Considerations in spinopelvic parameters and acetabular component orientation in patients with lumbar spinal fusion following total hip arthroplasty: A retrospective study

Abstract

Background: Although several authors have tried to describe the ideal acetabular component position, the influence of the spine on the orientation of the pelvis is not always considered. The aim of this study was to describe the spinopelvic behavior through body postural changes and its influence on acetabular component orientation in patients with previous spinal lumbar fusion who underwent total hip arthroplasty (THA). Methods: This is a retrospective case control study of 10 patients with previous lumbar spine fusion who underwent THA (study group) compared with 17 patients without lumbar spine pathology who underwent THA (control group). Spinopelvic parameters and acetabular component orientation were measured in each group on spinopelvic radiographs in standing and sitting positions, and dislocations were recorded. Results: From standing to sitting position, the pelvic tilt (PT) increased posteriorly, and the sacral slope (SS) decreased in both groups. However, the mean degree of change of PT was higher in the control than in the study group (−23.64 degrees vs. −12.8 degrees, P=0.017). Regarding acetabular component orientation, from standing to sitting position, the mean degree of change of the ante-inclination angle (AIA) was highest in patients in the control group as compared to the study group (−23.94 degrees vs. −13.9 degrees, P=0.017). Two study group patients and no control group patients experienced hip dislocation. Conclusions: The presence of concomitant spine disease should be considered in preoperative planning of THA because procedures such as lumbar spine fusion influence adaptability of spinopelvic parameters and acetabular component orientation in functional body position changes. Level of Evidence: Level III.