When the distal part of the medullary canal of the femur was plugged
with a bolus of methylmethacrylate prior to the insertion of cement and
femoral component, fixation of the prosthesis was improved in vitro. A
special syringe was devised to introduce the plug at the desired level.
When the plug was used, the penetration of the cement into the trabecular
bone lining the canal was increased, and subsequent push-out tests showed
that the force necessary to disrupt the methacrylate from the bone was
significantly greater. Casts of the methacrylate from femora with and
without plugged canals showed that the surfaces of the casts made with the
canal plugged conformed much more completely with the irregularities of the
bone and provided more intimate contact at the cement-bone interface.