The application of a computer-assisted thermoplastic membrane navigation system in screw fixation of the sacroiliac joint - A clinical study

BackgroundWe inserted iliosacral screws with the aid of a computer-assisted thermoplastic membrane navigation (CATMN) system which is widely used for the accurate and repeatable location tumour in radiation therapy. We hypothesised that application of the CATMN system on IS screws' insertion will provide a superior result to conventional fluoroscopic imaging with less operative time, more accuracy and lower complication rates.MethodsWe prospectively evaluated 26 consecutive patients who suffered from sacroiliac joint fractures and dislocations (type C, Tile classification) from April 2007 to June 2010 in our hospital. Patients were randomised into two groups: 13 patients in control group and 13 patients in CATMN groups. After operation, inlet and outlet X-ray views and computed tomography (CT) scanning were performed to confirm and compare the screw positions. The operative time, blood loss and accuracy (measured with postoperative CT) were analysed between groups.ResultsIn the control group, 18 screws were placed in 13 patients with conventional fluoroscopic technique; two of 18 (11.1%) screws were misplaced. The average intra-operative blood loss was 145.4 ± 112.0 ml, and operation time was 619.2 ± 199.5 s. In the CATMN group, 21 screws were placed in 13 patients with the application of the CATMN system. All 21 screws were in safe zones. The average intra-operative blood loss was 46.2 ± 24.3 ml and the operation time was 353.8 ± 111.2 s. Operative time and blood loss were reduced significantly with the CATMN system (p < 0.05).ConclusionApplication of CATMN system has high accuracy in treating sacroiliac joint dislocations and provides a new alternative method for guidance of the IS screw placement.