Evaluating the Reliability of the Lesser Trochanter as a Landmark for Limb Length Discrepancy in Direct Anterior Approach Total Hip Arthroplasty
Bibliographic record
Abstract
Background and aim Limb length discrepancy (LLD) is a common complication following total hip arthroplasty (THA), significantly impacting functional outcomes, patient satisfaction, and quality of life. The direct anterior approach (DAA) for THA has gained popularity due to its potential for minimizing LLD through precise intraoperative control. Despite advancements, achieving limb length equality remains challenging, particularly in the Indian patient population, where anatomical variations may affect surgical outcomes. The lesser trochanter (LT) is frequently utilized as a landmark for intraoperative LLD assessment. However, the reliability of the LT in DAA-THA remains debated. This study aimed to evaluate the accuracy and consistency of using the LT as an intraoperative reference for LLD correction in DAA-THA. Methods A retrospective cohort analysis was conducted on 130 patients who underwent DAA-THA at a high-volume tertiary care center between January 2023 and December 2023. Patients were selected based on the inclusion criteria of age >18 years, availability of preoperative and postoperative radiographs, and adequate fluoroscopic imaging during surgery. The LT was used as the primary landmark for limb length restoration. Intraoperative fluoroscopy and standardized leg positioning systems were employed to ensure accurate component placement. Preoperative and postoperative LLD were measured using standardized radiographic techniques, and functional outcomes were assessed through the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Forgotten Joint Score (FJS). Statistical analysis was performed to determine the association between LLD correction and functional recovery. Results The cohort had a mean age of 57.1 years, with 70% males and 30% females. The mean BMI was 27.1 ± 4.4 kg/m2. Primary indications were avascular necrosis (73.8%), femoral neck fractures (19.2%), rheumatoid arthritis (6.2%), and primary osteoarthritis (0.8%). The mean preoperative LLD of 1.5 cm was reduced to 0.2 cm postoperatively, with only two patients having LLD >1 cm. Functional outcomes improved significantly postoperatively, with HHS increasing from 40.7 ± 5.7 preoperatively to 95.1 ± 4.4 at 12 months (p < 0.001). The WOMAC score decreased from 60.7 ± 5.8 to 10.1 ± 6.7 over the same period (p < 0.001). The FJS improved from 19.9 ± 6.45 preoperatively to 85.5 ± 9.3 postoperatively, indicating high patient satisfaction. Patients with postoperative LLD ≤0.5 cm had significantly higher HHS and lower WOMAC scores compared to those with residual LLD >1 cm, highlighting the importance of precise LLD correction for optimal functional recovery. Conclusion The LT serves as a reliable anatomical landmark for correcting LLD during DAA-THA, particularly when combined with intraoperative fluoroscopy and standardized positioning systems. This approach resulted in favorable postoperative functional outcomes and high patient satisfaction. Implementing standardized protocols that include LT-based measurements and fluoroscopic validation can significantly reduce LLD, enhancing clinical outcomes in THA. Further research is warranted to validate these findings in larger, multicenter cohorts.
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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 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| 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".