No abstract

Elastic fibers and proteoglycans are major components of the extracellular matrix and their changes have been reported in some pathological conditions. Further, recent studies have indicated that some glycosaminoglycans and proteoglycans inhibit elastic fiber assembly. The purpose of this study was to investigate changes of the elastic fibers and proteoglycans in the ligamentum flavum and analyze their relationships to thickening of the ligamentum flavum from lumbar spinal canal stenosis (LSCS). Ligamentum flavum samples were collected from 20 patients with LSCS (thickened flavum group) and 10 patients with lumbar disc herniation (non-thickened flavum group) as a control. Elastica-Masson staining and alcian blue staining were used to compare the relationship between the changes in the elastic fibers and proteoglycans. Gene and protein expressions of the elastic fibers and proteoglycans were analyzed by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. Histological changes indicated that proteoglycans mainly increased on the dorsal side of the ligamentum flavum in accordance with the decreased elastic fibers in the thickened flavum group. The gene and protein expressions of fibrillin-2 and DANCE were significantly lower and decorin, lumican, osteoglycin, and versican were significantly higher in the thickened flavum group. Our study shows that elastic fibers decrease and proteoglycans increase in the thickened ligamentum flavum. Decreased gene expression of elastogenesis and disrupted elastic fiber assembly caused by increased proteoglycans may lead to a loss of elasticity in the thickened ligamentum flavum. Decreased elasticity may cause buckling of the tissue, which leads to thickening of the ligamentum flavum. ß

Objectives: Serious arm injuries in youth baseball players have been increasing. Though a breakage in the kinetic chain could affect arm injuries, an association between arm injuries and insufficient support of the trunk and lower extremities have not been well understood. The purpose of this study was to investigate the association of low back and knee pain with elbow and/or shoulder complaints among youth baseball players. Methods: Study participants were mostly school-aged athletes belonging to Junior Sports Club Association of Miyagi prefecture (aged 6 to 15 years old). A self-administered questionnaire and informed consent document were mailed to25,469 registered athletes. Of those, 7,333 athletes replied both written informed consent and questionnaire (response rate was 28.8%). Those who did not play baseball (n = 5,577) and played both baseball and the other sports (n = 26) were excluded from this study. Missing data on variables (n = 192) were also excluded. The final study population was comprised of 1,535 players. We used multiple logistic regression analysis to examine the association of low back and knee pain with elbow and/or shoulder pain. Variables considered in the models were sex, age, BMI, years of athletic experience, position, team level, the amount of practice, participating day in team practice and game per week, frequency of participation in games, and practice intensity. Results: The frequency of elbow and/or shoulder pain was 24.8% (n= 393); that of elbow pain, 14.3% (n = 226); that of shoulder pain, 17.3 % (n = 273); that of both elbow and shoulder pain, 6.6% (n = 105); and that of low back and knee pain were 8.4% (n= 134) and 13.1% (n = 208), respectively. The frequency of elbow and/or shoulder pain who had low back and knee pain were 61.2% (n = 82) and 51.9% (n= 108) (p<0.001), respectively. The presence of low back and knee pain were strongly associated with elbow and/or shoulder pain (adjusted ORs (95%CI): 4.23 (2.83 -6.34), p<0.001 and 3.11 (2.24 -4.31), p<0.001, respectively), elbow (adjusted ORs (95%CI): 3.19 (1.74 -5.83), p<0.001 and 2.45 (1.47 -4.07), p=0.001, respectively), shoulder (adjusted ORs (95%CI): 4.25 (2.59 -7.29), p<0.001 and 3.31 (2.17 -5.05), p<0.001, respectively), and both elbow and shoulder pain (adjusted ORs (95%CI): 5.49 (3.08 -9.79), p<0.001 and 3.52 (2.12 -5.85), p<0.001, respectively). Conclusion: Both low back and knee pain were significantly associated with elbow and/or shoulder pain in youth baseball players. This result suggests that checking the trunk and lower extremities as well as elbows and shoulders are important for preventing sever injuries in youth baseball players.

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.

Muscle pain is a common condition that relates to various pathologies. Muscle overuse induces muscle pain, and neutrophils are key players in pain production. Neutrophils also play a central role in chronic pain by secreting interleukin (IL)-18. The aim of this study was to investigate the involvement of neutrophils and IL-18 in a mouse model of muscle pain. The right hind leg muscles of BALB/c mice were stimulated electrically to induce excessive muscle contraction. The left hind leg muscles were not stimulated. The pressure pain threshold, number of neutrophils, and IL-18 levels were investigated. Furthermore, the effects of the IL-18-binding protein and Brilliant Blue G on pain were investigated. In stimulated muscles, pressure pain thresholds decreased, and neutrophil and IL-18 levels increased compared with that in non-stimulated muscles. The administration of IL-18-binding protein and Brilliant Blue G attenuated hyperalgesia caused by excessive muscle contraction. These results suggest that increased IL-18 secretion from larger numbers of neutrophils elicits mechanical hyperalgesia.