Biomechanical Assessment of Knee Laxity After a Novel Posterolateral Corner Reconstruction Technique
Bibliographic record
Abstract
Background: Different techniques to restore knee stability after posterolateral corner (PLC) injury have been described. The original anatomic PLC reconstruction uses 2 separate allografts to reconstruct the PLC. Access to allograft tissue continues to be a significant limitation of this technique, which led to the development of a modified anatomic approach utilizing a single autologous semitendinosus graft fixed on the tibia with an adjustable suspensory loop to enable differential tensioning of the PLC components. Purpose/Hypothesis: The purpose of this study was to compare the modified anatomic technique with the original anatomic reconstruction in terms of varus and external rotatory laxity in a cadaveric biomechanical model. The hypothesis was that both techniques would restore varus and external rotatory laxity after a simulated complete PLC injury. Study Design: Controlled laboratory study. Methods: Eight pairs of fresh-frozen cadaveric knee specimens were tested to compare the 2 techniques. Varus and external tibial rotation laxity of the knee were measured while applying 10-N·m varus and 5-N·m external rotatory torques at 0°, 30°, 60°, and 90° of flexion. These measurements were tested under 3 conditions: (1) intact fibular collateral ligament, popliteal tendon, and popliteofibular ligament; (2) complete transection of the fibular collateral ligament, popliteal tendon, and popliteofibular ligament; (3) after PLC reconstruction with either the modified (n = 8) or the original (n = 8) technique. Results: After PLC reconstruction, varus laxity was restored with no statistically significant differences from the intact condition after both reconstruction techniques. Similar outcomes were observed for external rotation in extension; however, in terms of the external rotation limit with respect to the intact joint, significant reductions of mean ± SD 4.1°± 6.3° ( P = .036) and 5.1°± 6.6° ( P = .016) were recorded with the modified technique at 60° and 90° of flexion, respectively. No significant effect was observed on the neutral flexion kinematics from 0° to 90° of flexion, and no significant differences were observed between reconstructions ( P = .222). Conclusion: Both PLC reconstruction techniques restored the normal native varus as compared with the intact knee. Although the modified technique constrained end-range external rotation at 60° and 90° of flexion, no differences were noted with neutral flexion kinematics. Care should be taken when tensioning in the modified technique so that the tibia is in a neutral position to avoid overconstraining the knee. Clinical Relevance: The modified technique may prove useful in situations where there are limited graft options, particularly where allografts are not available or are restricted.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".