The researchers undertook this study to examine the immediate effect of posteroanterior mobilization on back pain and the associated biomechanical changes in the lumbar spine. Grade III posteroanterior mobilization (3 cycles of 60s) was applied at the L4 level in people with (n=19) or without back pain (n=20) on 1 occasion. The main outcome measures were pain intensity, active lumbar range of motion, the magnitude of the posteroanterior mobilization loads, bending stiffness of the lumbar spine, and the lordotic curvature of the lumbar spine before and after 3 cycles of posteroanterior mobilisation. The level of pain of the patients was found by the authors to decrease substantially after posteroanterior mobilization treatment. There was also a significant decrease in the bending stiffness of the lumbar spine of the patients, which was derived from the posteroanterior load and the associated change in spine curvature. The stiffness was returned to a level that was comparable to that of the asymptomatic subjects. A strong correlation was found between the magnitude of pain and the bending stiffness of the spine before and after posteroanterior mobilisation.
Posteroanterior mobilization was found by the authors to illicit immediate desirable effects in reducing spinal stiffness and the severity of back pain. They concluded that restoration of the mechanical properties of the spine may be a possible mechanism that explains the improvement in following after manual therapy.