An update on primary hip osteoarthritis including altered Wnt and TGF-β associated gene expression from the bony component of the disease.

The study of primary hip OA is continuing to redefine what was once considered a stagnant pathology as one of dynamic change, occurring over a long period of time involving the many composite tissue types of the joint including the bone. Examination of the inverse relationships evident between OA and fracture cohorts, including individuals with osteoporosis (OP), indicates an imbalance in formation and resorption in the bony component of both pathologies. This review contains an overview of primary OA followed by an assessment of differential gene expression and altered cellular characteristics identified in the bony compartments of primary hip OA, with a focus on the wingless mouse mammary tumor virus integration (Wnt) and TGF-β signalling pathways. The studies reviewed here suggest that OA is a systemic disease involving the bone and validate the assessment of molecular changes to further investigate this complex disease.