Indications for computer-aided navigation are knee ligament reconstructions where accuracy and precision are desired. My preference is to use navigation in almost every case. Particular situations in which navigation is useful include:

Relative contraindications for computer-aided navigation are situations where there is an inability to palpate and register intra-articular landmarks accurately, or when kinematic data are unable to be obtained. The result would be potential errors in parts of the navigation; however, some of the data will remain useful. Caution should be used when there is significant bony loss or inability to obtain consistent flexion-extension data. When used in cases of multiple ligament injury, it is critical to keep the tibia reduced on the femur during acquisition of data. If this cannot be accomplished in the grossly unstable knee, the projection of the intercondylar notch on the tibia (impingement screen) will be incorrect, and the isometry data will also be incorrect.

Reflective balls are attached to the tibial, femoral, and instrument trackers, and the trackers are then placed in a secure location on the back table. The surgeon’s preferred graft type is harvested and prepared as usual. Data regarding the type of graft and size of graft are input into the computer. The computer is carefully positioned opposite the operative leg toward the foot of the bed with the camera facing the operative site (Fig. 25-1). Two stab incisions are made in the distal tibia, and two unicortical K-wires are placed into the tibia distally to avoid the tibial tunnel site (Fig. 25-2). Arthroscopy fluid can be used to irrigate and cool the K-wires as they are drilled in to the tibia. A pin clamp is attached to the K-wires and the tibial tracker is then attached to the clamp. Two K-wires are then drilled into the medial epicondyle, and the femoral tracker is attached to a clamp attached to the pins. I prefer to place the femoral tracker in an area with relatively less soft tissue motion to avoid stress on the pins.