The deep medial femoral sulcus sign: does it exist?

ABSTRACT

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.