MRI diagnostics of a new type of stress subchondral insufficiency fracture of the knee

Abstract

Subchondral insufficiency fracture of the knee is a new type of stress fracture, which was previously referred to as spontaneous osteonecrosis of the knee (SONK).Aim. To determine the informativeness of radiography and magnetic resonance imaging in subchondral fracture of knee insufficiency.Material and Methods. The study comprised 150 patients including 48% of men and 52% of women. The age of patients ranged from 46 to 82 years. The patients underwent radiography and magnetic resonance imaging of the knee joint followed by the calculation of sensitivity, specificity and accuracy of the methods.Results. The most common stress fracture of insufficiency was found in the medial condyle of the femur (79%) with the second most common in the lateral condyle of the femur (12%). Most fracture zones (7.9%) were localized in the medial condyle of the tibia, and only 1.1% of fracture zones were in the lateral condyle of the tibia. The informativeness of radiography was low: sensitivity of 68.4%, specificity of 30.0%, and accuracy of 55.1%. Parameters of magnetic resonance imaging informativeness were as follows: sensitivity of 100%, specificity of 99.0%, and accuracy of 98.0%.Conclusion. Magnetic resonance imaging is the method of choice for stress fracture knee insufficiency because it demonstrated very high indicators of informativeness.