Introduction. We report a single-centre, prospective, randomised study for pedicle screw insertion, by using a Computer Assisted Surgery (CAS) technique with three dimension (3D) intra-operative images intensifier versus conventional surgical procedure. Methods. 143 patients (68 women and 75 men) were included in this study. 72 patients underwent conventional surgery (C = conventional). 71 patients were operated on with the help of a 3D intra-operative imaging system (N = navigated). We performed 34 percutaneous surgeries in group N and 37 in group C; 25 open surgeries in group N and 35 in group C. 382 screws were implanted in group C and 174 in group N. We measured the pedicle screw running-time, and surgeon's radiation exposure. All pedicle runs were assessed according to Heary's classification by two independent radiologists on a post-operative CT. Results. 3D Fluoro-navigation appeared less accurate with percutaneous procedures (24% of misplaced pedicle screws versus 5% in Group C) (p=0,007), but more accurate in opened surgeries (5% of misplaced pedicle screws versus 17% in Group C) (p=0,025). In this study, 3D-fluoroscopy navigation increases the instrumentation time, with a strongly higher radiation rate. Conclusion. Therefore, our work hypotheses are partially confirmed according to the type of analysed criteria

Introduction We performed an audit of tunnel position in primary anterior cruciate ligament reconstructions performed by two surgeons at a single centre. The audit cycle was opened with a retrospective review of a cohort of patients in order to establish existing surgical practice. Following this review our practice changed with the use of intra-operative image intensifier to confirm tunnel positions. The audit loop was closed with a prospective study of a second cohort of patients undergoing surgery using the new technique. Results Twenty five patients were reviewed in each group. The case-mix for the two groups were similar with regard to age, sex, side, graft selection and surgical technique. The first cohort of patients had optimal tibial tunnel placement in 56% (sagittal) and 88% (coronal) of cases. The femoral tunnel was correctly positioned in the sagittal plane in 52% of patients. The second cohort, in which an intra-operative image-intensifier was used, had optimal tunnel position for the femur in 100% of cases and for the tibia (sagittal) in 48% of patients. Conclusion In this study we have shown that the use of an image intensifier, intra-operatively, greatly improved femoral tunnel position but had no significant effect on tibial tunnel placement. We have also demonstrated that audit is effective in improving clinical practice