Hinged Knee Braces - A knee brace or support with a hinge will provide a high level of support for the knee joint in general. To protect the ACL ligament specifically is difficult and something like the Don Joy Armour is specifically designed to do this. Other supports like the McDavid 429 Hinged Knee Brace or the Mueller Hg80 Knee Brace with Kevlar provide a good amount of support and protection at a lower price.
Elastic Rehabilitation Bands - Elastic rehab bands or stretch bands can be used to aid strengthening and rehabilitation both before and following surgery.