A thigh 'tingler' is the latest treatment being developed for arthritic knees. Researchers say the device could be an alternative to knee-replacement surgery for younger people with osteoarthritis - and it could also be used to delay the need for surgery in others.
The device works by electrically stimulating the muscles around the knee - this reduces the pain and helps strengthen the muscles, taking some of the load off the joint and increasing movement.
Up to seven million people in Britain have long-term health problems linked to arthritis; the Arthritis Research Campaign estimates that more than 550,000 men and women have moderate-to-severe disease of the knees.
With osteoarthritis, the cartilage that cushions and protects the bone gradually wears away, leading to the painful rubbing of bone on bone in the joints. This can occur in people as young as 30, although it generally affects the over-50s.
Risk factors include age, being overweight, previous joint injury and a family history of the disease. Many sufferers eventually need a knee replacement - more than 60,000 are carried out per year.