The two legs can not be crossed, commonly due to femoral head necrosis, acetabular labral injury and other reasons, as follows: 1, femoral head necrosis: after ischemic necrosis of one side of the femoral head, the hip joint will have internal and external rotation and flexion activity is limited, so you can not cross the two legs, there will be serious pain symptoms, most patients will have continuous and severe pain, pain symptoms are also very obvious in ordinary life, the symptoms will be reduced after rest. MRI will reveal internal necrosis of the femoral head; 2. Acetabular glenoid labral injury: Acetabular glenoid labral injury can occur in the process of strenuous exercise, and after acetabular glenoid labral injury, patients will show restricted hip movement and difficulty in crossing their legs, accompanied by severe pain. It can be recovered gradually.