Achieving cup target as per spinopelvic assessment is associated with improved THA outcome: a prospective, multicentre study
Bibliographic record
Abstract
Background: Different methods can help to optimise sagittal cup orientation in total hip arthroplasty (THA) based on individual spinopelvic characteristics. This study aimed to: (1) assess how often combined sagittal index (CSI) and hip-spine-classification targets were achieved post THA; (2) compare anteversion/inclination between cups in-/outside optimal CSI zone; and (3) determine association with outcome. Methods: This is a multicentre, prospective, case-cohort study of 435 primary THA for osteoarthritis (53% females; age: 65 ± 12 years; follow-up: 2.4 ± 0.6 years) (58% lateral, 29% anterior, 13% posterior approach). No robotics or dual-mobility were used. Patients underwent spinopelvic radiographs to measure parameters including lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), pelvic femoral angle (PFA), and ante-inclination (AI) on lateral spinopelvic radiographs. Unbalanced spine was defined as PI - LL ⩾ 10° (PI: pelvic incidence; LL: lumbar lordosis), stiffness as ∆LL < 20°. Optimal cup orientation was based on CSI targets: 205–245° for balanced spine ( n = 327), or 215–235° for unbalanced spine ( n = 108), hip-spine classification targets (±5°), and conventional inclination/anteversion (40/20° ± 10°) target. Patient-reported outcome was measured using Oxford Hip Score (OHS). Results: CSI targets were achieved in 60% ( n = 261/435), whilst 44% had cup position within hip-spine classification targets ( n = 125/284). Anteversion was higher among cups within CSI targets (26° ± 8° vs. 22° ± 10°; p < 0.001). Overall dislocation rate was 0.9% ( n = 4/435), without difference whether CSI targets were achieved (0.4% vs. 1.7%; p = 0.178). Postoperative OHS was better among those within CSI targets (42 ± 8 vs. 40 ± 9; p = 0.003) or within hip-spine-classification targets ( p = 0.028), but not according to conventional orientation ( p = 0.384). Conclusions: Awareness of adverse spinopelvic characteristics and using sagittal characteristics (especially CSI) can help surgeons to achieve optimal cup orientation, improving outcome and reducing dislocation risk post-THA.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".