Sagittal Spinopelvic Parameters in Scheuermann's Kyphosis: A Preliminary Study.

Study Design: Retrospective, controlled, clinical study.

Objectives: To define the average values for sagittal spinopelvic parameters including pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) in Scheuermann's kyphosis (SK); evaluate the differences in spinopelvic parameters among patients with SK and unaffected normal controls; and evaluate the correlation of various sagittal spinopelvic parameters to each other in SK and normal controls.

Methods: Prospectively collected radiographic data from a study on SK were compared with those from previously published series of unaffected patients. Measures were made according to standard, defined measurement methods. Parameters measured included PT, PI, SS, thoracic kyphosis, lumbar lordosis, and radiographic sagittal alignment. Values were compared using independent-samples t test. Pearson correlation coefficient was used to analyze relationships between variables.

Results: A total of 47 patients with SK and 50 control patients, mean age 16.1 and 13.5 years, respectively, were included. In SK, average PI was 42°, average PT was 7°, and average SS was 35°. These values were not different from those of normal controls (PI, 46° [p = .084]; PT, 8° [p = .476]; SS, 37° [p = .162]). Pelvic incidence directly correlated with lordosis in both groups (p < .005). T5-12 kyphosis correlated with lordosis in normal controls (p ≤ .05) but not in the SK group. Kyphosis in SK as quantified by greatest measurable Cobb angle did not correlate with PI or lordosis.

Conclusions: Sagittal pelvic alignment in patients with SK is not different from that in normal subjects. Furthermore, in SK thoracic kyphosis did not correlate with any distal region of the spine (lumbar or pelvic). Further understanding of the relationship between sagittal spinopelvic alignment in various conditions causing spinal deformity will lead to better treatment of these conditions.