Revision THA by Using Hydroxyapatite in Acetabular Massive Bone Defect

We began to use sintered HA granules clinically in 1983. As a material, sintered HA is osteoconductive, not resorbable, binds to the bone physicochemically, and is strong enough as a bone defect filler. We obtained good results in three revision cases by placing fine HA granules (300–500 μm) between the bone cement and the bone graft on the deficiencies of the femur in 1984. In addition, in massive bone deficiencies in both the acetabulum and the femur, the bone cement was filled after smearing HA granules (1.0–2.0 mm) on the bone in two to three layers, and we obtained an excellent clinical result. We call this technique Interface bioactive bone cement. Since 1985, this technique has been used in primary total joint arthroplasty by using HA granules (0.3–0.5 mm) [3, 5, 6, 9]. Since 1985, massive bone deficiencies have been filled with HA granules [1, 2, 4, 7, 8, 10, 11]. In the first generation (1985–1992), the entire surface of the exposed HA granules at the peripheral deficiencies after filling HA granules in the cavitary deficiency was covered with bone cement to reconstruct a stabilized complex. However, spaces were observed between HA granules and nearby bone, and the prostheses migrated in the case of enormous wall deficiency to allow stable filling of only HA granules. In consequence, in the second generation (since 1993), the peripheral segmental deficiency was covered with bulk allografts to gain stable filling of HA granules. Since 1995, the Kerboull cross-plate was used in some cases to obtain more stable fixation. However, the plate broke in 30% of cases. HA granules were manufactured by sintering at 1150°C with porosity of 35%–48% (mean, 42%) and then sieved to obtain granules of several sizes (Boneceram P®, Sumitomo Osaka Cement Co. Ltd., Tokyo, Japan). A. Revision THA filled with all cement by interposing HA granules between bone and bone cement (interface bioactive bone cement) (1984–1986)