Surgeons are using a new "longer-lasting" treatment for knee arthritis which involves injecting patients with a strengthened form of their own blood.

It is hoped the technique being trialled at Southampton General Hospital will provide a more effective alternative to steroid injections, currently the most common treatment.

Arthritis of the joints is known as osteoarthritis, the most common form of the condition in the UK, and osteoarthritis of the knees affects more than 4.7 million people, causing pain and reduced movement.

The study, led by Gorav Datta, a consultant orthopaedic surgeon at University Hospital Southampton NHS Foundation Trust, involves 60 patients aged between 18 and 75.

He said: "Arthritis in the knee is very common and a large proportion of patients suffer from knee pain that may not be bad enough for surgery but can require painkillers or regular steroid injections.

Osteoarthritis of the knees affects more than 4.7 million people, causing pain and reduced movement

"The negative effects of steroid injections, however, are that they do not last for long - usually a matter of weeks - and that repeated injections may cause further joint surface damage. "Through the development of this new customised treatment, using hyaluronic acid combined with platelet-rich plasma taken from each individual, we are hopeful of achieving longer-lasting pain relief with better knee joint function without the need for steroid injections."

The treatment sees researchers take a 4ml sample of each patient's blood which is then spun in a centrifuge. This enables the team to separate platelets - which contain hundreds of proteins known as growth factors that help to heal injuries - from the more common red blood cells to enhance their concentration and power.

Once separated, the platelet-only blood is mixed with hyaluronic acid, a substance similar to one that appears naturally in joint fluid and has been used on its own as a treatment for knee arthritis for the past 10 years.