@article{Athwal:2020:10.1007/s00167-020-05995-6,
author = {Athwal, KK and Willinger, L and Manning, W and Deehan, D and Amis, AA},
doi = {10.1007/s00167-020-05995-6},
journal = {Knee Surgery Sports Traumatology Arthroscopy},
pages = {659--667},
title = {A constrained-condylar fixed-bearing total knee arthroplasty is stabilised by the medial soft tissues},
url = {http://dx.doi.org/10.1007/s00167-020-05995-6},
volume = {29},
year = {2020}
}

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TY  - JOUR
AB  - PurposeRevision constrained-condylar total knee arthroplasty (CCK-TKA) is often used to provide additional mechanical constraint after failure of a primary TKA. However, it is unknown how much this translates to a reliance on soft-tissue support. The aim of this study was therefore to compare the laxity of a native knee to the CCK-TKA implanted state and quantify how medial soft-tissues stabilise the knee following CCK-TKA.MethodsTen intact cadaveric knees were tested in a robotic system at 0°, 30°, 60° and 90° flexion with ± 90  N anterior–posterior force, ± 8 Nm varus-valgus and ± 5 Nm internal–external torques. A fixed-bearing CCK-TKA was implanted and the laxity tests were repeated with the soft tissues intact and after sequential cutting. The deep and superficial medial collateral ligaments (dMCL, sMCL) and posteromedial capsule (PMC) were sequentially transected and the percentage contributions of each structure to restraining the applied loads were calculated.ResultsImplanting a CCK-TKA did not alter anterior–posterior laxity from that of the original native knee, but it significantly decreased internal–external and varus-valgus rotational laxity (p < 0.05). Post CCK-TKA, the sMCL restrained 34% of the tibial displacing load in anterior drawer, 16% in internal rotation, 17% in external rotation and 53% in valgus, across the flexion angles tested. The dMCL restrained 11% of the valgus rotation moment.ConclusionsWith a fully-competent sMCL in-vitro, a fixed-bearing CCK-TKA knee provided more rotational constraint than the native knee. The robotic test data showed that both the soft-tissues and the semi-constrained implant restrained rotational knee laxity. Therefore, in clinical practice, a fixed-bearing CCK-TKA knee could be indicated for use in a knee with lax, less-competent medial soft tissues.
AU  - Athwal,KK
AU  - Willinger,L
AU  - Manning,W
AU  - Deehan,D
AU  - Amis,AA
DO  - 10.1007/s00167-020-05995-6
EP  - 667
PY  - 2020///
SN  - 0942-2056
SP  - 659
TI  - A constrained-condylar fixed-bearing total knee arthroplasty is stabilised by the medial soft tissues
T2  - Knee Surgery Sports Traumatology Arthroscopy
UR  - http://dx.doi.org/10.1007/s00167-020-05995-6
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000528078900003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://link.springer.com/article/10.1007%2Fs00167-020-05995-6
UR  - http://hdl.handle.net/10044/1/79308
VL  - 29
ER  - 

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