Porous Coatings in Orthopaedics

Abstract

Problems with cemented implants inspired the use of cementless implants in which fixation is dependent upon tissues’ ability to integrate with the surface of the implant and maintain this interface over time. Over the past 40 years, porous coated implants have been utilized clinically, especially in younger and more active patients. This article provides a comprehensive discussion of porous coated implants in orthopedics. First, the objectives of biological fixation using porous materials are presented and the parameters dictating the success of porous coated joint replacements are defined. Next, specific materials used for porous coatings are discussed, including metals, ceramics, polymers and hybrid biomaterials. Properties of porous coated implants are detailed, focusing on mechanical and electrochemical properties and considerations needed when designing a material with an increased surface area. The design and characterization of porous materials are addressed, focusing on experimental and analytical techniques to measure coating architecture and mechanical properties, and advanced manufacturing techniques for controlling architecture. Lastly, the synergy between design strategies used in tissue engineering and in porous coated synthetic implants are discussed and use of more biologically proactive strategies to increase the amount and rate of tissue ingrowth is presented.