Usually acute (recent/fresh) muscle injuries heal just fine. Sometimes, however, they don't heal well and become chronically painful. This usually happens where the muscle becomes a tendon or the tendon attaches to a bone. This is common in the hamstring, rotator cuff, achilles, or at the elbow (tennis elbow). Three options are available to help patients avoid surgery: 1) physical therapy such as ASTYM which creates a painful response to breakdown "bad" muscle or tendon tissue and regenerate normal tissue; 2) PRP (platelet-rich plasma) which is an injection that triggers a similar tissue repair/regeneration response; and 3) eccentric exercises that seek to stretch out the muscle under tension. These treatments require guidance of trained professionals but can be very effective for those frustrating, hard-to-heal muscle or tendon injuries.