The FDA yesterday oversaw the convergence of two rare events: the approval of a 3D printed device, and the use of the humanitarian device exemption pathway. The Patient Specific Talus Spacer, made by Additive Orthopaedics, is used to replace the bone that connects the leg and the foot in patients with avascular necrosis of the ankle joint. This is a rare but serious disorder that causes the death of bone tissue in the talus; current treatments include fusing the joints in the foot and ankle together, which helps alleviate pain but eliminates motion in the joint, or below-the-knee amputation. Additive’s talus spacer, made from cobalt chromium, is modelled from computed tomography images and fitted to each patient’s specific anatomy. The approval was based on data in 31 patients, one of whom had operations on both ankles, showing that three years post-surgery average pain had decreased from “moderate to severe” to “mild”, and average range of motion in the ankle had improved. By the three-year mark, three of 32 cases had required additional surgeries. The HDE process is used for devices to treat rare conditions and is itself rarely used; only two HDEs were awarded last year and three in 2019.