Weakening of the knee ligament complex due to sequential medial release in total knee arthroplasty
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The purpose of this study was to investigate the effects of sequential medial release on the stiffness and collateral stability of the ligament complex of the knee. Irrespective of the implantation technique used, varus deformity frequently requires release of the capsular ligament complex. Yet, no data are available on how stiffness and stability of the knee ligament complex are weakened by such release.
After total knee arthroplasty, ten healthy Thiel-fixed knee joints were subjected to sequential medial release consisting of six release steps. After each step, stiffness and stability were determined at 0°, 30°, 60°, and 90°.
Sequential medial release increasingly weakened the ligament complex. In extension, release of the anteromedial tibial sleeve 4 cm below the joint line already weakened the ligament complex by approximately 13%. Release 6 cm below the joint line reduced stiffness and stability by 15–20% over the entire range of motion. After detachment of the medial collateral ligament, stability was only about 60% of its initial value.
Our study showed for the first time the association between medial release and stiffness and stability of the knee ligament complex. To maintain stability, vigorous detachment of the knee ligament complex should be avoided. Release of the anteromedial tibial sleeve already initiates loss of stability. The main stabiliser is the medial ligament, which should never be completely detached.
Level of evidence
KeywordsMedial release Knee balancer Ligament balance Ligament stiffness Soft-tissue balance Total knee arthroplasty
The authors thank Professor Friedrich Anderhuber (Institute of Anatomy at the Medical University of Graz, Austria) for providing the specimens for this investigation. The authors thank Martin Bauer and his team (Brainlab, Feldkirchen, Germany) for providing the navigation devices and the detailed information on the processed data. Furthermore, we thank Monika Schöll for the linguistic review of our manuscript.
There is no funding source.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
According to the local ethical committee, no approval was necessary.
For this type of study, formal consent is not required.
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