Precision of ACL tunnel placement using traditional and robotic techniques

The objective of this study was to examine the precision of ACL tunnel placement using: (1) CASPAR (orto MAQUET GmbH Co. KG)--an active robotic system, and (2) four orthopedic surgeons with various levels of experience (between 100 and 3,500 ACL reconstructions). The robotic system and each surgeon drilled tunnels for ACL reconstruction in 10 plastic knees (total n = 50) that included a reference cube in the medial aspect of the proximal tibia and distal femur. For the robotic system, the placement of each tunnel was planned preoperatively using custom software and CT data for each femur and tibia. The robotic system then drilled the tunnels in the femur and tibia based on the preoperative plan. For the surgeons, tunnel placement was accomplished using their preferred technique, which was based on the one-incision arthroscopic technique. The distribution of intra-articular points on the tibia was contained within a sphere of radius 2.0 mm (robot system), 2.1 mm (Fellow 1), 2.4 mm (Fellow 2), 3.4 mm (Experienced Surgeon 1), or 2.0 mm (Experienced Surgeon 2). On the femur, no significant differences in the distribution of intra-articular points could be demonstrated between the robotic system (2.1 mm), Fellow 1 (4.5 mm), Fellow 2 (4.1 mm), Experienced Surgeon 1 (2.3 mm), and Experienced Surgeon 2 (3.0 mm). The direction of the tunnels drilled in the femur and tibia was different with the robotic and traditional techniques. However, the robotic system had the most consistent tunnel directions, while the surgeons' tunnels were more dispersed. Variation in surgeon precision of tunnel placement for ACL reconstruction is greater on the femur than the tibia, and this can be correlated with experience. Our data also suggest that the robotic system has the same precision as the most experienced surgeons.