Prevalence and determinants of hip pain in non-ambulatory cerebral palsy children: a retrospective cohort study.

Background: Hip pain is common in cerebral palsy children, particularly at Gross-Motor Function Classification System level IV-V. It is associated to hip displacement and relates to the migration percentage. Recent literature suggested early reconstructive bone surgery, as the best approach to prevent hip luxation, then hip pain. Still, high rates of hip pain are reported.

Aim: To investigate prevalence and determinants of hip pain in an Italian cerebral palsy sample.

Design: Single-center retrospective cohort study.

Setting: Inpatient and outpatient.

Population: Patients with spastic or dyskinetic cerebral palsy, Gross-Motor Function Classification System level IV or V, age 0-18.

Methods: A chart review was implemented to report hip pain, as a dichotomous variable (pain/no pain), age, sex, cerebral palsy subtype, Gross-Motor Function level, lumbar scoliosis, migration percentage, previous orthopedic surgery, or botulinum injections, oral or intrathecal baclofen, drug-resistant epilepsy, assistive devices for standing or walking. Descriptive statistics and a multivariate logistic stepwise regression were performed.

Results: A total of 504 subjects were included: 302 level V, 209 females, 432 spastics. The mean length of follow-up was 6 years. The overall prevalence of hip pain was 8.9% (6.3% were at level V) and of hip dislocation was 19% (15.9% were at level V). Just 39% of dislocated hips were painful. Children at spastic subtype and level V were predominantly affected. Botulinum and soft tissue surgery related to lower rates of hip pain, without statistical significance. Age (OR 1.19, 95%CI 1.14-1.25, P value 0.000), sex (OR 1.72, 95%CI 1.18-2.52, P value 0.005), migration percentage (OR 1.02, 95%CI 1.02-1.03, P value 0.000) and lumbar scoliosis (OR 1.32, 95%CI 0.86-2.01, P value 0.200) resulted significant independent determinants of hip pain.

Conclusions: Hip pain relates with the migration percentage, but not all dislocated hips become painful. Hip pain may be transient and requires a targeted and individualized approach. Children at spastic subtype and level V were predominantly affected. Age and sex are confirmed as determinants. Specific validated measures are to be implemented to assess hip pain.

Clinical Rehabilitation Impact: Considering severe non-ambulatory cerebral palsy patients, pain and quality of life should be considered as outcomes, in the management of hip luxation.