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We studied 20 primary cemented total hip arthroplasties performed using Kerboull-type acetabular reinforcement device for rapidly destructive coxarthrosis. The average patient age at the time of surgery was 68.3 (range, 60-77) years. The mean follow-up period was 6.3 years (3.8-11.8). The mean preoperative Japanese Orthopedic Association hip score was 38.1 (16-70) vs 85.2 (70-93) at the latest follow-up. The radiographic outcome in 20 hips showed no migration or aseptic loosening. A partial radiolucent line at the cement-bone interface was noted in 2 hips (10%), but no progression occurred. There were no major complications. No patient required repeated surgery. The use of Kerboull-type acetabular reinforcement device for rapidly destructive coxarthrosis provided satisfactory 3-year to 11-year clinical and radiographic results.

An immortalized cell line exhibiting a well-differentiated osteoblast-like phenotype was established from calvaria of p53 tumor suppressor-deficient mice. This cell line, designated MMC2, showed several osteoblast-like properties such as high alkaline phosphatase activity, expression of type I collagen and osteocalcin mRNA, and differentiated in vitro to produce mineralized extracellular matrix. Alkaline phosphatase activity and the level of osteocalcin mRNA expression and the production of mineralized matrix were significantly enhanced by the addition of ascorbic acid. Although the cells proliferated rapidly and indefinitely, they did not grow in soft agar and were nontumorigenic in nude mice. These characteristics were equivalent to those observed in MC3T3-E1, a well-known osteoblast-like cell line. When inoculated in nude mice, however, MMC2 produced matured bone tissue, which was not observed in the case of MC3T3-E1. Expression of bone morphogenetic protein 2 and 4 and type IA receptor mRNA was demonstrated in cultured MMC2 cells. These results indicate that this new osteoblast-like cell line, MMC2, will be a unique material for the analysis of bone cell biology.