portal. These procedures are essential and reliable methods to release the entire joint capsule to regain full range of motion for frozen shoulder.

Adhesive capsulitis of the shoulder (also known as frozen shoulder) is a painful and disabling disorder with an estimated prevalence ranging from 2% to 5% in the general population. Although the precise pathogenesis of frozen shoulder is unclear, thickened capsule and coracohumeral ligament (CHL) have been documented to be one of the most specific manifestations. The thickened CHL has been understood to limit external rotation of the shoulder, and restriction of internal rotation of the shoulder has been believed to be related to posterior capsular tightness. In this paper, three cases of refractory frozen shoulder treated through arthroscopic release of a contracted capsule including CHL were reported. Two cases in which there is recalcitrant severe restriction of internal rotation after manipulation under anesthesia (MUA) were finally treated with arthroscopic surgery. Although MUA could release the posterior capsule, internal rotation did not improve in our cases. After release of the thickened CHL, range of motion of internal rotation was significantly improved. This report demonstrates the role of the thickened CHL in limiting the internal rotation of the shoulder. We highlight the importance of release of thickened CHL in addition to the pancapsular release, in case of severe limitation of internal rotation of shoulder.

Context: Range of motion (ROM) in the glenohumeral joint decreases with age in healthy subjects; however, the underlying mechanism remains unclear. The process of aging of the joint capsule, including the coracohumeral ligament (CHL), could affect ROM limitation. Objective: This study investigated correlations between elasticity of the CHL, evaluated by means of shear-wave elastography, and age, side dominance, and ROM in healthy individuals. Design: Experimental study. Setting: Laboratory. Subjects: Eighty-four healthy volunteers (39 men and 45 women, mean age: 42.6 y) were included. Main outcome measures: Subjects were divided into 3 age groups: younger (20-39 y), middle (40-59 y), and older (≥60 y) age groups. With participants in the supine position, CHL elasticity in both shoulders was evaluated in both neutral and 30° external rotation, with arms at the sides. ROM, including forward flexion, lateral elevation, external rotation, 90° abduction with external rotation, and hand behind the back were measured with participants in the standing position. Results: The CHL elastic modulus was higher in the older group than in the younger group in the neutral (78.4 kPa [SD: 37.1] and 56.6 kPa [SD: 31.7], respectively) and 30° external rotation positions (135.5 kPa [SD: 63.5] and 71.4 kPa [SD: 32.2], respectively). Negative correlations were found between the CHL elastic modulus and ROM in terms of 30° external rotation and both external rotation (R = -.59, P = .02) and 90° abduction with external rotation (R = -.71, P = .003) in the older group, with correlation coefficients increasing with age. Conclusions: Significant correlations were identified between CHL elasticity and ROM in both external rotation and 90° abduction with external rotation with increasing age. Decreased CHL elasticity was strongly associated with decreased shoulder ROM in middle-aged and older individuals. [ABSTRACT FROM AUTHOR]