Preoperative computerized radiograph measurement of Blumensaat's line as an aid to correct placement of the femoral tunnel in ACL reconstruction.

Numerous studies have shown that the improper placement of the graft in anterior cruciate ligament reconstruction is a major cause of graft failure, capturing of the knee, and notch roof impingement. The ideal femoral position is located in the posterior one quarter of Blumensaat's line as seen on a true lateral knee radiograph. We present a simple method that relies on the use of preoperative radiographic measurement and a calibrated guide to ensure that the femoral tunnel is sufficiently far back along the roof of the notch, using the easily identifiable anterior end of the notch as a reference point.