Abstract
Introduction
Spinopelvic parameters describe the orientation, shape, and morphology of the spine and pelvis. These parameters change during the first 10 years of life in children without spinal deformity; however, spinopelvic parameters have yet to be defined in children with significant early-onset scoliosis (EOS). Sagittal plane alignment could affect the natural history and outcome of interventions for EOS. As a result, spinopelvic parameters are being defined for this population. On the basis of the landmarks used for measurement of these parameters, there may be inherent error in performing these measurements on the immature pelvis. The purpose of this study is to define the variability associatedwith the measurement of spinopelvic parameters in children with EOS.
Methods
Standing, lateral radiographs of 11 patients with untreated EOS were evaluated. Sagittal spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and modified pelvic radius angle [PR]) were measured. To assess intraobserver reliability, these measurements were repeated 15 days apart. To define interobserver reliability, radiographs were measured by 2 independent observers.
Results
Average age was 5·7 years and average Cobb angle was 80·8°. Repeated measurements by one observer showed no significant differences for any of the parameters. Paired samples correlations showed a moderate correlation between measurements of PI (0·564), whereas stronger correlations were demonstrated for measurements of PT (0·816), SS (0·947), and PR (0·789). Interobserver analysis showed a significant difference in measurement of SS (p=0·003), whereasmeasurements of PI, PT, and PR did not differ significantly between independent observers.
Conclusions
Intraobserver variabilty yielded acceptable correlations for PT, SS, and PR; however, we noted only a moderate correlation for PI. Interobserver analysis showed a significant difference only in SS. The intraobserver and interobserver variablity of measurements for PT and PR were superior than were those for PI and SS. This finding may be related to difficulties in determining the orientation of the sacral endplate in the immature pelvis when measuring PI and SS.
