There has been and remains a strong theoretical basis for spinal MUA. However, considering the aforementioned differences in existing published studies, field practitioners have not had an objective and uniform means by which to establish evidence-based treatment protocols. Also, because the preponderance of studies are of lower level evidence the issue of long-term effectiveness of MUA in the management of specific spinal conditions has yet to be investigated. Another area for which basic experimental research is lacking to support the efficacy of MUA treatment of the low back, and other spinal regions, relates to the two presiding theories that flexibility of the spine may be increased when adhesions are reduced, and [B MUA is more effective at treating adhesions than office-based manual therapy methods. Perhaps of greater significance, the circumstances by which or how often spinal adhesions (scar tissue) may form in the general population, in the presence or absence of prior surgery or vertebral fracture, have not been addressed in the medical literature. To date, after tens of thousands of spinal MUA procedures having been performed in the United States, and with more than eight decades worth of related studies, there is only one published paper in the MUA literature that clearly demonstrates the presence of spinal adhesions. That relates to two patients, whose pre-MUA advanced diagnostic imaging revealed fibrosis after prior lumbar surgery.