Purpose: The goal of this study was to determine the femoral tunnel position by use of the head of a metallic femoral interference screw as a reference marker. In addition, we present postoperative films from an anatomically placed single-bundle anterior cruciate ligament with femoral interference screw fixation using the anteromedial portal drilling technique.
Methods: Two surgeons evaluated 43 random postoperative radiographs in patients who underwent anterior cruciate ligament reconstruction by a single surgeon. Four measurements were taken on lateral knee radiographs with superimposed condyles for each patient. These included the total sagittal diameter of the lateral condyle measured along the Blumensaat line (A1), the maximum intercondylar height from the Blumensaat line to the condyle edge along the center of the screw head (B1), the distance from the center of the screw head to the most dorsal contour of the lateral condyle (A2), and the distance from the center of the screw head to the Blumensaat line (B2). The latter 2 values were then expressed as percentages of the lengths A1 and B1. From the anteroposterior (AP) films, the angle between the axis of the screw and anatomic axis of the femur was determined.
Results: The center of the screw head was 31.3% of the Blumensaat line and 24.8% of the condylar height. The axis of the screw was found to be 43° from the anatomic axis of the femur on the AP radiographs.
Conclusions: The mean center of the screw head was 31.3% of the Blumensaat line and 24.8% of the condylar height. The mean axis of the screw was found to be 43° from the anatomic axis of the femur on the AP radiographs. Furthermore, we have described the appearance of a lateral radiograph with this technique.
Level of evidence: Level III, diagnostic study.
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