Preoperative laxity in ACL-deficient knees increases with posterior tibial slope and medial meniscal tears
Bibliographic record
Abstract
PURPOSE: The aim of this study was to determine patient and anatomic factors that influence anteroposterior and rotational laxity in knees with ACL tears. Based on the findings of biomechanical studies, we hypothesized that static and dynamic anterior tibial translation (ATT) as well as positive pivot shift would increase with female gender, tibial slope, and meniscal tears. METHODS: The authors prospectively collected preoperative data and intraoperative findings of 417 patients that underwent ACL reconstruction. The exclusion criteria were: revision ACL procedures (n = 53), other surgical antecedents (n = 27), prior osteotomies (n = 7) or concomitant ligament tears on the ipsilateral knee (n = 34), and history of ACL tears in the contralateral knee (n = 45), leaving a study cohort of 251 patients. Their preoperative anteroposterior knee laxity was assessed objectively using 'static' monopodal weight-bearing radiographs and 'dynamic' instrumented differential measurements of ATT. Rotational laxity was assessed subjectively using the pivot shift test. RESULTS: Multivariable regression showed that static ATT increases only with tibial slope (β = 0.30; p < 0.001), but dynamic ATT increases with tibial slope (β = 0.19; p = 0.041), medial meniscal tears (β = 1.27; p = 0.007), complete ACL tears (β = 2.06; p < 0.001), and to decrease with age (β = - 0.09; p < 0.001). Multivariable regression also indicated that high-grade pivot shift decreases with age (OR 0.94; p < 0.001) and for women (OR 0.25; p < 0.001), and to be higher for knees with complete ACL tears (OR 3.04; p = 0.002) or medial meniscal tears (OR 2.28; p = 0.010). CONCLUSION: Contrary to expectations based on biomechanical studies, static ATT was only affected by high posterior tibial slope, while dynamic ATT was affected by both high posterior tibial slopes and medial meniscal tears, but not by gender or lateral meniscal tears. Likewise, pivot shift was affected by gender and medial meniscal tears, but not lateral meniscal tears or posterior tibial slope. These findings are relevant to guide surgeons in optimizing their surgical procedures, such as conserving the menisci when possible, and rehabilitation protocols, by delaying full weight-bearing and return to sports in patients with anatomic and lesional risk factors. LEVEL OF EVIDENCE: Cohort study, Level IV.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".