The implications of developing materials with enhanced fracture toughness, damage resistance, reliability and ultra low wear is of significant interest to the orthopedic community, since it directly addresses a vital clinical concern- eliminating wear debris mediated THA implant failures. In Phase I we made a significant step towards addressing this central issue by successfully demonstrating a novel ceramic material with superior mechanical properties. An enhancement of 50 percent in fracture toughness, 50 percent in weibull modulus and significant damage resistance over conventional ceramics was demonstrated. Thus, we have been able to establish materials which, from a safety and design aspect, will have significantly lower risk of brittle failure in vivo. Furthermore, we have been able to adpat the ceramics for articulation with CoCr. From a bio-compatibility aspect, no adverse effects are expected in-vivo. Early wear performance results of head/cup components made from these ceramics also clearly show the ultra low wear characteristics, with wear volumes 2-3 orders of magnitude lower than present CoCr-PE. In Phase II, we propose to extend these promising results by optimizing the component design tolerances using a rigorous statistically valid approach, characterizing the static and fatigue strength of THA implant components, and performing a comprehensive in-vitro and invivo bio-compatibility evaluation. We also propose to extend the wear tests (n=6) to 10 million cycles in a hip simulator to confirm the functionality of the optimized components. Major orthopedic implant manufacturers have expressed interest in collaborating on the evaluation and optimization of the novel ceramic designs.
The combination of safety (mechanical and biological) and function (ultra-low wear) and compatibility with CoCr offers a new bearing materail set that promises to eliminate the central issue plaguing THA - wear debris mediated osteolysis and implant failures. A comprehanesive program to establish the safety and function of the materials will help speed the commercialization of these implants in Phase III.
| Bal, B Sonny; Khandkar, Ashok; Lakshminarayanan, R et al. (2009) Fabrication and testing of silicon nitride bearings in total hip arthroplasty: winner of the 2007 ""HAP"" PAUL Award. J Arthroplasty 24:110-6 |
| Bal, B Sonny; Khandkar, Ashok; Lakshminarayanan, R et al. (2008) Testing of silicon nitride ceramic bearings for total hip arthroplasty. J Biomed Mater Res B Appl Biomater 87:447-54 |
