The braces prescribe for this are done by the specialists called as physiatrist (MD in physical medicine and rehabilitation), called as rehab specialist. They first do a muscle charting of both the limbs and then do a gait analysis. According to muscle weakness, ligament laxity and instability they will prescribe a tailor made, specific orthosis / brace for you. This prescription is given to an orthotist who will make the brace. Wearing the brace and walking on it, the orthotist and physiatrist will test it, restructure it and then finalize the design.
Any big hospital with a good physical medicine and rehabilitation department or a hospital attached to the teaching hospital will have a good orthotic department.
Please feel free for your follow up questions.