Bone Ingrowth Fixation in Abnormal Bone

Abstract

In the past 10 years, bone ingrowth fixation has undergone intense clinical investigation as part of an effort to improve current arthroplasty reconstruction techniques. Significant investigative effort is being directed toward exploring the new possibilities provided by bone ingrowth fixation and clearly defining it limitations. This chapter considers the efficacy of using bone ingrowth fixation in various local and systematic bone diseases. In the final section we present experimental data on the effect of estrogen deficiency on bone ingrowth fixation. Long-term loss of fixation associated with the use of polymethylmethacrylate fixation of total joint prostheses compelled efforts to develop a more durable mechanism of biologic fixation (1-6). In vivo data have demonstrated that bone grows into surface pores in inert materials in both loaded and unloaded implants, provided the pore size in the range of 150 to 400 um and that motion is eliminated. Furthermore, this bone ingrowth leads to shear strengths at the bone-implant interface that equal or exceed those of trabecular bone itself (2, 3, 7). Clinically, bone ingrowth fixation is a successful tool when applied appropriately. Experimental and clinical results of acetabular fixation especially support the concept of porous ingrowth (8, 9): many surgeons now state that bone ingrowth is the preferred technique for the acetabulum. The preferred method of fixation for the femoral side remains unsettled, especially in light of recently reported excellent results of several large long-term series in which modern pressurization cementation of the femur was used. Can application of bone ingrowth techniwues be used to solve some of the special problems of reconstruction in patients with pathologic bone? From the outset, the reader must recognize that little clinical data and only limited experimental data are available. Most of this discussion is theoretical. Nevertheless, much can be gained by considering the principles of biologic fixation and then testing them individually against the common pathologic conditions in which biologic fixation might be considered.