The patient, already lying prone, places the hands (palms down) near the shoulders as for the traditional press-up exercise. He now presses the top half of his body up by straightening the arms, while the bottom half, from the pelvis down is allowed to sag with gravity. The top half of the body is then lowered and the exercise is repeated about ten times. The first two or three movements should be carried out with some caution, but once these are found to be safe the remaining extension stresses may become successively stronger until the last movement is made to the maximum possible extension range. If the first series of exercises appears beneficial, then a second series may be indicated. More vigour can be applied and a better effect will be obtained if the last two or three extension stresses are sustained for a few seconds.
It is essential to obtain the maximum elevation by the tenth excursion and once obtained the lumbar spine should be permitted to relax into the most extreme ‘sagged’ position.
Fig. Extension in lying.
This procedure is a further progression of the previous two. Instead of a sustained extension stress on the contents and surrounding structures of the lumbar segments, there is now an intermittent extension stress, having a pumping as well as a stretching effect.
This procedure is the most important and effective in the treatment of derangement as well as extension dysfunction. The very maximum degree of extension possible without external assistance, is obtained with this exercise. An increase of central low back pain at maximum elevation can be expected and should not cause any concern as it will gradually wear off. It is usually described as a strain pain and differs from the pain which has caused initial consultation. In addition to the effects on the disc and periarticular structures there are two other physiologically related phenomena that could possibly result from the performance of this exercise.
The self sealing phenomenon
Evidence gathered by Markolf and Morris suggests that a self sealing mechanism exists within the disc and appears shortly after injury. The initial injury weakens the annulus but appropriate stress applied subsequently results in restoration of near normal strength, suggesting that the disc has a remarkable recovery ability and that certain stresses may enhance rapid recovery. White and Panjabi conclude that the self sealing phenomena is mechanical in nature and is not dependent on the viscosity or softness of the disc, for the study was performed on degenerative as well as normal discs.
My question arising from this information is … Does the performance of repeated passive extension in lying cause a reversal of the posterior migration of the nucleus into the developing radial fissure? Does the movement then initiate the self sealing phenomena?
Following trauma articular surfaces are normally rested or immobilised to permit healing. It is well known that scar tissue is laid down under these circumstances and damaged articular cartilage is replaced with fibrous collagen. Recent investigations by Salter suggest that if passive continuous motion is applied to joints containing traumatised intra articular cartilage, the damaged cartilage is replaced by true cartilaginous cells instead of scar tissue, and further, these joints do not develop arthritic changes subsequently. The evidence has yet to be confirmed in human studies. We can now pose the question … Does the regular performance of passive extension following lumbar disc damage enhance the quality or improve the nature of the healing tissues of the posterior annulus?