 A new model for integrated care for patients with hip andor knee osteoarthritis OA in primary care will be developed and implemented. The purpose of the model is to improve quality of OA care in primary health care services by increasing the collaboration between health care professionals and across health care levels, providing an integrated care and a patient pathway, and facilitating an active and healthy lifestyle among individuals with OA. This implementation study represents a collaborative study between six municipalities and a hospital department aiming to fulfill the intentions of the Norwegian Health Care Coordination Reform. The main aim of the present study is to implement and perform process and effect evaluations of this new model for integrated OA care. The study design will be a cluster randomized controlled trial with a stepped wedge design. Six neighboring municipalities will constitute the six clusters, which will switch from control current OA care to intervention phase new OA model in a randomized order. All municipalities start the trial simultaneously and act as controls until the point in time they are randomized to crossover from control to intervention, and all municipalities have implemented the intervention by the end of inclusion. The method consists of two parts; 1 Identification of barriersfacilitators development of the model and interventions, 2 Implementation of the new model interactive workshops with process and effect evaluations. Participants will be general practitioners and physiotherapists in primary care as well as people with hip or knee OA. 