Biomechanical analysis of swing-through gait in paraplegic and non-disabled individuals

The purpose of this study was to determine if the deficit of motor function affects the displacement of the lower limbs and increases the physical strain of upper-body musculature in paraplegic individuals performing swing-through gait. A biomechanical model consisting of four linked rigid bodies was developed to analyze this type of gait. Data were obtained on the spatio-temporal characteristics, kinematics and kinetics from a sample of eight non-disabled and nine paraplegic individuals performing swing-through gait. Net muscle moments acting on the segments and mechanical powers at three joints (shoulder, elbow, hip) were estimated during a complete gait cycle from basic force equations and moments of force acting on a rigid body. Results show that the two groups selected a similar comfortable speed suggesting that the type of gait per se is an important factor in the selection of speed. Paraplegic individuals had a longer crutch stance phase duration than the non-disabled due to inadequate hip muscle activations as confirmed by the moment of force and power analyses. Moreover, a higher moment of force at the shoulder was observed in the paraplegics individuals, mostly during the crutch stance phase. Consequently, the loss of motor function of the lower limbs in paraplegic individuals modifies the biomechanical pattern of swing-through gait compared to non-disabled individuals, and seems to increase the physiological demand on the upper limbs during the stance and swing phases of the gait cycle.