Surgical Approach and Reaming Depth Influence the Direction and Magnitude of Acetabular Center of Rotation Changes During Total Hip Arthroplasty
Bibliographic record
Abstract
Background Changes in acetabular or hip center of rotation (HCOR) commonly occur during acetabular component preparation during total hip arthroplasty (THA). HCOR displacement in mediolateral or superoinferior directions is known to influence offset and leg length, but the incidence and range of HCOR change in the anteroposterior direction is less understood as the sagittal plane cannot be measured on standard anteroposterior radiographs. This study assessed the 3-dimensional displacement of HCOR after cup implantation and evaluated for potential factors associated with increased acetabular component translations. Methods A total of 894 THAs were performed using a posterior, lateral, or direct anterior approach. Only intraoperative data from the navigation device were included in the analysis. All THAs performed between September 2015 and October 2017 were included. Paired t - tests were used to compare native HCOR and new HCOR values. Results The mean HCOR displacement in 3 directions was 4.97mm medially ( P < .001), 0.83mm superiorly ( P < .001), and 0.64mm posteriorly ( P < .001). Subgroup analysis revealed greater posterior HCOR displacement with the anterior approach than the lateral/posterior approach (2.32mm vs 0.44mm; P < .001). Increasing medial HCOR displacement also resulted in increased superior and posterior HCOR displacement across surgical cases ( P < .001). Conclusions HCOR displacement is commonly observed in medial, superior, and posterior directions. HCOR changes are influenced by surgical approach, potentially secondary to patient positioning, with greater posterior HCOR displacement observed in anterior cases. Surgeons should be aware of these factors, particularly in cases with deficient or reduced posterior column bone stock.
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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 | 0.000 | 0.003 |
| 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 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".