Curtis, Neil, New, Andrew, Taylor, Mark and Browne, Martin
Effect of component alignment and ligament balancing on the passive stability of the replaced knee
In Proceedings of the 2003 Summer Bioengineering Conference.
American Society Of Mechanical Engineers (ASME)., .
Initial stability of the knee joint is essential if long-term
survivorship is to be achieved. At the time of operation the surgeon
can assess the stability of the joint by carrying out simple passive
stability tests, assessing the integrity of the joint and the laxity of the
ligaments. A fully mechanical model of a replaced knee has been
developed to simulate this passive stability testing, which is capable of
altering parameters such as component positioning and ligament
tensions simply and accurately. Internal/external rotational stability of
a posterior cruciate-retaining rotating platform knee was assessed
under a variety of different knee conditions.
Increasing the strains equally in both collateral ligaments
increased the axial stability of the knee, with lax ligaments causing the
stability to decrease. Varus or valgus malrotation of the femoral
component did not significantly affect the femoral rotations of the
knee, however the interaction between the femoral and tibial
components was significantly altered. A lax medial collateral ligament
combined with valgus malrotation of the femoral component caused
pivoting to occur on the lateral side of the knee, producing zero
internal rotation. This indicates that 100% of the load passes through
the lateral side of the knee. The opposite was seen in the varus knee
with a slack lateral collateral ligament.
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