Joint Space Narrowing

What's the Significance?


In healthy joints, articular cartilage serves as the cushion within the joint, and as a shock absorber. When cartilage deteriorates or wears away, the affected joint becomes painful, stiff, and limited in its range of motion. When imaging is done, X-rays often reveal joint space narrowing. What does this mean? Is it an important aspect of osteoarthritis?

Joint Space Narrowing is a Starting Point for Arthritis Diagnosis

Evaluating all forms of arthritis starts with measuring the joint space and evaluating whether it is narrowed.

A weight-bearing X-ray is taken to look for joint space narrowing in the hips and knees. In osteoarthritis, the joint space narrowing is usually asymmetric, it varies in the different knee compartments of the same knee and in the different migrations of the hip. But in osteoarthritis of the finger joints, it is usually symmetric.

While joint space narrowing is the starting point of a diagnosis, it is just one indicator. It has a different meaning and shows up at different times in various types of arthritis. The age of the patient will also factor into the meaning of joint space narrowing. It is only one factor to be considered.

Other radiographic findings and the results of the physical examination and blood tests will point to a diagnosis of osteoarthritis, rheumatoid arthritis, inflammatory arthritis, erosive osteoarthritis, gout, or systemic lupus erythematosus.

Joint Space Narrowing Means Osteoarthritis is Getting Worse

Osteoarthritis is characterized by joint deterioration and loss of cartilage.

When doctors assess the severity of osteoarthritis, they use imaging studies to quantify joint damage by measuring the space that exists between the bones of a joint. Narrowing joint space indicates cartilage loss and worsening osteoarthritis.

Joint Space Narrowing in the Knee

In the knee, joint space narrowing has been linked to loss of articular cartilage.

However, meniscal damage also contributes to joint space narrowing.​

In one study, MRIs of the knees of 264 study participants with symptomatic osteoarthritis were taken at the start of the study, taken again after 15 months, and again after 30 months. Researchers concluded that alterations in the meniscus (knee cartilage) accounted for changes that resulted in joint space narrowing. Researchers explained that with osteoarthritis, as articular cartilage becomes abnormal, the meniscus is damaged and displaced. Joint space narrowing is the consequence of changes to all of these structures.

How Joint Space Narrowing is Scored and Graded

According to Medscape, "The global system of Kellgren and Lawrence, developed for use in epidemiologic studies, comprises a 5-point scale for grading radiographs of osteoarthritic joints, in which 0 = no changes; 1 = doubtful joint space narrowing; 2 = minimal change, mostly characterized by osteophytes; 3 = moderate change, characterized by multiple osteophytes and/or definite joint space narrowing; and 4 = severe change, characterized by marked joint space narrowing with bone-on-bone contact with large osteophytes." This system is still used and is based on non-weight bearing X-rays.

Weight bearing X-rays are currently used to grade in the clinical setting.


Joint Space Narrowing: Cartilage Loss or Meniscus Position? Arthritis Foundation.

Management of Osteoarthritis Knee Pain: The State of the Science; Council for Osteoarthritis Pain Management, Medscape. Release Date: June 27, 2006

Jon A. Jacobson, et. al. "Radiographic Evaluation of Arthritis: Degenerative Joint Disease and Variations." Radiology, September 2008, Volume 248, Issue 3.

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