Med Hypotheses. 2009 Jun 12; Ishihara KAlthough there are numerous studies examining the relationship between spinal imaging abnormality and low back and leg pain, the majority are only concerned with the correlation between these two. If we were to attempt to use the results of these studies as the basis for a treatment plan, it would be necessary to investigate the presence (or absence) of a causal relationship between the two. However, upon examination of previous studies we consider that this causal relationship has in fact either not been proven or has been refuted. To this end, we have conducted this study based on the hypothesis that spinal imaging abnormality and low back and leg pain possess a spurious relationship wherein muscle tension is the lurking variable. Furthermore, we propose a five-phase hypothesis considering the generative sequence of and causal relationship between spinal imaging abnormality, low back and leg pain, and muscle tension. Specifically, Phase I represents the healthy condition; Phase II indicates the occurrence of muscle tension only; Phase III indicates the occurrence of pain resulting from muscle tension; Phase IV represents the occurrence of both pain and imaging abnormality as a result of muscle tension; and Phase V indicates residual imaging abnormality despite amelioration of muscle tension. We believe that this hypothesis has the potential to facilitate pathological understanding and resolve the current confusion surrounding the diagnosis and treatment of spinal disorders.