LKF050813

You need a nexus letter.  Dont expect VA to change the Caluza elements for you anytime soon.  The Caluza elements, required for service connection are:
1.  Current diagnosis of a disability.  
2.  Documentation of an in service event (you allege caused your disability).  
3.  Nexus, or doctor's opinion that your current condition is at least as likely as not due to one or more events in military service.  
Its shortened to 2 if you have an already service connected condion:
1.  Current diagnosis.
2.  Doctor's opinon that your Current diagnosis (newly applied for disability condition) is at least as likely as not related to your service connected disability.  (such as a result of medications for it, or, arthritis, if you injured a knee, etc).  
    The photo would help to establish Caluza  item number 2 (above, top) ...documentation of an in service event, but it does not prove your nexus.  
Your current disability could have been caused by stuff in the photo, by a car accident, or something entirely different later.   The photo helps document in service events, it does not provide a nexus in my opinion.  

I agree with john999. I would not give them anything that shows you running or exercising with a brace. I can almost guarantee that that VA will look at it and eater lowball your claim or deny it because the treatment you were getting at the time fix the problem. Hears what you need to look at.
Can you tell us what you were medically retired with? (list all of it.) The more information we have the better we can help.
1. Is there a in service medical record of you injuring your knee?
2. Have you been treated by the VA for your knee injury that you are claiming? 
3. It appears that you are treated for your chondromalacia / osteoarthritis by a non VA doc. This is very common condition as we age. (and abuse our knees) The question is will your doc write a Nexis letter saying it is more likely than not Grater than 50% that you R or L  knee chondromalacia / osteoarthritis was caused by your (Marching, combat boots, running in combat boots, or working on???) Your Nexis letter will have to state how you got injured. How it has worsened over time. And have to state;  "it is more likely than not Grater than 50% that you knee chondromalacia / osteoarthritis was caused by you service."
4. You will need a Disability Benefits Questioner, (DBQ) for a minimum of your knee. (maybe more than one) Most docs don't like to fill them out DBQ's because they are complicated and take to much time.
You might be able to secondary SC it to one of the reasons you were medically retired for.