Carol's pick:
Iyengar yoga for treating symptoms of osteoarthritis of the knees: a pilot study. Kolasinski SL, Garfinkel M, Tsai AG, Matz W, Van Dyke A, Schumacher HR. J Altern Complement Med. 2005 Aug;11(4):689-93. PMID: 16131293
CONCLUSIONS: This pilot study suggests that yoga may provide a feasible treatment option for previously yoga-naive, obese patients >50 years of age and offers potential reductions in pain and disability caused by knee OA. 
 

Leena Shama, MD, Dorothy Dunlop, Ph.D. Quadriceps Strength and Osteoarthritis Progression in Malaligned and Lax Knees. Annals of Internal Medicine, 2004 Jan 20; 140(2):149 American College of Physicians. Conclusion: Greater quadriceps strength at baseline was associated with increased likelihood of tibiofemoral osteoarthritis progression in malaligned knees and lax knees. Subset-specific approaches beyond strengthening exercises should be developed to enhance joint-protective muscle activity. 

Carol's comment: This says alignment must be considered when strengthening a badly aligned joint, or the arthritis gets worse. To me, the idea of strengthening with correct alignment shouts "yoga," even though the term is not used in the article.

Other Research