The findings of radiographic studies have suggested that the cementing
of an implant with a polished tapered stem into a bed of impacted bone
allograft may provide adequate function of the joint and may restore bone
in the proximal part of the femur. However, radiographs of hips with
cancellous bone graft adjacent to cement are difficult to interpret, and
the viability of impacted bone graft that is adjacent to cement and its
capability for remodeling are unclear. To evaluate this interface further,
we obtained biopsy specimens from the proximal part of the femur at the
time of removal of trochanteric wires from four patients eleven to
twenty-seven months after revision hip arthroplasty with cement and
impaction grafting. Three relatively ill defined zones were identified
histologically: an inner zone consisting of bone cement, fibrous tissue,
and partially necrotic trabeculae with evidence of bone-remodeling; a
middle zone consisting of viable trabecular bone and probable formation of
so-called neocortex with fewer particles of bone cement; and an outer zone
consisting of viable cortex. Fibrous tissue was present around some of the
incorporating fragments of bone graft, but no continuous fibrous membrane
was seen. Particles of cement were identified, but no polyethylene debris
was visible on examination with light microscopy. The results demonstrated
remodeling of bone and at least partial restoration of bone stock in the
proximal part of the femur after revision arthroplasty with cement and
impaction grafting.