Association between pelvic obliquity and scoliosis, hip displacement and asymmetric hip abduction in children with cerebral palsy: a cross-sectional registry study

Abstract

Background: Pelvic obliquity (PO) is common in individuals with cerebral palsy (CP). The prevalence of PO in a population of children with CP and its associations with scoliosis, hip displacement and asymmetric range of hip abduction were analysed. Methods: Over a 5-year period all pelvic radiographs from the Swedish surveillance programme for CP and the recorded data for scoliosis and hip abduction in children from southern Sweden at Gross Motor Function Classification System (GMFCS) levels II-V were analysed. PO and hip displacement calculated as migration percentage (MP) were measured on supine pelvic radiographs and compared with presence of scoliosis and side difference in hip abduction. Statistical analyses comprised chi-squared and binominal testing. Results: In total, 337 children were analysed, of whom 79 had a PO of ≥5°. The proportion of children with PO increased from 16% in GMFCS level II to 34% in level V. Scoliosis combined with PO was reported in 38 children, of whom 34 (89%, 95% confidence interval [CI] 80-99%) had the convexity opposite to the high side of the PO. Asymmetric abduction with PO was reported in 45 children, of whom 40 (89%, CI 79-99%) had reduced abduction on the high side of the PO. Asymmetric MP of ≥5% with PO was seen in 62 children, of whom 50 had higher MP on the high side of the PO (81%, CI 71-90%). Children in GMFCS levels II-IV more often had isolated infra-pelvic association with PO (47% versus 19% in GMFCS V, P = 0.025), while combined supra-and infrapelvic association was more common in GMFCS level V (65% versus 30% in GMFCS II-IV, P = 0.004). Isolated infrapelvic or no association was seen in 74% of children ≤10 years of age while 76% of children ≥11 years old had suprapelvic or combined supra-and infrapelvic association with PO (P < 0.001). Conclusions: There was a strong association between the high side of the PO and the side of scoliosis, highest MP, and lowest range of abduction when PO was measured in supine position. PO was more often associated with infrapelvic factors. PO was seen in young children indicating the need for early awareness of this complication.

Factors Influencing the Progression and Direction of Scoliosis in Children with Neurological Disorders

“…A secondary analysis of the factors determining the apex side of scoliosis demonstrated that PO was a significant factor; however, handedness or asymmetric upper limb function had no significant effect on the direction of scoliosis. The current results were consistent with the previous reports that 89% of the patients with CP had the convexity of scoliosis on the opposite side of the high side of the PO [ 5 ]. We additionally found that this tendency was offset in the case of patient whose secondary curve was at the lumbar level.…”

“…Previous researchers have investigated the association between coronal spine deformities and PO in scoliosis [ 5 , 19 ]. Biomechanically, the pelvis serves as an important pivot between the trunk and lower extremities, playing a fundamental role in maintaining an unsupported sitting posture and ambulation [ 20 ].…”

“…Few previous researchers investigated the factors determining the apex side of scoliosis. Hägglund et al [ 5 ] analyzed 79 patients with CP with a PO greater than 5°, suggested associations between the convexity of the scoliotic curve and the higher side of the PO, reduced range of hip abduction, and higher migration percentage of the hip displacement. Furthermore, Porter et al [ 6 ] suggested a significant association between the direction of the apex of scoliosis and the windswept hip deformity.…”

Hip reconstruction in cerebral palsy: Lessons from a single center and 137 hips

“…Hips were grouped into categories according to the MP: < 33% MP, 34%-50% MP, 51%-100% MP, and > 100% MP. 14 Pelvic obliquity, an established proxy for sitting balance, was measured on each radiograph while the patient was supine with legs straight, in the middle of the table, using the method described by Hägglund and his colleagues 31,32 preoperatively, postoperatively when out of brace or hip spica, and at final follow-up radiograph, prior to any further intervention.…”

The Importance of Pelvic Obliquity in Assessing Spinal Coronal Alignment

“…A prior study of 127 patients with degenerative scoliosis established that 91% had PO, though no definition of PO was provided. Additional sources have proposed thresholds of 3 degrees, 11 5 degrees, 12 15 degrees, 10 or 1 cm to define PO, 1 each citing different literature to support their threshold.…”