ACL and MCL injuries can take a long time to heal. It's important that you use the proper type of brace for a ligament injury. The medical billing code L1845 ensures certain features and standards are observed to ensure the finest quality. L1845 are first and foremost a workable double upright knee orthosis. This means that the brace can be worn during activity and has two supports that run horizontally around the leg on either side of the knee.