What is the prevalence of Baastrup’s disease (lumbar inter‑spinous bursitis) in the general population and among patients evaluated for low‑back pain?

Baastrup's Disease Prevalence

Prevalence in Symptomatic Populations

Baastrup's disease (lumbar interspinous bursitis) occurs in 8.2% to 37.8% of symptomatic patients undergoing lumbar spine MRI, with the wide range explained by differences in diagnostic criteria and imaging sequences used. 1, 2

• The most conservative estimate from a large symptomatic cohort found Baastrup's disease in 8.2% (44 of 539 patients) when using standard MRI sequences with strict criteria requiring fluid between spinous processes 1
• A more recent study using the highly sensitive STIR sequence—which better detects fluid and edema—identified Baastrup's disease in 37.8% (141 of 375 symptomatic patients), suggesting the condition may be substantially underdiagnosed with conventional imaging 2
• The STIR sequence detects not only interspinous bursitis but also hyperintense signal changes in adjacent spinous processes and ligaments, capturing earlier or subtler manifestations of the disease 2

Prevalence in General Population (Including Asymptomatic)

In unselected populations undergoing CT imaging for any reason, Baastrup's disease is remarkably common, affecting 41% overall and reaching 81.3% in patients over 80 years old. 3

• A large unselected cohort of 1,008 patients undergoing abdominopelvic CT found evidence of Baastrup's disease in 413 patients (41.0%) 3
• The prevalence increases decade-by-decade, demonstrating this is fundamentally an age-related degenerative process rather than a discrete pathological entity 3, 4
• Peak prevalence of 81.3% occurs in patients older than 80 years, and 87.5% in the oldest age groups when using sensitive MRI sequences 2, 3

Age-Related Patterns

Baastrup's disease shows a clear age-dependent progression, with minimal occurrence in younger patients and near-universal presence in the elderly. 2, 3, 4

• The condition demonstrates a decade-on-decade increase in frequency, establishing it as part of the expected spectrum of degenerative changes in the aging spine 3, 4
• Mean age of affected patients across studies is approximately 59.6 years 4
• The dramatic increase with age (from rare in young adults to >80% in octogenarians) suggests Baastrup's disease represents a normal aging phenomenon rather than a distinct pathological entity 3

Association with Other Degenerative Changes

Baastrup's disease is strongly associated with other degenerative spinal pathology, occurring alongside these changes in nearly all cases (899 of 901 affected levels). 1, 2, 3

• Significant associations exist with central canal stenosis (P=0.0013), disc bulging (P=0.0341), anterolisthesis (P=0.0429), disc herniation (P=0.0033), disc degeneration (P=0.0013), Modic changes (P=0.034), and facet osteoarthritis (P=0.0041) 1, 2
• The L4-L5 level is most commonly affected, consistent with the biomechanical stress distribution in the lumbar spine 3
• Most patients have single-level involvement (35.4%), though up to five levels can be affected in some cases (4.1%) 3

Clinical Significance and Diagnostic Caution

Because Baastrup's disease occurs with such high frequency in elderly patients and is nearly universally associated with other degenerative changes, extreme caution is warranted before attributing back pain specifically to this finding. 3, 5

• The near-universal association with other degenerative pathology makes it difficult to isolate Baastrup's disease as the primary pain generator 3
• Misattribution of pain to Baastrup's disease could lead to unnecessary interventions when other degenerative processes are the actual cause 5
• The condition appears more common than historically believed and is likely underdiagnosed, particularly when standard imaging sequences are used without STIR 2, 5