The Influence of Age on Compensatory Stepping Thresholds

The effects of increasing age on anterior and posterior compensatory stepping thresholds were studied. Young (18-35 years of age), middle-aged (55-64 years), and older (65 years and older) adults responded to anterior and posterior disturbances from surface translations. Stepping thresholds were defined as the disturbance displacements beyond which a single or second compensatory step was elicited. It was hypothesized that stepping thresholds would be reduced with increasing age. As an exception, it was hypothesized that posterior, single-stepping thresholds would not be reduced with increasing age. When disturbances were delivered as subjects were standing, and subjects were instructed to “try not to step," our hypotheses were supported. Young adults demonstrated larger anterior single-stepping thresholds than that of middle-aged and older adults. No influence of age on posterior single-stepping thresholds was observed. When, disturbances were delivered as subjects were standing, and subjects were instructed to “try to take only one step," our hypotheses were partially supported. Young adults demonstrated larger anterior multiple-stepping thresholds than middle-aged and older adults. Young adults demonstrated larger posterior multiple-stepping thresholds than older adults, but not middle-aged adults. When disturbances were delivered as subjects walked, and subjects were instructed to “try to take only one step”, our hypotheses were partially supported. A significant, yet weakly correlated decline in anterior, multiple-stepping thresholds was observed with increasing age. Young adults demonstrated larger posterior multiple-stepping thresholds than older adults and middle-aged adults at the lowest peak treadmill belt velocity. Regardless of initial condition, no significant differences were observed between the thresholds of middle-aged and older adults. The observed, age-related effects on the compensatory stepping response, manifested at an age as early as 55 years, are novel findings of clinical importance. Collectively, the results of this work identify potential targets for fall-prevention interventions. These targets include enhancing the muscular response of the lower extremities so that a disturbance imparts less dynamic instability and trunk rotation, as well as lengthening of the compensatory step. Interventions that are designed to focus on these targets and that consider the principle of specificity have potential for successful fall prevention

Walking Shoes and Laterally Wedged Orthoses in the Clinical Management of Medial Tibiofemoral Osteoarthritis: A One-year Prospective Controlled Trial

The purpose of the study was to examine the clinical efficacy of individually prescribed laterally wedged orthoses and walking shoes in the treatment of medial knee osteoarthritis using a prospective, single-blind, block-randomized controlled design. Sixty-six subjects (29 males, 37 females, mean age 62.4 years, mean BMI 33.0 kg/m2) were block-randomized to a lateral wedge (treatment) or neutral (control) orthotic group. Both groups were issued a standardized walking shoe for use with the orthoses. Primary outcome measures included the pain, stiffness, and functional limitations subscales of the Western Ontario and McMaster Universities index. Secondary outcome measures included the 6-minute walk distance and pain change, and stair negotiation time and pain change. A significant interaction (p=0.039) favoring the treatment group was observed for pain change during the 6-minute walk. The treatment group demonstrated significant improvements at both 1 month (ppp=0.017). No other interactions were observed. Both groups were improved at each follow-up in the WOMAC subscales for pain (ppppp=0.004), and stair negotiation test pain change (p\u3c0.001). The results suggest that both neutral and laterally wedged orthoses may be beneficial in the management of medial knee osteoarthritis when used with walking shoes. However, the addition of lateral wedging was associated with early improvements in 6-minute walk test pain change not seen in the control group

Mechanical Effectiveness of Lateral Foot Wedging in Medial Knee Osteoarthritis After 1 Year of Wear

The use of lateral foot wedging in the management of medial knee osteoarthritis is under scrutiny. Interestingly, there have been minimal efforts to evaluate biomechanical effectiveness with long‐term use. Therefore, we aimed to evaluate dynamic knee loading (assessed using the knee adduction moment) and other secondary gait parameters in patients with medial knee osteoarthritis wearing lateral foot wedging at a baseline visit and after 1 year of wear. Three‐dimensional gait data were captured in an intervention group of 19 patients with symptomatic medial knee osteoarthritis wearing their prescribed laterally wedged foot orthoses at 0 and 12 months. Wedge amounts were prescribed based on symptom response to a step‐down test. A control group of 19 patients wearing prescribed neutral orthoses were also captured at 0 and 12 months. The gait of the intervention group wearing neutral orthoses was additionally captured. Walking speed and shoes were controlled. Analyses of variance were conducted to examine for group‐by‐time (between the groups in their prescribed orthoses) and condition‐by‐time (within the intervention group) interactions, main effects, and simple effects. We observed increased knee adduction moments and frontal plane motion over time in the control group but not the intervention group. Further, within the intervention group, the mechanical effectiveness of the lateral wedging did not decrease. In patients with medial knee osteoarthritis, the effects of lateral foot wedging on pathomechanics associated with medial knee osteoarthritis were favorable and sustained over time

Altered brain tissue viscoelasticity in pediatric cerebral palsy measured by magnetic resonance elastography

Cerebral palsy (CP) is a neurodevelopmental disorder that results in functional motor impairment and disability in children. CP is characterized by neural injury though many children do not exhibit brain lesions or damage. Advanced structural MRI measures may be more sensitively related to clinical outcomes in this population. Magnetic resonance elastography (MRE) measures the viscoelastic mechanical properties of brain tissue, which vary extensively between normal and disease states, and we hypothesized that the viscoelasticity of brain tissue is reduced in children with CP. Using a global region-of-interest-based analysis, we found that the stiffness of the cerebral gray matter in children with CP is significantly lower than in typically developing (TD) children, while the damping ratio of gray matter is significantly higher in CP. A voxel-wise analysis confirmed this finding, and additionally found stiffness and damping ratio differences between groups in regions of white matter. These results indicate that there is a difference in brain tissue health in children with CP that is quantifiable through stiffness and damping ratio measured with MRE. Understanding brain tissue mechanics in the pediatric CP population may aid in the diagnosis and evaluation of CP. Keywords: Cerebral palsy, Magnetic resonance elastography, Stiffness, Brain, Pediatric, Viscoelasticit