Pelvis radiographs in children with cerebral palsy: effects of patient positioning on calculating migration percentages

Delma Y Jarrett; Catherine Stamoulis; Benjamin J Shore; Andy Tsai

doi:10.1007/s00247-023-05783-7

Pelvis radiographs in children with cerebral palsy: effects of patient positioning on calculating migration percentages

Pediatr Radiol. 2023 Dec;53(13):2662-2671. doi: 10.1007/s00247-023-05783-7. Epub 2023 Oct 14.

Authors

Delma Y Jarrett^{1

2}, Catherine Stamoulis³, Benjamin J Shore⁴, Andy Tsai⁵

Affiliations

¹ Divisions of Pediatric Radiology and Musculoskeletal Radiology, Weill Cornell Medical School, New York, NY, USA.
² Department of Radiology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA, 02115, USA.
³ Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
⁴ Department of Orthopedics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
⁵ Department of Radiology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA, 02115, USA. andy.tsai@childrens.harvard.edu.

PMID: 37833504
DOI: 10.1007/s00247-023-05783-7

Abstract

Background: Hip displacement in children with cerebral palsy (CP) is monitored by measuring migration percentage on anteroposterior pelvis radiographs. However, proper positioning for radiography in children with spasticity is difficult. The reliability and accuracy of migration percentage as a function of patient positioning is unknown.

Objective: To determine the effects of patient positioning on migration percentage measurements in children with CP.

Materials and methods: We identified children with CP (≤18-year-old) with pelvis CT and anteroposterior pelvis radiograph obtained <6 months apart (10/2018-11/2021). Digitally reconstructed radiographs were generated from each pelvis CT, to simulate nine different patient positions: neutral; 10° and 20° lordosis and kyphosis; and 10° and 20° right rotation and left rotation. Two radiologists measured migration percentages from the simulated and real pelvis radiographs. We used Spearman's rho to assess inter-rater reliability, and Wilcoxon signed rank test to determine statistical significance.

Results: We studied sixty-three children (male=41; median age=8 years; range=4-18 years). The two radiologists' migration percentage measurements were highly correlated with each other across all simulated and real radiographs (Spearman's rho=0.86-0.99, P<0.01). For both readers and hips, migration percentages measured from real radiographs were significantly different from those measured from neutral simulated radiographs (P<0.01), with median absolute difference=5-6 percentage points (PP) and interquartile range (IQR)=9-12 PP. When comparing migration percentage measurements from neutral simulated radiographs to those in kyphosis/lordosis and right/left rotations, median absolute differences were 2-4 PP (IQR=3-8 PP) and 4-15 PP (IQR=6-17 PP), respectively.

Conclusion: Inter-rater reliability of measured migration percentages is high, but accuracy decreases with patient positional changes.

Keywords: Cerebral palsy; Computed tomography; Hip subluxation; Migration percentage.

MeSH terms

Adolescent
Cerebral Palsy* / diagnostic imaging
Child
Hip Dislocation* / diagnostic imaging
Humans
Kyphosis* / diagnostic imaging
Lordosis* / diagnostic imaging
Male
Patient Positioning
Pelvis / diagnostic imaging
Radiography
Reproducibility of Results