Computer Navigation for Pediatric Femoral ACL Tunnel Placement

To compare accuracy, time and radiation exposure of pediatric femoral tunnel placement using computer navigation with a traditional freehand technique.

A single all-epiphyseal femoral tunnel was placed in the distal femur of 20 Sawbones™ adolescent knee models. Ten tunnels were drilled using standard fluoroscopic guidance (FG). An additional 10 tunnels were drilled using 3D fluoroscopic computer navigation (CN). Both techniques aimed to match an exact point described by the quadrant system of Bernard. Time to perform the procedure was recorded as were number of single shot fluoroscopic images and approximate effective radiation doses.

The deviation from ideal femoral tunnel position was on average 6.4 ± 4.2 mm for FG tunnels and 2.7 ± 3.1 mm for CN tunnels (p<0.05) . There was no violation of the femoral growth plate using either technique. The surgeon was exposed to 17 ± 5.3 and 3 ± 0.66 single fluoroscopy exposures for FG and CN guidance, respectively (p<0.05). However, the effective dose for the CN because of the acquisition of 3D images was 0.52±.003 mSv and for FG was only 0.09mSv ± .027 (p <0.001). CN however required on average 12.5 ± 3.4 min compared to 4.6 ± 1.7 for FG (p<0.05) to complete drilling of the tunnel.

CN achieves a more accurate epiphyseal femoral ACL tunnel position but requires more time to complete and has a higher effective radiation dose than FG. Whether the CN ACL tunnels can translate to improved clinical outcomes is still unknown.Level of Evidence: V.