Facet joints have been described as contributing to a significant proportion of patients suffering with persistent or chronic low back pain, variably from 15% to 45%. Since an obese patient is at a higher risk of disability compared to a patient with normal weight, obesity has been described as a confounding factor in persistent low back pain. This study included 100 patients, with 50 patients in Group I who were of normal weight and 50 patients in group II who were obese, by random allocation. Facet joints were investigated with diagnostic blocks using lidocaine 1% initially, followed by bupivacaine 0.25%. The results showed that the prevalence rate of facet joint pain in chronic low back pain in Group I or nonobese patients was 36%, in contrast to 40% in Group II, or the obese patient group, with no significant differences among the two groups. The study also showed a false-positive rate of 39% in the total sample, or 44% in Group I nonobese patients and 33% in Group II, or obese patients.

It is concluded that the prevalence of lumbar facet joint mediated pain of 40% in obese patients and 36% in patients of normal weight with a false-positive rate of 33% in obese patients and 44% in nonobese patients is similar to the results of multiple previous studies concluding that facet joint mediated pain is a common occurrence in obese patients; however, the incidence of facet joint mediated pain is similar in obese patients and nonobese patients.

Keywords: Obesity, persistent low back pain, facet joint mediated pain, comparative local anesthetic blocks, false-positive rate, facet joint nerve blocks