Shock-absorbing walking shoes that cushion the feet may be harmful for arthritic knees, according to a new study. Researchers examined the effects of different kinds of shoes on people with knee osteoarthritis and found that going barefoot or wearing flip-flops or flexible walking shoes were better options for minimizing knee load (the impact on knee joints from various movements) than many of the shoes designed to provide foot comfort.  Experts say that more research is needed for doctors who advise their patients to wear the shock-absorbing shoes.