Anterior tibial loading on the calf enhances anterior tibial translation in the anterior cruciate ligament deficient knee in the anterior gravity radiographic view.

BACKGROUND

Lateral radiograph in the prone position with the knee flexed at 15° (anterior gravity view (AGV)) is useful as a screening for anterior cruciate ligament (ACL) injuries, while it is sometimes difficult to find the side-to-side difference (SSD) in anterior tibial translation. Thus, we applied a weight (three kilograms) around the lower leg to increase anterior tibial translation. We aimed to determine whether weight load confers an advantage in visualizing anterior knee laxity in ACL injuries.

METHODS

Fifty-eight patients with confirmed unilateral ACL tears from February 2012 to April 2014 had consented to participate in this study. Lateral radiographs for both knees were taken in AGV and in AGV with a three-kilogram weight load applied to the proximal lower leg. Then, the SSD of tibial position related to the femur was measured in these radiographs.

RESULTS

The SSD with the weight was significantly greater than that without the weight (5.9 ± 2.1 and 3.5 ± 1.6 mm, respectively, p < 0.01). The ratio of patients with SSD of three millimeters or more in AGV with the weight was also significantly larger than that without the weight (p < 0.01).

CONCLUSIONS

The anterior laxity in AGV with the three-kilogram weight is larger than that without the weight. Thus, the AGV with the weight could be one of the helpful radiographic technique for auxiliary diagnosis of ACL injury. Level of evidence Cohort study, Level IV.