Spastic paretic stiff-legged gait: joint kinetics.

Objective: The authors previously suggested that spastic paretic stiff-legged gait, defined as reduced knee flexion in swing associated with upper-motor neuron injury, can be attributed to multiple impairments besides spastic quadriceps activity. This study hypothesizes that subjects with spastic paretic stiff-legged gait have altered kinetics not only about the knee but also about the hip and ankle.

Design: Joint kinetic data of 20 subjects with spastic paretic stiff-legged gait caused by stroke were compared with data obtained from 20 able-bodied subjects.

Results: Significant reductions in the subject group were found in both peak knee-joint power absorption (0.42+/-0.34 vs. 0.99+/-0.27 W/(kg x m x m/sec)) and peak ankle-joint power generation (0.74+/-0.42 vs. 1.51+/-0.17 W/(kg x m x m/sec); both P < 0.0001). The authors observed increases in peak external-hip flexion torque in stance, hip-power generation in loading response, knee-extension torque in midstance, ankle-dorsiflexion torque, and ankle-power absorption in stance. There was substantial variability in most torque and power values among subjects, which was significantly greater than that observed in the control subjects.

Conclusions: These findings, in conjunction with previous studies, support the likelihood of multiple mechanisms for reduced knee flexion in swing. Alternatively, some of the joint kinetic differences could be compensations for or associated with reduced knee flexion in swing. The substantial variability among subjects implies that despite a similar visual appearance of reduced knee flexion among subjects with a spastic paretic stiff-legged gait pattern, each individual has unique mechanisms associated with this observed gait pattern.