Should i wear a knee brace after acl injury?

Could help: If you are attempting to stay active, and not have the acl surgically reconstructed, a brace may be of benefit.

Your choice: Derotational or acl functional braces may have some protective effect at low speeds/torques, however numerous studies have demonstrated they will not stop the abnormal rotational motions that occur in an unstable acl deficient knee at the speeds involved in sports competition. Will also not prevent tearing of an acl or acl graft in a knee subjected to wrong combo of forces.

Depends.: It depends on your surgeon. some brace, some don't. There is no right or wrong answer to the question, so it comes down to your surgeons preference.

Ask your ortopedic: doctor. Depends on the injury and the orthopedic's preference.