The lateral notch sign associated with acute anterior cruciate ligament disruption

We prospectively studied all of the patients with anterior cruciate ligamen t disruptions who sought treatment at the senior author's office during a 3 6-month period. Plain radiographs identified depressions measuring 2 mm or more in the lateral femoral condyle (lateral notch sign) in 9 of 120 knees (7.5%) with acute anterior cruciate ligament disruption and in 2 of 44 knee s (4.5%) with chronic pivot shift instability. The depression ranged from 2 to 6 mm deep and from 20 to 25 mm long. The mean age for acutely injured p atients with lateral notch signs was 17.2 years, 6 years younger than the m ean age of the group with acutely injured anterior cruciate ligaments as a whole. Ten of the 11 patients (91%) with lateral notch signs were men, and all 6 patients with depressions shallower than prior descriptions of the no tch sign were men. In contrast, 67% (N = 110) of the entire group of patien ts who had anterior cruciate ligament disruption were men. Ten of the 11 pa tients (91%) with the lateral notch signs and 4 of the 6 patients (66%) wit h minimal depressions also had lateral meniscus tears, while 58 of 147 pati ents (39%) without lateral femoral condyle depression had lateral meniscus tears. Previous reports that the lateral notch is a sign of chronic anterio r cruciate ligament deficiency with recurrent pivot shifts are not supporte d by the number of prospectively recognized acute lateral femoral notch sig ns in this series. We found the presence of radiographic changes in the lat eral femoral condyle to have statistically significant correlations with yo ung age, male sex, lateral meniscus tears in general and anterior-horn late ral meniscus tears specifically, and lateral femoral chondral lesions.