Clinical Overview: The Challenge of Talar Avascular Necrosis

Total talar collapse, whether resulting from trauma-induced avascular necrosis (AVN) or severe osteoarthritis, presents one of the most significant challenges in reconstructive foot and ankle surgery. Traditional treatment pathways often defaulted to tibiotalocalcaneal (TTC) arthrodesis. However, fusion frequently results in a substantial loss of hindfoot mobility, altered gait mechanics, and secondary degeneration of adjacent joints.

The Total Talus Replacement application utilizes additive manufacturing to provide a motion-preserving alternative that restores joint height and anatomical alignment with extreme precision.

Anatomical Modeling and Patient-Specific Design

The process begins with high-resolution, thin-slice CT imaging of both the affected and contralateral (healthy) limb. By mirroring the healthy talus, our engineering team creates a digital "twin" that accounts for the patient’s unique articular geometry.

• Articular Surface Fidelity: The design ensures congruent contact with the tibial platter, the calcaneal facets, and the navicular bone.
• Mass Reduction: Unlike solid cobalt-chrome legacy implants, our 3D-printed titanium versions can incorporate internal hollows or lattice structures to optimize weight without sacrificing structural integrity.
• Ligamentous Attachment Points: Custom textures are applied to non-articular surfaces to promote soft-tissue interference and stability.

Material Science: The Role of Titanium LPBF

This application leverages Laser Powder Bed Fusion (LPBF) to print the device in medical-grade Titanium alloy (Ti-6Al-4V). Titanium is the material of choice for this application due to:

1. Biocompatibility: Proven long-term success in skeletal integration.
2. Modulus of Elasticity: Closer to natural bone than cobalt-chrome, reducing the risk of subchondral bone resorption in the calcaneus.
3. Surface Finish: The ability to achieve a dual-finish—highly polished articular surfaces for smooth joint gliding and a micro-rough underside for stable seating.

Surgical Integration and Clinical Outcomes

The 3D-printed talus is designed for a "press-fit" or "cemented" fixation depending on the quality of the surrounding bone stock. Because the implant is a geometric replica of the patient's original bone, the surgical team can minimize bone resection, preserving as much native vascularized tissue as possible.

Observed Clinical Benefits Include:

• Immediate Height Restoration: Correcting the "shortened limb" effect caused by talar collapse.
• Preserved Range of Motion: Maintaining sagittal plane motion at the ankle and subtalar joints.
• Rapid Rehabilitation: Patients often transition to weight-bearing sooner than those undergoing complex fusion procedures.

Summary of Evidence

Clinical validation through multi-centered studies suggests that patient-specific talar replacements provide superior functional scores (AOFAS) compared to traditional fusion. By combining regulatory-aware design with evidence-based innovation, this application represents the gold standard in limb-salvage technology.