Development and clinical application of artificial bone and bioactive bone cement in Japan

Summary form only given. Apatite- and wollastonite-containing glass-ceramic (AG-GC) was synthesized in 1981 at Kyoto University, Japan to be used as a strong and bone-bonding artificial bone. It is a hybrid material consisting of three phases of apatite, wollastonite, and glass with a chemical composition of MgO 4.6, CaO 44.9, SiO/sub 2/ 34.2, P/sub 2/O/sub 5/ 16,3, CaF/sub 2/ 8.5 in weight ratio. Its compressive strength, bending strength and elastic modulus are higher than those of human cortical bone. It has excellent biocompatibility and became firmly bonded directly with bone by 8 weeks when it was implanted into the tibia of a rabbit or fixed on the surface of the cortex of a rabbit tibia. After obtaining favorable results in animal experiments where vertebral prostheses made of AW-GC were used to replace the lumbar vertebra of sheep, the authors prepared an AW-GC made vertebral prosthesis for clinical use in 1983. Since then, the vertebral prosthesis has been used in 1,070 clinical cases to replace vertebrae which were affected by malignant tumors, burst fracture, compression fracture, and fracture dislocation. The prosthesis was firmly fixed to the adjacent bone with either Zielke´s instruments or a Kaneda device anteriorly, and if necessary, in combination with either Luque or Harrington rods posteriorly. The authors have not experienced, up to the present, dislocation, loosening, or breakage of the prosthesis. In 1987 the authors prepared an iliac crest prosthesis, a laminoplasty spacer, and a granular bone filler made of AW-GC. Since then, the iliac crest prosthesis has been used in 4,113 clinical cases to restore the shape of the iliac crest after harvesting a large bone graft from it. Patient satisfaction regarding appearance of the crest, pain, and foreign body feeling was excellent in 97% of the patients after two years postoperatively. New bone formation around the prosthesis progressed steadily, and one year after the operation, good new bone form- tion was observed in 90% of the patients.