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Interview with Miss Sarah Muirhead-Allwood

Interview with Miss Sarah Muirhead-Allwood

Posted on: 13-03-2018

Consultant Orthopaedic Surgeon, The London Hip Unit

 

There were clearly many technological developments during your career such as improved imaging modalities, tooling and implants. Which ones would you say had the most profound impact on your work?

Bearing surfaces such as polyethylene (PE) have had the most impact on my work. 22 years ago there was a major problem with wearing of the PE particle debris which led to osteolysis and subsequently failure of many implants. Little care was taken in regards to manufacturing processes and materials quality control. More recently subtle chemical changes with cross-linking (XLPE) processes and the addition of vitamin E has led to a significant reduction in failure rates in hip replacements.  Osteolysis has now pretty much disappeared. Around 19 years ago I changed to XLPE and now I do not see bearing surface wear at all in my patients.

 

You specialise in minimally invasive techniques for hip replacement – do you see a time when all patients might be afforded this treatment option?

I became interested in this when developing 2 incision hip replacement, which showed tissue damage below skin could be huge, defeating any advantages of minimally invasive surgery. Minimally invasive techniques need to be very deep tissue sparing, and a compromise may be needed in just how small the skin incision should be.

Nowadays my surgery is carried out through a single scar of around 6-10cm (compared to 20-30cm in conventional surgery). The benefit of a smaller incision is that less surrounding tissue is damaged during surgery. This results in reduced blood loss and reduced surgical pain. The final scar will also be much less noticeable.

Some of my colleagues find this difficult, particularly without very specific instruments, and it takes time to develop this technique with existing instruments reliably. For training surgeons a more generous incision is needed, but as experience develops more surgeons go for small incision surgery, provided they have suitable instruments.

 

What potential do you believe developments in robotics and IT might afford to orthopaedic surgery?

The biggest challenge in hip surgery is component placement, at present there is not complete confidence in correct function anti-version of the socket. Programmes that are developing, such as optimised positioning systems (OPS), have great potential, but the full potential of the advantages of having such systems during surgery are yet to be realised. At this stage it is too early to know which particular system will be the most useful. I personally believe robotic hip replacement hampers too much of the surgeons feel, and navigation either with patient specific instrument or virtual/augmented reality navigation systems offer a better solution. We must remember that hip replacement has become one of the most successful operations merely using the surgeon’s skills and cost will no doubt limit progress in these areas.

 

Who had the most positive impact on you during the development of your professional career?

Several people.  My first house officer job was for Ronald Furlong, which influenced my choice of hip surgery. My theatre and operative discipline came from a stint in cardiac surgery. Whilst training at RNOH I had the privilege of working with Mr Lorden Trickey and Tony Caterall who I think were the most technically gifted orthopaedic surgeons I have seen.

 

What career or personal achievements are you most proud of?

I was lucky enough to develop uncemented revision hip replacements with a programme at RNOH with Professor Peter Walker, whereby we carried out a huge number of CAD-CAMs for revision hip replacement, which paved the way to learning a lot about subsequent designs.

 

What have been the principal frustrations you’ve encountered during your career?

I am lucky to have practised medicine during a great period of time, and I am able to look back happily over my career. It was a time when one was pretty free from bureaucracy within the NHS, and I do believe nowadays it is a lot harder for surgeons setting out on their careers.

 

What would be your main wish / aspiration relating to the future development of hip replacements? 

We have started utilising the technology of additive layer manufacturing (3D printing), with this technology we can produce structures which not only encourage better bone growth, but also are able to potentially direct bone in growth and at the same time reduce the stiffness of the components which hopefully will reduce stress shielding of the surrounding bone. I fear that stress shielding of bone maybe become a significant problem of hip replacement when getting to the 30-40 year follow up stage.

 

What are your current research interests?

We are currently doing a follow up on a large database of hips in my practice (10,000 patients) however personal series of patients are less powerful these days than the national registries and are becoming increasingly hard to publish.

I have recently collaborated with Dr Jonathan Jeffers and the medical engineering department at Imperial College, to look at functioning of the hip capsule, an area I plan to invest more time into research with them.

 

How do you see orthopaedics evolving in the next 10 years or so?

People are currently frightened of litigation. Problems that have developed from ASR have caused huge damages, and I think industry are keen to pursue a more conservative device path in the future, for this reason lots of components of hip replacement that had potential, such as the silent hip, have been discontinued for commercial reasons.

 

What advice would you give to early career orthopaedic surgeons?

To be aware that they are going into a highly regulated and difficult profession, but I hope they are able to gain as much satisfaction from it as I have.

 

If you had to choose an alternative job what would it be and why?

A photographer, upon retirement I plan to dedicate lots of time to this. I very much look forward to shortly embarking on a trip to Kyrgyzstan to photograph a gold mine.

 

Which 3 people (alive or no longer with us) would you like to spend an evening with and why?

Ansel Adams (American photographer and environmentalist), an outstanding photographer, his work is stunning and has inspired my passion of photography.

Robert Rauschenberg (American painter and graphic artist whose early works anticipated the pop art movement) because of his ability to come up with new ideas in art, and I think he would be good company.

Bill Harris, (Orthopaedic Surgeon) one of the giants in hip surgery who has had a huge influence on my career.

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