Longitudinal Assessment of Impingement Risk Following Total Hip Arthroplasty Through the Direct Anterior Approach
Bibliographic record
Abstract
BACKGROUND: Component-on-component impingement following total hip arthroplasty (THA) can lead to postoperative complications, but its prevalence in nonfailed hips remains unclear due to dynamic factors and limited measurement methodologies. Mechanisms of impingement are mostly thought to be due to component malalignment, such as acetabular cups placed outside of the Lewinnek safe zones, or component sizing, such as the use of large head sizes. However, it is known that early migration of implant components does occur following THA, which may potentially impact postoperative impingement risk. The objective of this study was therefore to evaluate component-on-component impingement risk in patients who have undergone THA over a 5-year postoperative timeline and to evaluate positional impact by comparing impingement risk in the supine and standing positions. METHODS: There were 24 anterior-approach THA participants who underwent radiostereometric analysis at multiple time points: on the day of surgery, at two weeks, four weeks, six weeks, three months, six months, one year, two years, and five years. Impingement risk was calculated as per a custom computational tool, which measures the closest distance between the femoral stem and the polyethylene liner based on the 3-dimensional poses extracted from radiostereometric analysis. A threshold of one mm was defined to classify impingement, with distances approaching one mm being considered at higher impingement risk. RESULTS: Supine distances remained stable, though standing measurements showed significantly lower mean distances (P < 0.001). Smaller femoral heads (32 mm) had lower distances than larger heads (36 mm; P < 0.0001). Offset stems had significantly greater (P values = 0.016 to 0.046) neck-liner distances. There were no differences observed between collared and collarless stems. CONCLUSIONS: Our findings indicate that component-on-component impingement risk remains stable in the supine position, but increases in the standing position, suggesting that functional weight-bearing evaluations are critical for assessing postoperative impingement risk.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".