Measuring postural control during mini-squat posture in men with early knee osteoarthritis.

Studies have suggested a compromised postural control in individuals with knee osteoarthritis (OA) evidenced by larger and faster displacement of center of pressure (COP). However, quantification of postural control in the mini-squat posture performed by patients with early knee OA and its relation to muscle strength and self-reported symptoms have not been investigated. The main aim of this cross-sectional, observational, controlled study was to determine whether postural control in the mini-squat posture differs between individuals with early knee OA and a control group (CG) and verify the relation among knee extensor torque (KET) and self-reported physical function, stiffness and pain. Twenty four individuals with knee OA grades I and II (OAG) (mean age: 52.35±5.00) and twenty subjects without knee injuries (CG) (mean age: 51.40±8.07) participated in this study. Participants were assessed in postural control through a force plate (Bertec Mod. USA), which provided information about the anterior-posterior (AP) and medial-lateral (ML) COP displacement during the mini-squat, in isometric, concentric and eccentric knee extensor torque (KET) (90°/s) through an isokinetic dynamometer (BiodexMulti-Joint System3, Biodex Medical Incorporation, New York, NY, USA), and in self-reported symptoms through the WOMAC questionnaire. The main outcomes measured were the AP and ML COP amplitude and velocity of displacement; isometric, concentric, and eccentric KET and self-reported physical function, stiffness and pain. No significant differences were found between groups for postural control (p>0.05). Significant lower eccentric KET (p=0.01) and higher scores for the WOMAC subscales of pain (p=<0.001), stiffness (p=0.001) and physical function (p<0.001) were found for the OAG. Moderate and negative correlations were found between the AP COP amplitude of displacement and physical function (ρ=-0.40, p=0.02). Moderate and negative correlations were observed between the AP COP velocity of displacement and physical function (ρ=0.47, p=0.01) and stiffness (ρ=-0.45, p=0.02). The findings of the present study emphasize the importance of rehabilitation from the early degrees of knee OA to prevent postural instability and the need to include quadriceps muscle strengthening, especially by eccentric contractions. The relationship between the self-reported symptoms and a lower and slower COP displacement suggest that the postural control strategy during tasks with a semi-flexed knee should be further investigated.

Características cinemáticas, cinéticas e eletromiográficas do andar de adultos jovens com e sem suporte parcial de peso corporal / Kinematic, kinetic and electromyographic characteristics of young adults walking with and without partial body weight support

OBJETIVO: O objetivo deste estudo foi analisar as características cinemáticas, cinéticas e eletromiográficas do andar de adultos jovens em piso fixo sem colete e com suporte parcial de peso (SPP) de 0, 10, 20 e 30 por cento do peso corporal. MÉTODO: Oito jovens com idade média de 22,2 anos foram filmados andando sobre uma passarela que continha uma plataforma de força na região central para registro das componentes da força de reação do solo. Marcadores refletivos foram posicionados nos principais pontos anatômicos dos membros inferiores para registro dos dados cinemáticos, e eletrodos de superfície foram afixados nos músculos tibial anterior e gastrocnêmio medial para registro da atividade elétrica muscular. RESULTADOS: Diferenças significantes entre as cinco condições experimentais foram constatadas nas variáveis espaço-temporal, nos ângulos máximos e mínimos da coxa, joelho e tornozelo e nas amplitudes das componentes horizontal ântero-posterior e vertical da força de reação do solo. De forma geral, as maiores mudanças ocorreram na condição de SPP de 30 por cento do peso corporal. CONCLUSÃO: É importante considerar as compensações que ocorrem no padrão do andar com SPP no planejamento das intervenções terapêuticas. Ainda, para melhor definir a utilização dos sistemas de suspensão de peso na reabilitação, estudos futuros precisam ser realizados para verificar o comportamento do andar em populações com alteração de movimento em piso fixo.

OBJECTIVE: The aim of this study was to analyze the kinematic, kinetic and electromyographic characteristics of young adults walking on a fixed platform without a vest and with partial body weight support (PBWS) of 0, 10, 20 and 30 percent. METHOD: Eight young adults (mean age: 22.2 years) were videotaped walking on a walkway that contained a force plate embedded in its middle portion, to record the ground reaction force (GRF) components. Reflective markers were placed on the main anatomical points of the lower limbs in order to acquire kinematic data, and surface electrodes were attached to the tibialis anterior and gastrocnemius medialis muscles in order to record electromyographic muscle activity. RESULTS: Significant differences among the five experimental conditions were observed with regard to spatial-temporal variables, the maximum and minimum angles for the thigh, knee, and ankle, and the amplitudes of the anteroposterior horizontal and vertical GRF components. Generally, the greatest changes occurred with PBWS of 30 percent. CONCLUSION: It is important to take into consideration the compensations to walking patterns that occur with PBWS, in planning therapeutic interventions. Moreover, to better define the use of suspended weight systems in rehabilitation programs, further investigations should be conducted in order to verify the walking patterns on fixed platforms among populations with movement disorders.

Safety in road crossing of children with cerebral palsy.

AIM: Children with cerebral palsy (CP) are regularly confronted with physical constraints during locomotion. Because abnormalities in motor control are often related to perceptual deficits, the aim of this study was to find out whether children with CP were able to walk across a road as safely as their non-handicapped peers. METHOD: Ten children with CP and 10 non-handicapped children aged 4-14 y were asked to cross a simulated road if they felt the situation was safe. RESULTS: With respect to safety and accuracy of crossings, the behaviour of children with CP was comparable with that of non-handicapped children. However, a closer examination of children's individual crossing behaviour showed considerable differences within the CP group. In contrast to children with damage to the left hemisphere, children with damage to the right hemisphere made unsafe decisions and did not compensate for them by increasing walking speed. CONCLUSION: The differences in unsafe behaviour and in the ability to compensate for it within the group of children with CP might be related to damage to specific regions of the brain that are involved in the processing of spatial or temporal information.