A pioneering knee operation for arthritis sufferers which can halve recovery times has been developed, surgeons say.
The technique, known as bicompartmental knee resurfacing, involves replacing only the areas of cartilage affected and avoids removal of the ligaments.
This enables more natural movement immediately after surgery.
Professor David Barrett, a consultant orthopaedic surgeon at Southampton General Hospital, was the first in the UK to perform the procedure and said the early intervention gave patients a chance to extend the lifespan of their knee, as a total replacement could be used if needed in the future.
He said: "While total replacements, which can last for up to 20 years, have always been and remain a suitable option for people over 65, they can wear out much faster in younger, more active patients but, until recently, there was no alternative for them.
"Now, with increasing numbers of people in their 40s and 50s needing treatment, we are able to offer an alternative which extends the lifespan of their knee and allows them to make a quick return to daily and sporting activities - with the option of total replacement further down the line if required."
More than 70,000 knee replacements are carried out in England and Wales each year and, while the majority of patients are over 65, the biggest increase has been among those in their 40s and 50s.
Traditional replacement surgery to treat arthritis, which develops in the knee when cartilage protecting the end of the thigh and shin bones wears out, requires a large incision, removal of all four ligaments and full replacement of the joint regardless of the extent of damage.
However, using resurfacing, only the ligament on the inside of the knee and the kneecap are affected when a surgeon removes sections of damaged cartilage and replaces it with plastic or alloy metal implants.
The procedure, which is performed under general anaesthetic and takes about an hour, sees patients leave hospital after three days - less than half the time it takes after total replacement - without crutches, which would be required for up to six weeks following full surgery, according to a spokesman for the Hampshire hospital.