Total talus replacement can be an alternative option for pat
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Total talus replacement is a new alternative surgical option for patients with avascular necrosis (AVN), a condition in which poor oxygenated blood flow causes eventual death of the bone.

Preoperative plan
The surgeon obtains standing three-view ankle radiographs and preferably standing CT scans of the affected ankle and also of the contralateral ankle (Figure 1). In the case shown, the patient was a healthy 69-year-old woman with talar AVN. The acquired images are sent to Restor3D, where the team builds a talar replacement design based on surgeon-directed goals. Conference calls take place between the company and surgeon. The surgeon is able to modify the design as needed. Once the surgeon approves the final design, the custom talus implant is 3D-printed from cobalt chrome, which has better joint wear characteristics than titanium. Three implants are created; one that is true to size, one that is 5% smaller than the first implant and one that is 10% smaller than the true-to-size implant.

Surgical technique
An incision is made over the anterior ankle and the surgeon dissects down to the ankle joint, being careful to protect neurovascular structures. The surgeon should proceed through the floor of the extensor hallucis longus, maintaining the tibialis anterior tendon sheath. Next, the surgeon creates an arthrotomy of the ankle joint and exposes the talus. Using a saw, a complete osteotomy is made through the neck of the talus and the border of the body and neck junction, taking care not to penetrate the subtalar joint. The head and neck of the talus are removed. Using the saw, the surgeon makes two cuts in the sagittal plane through the talar body, dividing the talar body into thirds. In addition, another cut can be made in the axial plane to create six pieces. Next, using osteotomes, rongeurs, curettes and a pituitary, the talus is removed. It may prove difficult to remove the posterior pieces as these are adhered to the posterior ankle capsule. Once the entire talus is removed (Figure 3), the trials are inserted (Figure 4). The clinical fit, stability and range of motion are tested and intraoperative fluoroscopy is used. The appropriate 3D-printed implant is selected.

Postoperative plan
The patient is kept non-weight-bearing for 4 weeks. The patient returns for the first postoperative visit at 2 weeks for staple or suture removal, at which time three-view ankle radiographs are taken. A tall walker boot is provided, which is worn during sleep. The patient is enrolled in physical therapy, the focus of which is ankle and hindfoot motion, and swelling control. Titanium, alumina and ceramic implants have been described in the literature. In this case, cobalt chrome was chosen because it has a long track record in orthopedics as a superior joint replacement material.