The effect of serial casting on gait in children with cerebral palsy: preliminary results from a crossover trial.

Serial casting aims to improve an equinus gait pattern in children with spastic cerebral palsy (SCP). We evaluated the effect of short-term stretch casting on gait in children with SCP, compared to the natural history. A crossover trial, consisting of a control phase and a casting phase, was conducted with children randomised into two groups. Both groups were assessed clinically, and using 3D gait analysis, at 0, 5 and 12 weeks. Subjects in one group had the 3 month casting phase first and in the other had the 3 month control period first. Casts were changed weekly and set at maximum available ankle dorsiflexion. The mean changes at 5 weeks and 12 weeks from baseline measurements in the casting phase were compared with the change within the same time interval in the control phase. Significant improvements in passive ankle dorsiflexion (knee flexed) were found at 5 and 12 weeks. Passive ankle dorsiflexion (knee extended), ankle dorsiflexion in single support, ankle dorsiflexion in swing and minimum hip flexion in stance improved significantly at 5 weeks but not at 12 weeks from baseline. Other kinematic parameters, the score on the Gillette Functional Assessment Questionnaire, and maximum reported walking distance were not changed by casting. Casting to improve range appears to improve passive and dynamic ankle dorsiflexion, but the changes are small, short lived and do not appear to affect function.

Lower limb extensor moments in children with spastic diplegic cerebral palsy.

In this retrospective study, we quantified the mean extensor moment at the ankle, knee and hip over the stance period in a group of independently ambulant children with spastic diplegia (n = 90; 167 limbs) and in a group of normally-developing (ND) children (n = 22; 22 limbs). The mean knee extensor moment and the mean support moment demonstrated greater variance in children with diplegia than in normally-developing children (P < 0.0001 and P < 0.001). This was explained by a strong relationship between the mean knee extensor moment and minimum knee flexion in stance (r2 = 0.615; P < 0.0001) in the affected group with a positive mean knee extensor moment for all those children who walked in greater than 20 degrees of knee flexion. We also found a linear relationship between the support moment and knee flexion (r2 = 0.805; P < 0.0001). Our data supported the biomechanical analysis of Hof [Gait Posture, 12 (2000) 196] who suggested that his modified support moment should be a linear function with eccentricity at the knee. Extensor moments at the ankle (r2 = 0.001376; P = 0.641) and hip (r2 = 0.0860; P = 0.000168) bore weak relationships with increasing knee flexion even though there was a strong positive relationship between minimum knee flexion and minimum hip flexion (r2 = 0.316; P < 0.0001). We conclude that children with spastic diplegic cerebral palsy (SDCP) who walk with a crouch gait rely on their knee extensors to prevent collapse of the lower limbs. Intervention directed at redistributing extensor moments between the joints of the lower limbs may slow the increase in knee flexion and prolong reasonable walking function in this group.

Accurate measurement of muscle belly length in the motion analysis laboratory: potential for the assessment of contracture.

Two-dimensional ultrasound imaging was combined with motion analysis technology to measure distances between remote anatomical landmarks. The length of the belly of the medial gastrocnemius muscle in five normal adults (nine limbs) was estimated using this technique. Our results in vivo were similar to the reported data for the lengths of muscles in cadavers, and were consistent with the expected relationship between muscle belly length and ankle joint angle. Experiments in vitro demonstrated that the accuracy of the device was better than 2 mm over 20 cm. Measurements on the same subject on different occasions showed that the results were repeatable in vivo. Rendering of the reconstructed volume of a foam phantom gave results comparable to photographic images. This validated technique could be used to measure muscle lengths in children with spastic cerebral palsy and indicate which muscles had fixed shortening, and to what extent.