hyperextension of knee

My boyfriend was in a car accident 5 years ago. He was given a swedish knee brace and was wearing until his evil wife and her boyfriend threw it away. He has not worn one in about 2 years. He walks with a cane very slowly..he has very little balance. Would a knee brace help repair the tendons properly or just keep from getting worse. Either way I think he could benefit. Please advise. Thank you. karen away