Hip development in children with cerebral palsy and adductor spasticity treated with botulinum toxin type A: A two-year follow-up

Introduction: Lateralisation of the hip due to adductor spasticity and its consecutive dislocation is a common problem in children with cerebral palsy (CP) second only to Equinus foot deformity. The incidence (overall incidence 35%) varies depending on the neurological impairment. Short term studies have shown botulinum toxin A (BTX/A) to reduce spasticity of the adductor and harmstring muscles sufficiently but long term data especially with respect to hip dislocation are still missing.

Methods: We investigated radiographs from n=27 children (n=9 females; mean age 5.2±1.93) with bilateral cerebral palsy relating to the migration index (MI) at 3 different points in time (before therapy, after 1 year and after 2 years). Distribution of GMFCS level: GMFCS I: n=1, GMFCS II: n=3, GMFCS III: n=3, GMFCS IV: n=12, GMFCS V: n=8. BTX-A (Dysport®) was injected into adductor muscles and medial hamstring muscles (30 U Dysport® per kilogram body weight).

Results: The initial MI of the right hip was 25.5% (0%-48%) and 28.0% (0%-40%) of the left hip. After 1 year mean MI of the right hip was 25.6% (+0.1%, Range: 0%-53.0%) and 30.0% (+2.0%, Range: 6%-47%) of the left hip, after two years 26.7% (+1.2%, Range: 0%-79%) of the right hip and 30.6% (+2.6%, Range: 3%-84%) of the left hip. One patient (GMFCS level V) developed bilateral hip dislocation (MI>70%).

Discussion: The results of this trial of show a stable mean MI over the study period of 2 years although the study population was according to the GMFCS (GMFCS level > or=III: n=23) at high risk to develop progressive hip lateralisation and consecutive dislocation. In a comparable collective increase in mean MI was 7% per year (Terjesen, 2006).

Conclusion: Even patients with CP and high risk (GMFCS level > or=III) for hip dislocation can be kept stable in MI under therapy with BTX/A. Nevertheless, single hips may dislocate. They need to be identified early by strict hip surveillance. Strategies of a monitoring and management relating to GMFCS have to be developed and established with respect to the hip joint.