The patterns of ligament strain during passive motion can be modelled with or without the assumption of isometry, with similar results. Because of these isometric fibres, the width of the gap between the femoral and tibial components of the prosthesis in the medial component remains constant over the range of passive flexion and can be filled with a rigid meniscal bearing of the appropriate thickness.

Figure A10 Model knee at 99° flexion when patellar contact is about to transfer from the trochlea to the femoral component. The perpendiculars to the surfaces of the patella at the two contact points are parallel.

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