The effect of body mass index on lumbar lordosis on the Mizuho OSI Jackson spinal table

STUDY DESIGN  Prospective cohort study. CLINICAL QUESTION  Does the patients' body mass index (BMI) influence the degree of intraoperative lumbar lordosis in patients undergoing operative treatment on the Mizuho Orthopedic Systems Incorporated (OSI) Jackson spinal table? METHODS  Twenty-four consecutive patients undergoing posterior spinal instrumentation and fusion on the Jackson table, excluding those with sagittal malalignment, underwent standing preoperative and prone intraoperative lateral x-rays. Intervertebral body angle measurements were obtained from L1-S1 using the modified method of Cobb. Changes in angle measurements were compared to BMI using linear regression and ANOVA. RESULTS  We found a mean lordosis of 52.6° in standing preoperative x-rays compared to a prone position mean lordosis of 61.5° on the Jackson table. The mean change was 8.88° with a range of 0°-18°. A linear association between lordosis and BMI was demonstrated (P < .0022). As BMI increased, so did lordosis (correlation coefficient, 0.59). CONCLUSIONS  The current study is the first in which a correlation of patient body mass and use of the Jackson table has been evaluated. These data suggest that BMI influences lumbar lordosis on the Jackson table and that care must be used when dealing with a population with large BMI on the Jackson table. [Table: see text] The definiton of the different classes of evidence is available on page 83.