Osteochondral Lesions of the Knee: Differentiating the Most Common Entities at MRI

Radiographics. 2018 Sep-Oct;38(5):1478-1495. doi: 10.1148/rg.2018180044. Epub 2018 Aug 17.

Abstract

Several pathologic conditions may manifest as an osteochondral lesion of the knee that consists of a localized abnormality involving subchondral marrow, subchondral bone, and articular cartilage. Although understanding of these conditions has evolved substantially with the use of high-spatial-resolution MRI and histologic correlation, it is impeded by inconsistent terminology and ambiguous abbreviations. Common entities include acute traumatic osteochondral injuries, subchondral insufficiency fracture, so-called spontaneous osteonecrosis of the knee, avascular necrosis, osteochondritis dissecans, and localized osteochondral abnormalities in osteoarthritis. Patient demographics, the clinical presentation, and the role of trauma are critical for differential diagnosis. A localized osteochondral defect can be created acutely or can develop as an end result of several chronic conditions. MRI features that aid in diagnosis include the location and extent of bone marrow edema, the presence of a fracture line, a hypointense area immediately subjacent to the subchondral bone plate, and deformity of the subchondral bone plate. These findings are essential in diagnosis of acute traumatic injuries, subchondral insufficiency fracture, and its potentially irreversible form, spontaneous osteonecrosis of the knee. If the lesion consists of a subchondral region demarcated from the surrounding bone, the demarcation should be examined for completeness and the presence of a "double-line sign" that is seen in avascular necrosis or findings of instability, which are important for proper evaluation of osteochondritis dissecans. Subchondral bone plate collapse, demonstrated by the presence of a depression or a fluid-filled cleft, can be seen in advanced stages of both avascular necrosis and subchondral insufficiency fracture, indicating irreversibility. Once the diagnosis is established, it is important to report pertinent MRI findings that may guide treatment of each condition. ©RSNA, 2018 An earlier incorrect version of this article appeared online. This article was corrected on August 23, 2018.

Publication types

  • Review

MeSH terms

  • Bone Marrow Diseases / diagnostic imaging
  • Bone Marrow Diseases / pathology
  • Cartilage Diseases / diagnostic imaging
  • Cartilage Diseases / pathology
  • Diagnosis, Differential
  • Femoral Fractures / diagnostic imaging*
  • Femoral Fractures / pathology
  • Humans
  • Knee Injuries / diagnostic imaging*
  • Knee Injuries / pathology
  • Knee Joint / diagnostic imaging*
  • Knee Joint / pathology
  • Magnetic Resonance Imaging / methods*
  • Osteoarthritis, Knee / diagnostic imaging*
  • Osteoarthritis, Knee / pathology
  • Osteochondritis Dissecans / diagnostic imaging*
  • Osteochondritis Dissecans / pathology
  • Osteonecrosis / diagnostic imaging*
  • Osteonecrosis / pathology