Age and migration percentage as risk factors for progression in spastic hip disease.

Age and migration percentage were evaluated as risk factors for the progression of spastic hip subluxation in patients with cerebral palsy. Three age-groups were defined: group 1 (two to eight years), group 2 (nine to 18 years), and group 3 (over 18 years). Four subluxation groups were defined by migration percentage: group A (< 30 per cent), group B (30 to 60 per cent), group C (60 to 90 per cent), and group D (> 90 per cent). The risk of progression was the same in groups 1A and 2A, and both of these were higher than the risk in group 3A. All group B hips had similar risks for progression, and all group C hips progressed to group D (> 90 per cent migration percentage). Groups 1A, 1B, 2A, 2B and 3B hips need close radiographic follow-up to detect progressive subluxation. All group C hips required surgical treatment for progression to dislocation to be avoided.