Radiographic mobility of the lumbar spine and its relation to clinical back motion.

A sample of 194 examinees (117 women and 77 men), representative of the population, with a history of low back pain, were examined clinically and radiographed. The angles between vertebrae at the levels of L4-L5 and L5-S1 were measured from the lateral lumbar erect, maximal flexion, and maximal extension views. Average mobility at L4-L5 was 14.5 degrees in women and 13.4 in men, and at L5-S1 11.5 degrees in women and 12.1 in men. Mobility became more restricted with increasing age both in women and men; especially at L4-L5. In women decreased radiographic mobility at L4-L5 was significantly (p = 0.002) correlated with restricted side-bending and rotation found at the physical examination. These correlations were clearly less significant among men. At L5-S1, restricted extension in women but restricted flexion and Schober's test in men were significantly correlated with decreased radiographic mobility.