Related Experiment Video
Updated: Oct 11, 2025
The Transition to an Anterior-Based Muscle Sparing Approach Improves Early Postoperative Function but is Associated with a Learning Curve
Published on: September 7, 2022
Preoperative spinopelvic hypermobility resolves following total hip arthroplasty
Peter K Sculco1, Eric N Windsor1, Seth A Jerabek1
1Adult Reconstruction & Joint Replacement, Hospital for Special Surgery, New York, New York, USA.
Aims:
Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA.
Methods:
This study investigated patients with preoperative posterior hypermobility, defined as a change in sacral slope (SS) from standing to sitting (ΔSSstand-sit) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria.
Results:
A total of 136 patients were identified as having preoperative spinopelvic hypermobility. At one year after THA, 95% (129/136) of patients were no longer categorized as hypermobile on standing and sitting radiographs (ΔSSstand-sit < 30°). Mean ΔSSstand-sit decreased from 36.4° (SD 5.1°) at baseline to 21.4° (SD 6.6°) at one year (p < 0.001). Mean SSseated increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%.
Conclusion:
Spinopelvic hypermobility was found to resolve in the majority (95%) of patients one year after THA. The increase in SSseated was clinically significant, suggesting that current target recommendations for the hypermobile patient (decreased anteversion and inclination) should be revisited. Cite this article: Bone Joint J 2021;103-B(12):1766-1773.
