INCREASED POSTERIOR TIBIAL SLOPE AND VARUS ARE ASSOCIATED WITH A HIGHER RISK OF FAILURE FOLLOWING PRIMARY ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION: A RETROSPECTIVE COHORT STUDY OF 3,347 PATIENTS
Bibliographic record
Abstract
Despite favorable clinical outcomes, the risk of revision surgery following Anterior Cruciate Ligament reconstruction (ACLR) remains high (4.1 to 13%). An increased posterior tibial slope (PTS) has been identified as an independent risk factor associated with graft re-rupture. Knee varus has also been associated with altered joint biomechanics and ACLR revision. However, the isolated effect of an increased PTS or knee varus on the risk of revision for graft failure is still ill-defined and not unanimously agreed upon. The main objective of this study was to determine if an increased PTS is independently associated with an increased risk of revision following primary ACLR. The secondary objective was to determine if knee varus is also associated with revision surgery. Retrospective cohort study of all adult patients that underwent primary ACL reconstruction in three academic centers from January 1 st 2010 to January 1 st 2020. The main outcome was defined as revision surgery for graft re-rupture or laxity following primary ACLR. All radiological measurements were made on lateral and antero-posterior knee radiographs. The PTS was defined as the angle between a line parallel to the mid-diaphysis of the tibia and the tibial plateau on a lateral knee radiograph (measures were standardized). Coronal alignment was defined by the medial proximal tibial angle (mPTA), the joint line obliquity (JLO) and the joint line convergence angle (JLCA). Bivariate and multivariate analyses (logistic regression model) were performed. The cohort included 3347 patients aged 30 ± 11 years old in average. 3118 (97%) patients received a hamstring autograft. Three hundred and eleven patients (9.3%) required revision surgery. The main causes for revision surgery were traumatic re-rupture (65%) and postoperative laxity (24%). Patients in the revision group had an increased PTS when compared to patients undergoing primary ACLR (10.1 ± 3.1 versus 8.7 ± 3.1 degrees, p=0.0001, N=1814). Patients in the revision group presented with a PTS > 12 more frequently than patients undergoing primary ACLR (28% vs 13%, p=0.0001, N=1814). When controlling for age, sex, smoking status, chondropathy, meniscal tear and graft type, a posterior tibial slope > 12 significantly increased the risk of revision surgery (odds ratio, 5.3 [3.1–9.2]). Patients in the revision group also presented with a mPTA < 84 degrees (varus) more frequently than patients undergoing primary ACLR (15% versus 9%, p=0.01, N=1814). There was no difference between both groups with regards to JLO and JLCA (p >= 0.05). An increased PTS > 12 degrees is independently associated with a higher risk of revision surgery for graft re-rupture or postoperative laxity. Varus malalignment (mPTA < 84 degrees) is also associated with revision. Future research should focus on the management of the PTS and varus in patients at high risk of failure following ACLR.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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".