We x-rayed dozens of cadavers, supported in standing attitude to simulate live posture. Following analysis and interpretation of the radiographs, we carefully dissected specific vertebral sections which depicted signs of subluxation. Let me describe some of our findings and explain our concluding hypotheses:
In the typical lumbar subluxation, the vertebra would be found tilted to one side (lateral flexion malposition), the body usually rotated to the side of tilt, the spinous process to the opposite side and somewhat superior. Transverse bisection of the IV disc just below the tilted vertebra almost invariably would disclose the nuclear mass to be displaced to the side opposite the vertebral tilt, with conclusive evidence of annular laceration on the side and in the plane of nuclear shift. In severe cases the nuclear shift was enough to force extrusion into the spinal canal intruding upon adjacent neural elements. These findings prompted the hypothesis that the nuclear mass, poised in the central area of the disc, acted as a fulcrum of balance for the vertebra next above. As the nuclear mass shifted to one side, the vertebra above tilted to the opposite side.
At the posterior area of a vertebral joint, the inferior articular processes of the upper vertebra are embraced at the front and sides by the extending processes of the inferior vertebra, forming the apophyseal joints. The arrangement permits free movement in flexion of the lumbar joint, but limits lateral excursion and extension. Accordingly, as the vertebra tilts, it rotates to the side of tilt in pendulum fashion, since little rotation can occur at the posterior. However, the stress of rotation and tilt often increases friction in the apophyseal joint on the side opposite body rotation, while the capsular ligament on the opposite side is stretched and sometimes lacerated. Thus, the symptoms known as "facet syndrome" find reasonable explanation.
While the above scenario describes the scene which typifies joint failure in the lumbar spine, there are many factors which can exist to alter details of structural disrelation. These are mainly related to variations in structural form of vertebral segments, wedging of the vertebral body, asymmetrical concavity of the end-plates, tropism of the articular processes, congenital alterations in configuration of the spinal canal (stenosis, trefoil form), and other anomalies. The presence of such abnormality in structural form may cause atypical accommodation to nuclear shift. But, in the experience of the author in treating thousands of "low back" patients, failure within the IV disc in the containment of the nuclear mass is an ever-present factor.
Recognition of the role of the IV disc in lumbar biomechanics and the strong evidence that failure within the disc is the primary and usual cause of subluxation, it logically follows that corrective manipulative efforts must be directed at the disc. Obviously, adjustment and reshaping of the disc cannot be done directly. However, the proper combination of forces in controlled amounts and precise vectors of drive can, indeed, induce hydrokinetic forces upon the disc to restore nuclear position and rebalance the vertebra above. This is the precise effect of recoil adjusting, rotary adjusting, and other types of spinal manipulation which corrected lumbar subluxation inadvertently and coincidentally, if not by intention or design.
Once we were able to develop a clear mental image of the anatomical characteristics of a given subluxation, why the vertebra resided in its tilted and rotated attitude, what secondary factors existed, we fashioned subtle refinements in technic with consistent and predictable results. We identified details in patient preparation, design of adjusting table and positioning patient on it, and use of bimanual contacts on specific vertebral points applied in a precise and preconceived manner. We could perceive the exact direction of drive, the amounts of force, and the manner of its application to achieve the maximum benefit to the patient with the least pain and discomfort. We developed and patented a new table design to enable us to better handle the emergency-type of low-back patient who presents in a highly disturbed state, unable to move without excruciating pain.
This understanding also promoted the developments of new practices in the rehabilitation of low-back victims. Avoidance of flexion of the lumbar spine, which interrupts the annular repair process, became an important caution to the patient. Corrective exercises were devised emphasizing spinal extension in a passive and totally relaxed state. Other instructions were given in the conduct of living, in recreation, and at work, based upon a better understanding of spinal biomechanics.
Other disciplines of practice among the healing arts recognizing the value of manipulative therapy have begun to accept the biomechanical principles which we have defined and are adopting technics which we have developed. Unfortunately, too many chiropractors are looking for an easier way and departing from the use of fundamental dynamic technics which are our trademark. Such are the technics which brought chiropractic where it is today, and the premise of our establishment as primary health providers into the future. Let's not lose what we have gained.
Otto C. Reinert, D.C., F.I.C.C.