FDA Approves First-of-Its-Kind Implant to Treat Rare Bone Disease as a Humanitarian Use Device

Rare Daily Staff

The U.S. Food and Drug Administration approved Additive Orthopaedics’ Patient Specific Talus Spacer 3D-printed talus implant for humanitarian use.

The Patient Specific Talus Spacer is the first in the world and first-of-its-kind implant to replace the talus—the bone in the ankle joint that connects the leg and the foot—for the treatment of avascular necrosis (AVN) of the ankle joint, a serious and progressive condition that causes the death of bone tissue stemming from a lack of blood supply to the area. The implant provides a joint-sparing alternative to other surgical interventions commonly used in late-stage AVN that may disable motion of the ankle joint.

“Avascular necrosis of the ankle, while a rare condition, is a serious and potentially debilitating one that causes pain and can lead to inhibited motion of the ankle joint, and in some cases, removal of part of the leg,” said Raquel Peat, director of the FDA’s Center for Devices and Radiological Health’s Office of Orthopedic Devices. “Today’s action provides patients with a treatment option that could potentially reduce pain, retain range of motion of their joint and improve quality of life.”

AVN is often caused by a sudden injury—such as a broken bone or a dislocated joint—or sustained damage to the tissue that develops over time, and it occurs when there is a lack of blood supply to bone tissue, causing it to become necrotic. When the bones of a joint are affected, such as in the case of the ankle, the cartilage that keeps the bones from rubbing together can deteriorate, causing arthritis and pain. Late-stage AVN of the ankle may result in the talus bone partially or fully collapsing. Current available treatments include fusing the joints in the foot and ankle together—a procedure that helps to alleviate pain caused by AVN but eliminates motion in the joint—or below-the-knee amputation.

The Patient Specific Talus Spacer is a 3D printed implant that can be used in talus replacement surgery. The talus spacer is made for each patient individually, modeled from computed tomography imaging, and is fitted to a patient’s specific anatomy. During the replacement surgery, the patient’s talus bone is removed and replaced with the implant, which is made from cobalt chromium alloy.

While fusion may become necessary in the future should the condition worsen, talus replacement surgery with the Patient Specific Talus Spacer is intended to be a joint-sparing procedure, as it allows the patient to retain motion in the ankle joint.

The FDA reviewed data for the Patient Specific Talus Spacer through the humanitarian device exemption process. A Humanitarian Use Device is a device that is intended to benefit patients by treating or diagnosing a disease or condition that affects not more than 8,000 individuals in the United States per year.

Data supporting the safety and probable benefit of the Patient Specific Talus Spacer include results from 31 patients and 32 talus replacement surgeries (one patient had operations on both ankles) with the implant. At three years post-operation, the average reported pain decreased from “moderate to severe” prior to surgery to “mild” post-surgery, and average range of motion in the ankle joint also improved. These measures were assessed using standard subjective scoring systems for pain and functionality.

By the three-year mark, out of 32 cases, there were three reported additional surgeries. The most common reported adverse events were pain and scar tissue at the surgery site.