Doctors helping patients with hip replacements face a special problem. The use of some types of hip sockets can lead to bone loss around the implant. For instance, designs that have metal backing in the hip socket and that are not implanted using cement have a tendency to loosen round the implant. Too much bone loss causes the implant to come loose.
Doctors know they need to monitor these patients closely. But there’s no reliable way to measure the amount of bone loss. Often the patient has no symptoms, and it’s too late before the doctor finds the problem. The patient may end up in surgery again.
A major revision operation is expensive and complicated. X-rays to show bone loss around the implant aren’t accurate. CT (computed tomography) scans are affected by the metal, which can cause errors when the images are read.
A new kind of CT scan to measure bone loss is being studied. It’s called spiral CT scanning. This study reports that spiral CT scans allow a precise and reliable measure of metal-backed hip implants. Researchers used special computer software to reduce the extra signals that were showing up in a regular CT scan.
The use of this method to measure amount of bone loss is still in the experimental phase. It has only been tested on animals and cadavers (human bodies preserved for study after death). Still, it’s a very promising start.