Does integrating pelvic tilt change from sitting to standing in functional 3D planning enhance early complications of robotic-assisted total hip arthroplasty?

Aims: While robotic-assisted total hip arthroplasty (THA) improves implant positioning accuracy, it often overlooks dynamic lumbopelvic parameters, such as pelvic tilt changes between sitting and standing. These factors are increasingly recognized as critical in preventing early complications, such as impingement and dislocation. The aim was to determine whether integrating pelvic tilt variations into functional 3D planning reduces complications and improves outcomes following THA. Methods: In this retrospective cohort study, 656 patients underwent robotic-assisted THA using either conventional CT-based planning (V3) or functional kinematic-based planning (V4). The V4 group incorporated lumbopelvic kinematics, specifically pelvic tilt in seated and standing positions, into implant planning via a collision model. Outcomes at ≥ one year included complication rates (dislocations, periprosthetic fractures, reoperations) and functional outcomes (visual analogue scale, Harris Hip Score, Oxford Hip Score, Forgotten Joint Score). Results: Compared with V3, the V4 group had significantly fewer overall complications (2.8% vs 8.4%, p = 0.007), no dislocations (0% vs 1.7%, p = 0.048), and fewer reoperations (p = 0.017). Reoperation-free survival at two years was higher in the V4 group (97.2% vs 94.1%). Functional outcomes were significantly improved across all scores, with more patients achieving patient acceptable symptom state thresholds (p < 0.05). In multivariate analysis, functional planning (V4) was the only independent protective factor against reoperation, while age, sex, BMI, American Society of Anesthesiologists grade, smoking, approach, and insert type were not significantly associated. Conclusion: Functional planning that incorporates the kinematics of the lumbopelvic complex (V4) was the only independent protective factor against reoperation, highlighting the importance of integrating lumbopelvic dynamics into robotic-assisted THA.