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.
Exostosis of inferior humerus and/or glenoid measuring less than 3 mm
Moderate
Exostosis of inferior humerus and/or glenoid measuring 3–7 mm, and slight irregularity of the joint
Severe
Exostosis of inferior humerus and/or glenoid measuring more than 7 mm in height as well as sclerosis and narrowing of the joint space (normal joint space is 4–5 mm).[5]
The most commonly used radiographic classification system for osteoarthritis of the hip joint is the Kellgren–Lawrence system (or KL system).[6] It uses plain radiographs.
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.[8]
Severe (Tönnis grade 3) osteoarthritis of the hip.
For the grading of osteoarthritis in the knee, the International Knee Documentation Committee (IKDC) system is regarded to have the most favorable combination of interobserver precision and correlation to knee arthroscopy findings.[10] 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.[11]
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.[10] Systems that have been found to have lower interobserver precision and/or arthroscopy correlation are those developed by Kellgren and Lawrence, Fairbank, Brandt, and Jäger and Wirth.[10]
International Knee Documentation Committee (IKDC) system[10]
Grade
Findings
A
No joint space narrowing, defined in this system as at least 4 mm joint space
B
At least 4 mm joint space, but small osteophytes, slight sclerosis, or femoral condyle flattening
Joint 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.
II
Obliteration of the joint space
III
Bone defect/loss < 5 mm
IV
Bone defect/loss between 5 and 10 mm
V
Bone defect/loss > 10 mm, often with subluxation and arthritis of the other compartment
In the temporomandibular joint, subchondral sclerosis of the mandibular condyle has been described as an early change, condylar flattening as a feature of progressive osteoarthritis, and narrowing of the temporomandibular joint space as a late stage change.[14] A joint space of between 1.5 and 4 mm is regarded as normal.[15]
Ankle osteoarthritis.
For the ankle, the Kellgren–Lawrence scale, as described for the hip, has been recommended.[16] The distances between the bones in the ankle are normally as follows:[17]
^Page 722 in Gary S. Firestein, Ralph Budd, Sherine E Gabriel, Iain B. McInnes, James R O'Dell (2012). Kelley's Textbook of Rheumatology E-Book. Elsevier Health Sciences. ISBN9781455737673.{{cite book}}: CS1 maint: multiple names: authors list (link)
^Quintana, José M.; Escobar, Antonio; Arostegui, Inmaculada; Bilbao, Amaia; Azkarate, Jesús; Goenaga, J. Ignacio; Arenaza, Juan C. (2006). "Health-Related Quality of Life and Appropriateness of Knee or Hip Joint Replacement". Archives of Internal Medicine. 166 (2): 220–6. doi:10.1001/archinte.166.2.220. ISSN0003-9926. PMID16432092.
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