The Fixation of Femoral Components of Condylar Knee Prostheses

Although problems with fixation of cemented components have been more common with tibial components than with femoral, there is clinical evidence that femoral loosening may occur but after a longer interval of time. Experimental and theoretical studies were carried out to examine the motions and stresses in the implant-bone assembly. The effect of a central intramedullary stem, and of unbonding the interfaces of the patella flange and the posterior condyles, were particularly examined. Perfect bonding led to severe stress protection of the distal layer of bone. A central stem needed to project considerably above the flange to be effective and was recommended for special indications only.