Ex vivo analysis of failed resurfacing hip prostheses

Project leader

Dr Tom Joyce

Dates

April 2009 to October 2010

Project staff

Mr Dave Langton

Prof Andrew McCaskie

Sponsors

British Orthopaedic Association (Joint Action research appeal)

Partners

University Hospital of North Tees

Description

Millions of artificial hips implanted in people around the world bring with them pain relief and increased independence.  To bring these benefits to younger patients, the latest designs, known as hip resurfacings, are on offer. 

Most of these have given good clinical results. But a number have failed earlier than expected, particularly in female patients.

We work with a team of local orthopaedic surgeons. Working with them we obtained failed metal-on-metal resurfacing hip prostheses. 

Researchers studied the articulating surfaces of these implants in detail. 

Studies of ‘conventional’ hip prostheses found that their longevity is proportional to the amount of wear that occurs on the articulating surfaces. 

While wear rates are small, the body reacts negatively to any foreign particles within it. You must minimise wear as far as possible.   

The project studied the wear of the articulating surfaces of the resurfacing hip prostheses using three key methods. Each give valuable insights: 

• A non-contact profilometer allows measurements of surface roughness.
• A roundness measmostevice permits the quantification of maximum localised out of roundness and maximum wear depth.
• A high accuracy co-ordinate measuring machine allows the identification of localised areas of wear.

The project compared this information with relevant clinical data including acetabular cup position in two planes and blood metal ion levels.