Hi-tech healing breakthrough cuts to the bone

RICHARD GRAY
rgray@scotlandonsunday.com

TECHNOLOGY used in electric toothbrushes will dramatically cut the recovery time for patients with broken bones, returning them to a fully active life in half the time it takes at the moment.

Engineers at Edinburgh University have developed an implant, smaller than a battery watch, that can be placed against a fractured bone to deliver a minute electrical current which encourages bone growth.

The revolutionary device can be regularly recharged using a magnetic field to transfer energy to the battery without wires, in the same way modern electric toothbrushes are charged.

"It is a well known fact that if you apply an electrical current to bone it helps it heal faster," said Professor Joe McGeough, who is leading the team at the university’s bio-engineering department.

"The problem that has been faced before is the battery wears out and any stimulation it gave is then terminated.

"The only way around this was to have wires coming from the implant, sticking out of the patient’s body, to allow it to be recharged.

"Obviously this made them very unpopular and most doctors did not like the idea.

"Our approach was to take technology that is already available through rechargeable batteries and wireless technology to produce a small device that could be put inside the body. This way the battery can be recharged from outside the body using this wireless technology."

The device uses magnetic inductive power transfer to recharge its battery - a method presently used to charge batteries sealed inside electric toothbrushes and shavers.

An electromagnetic field forms around the charger, which produces an electrical current in the device when it is brought into range.

McGeough added: "It saves the need to have physical contact between the charger and the device itself, and so can be done through layers of skin."

It usually takes a healthy adult around six weeks to recover from a broken arm and around 12 weeks to heal a broken leg.

Some studies have shown electrical signals supplied to broken bones can reduce the length of time by up to three weeks. By surgically implanting the device doctors can pinpoint the signal from the device on to the fractured area.

The signal mimics the body’s own natural electric field produced when it wants bones to grow. The device needs to be surgically implanted to ensure there is contact between the two ends of broken bone.

Doctors will be able to monitor the rate of growth between the two ends and recharge the battery when necessary.

Electrically stimulated bone healing is usually used only in severe breaks and spinal injuries, where the body has difficulty healing itself. Each stimulator needs an attached wire to come out of the patient’s body.

But McGeough claims his device could be used in less serious fractures to help reduce the amount of time patients spend in plaster.

He said: "Bone is a material that is piezoelectric, which means it produces an electrical current when under load, for example when you jump up and down. This current stimulates cells in the bone which help it to grow and increase its density.

"Using this implant accelerates the amount of these bone cells at an area that is fractured by making the bone think it is getting exercise." The Edinburgh University team are currently waiting for their device to be patented and are in talks to develop it for clinical trials.

Michael Sommers, the chairman of the Patients Association, hailed the breakthrough. He said: "We really welcome this development and the breakthrough in the technology. The scientists at Edinburgh have made a remarkable breakthrough which should be of great help to patients.

"This is extremely beneficial and we hope the publication of their research will lead to these devices being made available for patients both north and south of the Border."

But some orthopaedic experts are sceptical about the effect electric fields have on the rate of bone healing.

Professor David Rowley, an orthopaedic surgeon at Dundee University, warned it might only help those who have poor rates of bone healing.

He said: "Large groups of people strongly believe this can work, but it is by no means fully accepted. Bone uses a series of complicated chemical and electrical signals to promote its growth, and it is all about the timing of these.

"If you are looking at speeding up normal bone healing then it will probably have little effect. Those who have slow bone healing, like smokers, could benefit as it will speed up their bone growth."

He added: "One thing this device could do is answer the question about the impact electrical stimulation has on bone healing by allowing clinical trials to take place."