The purpose of this investigation was to quantitatively compare synergistic movement patterns between seven children (four male, three female; aged 3 to 17 years; mean 6.7, SD 5.3) without cerebral palsy (CP) (controls) and 27 children (15 male, 12 female; aged 2 to 16 years; mean 5.7, SD 3.7) with spastic diplegic CP before and after selective dorsal rhizotomy (SDR). The study design was also descriptive, comparing results of before and after SDR to control children. A two dimensional video system and retroreflective markers were used to obtain sagittal plane angles for the hip, knee, and ankle during maximum active knee flexion and extension. Correlations were calculated between the knee and hip and between the knee and ankle joint pairs. Control children demonstrated non-synergistic movement patterns (–0.75 and –0.61). These results were significantly different from children with CP (0.40 and 0.43, p<0.05). Eight months after SDR, synergistic patterns did not significantly change from preoperative results (0.23 and 0.36, p>0.05) and remained significantly different from control children (p<0.05). We conclude that it may not be possible to significantly alter synergistic patterns after SDR.