Is there any evidence for treatment of osteoarthritis? Well, yes – lots, but its varried is the most straightforward answer. Things are never as straight forward as would make decision making easy. But here is a digest with some references.
There is evidence that manual physical treatment is beneficial for hip and knee osteoarthritis. The problem is that there is little definition of different types of manual physical therapy. And manual physical therapy is anything from Osteopathy to Physiotherapy to massage.
A bit more detailed: There is broad agreement that manual therapy is beneficial for hip osteoarthritis. NICE (2008) conclude there is sufficient evidence to recommend manual therapy as an adjunct to treatment for osteoarthritis. French et al (2011) conclude that due to methodological heterogeneity meta- analysis is not possible. They also conclude that there is silver level evidence that manual therapy is more effective than exercise on osteoarthritic hip, but that there is inconclusive evidence for improved pain and function from manual therapy.
French H.P., Brennan A., White B. & Cusack T.(2011) Manual therapy for osteoarthritis of the hip or knee – A systematic review. Manual Therapy 16(2) pp.109-117
NICE (2008) Osteoarthritis: National clinical guideline for care and management in adults. Royal College of Physicians. http://www.nice.org.uk/nicemedia/live/11926/39720/39720.pdf