The limited regenerative capacity of cartilage is part of this problem. Existing degenerative lesions lead to accelerated deterioration of the articular (joint) surface leading to end-stage arthritis. Any solution that can delay or reverse this process is therefore desirable. A number of non-invasive solutions do exist to treat painful knees that improve functionality but with varying rates of success. Two of the more promising agents are hyaluronic acid (HA) and platelet rich plasma (PRP). HA is widely applied in clinical practice with good results in many studies. HA forms part of the inflammatory process that can lead to the regeneration of cartilage in defective areas of the knee.