ABS0648 EFFECT OF SPINOPELVIC MOBILITY AND FUNCTIONAL SAFE ZONE ALIGNMENT ON PATIENT-REPORTED OUTCOMES IN TOTAL HIP ARTHROPLASTY
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".