Is osteoarthritis curable?

No. Osteoarthritis is a degeneration of the actual joint surface which in general is a non-eversible event. Exciting fast pace research is being conducted around the word in an attempt to discover the causes of joint degeneration and find ways to grow new cartilage. That research is in its' infancy and widespread clinical use of this research is years, or decades away.
While one cannot. Cure it, the symptoms can be treated. Medication, exercise, therapy, splinting, activity modification and surgery.