Deformity surgery is planned using the CORA method. The Taylor Spatial Frame^¯ is a six-axis deformity correction device in which this method can be put to use through the web-based software. Until recently there was no way of planning the correction with a computer. This was done with standard radiographs with the help of pencils, rulers and protractors or a linefinder^¯. Orthocrat^¯ has developed a piece of software that can plan the deformity correction from 2 orthogonal radiographs which can be imported into the computer via a PACS server as a DICOM image or as a JPEG. A Taylor Spatial Frame was programmed with a 5 degree valgus angle, with and without using the web based software in a chronic deformity mode of correction. The deformities were then analysed on paper with a linefinder and with the SpatialCAD^¯ software. The measured deformities were programmed into the web-based software in Total Residual Mode. The final frame configuration was then established based on the initial frame parameters. The programming based on the SpatialCAD^¯ software gave a more accurate result than the linefinder technique.

The SpatialCAD^¯ software is a useful tool for the planning of deformity correction with the Taylor Spatial Frame^¯. It is especially useful when the frame is mounted off the orthogonal axis of the limb or the frame is radiographed out of the plane of the reference ring. Interestingly the results showed that the accuracy of the deformity correction was much better when radiographs were taken in the plane of the reference ring using SpatialCAD, whereas the deformity correction was no more accurate with the linefinder method when comparing planar and non-planar radiographs.

Background

Paediatric pelvic corrective surgery for developmentally dysplastic hips requires that the acetabular roof is angulated to improve stability and reduce morbidity. Accurate bony positioning is vital in a weight-bearing joint as is appropriate placement of metalwork without intrusion into the joint. This can often be difficult to visualise using conventional image intensifier equipment in a 2D plane.