ACL-X -- The Smartphone App for ACL Surgery!

This App was developed for knee surgeons performing anterior cruciate ligament (ACL) reconstruction and using intraoperative fluoroscopy to increase precision of bone tunnel placement.

By means of supporting lines that you can overlay virtually over the X-ray photograph in the app, the app can calculate the relative distance of the target point for the k-wire for a femoral or tibial surgery.


In the medical literature, femoral measurement of a radiographic image is known as quadrant method by Bernard and Hertel. It may help knee surgeons identify the ideal position for bone tunnel placement during ACL reconstruction.

During the operative procedure, place a guide wire (or the tip of an microfracure awl) into the center of the femoral insertion area using your standard operative set up. Alternatively, you may may advance the k-wire in the center of the projected bone tunnel forward penetrating the skin on the lateral side of the femur so the end of the wire is flush with the femoral cortex of the insertion.

The app will display the relative ratio of your target point in reference to the outlines of the bone of the femoral condyles. The measurement values relate to the relative distance of the target point of the most posterior and proximal border of the condyles.


Tibia measurement of a radiographic image has been described by Stäubli und Rauschning. It may help knee surgeons identify the ideal position of the tibial bone tunnel during ACL reconstruction.

Place a guide pin into the center of the projected tibial bone tunnel using a drill guide in a normal fashion. The guide pin may intrude the joint beyond the cortical edge of the ACL footprint.

This app will display the relative distance (in percent) of the entry point of the guide wire into the joint in relation to the total anterior posterior (AP) distance of the proximal tibia (100 %).