Navigation in ACL reconstruction - comparison with conventional measurement tools.

Restoration of rotational and translational stability is a goal of ACL reconstruction. Intraoperative instability measurements of AP translation and rotation are not well established clinically. We compared navigated measurements of tibial AP translation and rotation with mechanical measuring devices: the KT 1000 and a modified goniometer tool. Tests were repeated with intact and dissected ACLs, and measures of translation and rotation statistically compared. There was no significant difference in AP translation between navigation, 3.2 mm (range 1-6 mm) and the KT 1000, 4.8 mm (range, 4-7 mm) in our experimental set up (p>0.05). Tibial rotation revealed no significant difference, 0.12 degrees (range, 0 degrees -1 degrees ) between navigation and goniometer (p>0.05). Total range of rotation was 4.2 degrees (range, 2 degrees -6 degrees ) in intact and 7.05 degrees (range, 4 degrees -9 degrees ) in dissected ACLs (p<0.05). Stability parameters in ACL navigation can be measured precisely under laboratory conditions and results are not significantly different from mechanical testing devices.