Good Morning Steve and welcome. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
Your vet is correct that dogs go through growth spurts at the end of the long bones which will cause pain, lameness and odd conformation. Along with this, the ligaments must grow at the same time to compensate for these growth spurts and that does not always happen and this is why your little guy may still appear knuckled over. The only thing you can do, Steve, that will help is to feed a daily supplement of calcium and phosphorus such as Pet tabs that can be purchased at the pet store. The physical therapy that you mentioned is important by walking him often ...this will help the ligaments stretch to accommodate the growing bones and with this walking, your guy will eventually mature to a normal conformation.
There are issues when one bone grows at a different rate than the others causing a compromised growth and defects in conformation...if this worsens, Steve, have your vet examine your guy and x ray to be sure that this will pass.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please Reply so I can clarify for you
Sincerely, XXXXX XXXXX
Thank you so much, Steve for your kind rating. It is very much appreciated! Even though you have rated, we can still communicate. If you have other questions, please Reply. I am always happy to help. I am sure with your care and love that your little guy will do well.