The future of hip replacements: cartilage grown from stem cells in your fat

There are around 80,000 hip replacements performed every year in the UK to address the pain and lack of mobility that results from cartilage and bone degeneration, yet hip replacements fashioned from metal, polyethylene or ceramic have an expiry date. Now, new research is focused on regenerating cartilage using stem cells.

Why do you need a hip replacement?

The hip is one of the largest, most flexible and weight-bearing joints in the body and, after the knee and hand, is the third most likely joint in the body to be affected by osteoarthritis. Our bones are covered with a tough, flexible substance called cartilage that allows them to move smoothly against each other, but over time this cartilage can wear down, causing the bones to rub against each other. Pain, stiffness and lack of mobility result and eventually this can severely limit your ability to perform normal, daily activities.

During joint replacement surgery, any or all of the joint can be replaced with artificial parts that are composed of metal, plastic or ceramic. However, an alternative approach is to regenerate the damaged cartilage, avoiding the need for joint replacement surgery.

Recently, scientists at Washington University in the US, led by Professor Farshid Guilak have extracted stem cells from adipose or fat tissue left over from liposuction. These stem cells are known as master cells because they are able to turn into different types of tissue as required by the body. The stem cells were placed on a circular frame which could fit over the ball of a hip joint. A cocktail of proteins was used to transform the stem cells into cartilage cells and, over a period of just six weeks, a thin layer of living, healthy cartilage tissue grew over the frame.

The cartilage is grown in a ‘weaving pattern’ that ensures the implant is strong enough to bear ten times the body’s own weight. Furthermore, gene therapy was utilised, causing the cells to release anti-inflammatory molecules which can help fight arthritis. At the moment, the living tissue implants are being tested on animals, with human trials expected in three to five years’ time.

Hip replacements and the young

A dodgy hip is seen as one of the costs of getting older, but figures released by the NHS earlier this year found that the number of hip replacements in the under-60s has risen by 76% over the last decade.

Partly this is due to improvements in surgical techniques that makes the procedure and recovery less arduous and technological advances in the prosthetic materials used. Previously, replacement joints had an expected lifetime of 15 years meaning revision surgery would be a must if performed at a young age. Newer prosthetics can now expect to last 20 years or more.

The figures from the NHS showed that the increase in hip replacements in the younger age group only reflected an overall increase across all age groups. With an ageing population, joint replacement surgery will only continue to rise, but as this new research indicates the future could be joint repair rather than replacement.

Professor Cathy Speed’s academic interests include regenerative medicine in joint disease. To arrange a consultation at her Arthritis Clinic at the Progress Clinic in Cambridge, call 01223 200 595.