By Melissa Jackson
BBC News Online health staff
An award-winning surgeon who helped pioneer the world's first bionic leg bone for children says Britain is the global leader in developing prostheses for young people with bone cancer.
Bionic boy James Gregory
The device allows doctors to lengthen the leg remotely as the child grows taller, removing the need for surgery.
Although specifically designed for child bone cancers, it has huge potential for other conditions affecting children, says orthopaedic surgeon Tim Briggs.
Bone cancer in children is rare, but usually occurs in the femur - the bone in the leg that extends from the hip to the knee.
Treatment requires drastic surgery to remove the tumour and the growth plate in the knee joint and replace the affected bone with a metal prosthesis.
But as the child grows in height, the device needs to be extended or they would have one leg shorter than the other.
Up until about 18 months ago, this required several operations as the child grew, to turn a screw in the prosthesis, which in turn extended the implant.
This meant further stays in hospital, risk of infection, pain and stiffness, increased cost and disruption to family life and schooling.
The "revolutionary" bionic prosthesis, which was six years in the making, enables the extension to take place at an out-patient appointment.
During the procedure, which takes about 15 minutes, the leg is placed through a special electromagnetic device.
The device is activated and the implant is extended by a specified amount.
The procedure takes about 15 minutes and the patient experiences no pain or discomfort and is free to go home immediately after the treatment.
The "growing prosthesis", also knows as the "bionic bone", was developed by Tim Briggs and Jay Meswania from the Royal National Orthopaedic Hospital (RNOH) in Stanmore, Middlesex and a team at University College, London.
Mr Briggs told BBC News Online, "In treatment for bone cancer using metal prostheses in children, we lead the world and it has all been developed at Stanmore.
Extension of the implant takes just 15 minutes
"This device has revolutionised care for these patients.
"Before this they might have required seven or eight operations.
"I think it has got huge potential.
"We are now working on Mark 2 - a smaller version.
"This will help children with leg-length discrepancy and we hope to treat children with curvature of the spine.
"At the moment we can straighten the curve, but it is a major surgical procedure, involving two operations.
"Using this type of device, we could do just one operation and the adjustments would be carried out as an out-patient.
"We are developing it at the moment, but it is probably another five years away."
The first growing prosthesis was fitted at the beginning of 2003 and since then another eight children with bone cancer have benefited from the procedure.
The aim is to increase that number to 20 or 30 operations per year.
The third recipient of the bionic bone is teenager James Gregory, who was treated in April 2003 after developing bone cancer.
He said: "I was very frightened by everything that was happening and was not looking forward to having an operation.
"When I had got better from the operation I was glad that I would not have to have another operation to make the implant longer."
The bionic bone inventors were recently presented with the National Health and Social Care Award for the Best Innovative Device to add to their BUPA Medical Futures Best Innovation in Child Health award last October.