Abstract Introduction Cup position adjustments using radiological spinopelvic parameters are necessary for hip-spine syndrome with disrupted spinopelvic compensation to avert post-total hip arthroplasty (THA) cup malpositioning. This study primarily aimed to, through evaluating the spinopelvic epidemiology of Hong Kong, identify high-risk diagnoses for cup malpositioning among Chinese THA patients. The secondary aim was to outline the cup position adjustment principles for these diagnoses to optimize functional orientation and thereby prevent complications. Methods This two-observer retrospective study evaluated the distribution of pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, change in SS from standing to sitting, and Vigdorchik's Hip-Spine Classification among primary THAs performed at a tertiary institution in Hong Kong from May 2017 to November 2022. Chi-square test compared the results with Vigdorchik's study. Intraclass correlation coefficient (ICC) defined the interobserver and interobserver variabilities. Results 345 out of 570 THAs reviewed were included. The mean PT, SS, PI, LL, PI-LL and ΔSS were 8.9° ± 13.4°, 38.3° ± 10.5°, 48.1° ± 13.6°, 46.3° ± 14.1°, 1.8° ± 18.9°, and 24.4° ± 12.1°, respectively. 227 (34.2%) THAs were grouped as 1A, 28 (8.1%) as 1B, 73 (21.1%) as 2A and 17 (4.9%) as 2B. Chi-square test demonstrated good correlations with Vigdorchik's study (p = 0.213). ICC indicated excellent reliability. Discussion and Conclusion AS, inflammation, osteoarthritis, infection, and trauma were high-risk diagnoses for cup malpositioning among Chinese THA patients. Cup anteversion should be decreased in high PT; inclination and anteversion increased in reduced pelvic mobility; and positioned within the Lewinnek ‘safe zone’ in flatback deformity with normal pelvic mobility.
LAM et al. (Thu,) studied this question.