The deep medial femoral sulcus sign. Does it exist?

To determine the normal depth of the medial femoral sulcus on lateral radiographs of the knee and determine if abnormal deepening of the medial femoral sulcus exists as a radiographic indicator of intra-articular knee abnormalities. A retrospective search was performed over a period of 10 years to identify all individuals with a bone contusion of the anterior medial femoral condyle at MR imaging. Study patients had documented acute knee injuries and radiographs 6 weeks or less prior to their MR. A control group had normal MR exams and radiographs 6 weeks or less prior to their MR. Two fellowship-trained musculoskeletal radiologists independently measured the depth of the medial femoral sulcus on lateral radiographs blinded to control or study individuals. The study group consisted of 76 patients (57 men, 19 women; age range, 18–50 years; mean age, 27 years) and 92 control patients (33 men, 59 women; age range, 18–46 years; mean age 26 years). Sulcus depth was (0–2.3 mm reader 1 and 0–1.7 mm reader 2 for controls; 0–2.2 mm reader1 and 0–1.8 mm reader 2 for study patients). No significant difference in sulcus depth was identified between the control and study groups. Inter-reader agreement was very strong. The most common cause of injury in the study group was motor vehicle accidents followed by hyperextension and twisting injuries of the knee. The normal medial femoral sulcus ranges in depth from 0 to 2.3 mm. Although impaction of the sulcus does occur following knee injuries, the sulcus does not deepen.