The relationship between low pH in intervertebral discs and low back pain: a systematic review

INTRODUCTION: To systematically review the relationship between low pH in intervertebral discs and low back pain. MATERIAL AND METHODS: Electronic database (PubMed, ISI Web of Science, Cochrane Library, CINAHL, AMED, and China National Knowledge Infrastructure) searches and hand searching of conference proceedings were conducted. Two authors independently evaluated the methodological quality and abstracted relevant data according to standard criteria. Then the experimental methods and samples employed in the finally retrieved articles were assessed. RESULTS: We first retrieved 136 articles regarding pain and pH, and only 16 of them were mainly about low back pain and pH. Finally, 7 articles met our expectation to focus on the pathogenesis of low back pain caused by pH. In these 7 studies the authors held three opinions to explain the pathogenesis of low back pain in relation to low pH. First, low pH caused by lactate stimulates the muscle and increases the muscle tension, which causes low back pain. Second, low pH stimulates the nerve roots and produces the feeling of pain. Third, low pH changes the matrix metabolism, leading to neuronal death and low back pain. CONCLUSIONS: In this systematic review we propose a new hypothesis that low back pain may be caused by low pH based on the previous literature. Further experimental studies are necessary to verify our hypothesis. This hypothesis will promote our understanding of the pathogenesis of low back pain and the development of novel diagnostic and therapeutic approaches for low back pain.