Joint angular velocity in spastic gait and the influence of muscle-tendon lengthening

Background Joint angular velocity (the rate of flexion and extension of a j oint) is related to the dynamics of muscle activation and force generation during walking, Therefore, the goal of this research was to examine the joi nt angular velocity in normal and spastic gait and changes resulting from m uscle-tendon lengthening (recession and tenotomy) in patients who have spas tic cerebral palsy, Methods: The gait patterns of forty patients who had been diagnosed,vith sp astic cerebral palsy (mean age, 8.3 years; range, 3.7 to 14.8 years) and of seventy-three age-matched, normally developing subjects were evaluated wit h three-dimensional motion analysis and electromyography, The patients who had cerebral palsy were evaluated before muscle-tendon lengthening and nine months after treatment, Results: The gait patterns of the patients who had cerebral palsy were char acterized by increased flexion of the knee in the stance phase, premature p lantar flexion of the ankle, and reduced joint angular velocities compared with the patterns of the normally developing subjects, Even though muscle-t endon lengthening altered sagittal joint angles in gait, the joint angular velocities were generally unchanged at the hip and knee. Only the ankle dem onstrated modified angular velocities, including reduced dorsiflexion veloc ity at foot-strike and improved dorsiflexion velocity through midstance, af ter treatment, Electromyographic changes included reduced amplitude of the gastrocnemius-soleus during the loading phase and decreased knee coactivity (the ratio of quadriceps and hamstring activation) at toe-off. Principal c omponent analyses showed that, compared with joint-angle data, joint angula r velocity was better able to discriminate between the gait patterns of the normal and cerebral palsy groups. Conclusions: This study showed that muscle-tendon lengthening corrects biom echanical alignment as reflected by changes in sagittal joint angles. Howev er, joint angular velocity and electromyographic data suggest that the unde rlying neural input remains largely unchanged at the hip and knee. Converse ly, electromyographic changes and changes in velocity in the ankle indicate that the activation pattern of the gastrocnemius-soleus complex in respons e to stretch was altered by recession of the complex.