Although the injury to the brain is static and non-progressive, clinical effects and symptoms of CP, such as increased muscle tone, and the impact on functional ability may be subject to change as children develop and their nervous systems mature.

Spasticity may also evolve over time. Below the age of 5 years, contractures are rare with spasticity often presenting as intermittent episodes, relaxed during sleep and rest, but aggravated when stimulated or when the child is ill. Around the time of the first growth spurt from 8 to 10 years of age contractures can become a feature. These contractures can cause the joints to become stiff, affect their range-of-movement making posture, seating, positioning and general handling difficult.

In general, the lower limbs, ankles and knees are affected first. This leads to the nearly constant feature of the “equinus foot”. The heel can’t be put on the floor and the child tiptoes. Later the anklebones displace. Knees and hips follow by bending. The effect in the upper limbs is less noticeable at the start but soon wrists and elbows become flexed, sometimes to the point that the hands are no longer functional and the elbow can no longer be stretched.