3D Printed Talus Replacement

A custom designed talus replacement was first published by Harnroongroj T and Vanadurongwan V with first-generation talar body prosthesis in 1997. First-generation talar prosthesis preserved the head and neck of the talus to allow the insertion of the prosthetic peg into the bone.11 Then, in 1999, Tanaka Y et al. designed second-generation alumina-ceramic talar body prosthesis without a peg for the neck of the talus.12In 2005, Taniguchi et al. reported excellent pain and functional outcomes in 55 ankles with a total talar replacement (TTR).

The contralateral talus is utilized for radiographic data and computed tomography (CT) to obtain 3dimensional model to replicate its biomechanical and anatomical properties. Patient specific and anatomic based design talar prosthesis will be constructed with 3D printed using polymeric biocompatible powders.14,15Production of TTR generally requires 4 to 6 weeks for completion and stainless still, titanium, alumina ceramic, and cobalt chrome are the most commonly used materials.

The most commonly used surgical approach is the anterior ankle approach, where a 10 to 14 cm anterior longitudinal midline incision is made to the talonavicular joint level. Care should be taken to identify and protect all vital neurovascular structures. Upon performing an anterior capsulotomy, the ankle joint is exposed after elevation of the periosteum. Then the talar body is carefully dissected out for complete extrusion. Any remaining osteophyte should also be removed. Then appropriate soft tissue manipulation was performed to maintain a functional ankle joint space. The new custom-built implant was then fitted into the patient's ankle, and the most appropriate fit of the polyethylene component is inserted after trial polyethylenes were tried. Insertion of the tibial portion of the arthroplasty system is also carried out with the system based on the surgeon’s choice. A gastrocnemius recession or Achilles tendon lengthening is required when it is clinically indicated. A below-knee cast will be applied for 2 weeks then the patient will begin weight-bearing in a CAM boot. Then supportive shoes and a lace up ankle brace will be used at 6 to 8 weeks. Outcomes will be measured by inspecting maintained postoperative ankle range of motion as well as clinical and functional surveys such as the AOFAS score and SF–36.

Highlighted benefits of the TTR are good restoration of the physiological motion without limb length shorteningas demonstrated in multiple studies.14,16,17 TTR also produces stability with preventing degenerative changes to adjacent joints and dispersing pressures appropriately. Thus, TTR is an excellent surgical treatment option for patients with advanced OA from trauma, talar osteonecrosis, infectious origin, talus bone tumor, and failed TAR.