The effect of shark cartilage on arthritis is well documented, and in one study only 11% of patients did not respond well to a treatment of cartilage injections. The pain relief the injections provided lasted from six weeks to over a year, though no reason could be provided for the vast difference. However, it did seem to demonstrate that the remedy was more than just a placebo. In another study involving bedridden osteoarthritis patients, eight out of ten could leave their beds after only three weeks of oral cartilage treatment. Shark cartilage appears to be effective when administered both intravenously and orally.