Relationship between vertebral intraosseous pressure, pH, PO2, pCO2, and magnetic resonance imaging signal inhomogeneity in patients with back pain. An in vivo study.

The cause of back pain in many patients in unknown. The pain experienced by patients with osteoarthritis of large joints has been associated with intraosseous abnormalities of elevated pressure, venous dilatations, and abnormalities of pH, pCO2, and pO2. Magnetic resonance imaging demonstrates an abnormal signal in the vertebral bodies of some patients with degenerative disc disease. The intraosseous pressure as well as the intraosseous pH, pO2, and pCO2 in a group of patients undergoing anterior spine surgery was studied, and the results were correlated to the preoperative magnetic resonance imaging appearance. Vertebral bodies with an abnormal magnetic resonance imaging signal had pressures 55% higher than vertebral bodies with a homogeneous signal; they also had significantly decreased pH and increased pCO2. Bodies with Type I changes had pressures 73% higher than those with a normal signal. No differences in pO2 were identified. These findings suggest that abnormalities of intraosseous pressure or blood gas concentrations may be related to mechanisms of pain production in some patients with back pain. These abnormalities can be identified by magnetic resonance imaging. Further investigation is needed to determine if therapeutic manipulation of these variables can be effective in relieving axial spinal pain.