The potential of Ti-6Al-7Nb, and design for manufacturing considerations in mitigating failure of hip implants in service

Abstract

The hip prosthesis, used to repair or recreate the diseased or damaged hip joint's articulation functionality, greatly influences the outcome of total hip arthroplasty (THA). Currently, the limited lifespan (10–15 years) of hip prostheses presents a serious challenge stemming from poor materials selection, design, as well as manufacturing techniques and this has been amplified further by the rising human life expectancy. Today's hip prostheses are predominantly made of Ti-6Al-4V alloy, which frequently fail owing to wear, modulus mismatch, corrosion, and poor osseointegration. To prolong hip implants’ useful life within the body system, it is crucial to comprehend human hip anatomy and biomechanics, investigate the modes and mechanisms of prosthesis failure, and identify mitigation measures pertaining to materials selection, prosthesis design, and production processes. From this point of view, this article firstly explores the intricate hip joint's structural anatomy in the context of biomechanics principles that influence joint movement and weight bearing. Then, hip implant failure modes and mechanisms are discussed and lastly, the failure mitigation measures are proposed. From this review, Ti-6Al-7Nb known for its excellent corrosion resistance and superior biocompatibility is considered a promising substitute for the mostly used cytotoxic Ti-6Al-4V, functionally graded porosity design mimicking the human bone to enhance mechanical and biomedical properties, more precisely osseointegration and stress shielding, and utilization of the selective laser melting technique capable of fabricating Ti-6Al-7Nb components with intricate shapes and high geometrical accuracy can play a significant role in preventing current hip implant failures.

Keywords

• Total hip arthroplasty
• Failure mechanisms
• Hip biomechanics
• Failure modes
• Risk factors, Selective laser melting (SLM)