Hip Replacement - History

There are numerous types of hip replacement available each with a different design, fixation, bearing surface and size of femoral head. The most widely used consist of a metal ball articulating with a plastic socket (UHDP ultra high density polyethylene). Some hip replacements are designed to be used with acrylic cement, which acts as a grout to secure the implants in the bone bed (cemented); others are designed with special coatings and surfaces to encourage bone growth onto the prosthesis to give biological in growth and long term stability (uncemented).

In the metal on plastic bearing surface, it is the plastic liner that wears out with time and is related to the load, activity levels and type of activity being undertaken.  Advances in technology and better understanding of joint mechanics has led to the development newer bearing surfaces which can tolerate  higher levels of activity and will therefore wear out more slowly. These bearing surfaces are either metal-on-metal (As in the resurfacing arthroplasty). or ceramic-on-ceramic (Mostly uncemented implants). Patients who are young and physically active may be candidates for these new bearing surfaces. As wear rates and ultimate failure of the joint replacement may well be significantly reduced.