Pelvic Compensation in Sagittal Malalignment: How Much Retroversion Can the Pelvis Accommodate?

Study Design. Single-center retrospective study. Objective. Investigate how differing degrees of pelvic incidence (PI) modulate the recruitment of pelvic tilt (PT) in response to similar amounts of sagittal malalignment as measured by T1-Pelvic Angle (TPA). Summary of Background Data. Past research has shown that some patients do not recruit PT in response to sagittal malalignment. Given the anatomic relationship between PI and PT, we sought to determine whether differing PI is associated with variable recruitment of PT. Methods. Single-center retrospective study of 2077 patients undergoing full body radiographs and TPA>10°. Five groups of patients (Very Low, Low, Average, High, and Very High PI) were defined utilizing PI ranges on a Gaussian distribution. Linear regression (LR) evaluated correlation of TPA to PT within each PI group. Multivariate LR evaluated whether correlation between TPA and PT differed between each PI group. Results. Mean PT increased with increasing levels of PI (P 
Source: Spine - Category: Orthopaedics Tags: DEFORMITY Source Type: research