Prevalence and causing factors of skipped level in multiple degenerative lumbar patients

Abstract

Background: Disc degeneration has been attributed to the accumulation of environmental effects, mechanical injuries and insults, imposed on normal aging changes in general. Mostly there are confined to the effects of age and biomechanics associated with disc degeneration. Most common lesions of disc degeneration L4/5 level in lumbar spine and also adjacent lesions to the above level are frequently involved anatomically. Sometimes degenerative disc disease is not consecutive, but the cause is not known yet. Especially, it is difficult to determine the extent of surgery in skipped level disc degeneration patients. We investigated the causing factors of skipped level in multiple degenerative lumbar disc patients.Methods: We evaluated 1353 outpatients who were visited to Gangnam Severance Spine Hospital from January 2010 to April 2010 (mean age 47.5 years old, range 13–85 years). The exclusion criteria were scoliosis, trauma, previous spine operation, infection, and spinal tumor patients. All 474 patients without excluded patients took whole sagittal T2-weighted MRI scans. We measured pfirrmann classification for each level and checked the presence of Schmorl’s node, spondylolisthesis, spondylolysis, ossification of ligamentum flavum, ossification of posterior longitudinal ligament, and bony spur for each level.Results: The total skipped lesion patients (Group S) were 105 (men; 65, women; 40) and non-skipped lesions patients (Group NS) were 369 (men; 179, women; 190). Group S consisted of more males compared to group NS. Group S was significantly associated with the presence of bony spur (p=0.002), instability (p=0.030), schmorl`s nodule (p<0.05), and male (p=0.021). Other MRI findings did not significantly differ between groups (p>0.05). In group S, disc degeneration increased at age 50 to 60 years old, while in group NS, disc degeneration abruptly increased from age 60.Conclusion: Although many factors associated with degeneration have been studied, there are few regarding non-contiguous disc degeneration. In our study, male sex, presence of bony spur, spinal instability, and presence of Schmorl`s nodule were significantly associated with skipped lesion disc degeneration. Our results may provide further evidence in the pathogenesis of lumbar disc degeneration.