ABS0648 EFFECT OF SPINOPELVIC MOBILITY AND FUNCTIONAL SAFE ZONE ALIGNMENT ON PATIENT-REPORTED OUTCOMES IN TOTAL HIP ARTHROPLASTY

Background: Total hip arthroplasty (THA) is a highly effective treatment for hip osteoarthritis; however, implant malpositioning significantly increases the risk of complications, including dislocation and wear. The traditional "Lewinnek Safe Zone" does not account for dynamic spinopelvic movements, which are critical for joint stability. The "Functional Safe Zone" (FSZ), a dynamic and patient-specific approach, offers a promising alternative. Despite its potential, the impact of FSZ adherence on functional outcomes and quality of life in THA patients remains inadequately studied. Objectives: To evaluate the impact of spinopelvic mobility and Functional Safe Zone (FSZ) adherence on functional outcomes and quality of life in patients who underwent total hip arthroplasty (THA). Methods: This cross-sectional study included 60 patients with a mean (SD) age of 62.5 (9.7) years and a mean (SD) BMI of 29.9 (4.2) kg/m², all of whom underwent primary THA with a minimum follow-up of one year. Spinopelvic mobility was evaluated radiographically by measuring changes in sacral slope (ΔSS) in both standing and sitting positions. ΔSS was classified as a dynamic indicator of spinopelvic mobility into three categories: normal (ΔSS 11°–29°), stiff (ΔSS <10°), and hypermobile (ΔSS >30°). Acetabular component alignment was retrospectively assessed for conformity to the FSZ. Conformity was determined using the combined sagittal index (CSI): hips were classified as FSZ-conforming if the CSI was greater than 151° in the sitting position and less than 242° in the standing position; hips were considered non-conforming if the CSI was less than 151° in the sitting position or greater than 242° in the standing position. Functional outcomes were measured using the Harris Hip Score (HHS), Oxford Hip Score (OHS), Short Form-12 (SF-12), and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Statistical analyses were performed using SPSS v22.0. The normality of continuous variables was assessed using the Shapiro-Wilk test. Differences among the three spinopelvic mobility groups (stiff, normal, hypermobile) were analyzed using one-way ANOVA, with post-hoc pairwise comparisons conducted to identify specific group differences. Comparisons between FSZ-conforming and FSZ-non-conforming groups were performed using the independent samples t-test. Statistical significance was set at p < 0.05. Results: Spinopelvic mobility analysis revealed that 30% of patients exhibited stiff motion, 56.6% had normal motion, and 13.3% were hypermobile. Patients with normal spinopelvic motion demonstrated significantly better functional outcomes compared to those with stiff or hypermobile motion (p < 0.001 for HHS, OHS, SF-12, and WOMAC). Notably, outcomes for the stiff and hypermobile groups were similar (p>0.05). Acetabular components that conformed to the FSZ (n = 38) were associated with significantly better functional outcomes, as evidenced by higher HHS, OHS, and SF-12 scores, and lower WOMAC scores compared to non-conforming components (n = 22) (p < 0.05). Conclusion: Normal spinopelvic motion and FSZ-conforming acetabular alignment were strongly associated with improved functional outcomes and quality of life. These findings advocate for the incorporation of a dynamic, patient-specific approach in preoperative planning and surgical execution to maximize THA success. Future research should focus on integrating routine spinopelvic mobility assessments into clinical practice. REFERENCES: NIL . Figure 1Illustration of radiographic measurements for cup inclination (IN), anteinclination (AI), sacral slope (SS), pelvic femoral angle (PFA), and combined sagittal index (CSI) in standing and relaxed seated positions. The measurements are as follows: IN: 49°, SS (standing): 29°, SS (sitting): 22°, ΔSS: 7°, AI (standing): 40°, PFA (standing): 183°, CSI (standing): 223°, AI (sitting): 64°, PFA (sitting): 122°, CSI (sitting): 186° Figure 2Patient-Reported Outcome Scores (HHS, OHS, WOMAC, SF-12) Categorized by FSZ Conformity (Conforming vs. Non-Conforming and Spinopelvic Mobility Types (Stiff, Normal, Hypermobile). Acknowledgements: NIL . Disclosure of Interests: None declared . © The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.