Hip Replacements- Made Real by Surgery and Stem Cells

When my friend's mum fell and broke her femur about 3 years ago, she had to have almost complete bed rest for six months and physiotherapy and rehabilitation for close to three months after that. With a metal screw pin in her thigh bone and a cast around her leg, it was probably the most uncomfortable and frustrating experience for someone who was living a very active lifestyle (tai chi, walking in parks, overseas travel etc.) prior the incident. She has since recovered from the injury but mentions feeling occasional discomfort and tightness in her thigh.

Most people live their early and active life not expecting any bone surgery (unless it is cosmetic) and most fractures tend to happen in osteoporosing elders over sixty. However, hip fractures are far worse than femur fractures the incidence of hip fractues increase with age, doubling for each decade after fifty. Most people who fracture their hips in old age have a poor quality of life and often get depressed and there are estimates that one in four people who fracture their hips completely heal while 20% of those who fracture their hips do not survive the year of their injury.

Given these considerations, it is therefore not surprising that doctors and bio-engineers are often looking at ways to make prostheses more natural and better accepted by the body. In the reported work that is currently being done at University College London (UCL), the doctors are keen on ensuring that people who require a second hip replacement (about 25% undergo a second surgery) will have a better outcome rather than suffer a crumbling joint with a high probability of trauma (apart from a nasty scar) and protracted recovery period involved.


Professor Gordon Blunn's team at UCL's Institute of Orthopaedics collaborates with Dr. John Skinner's group from the Royal National Orthopaedic Hospital in Stanmore, are conducting a trial with a GBP 130,000 (approx. RM 897, 150) grant from the UK Stem Cell Foundation and the Medical Research Council for a preliminary trial -to boost patient's bone growth by 75%- which will lead to a larger trial of 80 patients next year.

The current method of surgery requires bone chips to be packed into damaged hip joints to rebuild, followed by the insertion of the artificial replacement hip. What the research team will do is to improve the quality of the implants by infusing the bone chips with the patient's own stem cells, which they believe might act as a better cement and cause less inflammation.

The cells would be obtained from each individual patient's bone marrow which is extracted from the patient's hip bone under anaesthesia, isolated and grown in the laboratory and used to seed the bone chips.

The cell culture is estimated to cost approximately GBP 2,000 (approx. RM 14,000) and this probably excludes the cost of the surgery and any ancillary medical care.

The Chief Executive of the Medical Research Council, Sir Leszek Borysiewicz summarized this work most clearly when he said:

"The idea is to use autologous stem cells [taken from the patient themselves] to accelerate healing and outcome."



QUESTIONS AND THOUGHTS

I thought that there were a few interesting points to take from the concept and the trial.


APPLICATION IN OTHER BONES

Firstly, that marrow stem cells were being infused into the interior of artificial bone as seeding for normal bone structures to form.
-This is not the first time that stem cells have been used to seed bone growth and to kickstart the healing process. It would be interesting to see this method applied in other bones too.


AGE IS NOT AN ISSUE

Secondly, that the autologous stem cells harvested from the patient (usually 60-80 years of age) would still be clearly functional for this purpose, demonstrating that stem cells obtained from an older individual is still useful.


ENOUGH FROM THE SOURCE?

Thirdly and curiously, I wondered where the stem cells would be harvested from in these patients. One has to bear in mind that marrow stem cells are usually collected by puncturing the hip bone. Hence, if these patients are already having their second hip replacement, there can't be much left after all the inflammation and debris to harvest. This might provide the reason why stem cell isolation and growth in the lab becomes an important factor.

The number of stem cells infused needs to be optimal in order for the healing to accelerate and outpace the degenerating tissue, by signalling the required repair factors. I would be most interested to know what that optimal number might be in these cases.



*An renown South African orthopaedic surgeon that I spoke to recently told me that at a recent medical convention, he asked the audience (all doctors) who would undergo and prefer a prosthesis vis-a-vis a natural joint. The answer? Nobody raised their hands for a prosthesis.

Verdict: 100% of doctors themselves would opt for a natural method of joint salvage than have a prosthesis inserted.


If you'd like to watch a hip replacement procedure, here's one I found which gives you an idea of what happens but is censored so that there is none of the gore...