Radiographic classification of osteoarthritis


Radiographic systems to classify osteoarthritis vary by which joint is being investigated. In osteoarthritis, the choice of treatment is based on pain and decreased function, but radiography can be useful before surgery in order to prepare for the procedure.

Vertebral column

There are many grading systems for degeneration of intervertebral discs and facet joints in the cervical and lumbar vertebrae, of which the following radiographic systems can be recommended in terms of interobserver reliability:
I
II
  • Definite anterior osteophytosis
  • Possible disc space narrowing
  • Some endplate sclerosis
    • III
  • Moderate disc space narrowing
  • Definite endplate sclerosis
  • Osteophytosis
    • IV
  • Severe disc space narrowing
  • Endplate sclerosis
  • Multiple large osteophytes.
    • GradeJoint space narrowingOsteophytesSclerosis
    0---
    1Definite but mild narrowingSmallPresent
    2ModerateModerate–
    3Severe Large–

    The Thomson grading system is regarded to have more academic than clinical value.
    GradeNucleusAnulusEndplateVertebral body
    IBulging gelDiscrete fibrous laminaeHyaline, uniform thicknessRounded margins
    IIPeripheral white fibrous tissueMucinous material between laminaeIrregular thicknessPointed margins
    IIIConsolidated fibrous tissueExtensive mucinous infiltration; loss of annular-nuclear demarcationFocal defects in cartilage Small chondrophytes or osteophytes at margins
    IVHorizontal clefts parallel to endplateFocal disruptionsFibrocartilage extending from subchondral bone; irregularity and focal sclerosis in subchondral boneOsteophytes smaller than 2 mm
    VClefts extended through nucleus and annulusDiffuse sclerosisOsteophytes greater than 2 mm

    Shoulder

    The Samilson-Prieto classification is preferable for osteoarthritis of the glenohumeral joint.
    GradeDescription
    MildExostosis of inferior humerus and/or glenoid measuring less than 3 mm
    ModerateExostosis of inferior humerus and/or glenoid measuring 3–7 mm, and slight irregularity of the joint
    SevereExostosis of inferior humerus and/or glenoid measuring more than 7 mm in height as well as sclerosis and narrowing of the joint space.

    Hip

    The most commonly used radiographic classification system for osteoarthritis of the hip joint is the Kellgren-Lawrence system. It uses plain radiographs.
    GradeDescription
    0No radiographic features of osteoarthritis
    1Possible joint space narrowing and osteophyte formation
    2Definite osteophyte formation with possible joint space narrowing
    3Multiple osteophytes, definite joint space narrowing, sclerosis and possible bony deformity
    4Large osteophytes, marked joint space narrowing, severe sclerosis and definite bony deformity

    Osteoarthritis of the hip joint may also be graded by Tönnis classification. There is no consensus whether it is more or less reliable than the Kellgren-Lawrence system.
    GradeDescription
    0No osteoarthritis signs
    1Mild:
    • increased osteosclerosis
    • minor joint space narrowing
    • no or minor loss of head sphericity
    2Moderate:
  • small bone cyst
  • moderate joint space narrowing
  • moderate loss of head sphericity
    • 3Severe:
  • large bone cysts
  • severe joint space narrowing, or joint space obliteration
  • severe deformity of the head

    • Knee

    For the grading of osteoarthritis in the knee, the International Knee Documentation Committee system is regarded to have the most favorable combination of interobserver precision and correlation to knee arthroscopy findings. It was formed by a group of knee surgeons from Europe and America who met in 1987 to develop a standard form to measure results of knee ligament reconstructions.
    The Ahlbäck system has been found to have comparable interobserver precision and arthroscopy correlation to the IKDC system, but most of the span of the Ahlbäck system focused at various degrees of bone defect or loss, and it is therefore less useful in early osteoarthritis. Systems that have been found to have lower interobserver precision and/or arthroscopy correlation are those developed by Kellgren-Lawrence, Fairbank, Brandt, and Jäger-Wirth.
    GradeFindings
    ANo joint space narrowing, defined in this system as at least 4 mm joint space
    BAt least 4 mm joint space, but small osteophytes, slight sclerosis, or femoral condyle flattening
    C2–4 mm joint space
    D<2 mm joint space

    GradeFindings
    IJoint space narrowing, with or without subchondral sclerosis. Joint space narrowing is defined by this system as a joint space less than 3 mm, or less than half of the space in the other compartment, or less than half of the space of the homologous compartment of the other knee.
    IIObliteration of the joint space
    IIIBone defect/loss <5 mm
    IVBone defect/loss between 5 and 10 mm
    VBone defect/loss >10 mm, often with subluxation and arthritis of the other compartment

    For the patellofemoral joint, a classification by Merchant 1974 uses a 45° "skyline" view of the patella:
    StageDescription
    1 Patellofemoral joint space > 3mm
    2 Joint space < 3 mm but no bony contact
    3 Bony surfaces in contact over less than one quarter of the joint surface
    4 Bony contact throughout the entire joint surface

    Other joints