The lumbar interspinous bursae and Baastrup's syndrome. An autopsy study.

This study describes the prevalence, distribution, pathology and pathogenesis of lumbar interspinous bursitis (described as a clinical syndrome by Baastrup in 1933). It is based on an anatomic study of 152 lumbar spines derived from routine and random postmortem material, together with selected specimens from autopsies on patients with various rheumatic diseases. From a statistical study of 50 randomly chosen spines, bursae are found when the interspinous distance is small compared with the total height of the lumbar spine ('bursal index'): nearly all bursal spaces show some sign of inflammation and a few show severe bony erosion. Crystal deposits therein are also described.