Feb 6 (Reuters) - Getting a cortisone injection won't help tennis elbow any more than a drug-free saline shot - and it may actually slow recovery, according to an Australian study. Researchers writing in the Journal of the American Medical Association found that a few weeks after receiving the steroid shots, people reported less pain and disability than those who'd been given placebo injections. But a year later, those same patients lagged behind the placebo group in their likelihood of complete recovery.