When you have a twisted or swollen ankle, the discomfort can last a long time if you don't treat it right. When you go to get it treated the doctor, or nurse practitioner may write you a prescription for an ankle splint with the L4350 medical billing code. Medical billing codes, such as L4350, are used so the medical insurance companies know what kind of treatment the patient is receiving. Theses medical billing codes have regulations that must be met and approved by third party. The regulations for L4350 ankle orthosis are indicated below.