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In-vitro ligament tension pattern in the flexed knee in passive loading
Summary
This study measured knee ligament tensions during tibial movements. The anterior cruciate ligament (ACL) showed significant tension during anterior translation, while rotation responses varied, highlighting potential ACL injury mechanisms.
Area of Science:
- Biomechanics
- Orthopedic Surgery
- Sports Medicine
Background:
- Understanding knee ligament function is crucial for diagnosing and treating injuries.
- Previous research has explored ligamentous responses to knee motion, but detailed tension analysis under combined loads is less understood.
Purpose of the Study:
- To quantify in vitro tensions in major knee ligaments during simulated anterior tibial translation and axial rotation.
- To investigate the influence of compressive preload on ligamentous tension responses.
- To correlate ligamentous function, particularly the lateral collateral ligament (LCL), with anterior cruciate ligament (ACL) strain patterns.
Main Methods:
- Buckle transducers were used to measure tensions in the anteromedial band of the ACL, posterior fibers of the PCL, superficial MCL, and total LCL.
- Measurements were performed on 30 fresh-frozen knee specimens subjected to passive tibial anterior translation (up to 5 mm) and axial rotation at 40-90 degrees flexion.
- The study included assessments with and without compressive preload, with careful attention to transducer accuracy.
Main Results:
- Substantial tension (>20 N) was primarily observed in the ACL anteromedial band during anterior tibial translation.
- Ligament tension responses to axial rotation were complex and specimen-variable; MCL and LCL were generally tensed, with higher tension during external rotation.
- At 40° flexion, ACL anteromedial band tension occurred mainly in internal rotation; at 90° flexion, PCL posterior fibers were tensed in both rotation directions. A significant correlation was noted between higher ACL anteromedial band tension and negligible LCL tension.
Conclusions:
- The ACL anteromedial band is a primary stabilizer against anterior tibial translation.
- Complex and variable responses of the MCL and LCL to axial rotation suggest their roles are dependent on flexion angle and rotational direction.
- The observed correlation between ACL anteromedial band tension and LCL insufficiency highlights a potential mechanism for ACL injuries and informs repair strategies.