Abstract
Background
Using digital X-rays to plan a hip replacement can cause problems with sizing and templating the prosthesis. Using an AP view of both hips is desirable as this allows the use of the sometimes unaffected contralateral hip for templating.
Method
We devised a method of using a 20mm ball bearing as a marker positioned at the same depth as the greater trochanter, but between the patient's legs. Placing the marker between the patient's legs avoids the problem of the marker disappearing off the side of the X-ray, as is seen when placing the marker at the side of the obese patient. The marker is then used to calibrate the size of the digital X-ray. We used a hundred consecutive post-operative X-rays, comparing the size of the head of the femoral prosthesis used at surgery with the size measured pre-operatively using the marker.
Results
There was a mean difference of 0, 3 mm between the size predicted using the marker and the actual prosthetic head used.
Conclusion
This is an accurate and repeatable method of calibrating a digital X-ray to measure the required size of a prosthesis.
NO DISCLOSURES
