Hip displacement in children with cerebral palsy

Abstract

Aims The migration percentage (MP) is one criterion used for surgery in dislocated or displaced hips in children with cerebral palsy (CP). The MP at which a displaced hip can no longer return to normal is unclear. The aim of this paper was to identify the point of no return of the MP through a large population-based study. Methods All children registered on the Cerebral Palsy Integrated Pathway Scotland surveillance programme undergo regular pelvic radiographs. Any child who had a MP measuring over 35% since the programme’s inception in 2013, in at least one hip and at one timepoint, was identified. The national radiography database was then interrogated to identify all pelvic radiographs for each of these children from birth through to the date of analysis. A minimum of a further two available radiographs following the initial measurement of MP ≥ 35% was required for inclusion. Results A total of 239 children (346 hips) were identified as suitable for analysis at a mean of 6.5 years (2.0 to 14.8) follow-up. In all, 1,485 radiographs taken both prior to and after a hip had a MP ≥ 35% were examined and the MP measured to identify any progression of displacement. Interrogation of the data identified that hips with a MP up to 46% returned to a MP below 40% without intervention, and all hips with a MP equal to or greater than 46% displaced further and the MP did not return to the normal range. Statistical analysis showed the result to be 98% specific with this degree of certainty that hips reaching a MP ≥ 46% would not spontaneously regress. Conclusion These findings are clinically relevant in showing that it may be reasonable to continue to monitor hips with a MP not exceeding 46%. This threshold will also guide referral for further management of a displacing hip. Cite this article: Bone Joint J 2021;103-B(2):411–414.

A retrospective cohort study about hip luxation in non-ambulatory cerebral palsy patients: The point of no return

“…The relevant finding is that the cutoff value that resulted from the present study is not lower than Wordie’s, 21 contrary to expectations, considering the sample of GMFCS IV–V. This might be attributed to individual characteristics of the population that was examined, which is not representative of the Italian population.…”

“…This value is a little higher than the cutoff found by Wordie et al 21 (MP ≥46%), but the difference is comprised in the measurement error of ±5°, 23 so it should not be considered as significant.…”

“…This might be attributed to individual characteristics of the population that was examined, which is not representative of the Italian population. In fact, different from Wordie et al, 21 the sample was recruited among patients having attended the Unit that promoted this study, not from a surveillance program of the general CP population in Italy, although patients referred to this Unit, a tertiary referral center, may have presented a more severe or complicated clinical situation than that of the general quadriplegic CP population.…”

“… 14 – 16 , 18 The MP is mostly advocated as the parameter to address surgery; generally, it is considered for MP >40%. 16 , 19 , 20 Wordie et al 21 specifically investigated this aspect in children registered in the Cerebral Palsy Integrated Pathway (CPIP) Scotland surveillance program, who did not undergo any surgical approach to the hip. The authors performed a remarkably interesting analysis to find out a cutoff MP value, which determined the point of no return: it corresponded to MP ≥46%.…”

The CPUP Hip Score predicts displacement of the hip in children with cerebral palsy

“…2 Children with a MP of > 40% are at a high risk of further displacement. 3,4 Hermanson et al 5 showed that a high head shaft angle (HSA) also correlates with an increased risk of displacement. The risk is higher in children with more severe functional impairment as measured using the Gross Motor Function Classification System 6 (GMFCS) and, finally, the risk is higher in younger children.…”