Radiographic threshold values for hip screening in cerebral palsy

Abstract

Purpose To analyse the consequences of using different radiographic measurements and different threshold values for hip screening in children with cerebral palsy (CP).Methods In a total sample of children with CP a standardised radiological follow-up of the hips was carried out as a part of a hip prevention programme. Acetabular index (AI) and migration percentage (MP) were measured on all radiographs. In this study, 1,067 radiographs of 272 children born 1992-1998 were analysed. Results Lateral displacement of the femoral head was common without acetabular dysplasia, and acetabular dysplasia occurred at a later stage than femoral head lateralisation. Hip dysplasia without lateral displacement of the femoral head was rare. In 16 of the 56 hips (29%) with AI ‡ 27°and in 23 of the 71 (32%) hips with MP ‡ 33% the values decreased below the threshold value without operative treatment. In hips with AI ‡ 30°only 2 of 31 hips (6%) and in hips with MP ‡ 40% only 5 of 44 hips (11%) decreased below the threshold values without operative treatment. Conclusions Radiographic follow-up with only measurement of the MP seems sufficient in screening for dislocation in children with CP. MP ‡ 33% is recommended as threshold for reaction or intensified observation. In children with MP ‡ 40%, the lateral displacement increased over time in most hips, thus indicating the need for operative intervention. In children with MP 33-40%, treatment should be based on other clinical signs and the progression of MP over time.

Hip surveillance and management of the displaced hip in cerebral palsy

“…Most reports define a hip with an MP of [30-33 % as displaced and a hip with an MP of [90-100 % as dislocated [12,14,16]. Some hips with an MP of \40 % do not progress to dislocation, while almost all hips with an MP of [40 % need preventive surgery to prevent dislocation [10].…”

Bilateral hip reconstruction improve hip stability, pelvic balance and mobility function in children with cerebral palsy

“…Range of motion of the hip was examined by manipulation and the migration percentage was assessed by intra operative radiography. If the migration percentage was still more than 30% and the acetabular index was more than 25 degree, Dega type pelvic osteotomy [16][17][18][19] would be performed. If the range of hip abduction was still less than 60 degree, percutaneous release of hip adductor longus muscle and more shortening of femur would be considered.…”

“…The MP describe the subluxation of the femoral head out of the acetabulum relative to the width of femoral head [17]. The MPD is the difference between the MP of one hip and the MP of the other hip in the same patient.…”

“…The inclusion criterion for bilateral hip reconstruction in our clinic are patients with spastic diplegic or quadriplegic cerebral palsy who have at least one side of hip displacement (Migration Percentage (16,17) ≧ 40%), hip abduction < 60 in extension, coxa valga, and excessive femoral anteversion. The patients presented a minimum follow up period of 24 months with clinical and radiological documentation at pre-operative point, 1 year and 2 years post-operative point.…”

Cerebral Palsy and Rehabilitation

“…MO; asetabulum lateral köşesinden vertikal inen hattın lateralinde kalan femur başının (a), femur başı çapına (b) oranıdır (a/bx100). MO'nın >%30 olması anormal kabul edilir ve takiplerde artan MO oranı ilerleyen olan kalça subluksasyonunu gösterir (17).…”