Functional radiography of the lumbar spine.

Functional methods utilising the effects of gravity on the upright lordotic spine were developed for both static and dynamic radiography. Static standing orthoradiography of the lumbar spine and weight-bearing joints of the lower extremities shows constitutional and functional abnormalities not visible in conventional recumbent radiography, e.g., postural scoliosis, hypo- or hyperlordosis, "kissing spine"-syndrome and signs of segmental instability. In dynamic traction-compression radiography segmental instability is provoked by axial traction and compression of the spine. With this method translatory instability of 5 to 15 mm was found in about half of the patients with lytic spondylolisthesis of L5 for which flexion-extension radiography had consistently failed to produce any abnormal movement. The amount of anterior spondylolisthetic and posterior retro-olisthetic instability correlated significantly with the severity of back pain symptoms, the degree of maximal static slip, however, being without significance. Functional radiography showed positive findings in most patients suffering from chronic low back pain of otherwise unknown aetiology.