Synovial fluid from loose hip arthroplasties inhibits human osteoblasts

Aseptic loosening of prosthetic components in patients who have undergone total hip arthroplasty is a major clinical problem. Earlier studies on this topic have focused mainly on different aspects of bone resorption. The current study investigated the influence of synovial fluid from patients who underwent revision surgery because of aseptic loosening and synovial fluid from patients with osteoarthritis on the proliferation of primary cultures of human osteoblasts. Incubation of cells with 10% synovial fluid from patients who had revision surgery significantly inhibited [3H]thymidine incorporation into deoxyribonucleic acid in human osteoblasts compared with control conditions, whereas 10% synovial fluid from patients with osteoarthritis had a significant stimulatory effect. These findings correlate well with clinical features seen in these diseases, such as increased net bone resorption around the prosthesis in patients with loosening, and increased periarticular bone formation in patients with osteoarthritis.