Association between hip extensor muscle weakness and disability of activities of daily living in patients with early-stage knee osteoarthritis.

INTRODUCTION: This study aimed to investigate the association between hip extensor muscle weakness and performance of activities of daily living (ADL) including stair ambulation, sit-to-stand (STS), and walking in patients with early-stage knee osteoarthritis (OA). METHODS: Community-dwelling older individuals (age ≥ 65 years and Kellgren-Lawrence grade 1-2) were recruited in this cross-sectional study. The ability to perform stair ambulation, STS, and walking was measured using the Japanese Knee Osteoarthritis Measure. The maximum isometric knee extensor and hip extensor muscle strengths were evaluated. To investigate the association between hip extensor muscle strength and performance on ADL, a multivariate logistic analysis was conducted, adjusting for age, sex, and knee extensor muscle strength. RESULTS: A total of 161 participants were included in this study. Multivariate logistic analysis revealed a significant association between lower hip extensor muscle strength and higher presence of difficulty in stair ambulation [odds ratio (OR), 0.33; 95% confidence interval (CI), 0.11. 0.98; p < 0.05] and STS (OR, 0.32; 95% CI, 0.11. 0.92; p < 0.05). No significant association between hip extensor muscle strength and difficulty in walking was observed (OR, 0.47; 95% CI, 0.14. 1.62; p = 0.23). CONCLUSIONS: Hip extensor muscle weakness was associated with difficulty during stair ambulation and STS in patients with early-stage knee OA, after adjusting for knee extensor muscle strength. The results suggest that hip extensor muscle strength may be important to improve or maintain ADL in patients with early-stage knee OA.

The shape of the transverse arch in high heels while standing.

INTRODUCTION: High heeled shoes have long been worn in society and they are known to cause biomechanical imbalances to not only the foot, but the whole musculoskeletal system. This study aims to show the detailed changes that happen to the shape of the transverse arch of the foot in high heels, using two different inclination degrees. METHODS: 68 women participated in this study. Two custom-made high heels were made with inclinations of 15 degrees and 30 degrees (cm). A weight-bearing ultrasound was used to assess the coronal view of the transverse arch in standing. ANOVA and Tuckey tests were used to compare the results between 0 degrees, 15 degrees and 30 degrees inclinations. RESULTS: The transverse arch height was slightly increased as the heel height increased (0DI-15DI: p = 0.5852 / 15DI-30DI: p = 0.395 / 0DI-30DI: p = 0.0593). The transverse arch length (0DI-15DI: p = 0.0486 / 15DI-30DI: p = 0.0004 / 0DI-30DI: p = 0.1105) and the area under the metatarsal heads (0DI-15DI: p = 0.0422 / 15DI-30DI: p = 0.0180 / 0DI-30DI: p = 0.9463) significantly decreased as the heel height increased. DISCUSSION: The main changes were viewed in the 30 degrees inclinations compared to 0 degrees inclination. When the toes are dorsiflexed in high heels, it stimulates the Windlass mechanism which in turn stiffens the plantar fascia and adducts the metatarsal heads, while the soft tissues shrink in response to loads. CONCLUSION: High heels affected the shape of the transverse arch even in short term standing, and these effects increased as the height of the heel increased.