Management of Moderate to Severe Hip Displacement in Nonambulatory Children with Cerebral Palsy
The classification of cerebral palsy can be made according to topographic distribution, function severity, and motor type. Five motor types of cerebral palsy include spastic, hypotonic, ataxic, dystonic, or mixed, and the definitions for each continue to be updated8,9. The most common topographic distributions are spastic diplegia, spastic quadriplegia, and spastic hemiplegia, with asymmetric diplegia and triplegia also recognized3. Yet one of the challenges in cerebral palsy is that neither the definition nor the descriptors of motor type and topographic distribution have been proven to be prognostic or reliable in terms of assessing functional or disease severity10.
In the late 1990s, the Gross Motor Function Classification System (GMFCS) was developed, and over the past 20 years, it has developed into the gold-standard communication tool used for clinicians caring for children with cerebral palsy11. The GMFCS is a 5-level ordinal classification in which different descriptors are used according to the age of the child. The GMFCS has been shown to be valid, reliable, stable, and predictive of long-term gross motor function in children with cerebral palsy who are between 2 and 18 years of age12. A series of population-based studies have demonstrated that the risk of lateral hip displacement for a child with cerebral palsy is related to the severity of neurologic involvement13,14 and limitations in walking ability15,16 and is directly related to gross motor function as classified by the GMFCS6.
Historically, the incidence of cerebral palsy has been reported to range from 1.5 to 2.5 per 1,000 live births in several well-designed, population-based studies17. However, with recent improved resuscitation and care of the premature infant, a modest increase (3 per 1,000 live births) has been reported in North America and Asia18-20. A series of authors have reported that the prevalence of hip displacement in cerebral palsy is related to the degree of body involvement, ranging from very low risk in children with spastic hemiplegia (1%) to very high risk in children with spastic quadriplegia (75%)7,15. Three large population-based studies have calculated that the overall prevalence of hip displacement is approximately 35% across a population of children with cerebral palsy6,21,22. Soo et al.6 demonstrated that the population-based prevalence of hip displacement in nonambulatory children (GMFCS IV or V) ranged between 69% and 90% and the relative risk of hip displacement in this cohort was between 4.6 and 5.9 compared with ambulant children (GMFCS II). Progressive lateral hip displacement in nonambulatory children with cerebral palsy is commonly not painful until substantial femoral and acetabular deformities are present15. Furthermore, the associated communication difficulties and concomitant medical comorbidities in this subset of children with cerebral palsy make it easy to forget and overlook progressive lateral hip displacement15,16.