Systems for delivering an anti-inflammatory drug and methods for treating osteoarthritis are provided. Such systems can comprise, in one embodiment, a transdermal patch with a sufficient amount of anti-inflammatory drug in a formulation for sustained transdermal delivery at a human skin site. The system can further include a permeation composition or device, such as a heating device. The heating device can be configured for application over the transdermal patch and the human skin site. Further, the heating device can be configured for heating the human skin site to a specific temperature range from 36.degree. C. to 42.degree. C., and for maintaining the human skin site within that temperature range for a period of at least 4 or 5 hours.