Profile: Miss Sarah Muirhead-Allwood

Elite sports are consistently placing increasing demands on athletes’ bodies, with surgeries to repair damaged bones and tissue effectively shortening careers.
We speak to Consultant Orthopaedic Surgeon Miss Sarah Muirhead-Allwood and question if we’ll see an increase in professional athletes undertaking surgery due to the advances in techniques.

Once I had made the decision to specialise in orthopaedics I also had an immediate interest in hip surgery. At this time hip replacement surgery was becoming commonplace as it had revolutionised the treatment of hip arthritis, but the longevity of joint replacement was not good. There was a huge need to pioneer techniques of revising these failing joints which totally fascinated me. What also went hand-in-hand with that was the development of new materials and fixation methods to increase the longevity of primary hips. We have changed from a situation where you were lucky if your hip replacement lasted 10 years to a position now where you are unlucky if it does not last 20 years.

Hip resurfacing has always been an attractive option for orthopaedic surgeons as more of the patient’s bone is preserved. This became initially popular in the early 1970s with independent developments in London, California, US, and Germany. However, it was abandoned because of severe wear problems and loosening associated with the polyethylene cup. In the late 1990s it was reintroduced as a metal-on-metal bearing by McMinn in Birmingham and has survived much better. 
In essence, the socket is replaced with a hemispherical shell as in total hip replacement but in resurfacing, the bearing is metal and its internal diameter approximates the native femoral head diameter. On the femoral side, instead of replacing the femoral head and neck with a metal stem fixed in the femoral medulla, the existing femoral head is capped with a hollow, metal ball.
We believe this solution can produce a result with higher function and a reduced risk of dislocation, although the downside is the problems associated with metal bearings and compromises to longevity.

The preferred candidates for hip resurfacing are young men because this group is the group which in large series such as the British Hip Registry have been shown to have the lowest failure rates and to have failure rates approximating to conventional hip replacement. Women, because of their smaller femoral head sizes and possibly greater range of hip movements, have had a much higher failure rate. Because of the improvement in function, keen sportsmen have been opting for resurfacing for the last two decades. Elite sportsmen now seem to be trying to return to their super demanding sports and are succeeding. Providing that they continue to succeed, undoubtedly the number of elite sportsmen will choose this option rather than retire.

The future of hip surgery is, to some extent, constrained by its success. Hip replacement hardware is now so reliable there is little appetite from healthcare providers to invest more money in anything other than cost-saving innovation. Trials of hip resurfacing using either ceramic-on-ceramic or metal on highly crosslinked poly bearings are underway.

Interest in different approaches to the hip such as the direct anterior approach is encouraged in the US as it is seen to reduce patient cost, though not improving function and having probably a higher complication rate.

Prosthesis companies are championing robotically assisted surgery in order to improve their market share and these technologies are attractive to surgeons wanting to practice build. Existing robotic hip surgery adds significant cost to the procedure and studies will have to show a benefit if it is to gain acceptance. Linking navigation programmes with augmented reality and AI technology to fine tune the component positioning may well prove to be a better route. 

Miss Sarah Muirhead-Allwood BSc (Hons) MB BS FRCS is a consultant orthopaedic surgeon with 25 years of experience as a specialist hip surgeon. She operates exclusively on hips, performing hundreds of hip replacements and resurfacings a year. She specialises in complex hip revisions and unusual hip replacements at the London Hip Unit, based at The Princess Grace Hospital.

More information here.