Background: Selective Laser Sintering (SLS) Cobalt Chrome (CoCr) has been utilized extensively in medical implants. However, Electron Beam Manufacturing (EBM) 3D Printed Titanium-6 Aluminum-4 Vanadium Extra Low Interstitial (Ti6Al4V ELI) is increasingly being utilized due to its higher strength to weight ratio, biocompatibility, resistance to corrosion, and capacity for osseointegration. More recently, Titanium Nitride (TiN) coatings have been applied to Ti6Al4V ELI to improve its long-term durability. While durability and tribology are a critical measure of an implant’s overall performance, no studies comparatively examine these properties in Ti6Al4V ELI TiN and CoCr talar implants.

Methods: As a result, two independent laboratories were engaged to test these properties using: ASTM F1978-18 “Standard Test Method for Measuring Abrasion Resistance of Metallic Thermal Spray Coatings by Using the Taber Abraser”, and ISO 22622:2019 “Implants for surgery-Wear of total ankle-joint prostheses”.

Results: Testing using method ASTM F1978-18, Ti6Al4V ELI TiN performed 34x more favorably than mirror polished CoCr. Using method ISO 22622:2019, Ti6Al4V ELI TiN and SLS performed similarly, showing only slight wear when tested against Ultra High Molecular Weight Polyethylene (UHMWPE) over 5 million cycles.

Conclusion: With density, durability, tribology and ingrowth potential as a combined measure of overall performance, results support Ti6Al4V ELI TiN being favorable to CoCr in certain talar implants.

Clinical Relevance: In addition to offering superior abrasion performance and slightly better wear resistance, 3D printed Ti6Al4V ELI TiN coated implants offer physicians and patients a highly customizable implant with a lower strength to weight ratio than existing CoCr SLS implants.

Level of Evidence: V.