Association between pain-related activity-limitation and lumbar facet joint osteoarthritis

Of the many problems impacting the health care system, low back pain (LBP) causes the most disability under the age of 45 and affects 80% of the population at some point of their lifespan. Treating and diagnosing LBP correctly remains a challenge for all clinicians. MRI provides a non-invasive/non-radioactive means of diagnosis, however it is still very expensive and evidence-based medicine has struggled to demonstrate correlation of MRI findings with LBP symptomology. Current research suggests facet joint osteoarthritis is a feasible contributor to LBP; however no known research has demonstrated correlation of LBP with MRI findings. The main purpose of this study was to investigate the associations between low back pain during activity and the degree of lumbar facet joint osteoarthritis visible on MRI. Of a total 213 subjects from a previous VA study, 79 subjects were included in the data set (72 male and 7 female, mean age 52.24 years). MRI reports and lumbar series were obtained for all subjects. Of a total 79 series, 21 were rated for both lumbar facet joint spacing and degree of osteophyte production by two separate readers to establish inter-rater reliability. The remaining 58 lumbar series were rated by one reader using the same scales. Data was coded and entered into an existing SPSS 12.0 data base which included demographics, activity-based/pain-intensity related questions, and a Roland-Morris questionnaire. Inter-rater reliability was assessed using Cohen's Kappa (K). Associations between facet joint spacing/degree of osteophytes and pain symptomology were determined using t-tests and one-way ANOVA. Inter-rater reliability after collapsing the rating scales was K = .66 for facet joint spacing and K = .62 for osteophyte production. Facet joint narrowing was associated with pain levels only at the L4-5 level on the left. Osteophyte size using the collapsed version of the rating scale discriminated between age at L3-4 and L4-5, and several pain variables with moderate-large effect size at L3-4. These are the first data that describe the specific relationship between degenerative osteoarthritis and symptoms for individuals undergoing lumbar MRI. The collapsed version of the Fujiwara scale may be useful in classifying MRI findings related to pain especially when classifying osteophyte size.