Osteoarthritis is characterized by the progressive degeneration of cartilage glycosaminoglycans. The formation of glucosamine is the rate limiting step in glycosaminoglycans synthesis thus the addition is glucosamine , would in theory provide a building block towards the synthesis of glycosaminoglycans and thus slow down the progression of osteoarthritis. Thus far however, the results have not been conclusive.
Scientific References :
1. PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/439213