Associations of the step-up test and lower limb dysfunction: A post-hoc analysis of a prospective cohort study.

BACKGROUND: Step-up ability is considered to be associated with lower limb dysfunction. The objective of this research was to assess the height of the tallest step that could be mounted and to investigate its association with lower limb dysfunction. METHODS: We previously conducted a two-year follow-up prospective cohort study. The study subjects were 119 patients receiving physiotherapy or exercise therapy at an orthopedic surgery clinic. The items evaluated were step-up ability (maximum step height), the timed up and go test, one-leg standing time and the 5-question Geriatric Locomotive Function Scale. The primary endpoint was the prevalence of locomotive syndrome, whereas secondary endpoint was musculoskeletal ambulation disability symptom complex (MADS). Evaluations were carried out at the time of the initial assessment and two years later. We used a multiple logistic regression model with age, sex, height, weight and each functional test as exploratory variables. R2 and C-statistics were calculated and these "optimism" biases were corrected using a bootstrap technique. RESULTS: Maximum step height was strongly correlated with the prevalence of locomotive syndrome [odd ratio (95% confidence intervals), 0.52 (0.32, 0.87), p = 0.0074] and was correlated with MADS [0.45 (0.22, 0.92), p = 0.0138]. Additionally, maximum step height was also strongly correlated with post follow-up locomotive syndrome [0.39 (0.18, 0.84), p = 0.0010]. CONCLUSION: The results suggest that step-up ability may represent a simple and useful tool which is associated with lower limb dysfunction.

Navicular drop is negatively associated with flexor hallucis brevis thickness in community-dwelling older adults.

BACKGROUND: Flatfoot is characterized as a lower longitudinal arch and is a common foot deformity in older adults. Foot intrinsic muscle dysfunction has been considered as one of the factors for a lower medial longitudinal arch. The objective of this study was to investigate the association of the navicular drop with the thickness of foot intrinsic muscles in older adults. RESEARCH QUESTION: Which intrinsic muscle contributes most to support the medial longitudinal arch in older adults? METHODS: We studied 88 community-dwelling older adults (mean age 74.2 ± 6.2 years). We measured the navicular height, the calcaneus inclination, and hallux valgus angle on the right foot in the sitting and standing positions using a 3D foot scanner. Then, we calculated the navicular drop and changes in the calcaneus inclination from the sitting to the standing position. The muscle thickness of the flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and abductor hallucis (AbH) was measured on the right foot using Bmode ultrasonography. RESULTS: Multiple regression analysis demonstrated that FHB thickness was significantly associated with navicular height in the standing positions (ß = 8.568, P = 0.016) as well as navicular drop (ß = -9.495, P = 0.037) after adjusting for age, sex, height, weight, and hallux valgus angle. There was no association with FDB or AbH. The thickness of any intrinsic muscle was not associated with the calcaneus inclination or changes in the calcaneus inclination. SIGNIFICANCE: Our data suggest that FHB plays an important role in preventing navicular drop and that intrinsic muscles likely do not contribute to the rearfoot angle in older adults.