Oxygen and Lactate Concentrations Measured in Vivo in the Intervertebral Discs of Patients With Scoliosis and Back Pain

Study Design. Oxygen concentrations in intervertebral discs were measured in 10 patients during discography and in 13 patients with scoliosis and 11 patients with back pain during spinal surgery. Lactate concentration profiles were measured in 12 of these discs. The discs were graded for degeneration by magnetic resonance maging and histology where possible. Objectives. To determine if oxygen and lactate levels in human discs vary with degree of degeneration. Failure of nutrient transport is thought to lead to disc degeneration. Summary of Background Data. The disc is avascular. Oxygen is used by the disc cells, and lactate is produced. Low oxygen and high lactate concentrations have been measured in the center of healthy animal discs. Methods. Oxygen concentrations were measured amprometrically. The sterilized gold-needle electrode was introduced into the disc during discography or after the disc was exposed surgically via an anterior approach. Concentration profiles of each disc took approximately 5 minutes to measure. Lactate concentrations were measured biochemically on the excised disc segment. Results. Oxygen concentrations were highest at the disc surface and fell toward the center. Lactate concentrations showed the reverse profile. Oxygen levels were very variable, ranging from 5-150 mm Hg in the center of the nucleus. No correlation was seen with age, pathology, or degree of degeneration. Lactate concentrations ranged for the most part from 2 mmol/L to 6 mmol/L. Conclusions. Concentrations of metabolites depend on cellular activity and on transport of the metabolite between the blood supply and the cell. The correlation between degeneration and nutrition cannot be determined only from metabolite concentrations; measurements of metabolic activity and nutrient transport rates also are required.