Joint space

a normal or abnormal gap between components of a joint. Under pathologic conditions the joint space may be either widened or narrowed.

In the hip, the normal joint space can be divided into three segments on radiographs (superior, axial, medial) for diagnostic purposes. Usually the superior and axial spaces are very similar, providing useful information in various pathologic situations.

2. Pathology

Joint space narrowing is common in rheumatoid arthritis, ankylosing spondylitis, juvenile chronic arthritis, psoriatic arthritis, mixed connective tissue disease, the later stages of gout and numerous other conditions. Unusual patterns of joint space loss are seen in alkaptonuria.

Widening of the joint space may be a feature of psoriatic arthritis, acromegaly, Ehlers Danlos syndrome, and trauma. The symphysis pubis may also undergo normal and reversible separation during pregnancy.

DR