Creatine. If it's good for the knees, it might be good for the shoulder and spine?
.Beneficial effect of creatine supplementation in knee osteoarthritis - PubMed
CR supplementation improves physical function, lower limb lean mass, and quality of life in postmenopausal women with knee OA undergoing strengthening exercises.pubmed.ncbi.nlm.nih.gov
Anybody have a recommendation for a good, inexpensive creatine brand. I think I'm going to make that protein/creatine drink....