BACKGROUND
The Taylor Spatial Frame® is an external fixator used in the management of limb fractures and deformities (Smith and Nephew, 15 Adam Street, London WC2N 6LA, UK). Two rings are connected to the bone segments and are connected by six telescopic struts. These struts can then be adjusted and readjusted to correct complex deformities. Correction requires anterior-posterior and lateral radiograph to be taken in an orthogonal plane to the reference ring. Measurements of the deformity and frame position are determined from the radiograph and a computer program determines required strut lengths. In our unit, many radiographs were being taken not perfectly orthogonal to the ring, requiring numerous repeat radiographs. We have made a device that allows the radiographer to align radiographs orthogonal to the desired ring.
TECHNIQUE
A spirit level is attached to a standard bolt. This bolt is attached to the reference ring prior to the radiograph being taken (Fig. 1). The radiographer then aligns the limb until the spirit level shows the reference ring is orientated at 90° to the ground. A radiograph taken in the standard vertical direction will then be perfectly orthogonal to the reference ring. The X-ray beam is then rotated 90° to obtain the second radiograph, also orthogonal to the reference ring.
Figure 1.
The frame mounted X-ray guide.
DISCUSSION
This device is easy to manufacture and inexpensive to produce. Its placement on the desired ring assists the radiographer in producing perfectly aligned radiographs. It also makes it clear which ring the surgeon needs the radiograph centred on. In our unit, this has virtually abolished the need for repeat radiographs, reducing X-ray exposure and saving time for patients, radiographers and surgeons.