The rate of pseudarthrosis (surgical nonunion) in patients who are smokers and patients who are nonsmokers: a comparison study.

To investigate the relationship of smoking with the rate of pseudarthrosis (surgical nonunion), 50 patients, who were smokers, and 50 patients, who were not, and who had had a two-level laminectomy and fusion during 1977 and 1978 were randomly selected for this study. Most of those participating had sustained job-related injuries whereas the others had no common etiology for their back dysfunction. Most of the patients were from the southeastern United States. Ages ranged from 23 to 62 years, with a mean age of 42.4 years for smokers and 42.7 years for nonsmokers. There was an equal representation of males and females, with minorities represented according to their general percentage in the population. Examination 1 to 2 years after surgery revealed that 40% (20) of the smokers had developed a pseudarthrosis, whereas among nonsmokers, the rate was 8% (4). This finding appears to be independent of age, sex, or race and was statistically significant (chi 2 = 14.035, P = .001). It was hypothesized that the higher incidence of surgical nonunion among smokers may be related to blood gas levels. Nonsmokers showed no significant deficiencies, whereas smokers showed a mean PO2 level of 78.5% (normal = 95-97) and a mean O2 saturation level of 92.9% (normal = 95 or above). Implications and suggestions for further research are also discussed.