Inter- and Intraobserver Reliability of Pelvic Obliquity Measurement Methods in Patients With Cerebral Palsy.

Study Design: Retrospective, chart review.
Objectives: The identification and management of pelvic obliquity in neuromuscular scoliosis can be difficult; therefore, appropriate evaluation of this pathology is important. Variations in presentation have resulted in various methods of measurement, without a consensus or gold standard measurement. This study is the evaluation of reliability of five methods commonly used to determine pelvic obliquity in the frontal plane.
Summary of Background Data: Previous studies have used five different methods (ie, the Maloney method, the O'Brien method, the Osebold method, the Allen and Ferguson method, and the Lindseth method) to determine pelvic obliquity in the frontal plane.
Methods: Radiographic images of 50 patients with neuromuscular scoliosis involving the pelvic girdle were identified and evaluated by a team of 5 raters. Each rater was instructed to apply five commonly used methods of measuring pelvic obliquity. The same raters were asked to rate the same radiographs again after a minimum of one month. The interobserver reliability was assessed using the intraclass correlation coefficient (ICC) and the intraobserver analysis was assessed using the Pearson correlation. A rating greater than 0.8 was considered excellent reliability.
Results: The Maloney method showing the highest interobserver reliability of ICC of 0.965 and 0.964. The Lindseth method had the lowest ICC, but all the methods were considered highly reliable by the rating classification system. The Maloney method also showed the highest intraobserver reliability, ranging from 0.845 to 0.962. The Allen and Ferguson method had the lowest intraobserver reliability.
Conclusions: Many of the methods tested had excellent reliability in this study, but our data suggest the Maloney method is the most reliable method of measuring pelvic obliquity on a frontal view radiograph.
Level of Evidence: Level III, retrospective, comparative study.
(Copyright © 2017 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.)