RESEARCH REPORT PLATFORM PRESENTATION

KINEMATIC ANALYSIS AND MUSCLE ACTIVATION PATTERNS IN GAIT OF ELDERLY WOMEN WITH KNEE OSTEOARTHRITIS. Dias J, Arantes P, Kirkwood R, Alencar M, Dias R; Department of Physical Therapy, Federal University of Minas Gerais, Belo Horizonte, Brazil

PURPOSE: This study was conducted to compare the kinematics of hips, knees and ankles as well as the muscle activation pattern in the gait of elderly women with and without knee osteoarthritis (OA) and to investigate the association between quadriceps strength and phase of load response. RELEVANCE: Knee OA is the main cause of incapacity in elderly people. Understanding gait alterations of elderly women with knee osteoarthritis is critical for the outlining effective physical therapy interventions to prevent the incapacity knee OA generates. PARTICIPANTS: The sample of this study was composed by 21 community-dwelling elderly women with clinical and radiographic diagnosis of knee osteoarthritis and 21 asymptomatic age and mass-matched elderly women with no diagnosis of knee OA. This study was approved by the Federal University Ethics Committee-number 2005/05). METHODS: A motion analysis system was used to track the usual gait of the subjects. Intensity and duration of the activity of the vastus lateralis, biceps femoris, tibialis anterior, gastrocnemius and soleus muscles while walking was assessed through surface electromyography. Isokinetic dynamometry was used to assess the strength of the quadriceps and hamstrings muscles. ANALYSIS: Shapiro-Wilk and Lilliefors tests were carried-out to verify the normality distribution of the variables. ANOVA test was used to determine differences between groups and correlations were calculated using the Pearson correlation coefficient. The level of significance was set at 5%. RESULTS: No statistical difference was found between subject’s age (p = 0.970) and BMI (p = 0.300). Elderly women in the OA group walked with a significantly reduced gait velocity (p= 0.017), cadence (p = 0.009) and stride length (p = 0.010), and a significantly increased gait cycle duration (p = 0.012) when compared to asymptomatic elderly women. Subjects in the knee OA group, demonstrated less peak knee flexion during the initial swing phase (p = 0.003), less knee flexion excursion during weight acceptance (p = 0.019) and stance (p = 0.046) and less hip extension excursion during stance (p = 0.007). There were no significant differences between groups with regard to muscle activation patterns during gait or strength of quadriceps and hamstrings. CONCLUSIONS: Elderly women with knee osteoarthritis walk with different hip and knee kinematics than matched asymptomatic subjects. There were no differences in muscle function between groups, suggesting that gait alterations may occur even with no decrease in strength. Further studies are needed to clarify the effects of a rehabilitation program on the kinematics parameters of gait in elderly women with knee osteoarthritis. IMPLICATIONS: The results of this study suggest that Physical Therapy programs for elderly women with knee OA should also focus on gait rehabilitation to enhance functional performance in daily living activities. KEYWORDS: elderly women, knee osteoarthritis, gait kinematics. FUNDING ACKNOWLEDGEMENTS: Financial support: CNPq – Brazilian Funding Research Agency. CONTACT: jmdd@ufmg.br

ETHICS COMMITTEE: Federal University Ethics Committee-number 2005/05