Actually, it's muscular pain--especially in the long, weightbearing ones like quadriceps and gastrocnemius, that's a more common side effect of statins. Joint pains have been reported by patients, but there has been no correlation with statin use the way there is with muscle pain (sometimes the first sign of a potentially fatal muscle-wasting process called rhabdomyolisis). In the case of joint pain, there's often a demographic overlap between patients with preexisting OA and those with hyperlipidemia (for which statins are the most effective treatment), who hadn't noticed their joint pain until after reading the side effects. My husband the cardiologist still scoffs at my not taking Lipitor, saying most of his patients blame joint pain on everything but OA (or RA). For his patients who claim they can't tolerate statins, he has them take it just once a week--and sees a 20% reduction in LDL (but no effect on other blood lipids). But my FP, as soon as I told him my thighs felt achy, pulled me off Lipitor pronto (despite its dramativ improvement in all my blood lipids) and said to revisit the issue once I feel I've gotten far enough in my TKR recovery & weight loss.
One other undesirable side effect of statins can be a rise in both fasting blood glucose and hemoglobin a1c. Gives one pause if they're predisposed to metabolic syndrome or are already prediabetic.