The objective and dynamic documentation of the knee kinematics in ambulatory children with spastic cerebral palsy and the examination of possible causes of differences when compared to normals.

17 ambulatory patients with an average age of 10,5 years (6–17 years) with cerebral palsy, spastic diplegia where examined clinically including Duncan-Ely test. They were also examined with 3-D instrumented gait analysis. The Elite system with six cameras was used and the knee kinematics in the sagittal plane was recorded.

Almost all patients (16/17) had a positive Duncan-Ely test during clinical examination. The knee kinematics in the sagittal plane showed that in 20/34 knees the range of motion was decreased compared to normal values. In 30/34 knees there was a delayed maximum knee flexion in swing phase and in 16/34 knees the amplitude of the maximum knee flexion was decreased compared to normals. Patients with severe crouch or mild rectus spasticity had almost normal knee flexion.

Foot clearance in swing phase is one of the basic prerequisites of normal gait. Patients with spastic cerebral palsy who are able to walk have an impaired foot clearance because of the pathological action of the rectus femoris.

In our study the majority of the patients with clinically confirmed rectus spasticity had decreased timing and amplitude of max. knee flexion in swing. In patients with severe co-contraction of the knee flexors and extensors max. knee flexion within normal range. Therefore it should not be considered as the only evaluation parameter in rectus femoris spasticity.