Short History of Biomaterials Used in Hip Arthroplasty and Their Modern Evolution

The hip joint is one of the largest joints in the body and is a major weight-bearing joint. The function of the hip is to withstand body weight during standing and walking; during single leg stance the hip joint must carry a load three times greater the body weight. However, Joint degeneration is the final phase of the joint cartilage destruction, leading to severe pain, loss of mobility, and sometimes even angular deformity of the limbs. The primary reasons for a large number of total hip replacements are osteoarthritis and osteoporosis of the femoral neck, which often leads to hip fractures. One of the most successful techniques to restore function of a degenerated joint is the total joint replacement. In this surgical procedure, diseased cartilage and parts of the bone are removed and replaced with an appropriate joint prosthesis. Several types of materials and techniques have been developed for this purpose: glass, polymer, metal alloy, ceramics, etc. Earliest prosthesis designs and biomaterials that have been developed to treat osteoarthritic hip degenerated joint surfaces were for the most part empirical and unsuccessful. Joint replacement heralded a revolution after the materials and replacement procedures developed by Sir John Charnley. A modern total hip prosthesis consists of a femoral and acetabular component, where the femoral head is made of cobalt-chrome alloy, alumina or zirconium, and the stem component is now usually made of Ti- or Co-Cr-based alloy. The search for improved designs and new hip implant biomaterials with better biocompatibility and more desirable mechanical properties is still underway.