In my practice, medial and lateral epicondylitis are tough to deal with. 90+% of the time it is self limiting and resolves, but the average time for resolution is 18-24 months (this is adults). Stretching is the key treatment for either. Formal PT and cortisone injections have recently shown to have no benefit in the early phase (I disagree with this, but it is a brand new study that I haven't had a chance to scrutinize). I have had great luck with ultrasound guided percutaneous tenotomy. (See Tennex procedure). They feel like they get hit with a baseball bat for a couple of days, but I've had 80-85% success rate with it. It is a little more tricky on the ulnar side due to the nerve being in close proximity. The surgery sucks. Patients feel better, but it isn't as good as the other methods.