Erschienen in:
27.05.2021 | Knee Arthroplasty
Functional stability: an experimental knee joint cadaveric study on collateral ligaments tension
verfasst von:
Bernardo Innocenti, Edoardo Bori, Thomas Paszicsnyek
Erschienen in:
Archives of Orthopaedic and Trauma Surgery
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Ausgabe 6/2022
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Abstract
Introduction
Applying proper tension to collateral ligaments during total knee arthroplasty surgery is fundamental to achieve optimal implant performance: low tension could lead to joint instability, over-tensioning leads to pain and stiffness. A “functional stability” must be defined and achieved during surgery to guarantee optimal results. In this study, an experimental cadaveric activity was performed to measure the minimum tension required to achieve knee functional stability.
Materials and methods
Ten knee specimens were investigated; femur and tibia were fixed in specifically designed fixtures and clamped to a loading frame; constant displacement rate was applied and resulting tension force was measured. Joint stability was determined as the slope change in the force/displacement curve, representing the activation of both collateral ligaments elastic region; the tension required to reach joint functional stability is then the span between ligaments toe region and this point. Intact, ACL (anterior cruciate ligament)-resected and ACL & PCL (posterior cruciate ligament)-resected knees were tested. The test was performed at different flexion angles; each configuration was analyzed three times.
Results
Results demonstrated an overall tension of 40–50 N to be enough to reach stability in intact knees. Similar values are sufficient in ACL-resected knees, while significantly higher tension is required (up to 60 N) after cruciate ligaments resection. The tension required was slightly higher at 60° of flexion.
Conclusion
Results agree with other experimental studies, showing that the tensions required to stabilize a knee joint are lower than the ones applied nowadays via surgical tensioners.
To reach functional stability, surgeons should consider such results intraoperatively and avoid ligament laxity or over-tension.