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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 teacher head, 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".