The talus, part of the tarsus group of foot bones that transmits the entire weight of the body to the foot, is a large ankle bone that articulates with the tibia and heel bone. Obviously it’s a pretty important bone in terms of comfort while walking and performing other activities, like flying a plane, so when a 69-year-old airline pilot was experiencing major pain in the area, she needed to find a way to fix it fast.

The patient turned to Duke Health for help from a foot and ankle orthopaedic surgeon who has experience 3D printing replacement bones, an application we’ve seen before. The organization integrates several of the health and medical schools from Duke University, including the Duke University School of Medicine, which has experience in 3D printing for surgical care.

Preoperative CT scan of the patient’s ankle showing degenerative changes and large cysts abutting the subtalar joint.

The pilot was suffering from severe ankle arthritis, along with talus bone cysts that were so large they reached the subtalar joint. Treatment options included total ankle replacement or fusion surgery, and as fusion would limit her mobility, it could potentially spell the end her career. However, due to the size of the cysts, replacement surgery was very risky.

So, she contacted Selene Parekh, MD, a co-chief of the Division of Foot & Ankle, for a consultation.

Dr. Parekh explained, “She said she would do anything to try and maintain her motion and was adamant about not having fusion surgery. The type of fusion she needed would have locked up both the ankle joint and the subtalar joint.”

To have any hope of taking to the sky again, she would need to have replacement surgery. So, once they had reviewed all of the options and risks, Dr. Parekh and his patient decided to go ahead with a total talus replacement. A 3D printed bone replica would be used, and combined with a tibial component from a total ankle replacement.

3D printed talus ready for implantation. The top of the talar dome marries perfectly with the polyethylene of a total ankle replacement.

While Dr. Parekh had experience using 3D printed devices in total talar replacements to recreate bones for the ankle and foot that perfectly replicated the native bones, normally the 3D printed replica replaces only the talus bone itself. It’s rare to see 3D printing used to replace the total talus, but the surgeon thought it would be the best option. He was sure that the procedure could not only relieve his patient’s pain, but also preserve her full range of motion for the foot at the subtalar and ankle joints.

Intraoperative photograph shows the insesrted 3D printed total talus and a poly and tibial component from a total ankle replacement.

Dr. Parekh took radiographs and MRI scans to evaluate the depth and size of the patient’s talus bone cysts. To make sure that a 3D bone could even be created for a total talar replacement, he performed a CT scan, in very thin slices, to get a highly detailed view of the anatomy. CAD drawings were prepared for both the affected limb and the unaffected one in order to compare the two – a mirror image of the healthy ankle could be used to fix any issues on the 3D model the surgeon would use to 3D print the bone, in case the native talus was permanently damaged.

Using the 3D model made with the CAD drawings, Dr. Parekh completed the design of the new talus, being careful that the top of it would marry properly with the polyethylene total ankle replacement. Then, he 3D printed, sterilized, and polished the replica talus bone, before successfully completing the patient’s surgery.

After the procedure was over, the patient completed normal post-op procedures, like going to physical therapy to increase strength and motion and spending several weeks in a boot and cast. The total talar replacement, complete with 3D printed bone replica, enabled her to continue her career as a pilot, and Dr. Parekh expects that she will not have any problems with her ankle function in the future.

“She did fantastic. Her pain is reduced, she has better motion, and her quality of life has been restored,” Dr. Parekh said.

According to the case study, Dr. Parekh says that orthopaedic surgeons from Duke have been “changing the algorithms of care for certain disease states.”

“Using these techniques, we’ve been able to revolutionize treatment for patients who have had a failed total ankle replacement and perform a revision replacement using total tali. We’ve also revolutionized treatment for patients with avascular necrosis of the talus,” Dr. Parekh explained. “In the past, the only solution for that was to perform fusion or major revascularization procedures, but now we can treat them with total tali.”

Postoperative radiograph shows 3D printed talus with the tibial component of a total ankle in place.

Surgeons from Duke have actually performed one of the highest numbers of total talus replacements, using 3D printing technology, in the US.

Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below.

[Source/Images: Duke Health]

 

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