I would disagree with your PM&R doctor regarding injections. Epidural injections are the best single treatment for thoracic disc hernations in my opinion. The steroid can be delivered through a nerve block or through the posterior route depending upon the comfort level of the injectionist.
Don’t pay too much attention to the rib or the rib muscle mass. You will lose some mass and it really won’t matter to your function too much. You still have a complete tear in the annulus of the disc (see website under lumbar disc herniation as some of it applies to the thoracic spine as well). You could develop a recurrent disc herniation but that would be very rare.
You have picked two sports that do put significant G forces on the spine, skiing and diving. You now have to think in terms of risk. I don’t think your risk is very high with either sport but these two do increase the risk of a recurrent hernation.
You are correct that thoracic disc herniations do tend to calcify but lumbar disc herniations do too. It is just that the annulus is so much bigger in the lumbar spine that the calcification does not cover as much area as the thoracic spine does.
Before you consider competing in the Master’s division in diving or hard core skiing, you need to have fluid, strong and controlled movements to the complete end range of motion in your thoracic spine. If you have an impact or fall that can carry you beyond the normal physiological limitations of the thoracic spine, you have a chance of recurrent injury.
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.