At the tender age of 12, Zoe Pearson was already an accomplished athlete, good enough to represent her county at netball.
Zoe was a promising netball player
But a minor injury during a match was to spark a crippling condition that left her in agony and meant she spent most of her teenage years in a wheelchair.
Zoe had been struck down by a rare and complex syndrome called Reflex Sympathetic Dystrophy, also known as complex regional pain syndrome.
Extremely difficult to diagnose, it can cause such severe pain and swelling in the hands, wrist, ankles or knees that some victims have been known to resort to amputation just to ease their agony.
In Zoe's case, it took more than a year for doctors to pinpoint her problem.
"The problems started after I twisted my knee during a game," says Zoe, from Nottingham. "The pain that followed was excruciating and I ended up spending four-and-a-half years in a wheelchair."
Despite missing two years of school, 18-year-old Zoe is now preparing for her A levels in the summer and hopes to get a place in medical school.
Because RSD involves joint pain and swelling, it is closely related to other rheumatic and arthritic conditions. The Arthritis Research Campaign is therefore campaigning to raise awareness of it.
It claims some sufferers compare the pain from RSD to "putting their hand into boiling water┐and never being able to take it out".
But the exact cause of the condition remains a mystery. Although doctors know it can be triggered by a fracture or some other injury, they are baffled by why it only seems to affect some people and not others.
To complicate things further, RSD can also develop after heart attacks or head injuries, or even in people with no obvious trigger.
It's thought a group of special nerve fibres, called the sympathetic nervous system, are involved in RSD. This nerve system has several functions, including regulation of blood flow and skin temperature.
The area of the body affected by RSD is highly sensitive and simply stroking it can result in severe pain. It may also vary in colour and temperature from the rest of the body.
Although RSD can be treated, therapy must begin as soon as possible. The longer the symptoms are left, the harder it is to control the pain and swelling.
Specialists inject anaesthetic drugs to block the sympathetic nervous system, while physiotherapy can also help ease stiffness.
But the biggest problem is that many sufferers are left in agony because doctors write them off as healthy people who simply want attention.
"As well being a horrible condition, RSD is often not diagnosed and patients are written off as being mad or odd," says Dr Chris Spanswick, a consultant in pain management at Hope Hospital in Manchester.
"People get very angry and distressed as a result and this makes the whole situation worse. Some doctors believe RSD is driven by an abnormality in the nervous system, others that it is a psychiatric disorder.
"I believe the psychological problems are a consequence of the condition rather than driving it.'
Dr Spanswick is currently involved in a project - funded by the Arthritis Research Campaign - to study the mechanism behind the disease.
A separate study being carried out at Bristol Royal Infirmary - also paid for by the ARC - is looking at whether a simple course of vitamin C supplements could treat RSD.
Orthopaedic surgeon Andrew McBride is recruiting 300 patients who have suffered wrist fractures to assess whether vitamin C will prevent the painful condition.
The study is based on the theory that RSD may partly be caused by an inflammatory reaction, similar to that involved in rheumatoid arthritis.
"Previous research has suggested the inflammatory process may be sparked off by free radicals - molecules that damage the body's cells and tissues," says McBride.
"Countering these effects with vitamin C - an antioxidant which disarms free radicals - could be a very simple but effective way of helping people who suffer from this horribly painful condition."
An earlier, smaller study revealed that only eight per cent of fracture victims given vitamin C developed RSD, compared with 22 per cent in a group not given vitamins.
Zoe still occasionally has nerve block treatment but is living a near-normal life after discovering that regular sessions in a hyperbaric oxygen chamber helped her condition. She now has one installed in her garage at home and uses it almost every day.
"I haven't had to use my wheelchair since last April," she adds.