To determine the spasticity and strength relationships within a single muscle group and in opposing muscle groups at the knee and ankle joints in participants with spastic diplegia cerebral palsy (CP).

Design: Descriptive study comparing measures for spasticity and strength at both the knees and ankles in the same participants with CP.

Participants: Sixty participants with spastic diplegia CP (mean age 12 years, range 3 to 38 years) were tested for spasticity and strength at the knees and ankles

For the spasticity measure, a KinCom dynamometer dorsiflexed/extended the passive ankles/knees of each subject at speeds of 10, 30, 60, 90, and 120o/s (120o/s at ankle only) while monitoring the resistive torque from the ankle plantarflexors/knee flexors. For the strength measure, the machine moved at 10o/s while the subject performed a maximum contraction of the dorsiflexors(df)/plantarflexors(pf) and knee flexors(fl)/extensors(ext). Work values from the torque-angle data were calculated for each speed and subject. The spasticity measures for the ankles and knees were slopes of the lines of best fit for the work-velocity data. The strength measures were the maximum (max) torques generated and the work done by the ankle and knee muscles. A Pearson correlation coefficient was used to determine if a significant relationship (p<0.05) existed between spasticity and strength within the same muscle group and at opposing muscle groups at the ankle and knee joint.

Conclusions:
There were no significant relationships between spasticity and strength both within the same muscle group and between opposing muscle groups at the knee and ankle joints in participants with CP. The literature suggests that a spastic muscle is strong and that the muscle imbalance imposed by the spastic muscle causes weakness in the opposing muscle group. The results of this study do not agree with the literature. There appears to be no relationship between spasticity and strength for these muscle groups in participants with CP.

Childhood Disablity Update 2005 - Conference Abstracts.Pediatric Oncall [serial online] 2006 [cited 15 January 2006(Supplement 1)];3. Available from:
http://www.pediatriconcall.com/fordoctor/Conference_abstracts/
spastic_diplegia_cerebral_palsy.asp