The bulletproof vest that saves arthritic ankles
AN ARTIFICIAL ankle made from the plastic fibres used in bulletproof vests is helping those with painful joints to walk pain-free again. The implant, given to those with osteoarthritis, is expected to last much longer than current replacements.
Called Rebalance, its secret is a tough plastic called polyethylene made with Vitamin E – a nutrient found in broccoli, nuts and avocado. The vitamin stops plastic breaking down once inside the body, a common problem with some types of implants.
Manufacturers of bulletproof vests and artificial hips have been adding it to their products for more than a decade with impressive results. Now the same technology is being applied to synthetic ankle joints to make them last longer.
About 30,000 people a year need surgery for osteoarthritis of the ankle, where cartilage wears out and patients suffer agony as bones rub together. But only around 1,200 are offered replacement joints. Others have fusion surgery, where the bones of the joint are screwed together to keep it stable. This banishes pain but leave ankles permanently stiff, making it harder to climb stairs or run.
However, many artificial-joint recipients need another one within ten or 15 years. As a result, NHS surgeons are generally reluctant to implant them in those under 65.
It is hoped the new type of implant will boost the numbers receiving replacement joints.
The problem with current products is that tiny pieces of the plastic lining the outside of the implant break off after reacting with oxygen molecules – called free radicals – inside the body. This causes the plastic to rot in much the same way as rust destroys a car. Loose fragments then wear
away surrounding bone, loosening the implant and making it harder to carry out a later replacement.
US scientists discovered ten years ago that bathing the plastic with liquid Vitamin E meant it lasted years longer by reducing the rate of wear and tear by 85 per cent. The vitamin protects the plastic joint by mopping up free radicals before they do any damage, and now surgeons who have been using Vitamin E-enhanced hip and knee joints for several years are turning to ankles.
Professor Nick Harris, consultant orthopaedic and trauma surgeon who has performed the surgery at Spire Leeds Hospital, says: ‘There is an 80 to 90 per cent chance at present that an ankle replacement will last for just ten to 15 years. The use of Rebalance may improve this.’
During the hour-long procedure under general anaesthetic, surgeons make a 6in-long vertical incision on the front of the ankle. The next step is to cut away any leg bone that has been damaged, replacing it with hollow metal implants, hammered into place.
These implants are designed to stimulate growth of the patient’s own bone cells, so they eventually engulf the metal parts.
The top of the ankle bone – the talus – is also removed and replaced with metal, as it is usually damaged from osteoarthritis too. These metal parts are covered with the hardwearing plastic implant and the foot is sewn up, before being encased in plaster to aid recovery.
Patients have regular physiotherapy and wear a supportive boot for six weeks.
Neil Shuttleworth, a retired printing specialist from Huddersfield in West Yorkshire, was one of the first patients in the UK to receive the Rebalance ankle. Despite a highly active lifestyle, including cycling across Europe, the grandfatherof-seven and great-grandfatherof-two was left barely able to walk more than a few hundred yards due to pain in his ankle.
Problems began when he stepped into a pothole while on holiday in Cyprus several years ago and tore ligaments. The pain worsened steadily over the years until it became unbearable due to boneon-bone contact. Neil, now 81, took regular doses of painkillers to keep the agony at bay. ‘I knew I had to do something about it,’ he says. ‘My condition had become intolerable. I had virtually no cartilage and the pain was agonising.’ Prof Harris told him that ankle fusion was a tried-andtested remedy but took months to recover from. Joint-replacement was less common but with a speedier recovery time of a fortnight or so.
Neil opted for privately funded joint-replacement, and in January 2018 he had the ankle implanted.
He says: ‘When my surgeon asked what I expected from the operation, I said I would like to walk along a promenade with my wife Christine, eating ice cream, and be pain-free. We did it and I got a photo and sent a copy to my surgeon.’
He adds: ‘The implant is very flexible and means my ankle moves naturally. I can still bend my foot up and down instead of being fixed.
‘I’m looking forward to a long, active and pain-free life.’
I just wanted to stroll pain-free along the prom with my wife, eating an ice cream