Internal fixation of femoral neck fractures assisted by bi-planar navigation robot system: an experi-mental study

Abstract

Objective To assess accuracy of inserting the cannulated screw guide pin and paral-lelism of implanting the screws with the assistance of an improved bi-planar navigation robot system. Methods In 12 synthetic proximal femoral bones, insertion of cannulated hip screws was simulated under navigation of an improved bi-planar robot system. After every 3 guide pins were inserted in each case, the accuracy of insertion was evaluated by direct measurement of the transverse section of femoral neck, and the parallelism was accessed by calculating an index from the angles measured on the AP and lateral views of X-ray film. A statistical comparison was made with the conventional surgeries. The frequency of intraoperative flu-oroscopy was also compared between the 2 operations. Results All guide pins were successfully inserted at one time. The measurement in the specimens revealed an error range of about 1 mm between the actual insertion site and the planned site. Statistical analysis of the screw parallelism index showed that the paral-lelism and operative stability in the computer-assisted navigation group were more satisfactory(P<0.05) than those in the conventional operation group. And the fluoroscopic frequency in the navigation group was also lower than that in the conventional operation group. Conclusion The improved bi-planar navigation robot system can effectively assist the fixation of the cannulated screws in the treatment of femoral neck fractures, because pin insertion can be more accurate, the parallelism of screws improved and the X-ray exposure reduced. Key words: Surgery, computer assisted; Femoral neck fractures; Fracture fixation, internal