I can give you a little perspective as a patient with OCD and as a PT. I was 14 when I was diagnosed with OCD in the L knee (medial femoral condyle). Unfortunately I went about a year and a half with symptoms. I ended up needing surgery to revascularize the tissue. The symptoms were somewhat vague and it wasn’t until I started having difficulty jumping while playing basketball that we really began to investigate the issue. I believe I was a grade 3 lesion which means that the sub chondral bone was separating into the joint space. I had a very good surgeon in Houston that helped me get back to playing basketball but I have thought that if we had gotten to I sooner then I would have been better off as I still lost cartilage in my knee and have early arthritis. 

I am not suggesting that your son needs surgery as I am not involved directly in your son’s treatment or care. However, symptoms are not always clear until they become severe so monitoring by symptoms alone may not tell you if things are progressing or regressing. An MRI really helped to elucidate what grade of a lesion I had. X-ray alone is not that clear.

A few things to consider:

A second opinion maybe a good idea.

OCD is somewhat common but in working as a PT and in PT clinics for 10 years I have only seen 4-5 patients for it. We got two opinions for me and there was a big difference in experience and recommendations between the orthopedists with respect to surgical intervention.

Lesions can definitely be treated conservatively but he should have relatively frequent follow ups to monitor progression or improvement.

Improvement can take months with conservative treatment. It is not a quick healing process. 

The good thing is that ya’ll seem to have caught it early so there maybe a lot more options available to you than for me. I hope that this was helpful. Let me know if you have any questions.