Purpose: Several studies have reported results of anterior cruciate ligament (ACL) reconstruction showing the influence of the position of the transplant. We choose the anatomic position. In order to optimise this position, we developed a navigation system using intraoperative fluoroscopic imaging.

Material and methods: Thirty-five patients underwent ACL reconstruction using the computer-assisted technique. We used a fluoroscope connected to the computer equipped with an acquisition module and an image processing module which captures the lateral view of the knee provided by the fluoroscope. Surgery was performed arthroscopically. After inserting landmarks (mini-screws for the femoral end and pins for the tibial end) on the theoretically ideal positions, the computer determined the theoretical anatomic position of the tibial and femoral insertions of the ACL. The position was then validated or modified and re-validated. Postoperative radiograms (lateral view of the knee) were used to analyse the position in relation to the anatomic centre of the ACL insertion. Two groups of patients matched for sex and age were compared, 35 patients undergoing ACL reconstruction with the navigation technique versus 35 patients undergoing the same procedure without navigation. Results were compared with the nonparametric Wilcoxon test.

Results: Computer-assisted positioning provided a mean difference of 5.1±1.3 mm between the centre of the transplant and the theoretical ideal point compared with 7.7±1.9 mm without assistance.

Discussion: Comparison using adapted statistical tests (Wilcoxon text) demonstrated a significant difference (p=0.001) between the two groups. These findings demonstrate the improved precision and reproducibility achieved with the navigation technique.

Conclusion: This technique allows the surgeon to obtain an excellent precision of the transplant insertion with excellent reproducibility. There are two drawbacks: the longer operative time (mean 15±7 minutes) and radiation exposure. But this technique is simple, easy to use and low-cost.