I.4 “Implantable” Trial to Assess Anatomical Fit

Talus avascular necrosis is a complex medical condition involving severe degradation of the Talus. This disease can be debilitating and cause high levels of pain and discomfort, often limiting the physical use of that joint. A Total Talus Replacement (TTR) is a treatment option which replaces the native bone, usually with a metallic implant. Implants may be aimed at fusion or articulation. The native bone is removed via surgical resection, and the Talus implant placed in its stead. In cases without ancillary fixation, the Talus implant is free to articulate in the joint space, surrounded on all sides by native bone and tissue. restor3d has taken a large space in the market of TTR surgeries, using 3D printing of metal for the implants and polymer for the trials. To date, the company has successfully completed over 170 TTR surgeries with high patient and surgeon satisfaction.

TTR procedures are relatively new in the medical world for ankle salvage. Advances in additive manufacturing and patient specific implants have expanded some of the possible uses for a Talus replacement to include cases with severe bone loss or degradation, where a normal implant would fail. A challenge with current patient-specific implants is how to assess appropriate articulation without implantation. Due to the lack of fixation used in a TTR surgery, implant removal can be very difficult, often requiring significant application of force. Mis-sized implants may require revision surgery, or cause the patient undue pain and discomfort, hampering good clinical outcomes. Trialing devices are normally used to assess the quality of the fit, but do not allow for correct anatomical positioning of the ankle and assessment of articulation due to the requirement for handles and other features that allow for trial removal.

The goal of this project is to design and develop TTR implant trials that allow for full anatomical positioning and for the surgeon to assess articulation prior to implantation. Improved trialing devices lead to better implant fit and thus more successful clinical outcomes. The handle of the current devices impedes surgeons from returning the joint to correct anatomical position, therefore not allowing full trial of the implant size and fit. The trial device should be 3d printed out of a polymer, and must allow for the use of fluoroscopy during surgery to assess fit in the joint space.