Because the ligaments connecting the spinal bones are quite strong, vertebral dislocations rarely occur after birth and are unlikely without severe injury that would require surgical treatment. Some occupy a middle ground that includes any or all of these concepts. During the early 1970s Dr. Edmund Crelin, a prominent anatomist at Yale University, subjected this theory to an actual test. After collecting the spines of six people who had died a few hours earlier, he twisted them with instruments and observed the spaces between the vertebrae through which the spinal nerves passed. No nerve compression occurred, regardless of the force applied.
Some chiropractors say that subluxations at the top of the spine are the ones that really matter.
Some focus on the bottom of the spine. Some work at both ends. Others locate and treat them throughout the spine. Undercover investigations in which many chiropractors examine the same patient have found that the diagnoses and proposed treatments differ greatly from one practitioner to another. The chiropractors were told that the girl was generally in good health, but suffered a few earaches, some mild headaches, and a few signs of allergy symptoms.