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 measu red in 10 patients during discography and in 13 patients with scoliosi s and 11 patients with back pain during spinal surgery. Lactate concen tration profiles were measured in 12 of these discs. The discs were gr aded for degeneration by magnetic resonance imaging and histology wher e possible. Objectives. To determine if oxygen and lactate levels in h uman discs vary with degree of degeneration. Failure of nutrient trans port is thought to lead to disc degeneration. Summary of Background Da ta. The disc is avascular. Oxygen is used by the disc cells, and lacta te is produced. Low oxygen and high lactate concentration have been me asured in the center of healthy animal discs. Methods. Oxygen concentr ations were measured amprometrically. the sterilized gold-needle elect rode was introduced into the disc during discography or after the disc was exposed surgically via an anterior approach. concentration profil es of each disc took approximately 5 minutes to measure. Lactate conce ntrations were measured biochemically on the excised disc segment. Res ults. 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 cent er of the nucleus. No correlation was seen with age, pathology, or deg ree of degeneration. Lactate concentrations ranged for the most part f rom 2 mmol/L to 6 mmol/L. Conclusions. concentrations of metabolites d epend on cellular activity and on transport of the metabolite between the blood supply and the cell. The correlation between degeneration an d nutrition cannot be determined only from metabolite activity and nut rient transport rates also are required.