Using agents that suppress bone remodeling to treat or prevent joint disease: Quo vadis?

Abstract

Treatment of osteoarthritis (OA) with antiremodeling agents has had a mixed record of results. It is likely that remodeling suppression is only effective when used in the early phases of OA, before significant progression. Animal and human studies largely bear this out. Treatment of young mice with a RANKL inhibitor suppresses bone resorption and prevents OA progression. Likewise, bisphosphonate treatments in rodents and rabbits with induced injury or inflammatory arthritis, reduced cartilage degeneration when administered preemptively, but later administration did not. The increased prevalence of OA in women after the menopause, and presence of estrogen receptors in joint tissues, suggests that treatment with estrogens or Selective Estrogen Receptor Modulators may be effective. However, in clinical trials of knee and hip, results show decreased or increased risk for OA, or no effect. Raloxifene had positive effects in animal models, but no effect in human studies. More recent potential treatments such as strontium ranelate or cathepsin-K inhibitors may be effective, but may work directly on the cartilage rather than through their well-known effects on bone. The conclusion from these studies is that anti-remodeling agents must be administered pre-emptively or in the very early stages of disease to be effective. This means that better imaging techniques or identification of early structural changes in bone that occur before progressive cartilage destruction must be developed.