Have you had physio at all? Usually tennis elbow resolves very well without surgery. I'd look at the enthesopathy as part of the whole tennis elbow package. In the literature tennis elbow is aka lateral epicondilytis and is aka enthesopathy of the elbow.

There are numerous physio approaches to tennis elbow:

Release the muscles involved via some type of massage: soft tissue release, trigger point release, etc.
Appropriate stretches.
Acupuncture.
Ultrasound affected tendons. Some may cross friction the tendons.
Mulligan techniques for tennis elbow.
Strengthening with eccentric exercises.
The strap you mentioned.
Ergonomic assessment work/sport.

That's just a basic approach. I'd go see a physio to see if you can resolve the problem before resorting to surgery.