Abstract
The Ilizarov frame is a circular external fixator, invented by Professor Ilizarov in Siberia during the 1950’s. It uses the principle of distraction osteogenesis to form new bone in a variety of clinical situations where bone lengthening or realignment is needed. The Ilizarov frame began to be used in western medicine during the 1980’s and by 1993 over 6000 cases had been performed in Europe.
Plain x-ray is one of the methods used to monitor the progress of patients fitted with an ilizarov frame.
The aim of this study is establish a pattern of healing over time in patients with the Ilizarov frame using plain x-ray films. This will improve understanding of the procedure, aid clinicians in deciding when frame removal is appropriate and provide a method of early detection should healing not be progressing appropriately.
This is a retrospective study looking at a series of 58 digitised anterior-posterior x-ray films of the tibia and fibula, taken at set time points post-operatively, from 17 patients fitted with an ilizarov frame (19 separate legs with ilizarov frames in total). Image J, an image analysis system, was used to measure pixel density from vertical slices down the centre of each fracture gap and at set intervals horizontally across the fracture gap. A mean pixel density value for each fracture gap was also calculated. The x-rays were standardised using a standard step wedge.
Promising preliminary results show pixel density to be greater towards the medial aspect of the tibia, but this difference in pixel value decreases with time. This suggests that calcification of the new bone occurs medially to laterally across the tibia. Full results will be available in April and aim to build a picture of the fracture gap at set time points post-operatively, showing a pattern of calcification in patients with the Ilizarov frame that will become a useful clinical tool for deciding time of frame removal as well as affording early knowledge of problems with the healing process.
Correspondence should be addressed to Mr Carlos Wigderowitz, Senior Lecturer, University Department of Orthopaedic and Trauma Surgery, Ninewells Hospital and Medical School, Dundee DD1 9SY.
