Metal alloys like stainless steel, titanium, and cobalt-chromium alloys are preferable for bio-implants due to their exceptional strength, tribological properties, and biocompatibility. However, long-term implantation of metal alloys can lead to inflammation, swelling, and itching because of ion leaching. To address this issue, polymers are increasingly being utilized in orthopedic applications, replacing metallic components such as bone fixation plates, screws, and scaffolds, as well as minimizing metal-on-metal contact in total hip and knee joint replacements. Ceramics, known for their hardness, thermal barrier, wear, and corrosion resistance, find extensive application in electrochemical, fuel, and biomedical industries. This review delves into a variety of biocompatible materials engineered to seamlessly integrate with the body, reducing adverse reactions like inflammation, toxicity, or immune responses. Additionally, this review examines the potential of various biomaterials including metals, polymers, and ceramics for implant applications. While metallic biomaterials remain indispensable, polymers and ceramics show promise as alternative options. However, surface-modified metallic materials offer a hybrid effect, combining the strengths of different constituents. The future of biomedical implant materials lies in advanced fabrication techniques and personalized designs, facilitating tailored solutions for complex medical needs.

Zirconia-based ceramics are the most preferred materials used in implants due to their excellent mechanical properties compared with other alternatives. These materials available in the pre-sintered form are appropriate to grind due to their soft nature. However, it is challenging to achieve a required surface finish in grinding these ceramic materials owing to chipping, which limits its usage in industries. In this work, the pre-sintered yttria stabilized tetragonal zirconia (Y-TZP) component was ground using a resin-bonded diamond-grinding wheel under different cooling environments. The components ground under the minimum quantity lubrication conditions exhibited a reduced grinding force with better surface finish compared to wet (flood coolant) and dry conditions. The resultant specific energy was reduced with the increase in maximum chip thickness for different cooling conditions. The critical depth of cut estimated from the pre-sintered zirconia was witnessed to be higher, which indicated that the initiation of ductile to brittle transition occurred at a deeper depth of cut. The material removal mechanism observed in the pre-sintered zirconia was dominated by brittle fracture. This was evident from the obtained chips and ground surface morphology.

Cobalt-chromium alloys and Ultra High Molecular Weight Polyethylene (UHMWPE) are widely used in total hip replacement due to their multifunctional properties such as high mechanical strength, hardness, fatigue, and tribological properties. The material has been more popular among researchers that pushing them to refine the multifunctional properties of materials by using different fabrication and post-processing methods. Recent studies found that the Selective Laser Melting (SLM) technique of additive manufacturing (AM) shows a major response in changing the properties over the traditional methods, but there exist few problems while printing the cobalt-chromium alloys in SLM. However, it is hard to use cobalt-chromium alloys directly in the human body without post-processing stages such as post-heat treatment, surface modification, and Osseo-integration stage because it helps to improve the durability, reduce the ion elements release, wear debris, and promotes more adhesive strength between the tissue and stems. This review article explores the effects of process parameters on the SLM printed product and analyzes the post-processing stages to enhance the properties of printed components for total hip replacement. Furthermore, the solution for the problems and future research work are adequately discussed for restricting the ion element leaching of Cobalt-Chromium alloys.

Stainless Steel 316L (SS316L) is widely used in orthopaedics due to its biocompatibility, affordability, ease of fabrication, adequate mechanical strength and corrosion resistance. Despite its many benefits, the stiffness of SS316L has been a significant cause for concern since it causes stress shielding and implant failure. A potential solution for stress shielding in orthopaedic implants is lattice SS316L, which can be fabricated using the laser powder bed fusion (LPBF) process. The development of lattice structures using the LPBF process allows the scaffolds to adhere, grow and differentiate bone cells with specific mechanical properties suitable for bone implants. The study highlights different lattice structures employed in orthopaedic implants, mainly focusing on the gyroid structures and delves into the fabrication of SS316L lattice structures. Compared to traditional solid implants, the TPMS SS316L gyroid showed at least a 30%–70% improvement in weight reduction, reduced stress shielding by 80%, material saving and a 10%–20% improvement in biocompatibility and 50%–200% osseointegration. Compared to other porous metallic implants, there was a 10%–15% improvement in the compressive and tensile strengths. A 10%–20% at reduced weight concerning strength-to-weight ratio and 40% economically viable. The review also highlights the influence of various lattice parameters on the mechanical and biological attributes of lattice structures, emphasizing the benefits of gyroid lattice structures and their potential impact on the Orthopaedics sector. Furthermore, by leveraging the unique properties of gyroid lattices, SS316L offers a promising solution for stress shielding in orthopaedic implants, with an affordable and compatible alternative to titanium implants in orthopaedics.