Britain is facing a "tsunami" of pain as the number of osteoarthritis cases soars in the future, a leading expert has warned.

Increased life expectancy and rising levels of obesity mean osteoarthritis cases are set to double to more than 17 million by 2030, the charity Arthritis Care has predicted.

The warning was made after a survey commissioned by the charity showed 71 per cent of the UK's 8.5 million osteoarthritis (OA) sufferers are in some form of constant pain and one in eight describes the pain as often "unbearable".

Philip Conaghan, professor of musculoskeletal medicine at the University of Leeds, predicted that millions more people would soon be affected by the joint-related illness because of an ageing population and a growing obesity problem.

"Britain is facing a tsunami of pain due to osteoarthritis as the number of people over 50 increases dramatically and obesity levels continue to rise," he said.

"Action is needed immediately - we have to bust this myth that painful joints are an inevitable part of getting older that we have to put up with."

The online survey of 2,001 people with osteoarthritis, conducted between November and December last year, found the average age of diagnosis was 57 but as many as one in five are now being diagnosed aged younger than 45.

People with osteoarthritis - which most commonly affects the hips, knees and hands - face £2.6 billion in extra costs a year as a result of paying for medical prescriptions, heating bills and transport costs, the research found. One in five have had to give up work or retire early because of their symptoms.

Just over half of those questioned - 52 per cent - said they had given up or reduced walking since being diagnosed with the condition and 44 per cent said they did no exercise at all, in spite of expert advice that exercise is one of the best treatments for the illness.

Professor Conaghan said: "It's frustrating that this survey reveals many people become less active when diagnosed with OA, when all the clinical evidence available suggests this is the worst thing you can do because keeping moving can actually strengthen joints and improve symptoms.

"We have to make sure that patients get better information and advice about this."

He added: "There are so many ways to help with osteoarthritis pain including taking pain relief medication, strengthening muscles, taking aerobic exercise, losing weight if appropriate and, in the worst case scenario, joint replacement surgery - so it's by no means all doom and gloom."

Liam O'Toole, chief executive of Arthritis Research UK, said: "We welcome this report.

"The increasing burden of osteoarthritis is exactly the reason we have continued to increase our research funding into this disease over the last few years.

"An ageing and obese population will have an increasingly dramatic effect on the levels of osteoarthritis but as the UK's biggest funder of research into the cause, treatment and cure of arthritis, we know that the real difference will come from scientific breakthroughs."