Hallux valgus and plantar pressure loading: the Framingham foot study.

BACKGROUND: Hallux valgus (HV), a common structural foot deformity, can cause foot pain and lead to limited mobility. The purpose of this study was to evaluate differences in plantar pressure and force during gait by HV status in a large population-based cohort of men and women. METHODS: A trained examiner performed a validated physical examination on participants' feet and recorded the presence of hallux valgus and other specific foot disorders. Each foot was classified into one of four mutually exclusive groups based on the foot examination. Foot groups were: (i) HV only, (ii) HV and at least one additional foot disorder (FD), (iii) no HV but at least one other FD, and (iv) neither HV nor FD (referent). Biomechanical data for both feet were collected using Tekscan Matscan. Foot posture during quiet standing, using modified arch index (MAI), and foot function during gait, using center of pressure excursion index (CPEI), were calculated per foot. Further, walking scans were masked into eight sub-regions using Novel Automask, and peak pressure and maximum force exerted in each region were calculated. RESULTS: There were 3205 participants, contributing 6393 feet with complete foot exam data and valid biomechanical measurements. Participants with HV had lower hallucal loading and higher forces at lesser toes as well as higher MAI and lower CPEI values compared to the referent. Participants with HV and other FDs were also noted to have aberrant rearfoot forces and pressures. CONCLUSIONS: These results suggest that HV alters foot loading patterns and pressure profiles. Future work should investigate how these changes affect the risk of other foot and lower extremity ailments.

Correlations of clinical and laboratory measures of balance in older men and women.

OBJECTIVE: It is known that impaired balance is associated with falls in older adults; however, there is no accepted gold standard on how balance should be measured. Few studies have examined measures of postural sway and clinical balance concurrently in large samples of community-dwelling older adults. We examined the associations among 4 types of measures of laboratory- and clinic-based balance in a large population-based cohort of older adults. METHODS: We evaluated balance measures in the Maintenance of Balance, Independent Living, Intellect and Zest in the Elderly Boston Study (276 men and 489 women ages 64-97 years). The measures included laboratory-based anteroposterior (AP) path length and mean sway speed, mediolateral (ML) mean sway and root mean square, and area of ellipse postural sway; the Short Physical Performance Battery (SPPB); the Berg Balance Scale; and the one-leg stand test. Spearman's rank correlation coefficients were assessed among the balance measures. RESULTS: The area of ellipse sway was highly correlated with the ML sway measures (r = >0.91, P < 0.0001) and sway speed was highly correlated with AP sway (r = 0.97, P < 0.0001). The Berg Balance Scale was highly correlated with the SPPB (r = 0.74, P < 0.001) and the one-leg stand test (r = 0.82, P < 0.001). Correlations between the laboratory- and clinic-based balance measures were low but statistically significant (-0.29 ≤ r ≤ -0.16, P < 0.0001). CONCLUSION: Clinic-based balance measures, and laboratory-based measures comparing area of ellipse with ML sways or sway speed with AP sway, are highly correlated. There is less correlation between the clinic- and laboratory-based measures. Since both laboratory- and clinic-based measures inform balance in older adults, but are not highly correlated with each other, future work should investigate the differences.

The nonlinear relationship between gait speed and falls: the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly of Boston Study.

OBJECTIVES: To examine the relationship between gait speed and falls risk. DESIGN: Longitudinal analysis of the association between gait speed and subsequent falls and analysis of gait speed decline as a predictor of future falls. SETTING: Population-based cohort study. PARTICIPANTS: Seven hundred sixty-three community-dwelling older adults underwent baseline assessments and were followed for falls; 600 completed an 18-month follow-up assessment to determine change in gait speed and were followed for subsequent falls. MEASUREMENTS: Gait speed was measured during a 4-m walk, falls data were collected from monthly post-card calendars, and covariates were collected from in-home and clinic visits. RESULTS: There was a U-shaped relationship between gait speed and falls, with participants with faster (≥1.3 m/s, incident rate ratio (IRR)=2.12, 95% confidence interval (CI)=1.48-3.04) and slower (<0.6 m/s, IRR=1.60, 95% CI=1.06-2.42) gait speeds at higher risk than those with normal gait speeds (1.0-<1.3 m/s). In adjusted analyses, slower gait speeds were associated with greater risk of indoor falls (<0.6 m/s, IRR=2.17, 95% CI=1.33-3.55; 0.6-<1.0 m/s, IRR=1.45, 95% CI=1.08-1.94), and faster gait speed was associated with greater risk of outdoor falls (IRR=2.11, 95% CI=1.40-3.16). A gait speed decline of more than 0.15 m/s per year predicted greater risk of all falls (IRR=1.86, 95% CI=1.15-3.01). CONCLUSION: There is a nonlinear relationship between gait speed and falls, with a greater risk of outdoor falls in fast walkers and a greater risk of indoor falls in slow walkers.

Subsensory vibrations to the feet reduce gait variability in elderly fallers.

The purpose of this study was to investigate the effect of subsensory vibratory noise applied to the soles of the feet on gait variability in a population of elderly recurrent fallers compared to non-fallers and young controls. Eighteen elderly recurrent fallers and 18 elderly non-fallers were recruited from the MOBILIZE Boston Study (MBS), a population-based cohort study investigating novel risk factors for falls. Twelve young participants were included as controls. Participants performed three 6-min walking trials while wearing a pair of insoles containing vibrating actuators. During each trial, the noise stimulus was applied for 3 of the 6min, and differences in stride, stance, and swing time variability were analyzed between noise and no-noise conditions. The use of vibrating insoles significantly reduced stride, stance, and swing time variability measures for elderly recurrent fallers. Elderly non-fallers also demonstrated significant reductions in stride and stance time variability. Although young participants showed decreases in all variability measures, the results did not achieve statistical significance. Gait variability reductions with noise were similar between the elderly recurrent fallers and elderly non-fallers. This study supports the hypothesis that subsensory vibratory noise applied to the soles of the feet can reduce gait variability in elderly participants. Future studies are needed to determine if this intervention reduces falls risk.