Lumbar interspinous bursitis (Baastrup disease) in a symptomatic population: prevalence on magnetic resonance imaging.

STUDY DESIGN: Cross-sectional retrospective review of 539 patients with lumbar spine magnetic resonance imaging (MRI).

OBJECTIVES: The purpose of this study was to determine the prevalence of lumbar posterior element interspinous bursitis (Baastrup disease) and to measure the association with degenerative disc disease findings, deformities, age, and gender in symptomatic people.

SUMMARY OF BACKGROUND DATA: Case reports and small case series describing Baastrup disease exist. The prevalence of Baastrup disease on MRI and association with other degenerative-related findings has not been reported.

METHODS: The study group consisted of 539 patients (51% males, 49% females; age range, 7-89 years old) undergoing routine lumbar spine MRI using sagittal T1-weighted, sagittal T2-weighted, and axial T2-weighted pulse sequences. Retrospective consensus review by 2 observers evaluated for the presence of: fluid intervening between consecutive spinous processes (criterion for Baastrup disease), disc degeneration (spondylosis) and contour abnormalities (bulges, herniations), marrow endplate signal alteration (Modic changes), central canal stenosis, lordosis, scoliosis, and displacement (anterolisthesis, retrolisthesis). Statistical analyses were descriptive statistics and determining associations between these MRI findings and Baastrup disease (using chi and Wilcoxon rank sums).

RESULTS: Lumbar interspinous bursitis (Baastrup disease) was present in 8.2% (44 of 539) of the study population. There were associations between the presence of Baastrup disease and age (P = 0.001), central canal stenosis (P = 0.0013), disc bulging (P = 0.0341), and anterolisthesis (P = 0.0429). There were not associations between Baastrup disease and disc degeneration, disc herniation, endplate findings, retrolisthesis, scoliosis, lordosis, or gender.

CONCLUSION: Lumbar interspinous bursitis (Baastrup disease) is uncommon but not infrequent in symptomatic patients undergoing lumbar spine MRI. Patients with MRI evident Baastrup disease tend to be older, have central canal stenosis, bulging discs, and anterolisthesis. Further investigations determining the clinical significance of this finding are necessary.