Subtype analysis of Schmorl's nodes in the lumbar spine and the association with lumbar degeneration: a retrospective evaluation of 2262 abdominal CT scans.

Objective: To investigate the epidemiology and the association with lumbar degeneration of lumbar schmorl's node (SN) subtypes in the general population using abdominal CT scans.

Methods: Patients underwent abdominal CT scans from Jan, 2023 to December, 2023 with all lumbar levels included were retrospectively reviewed. Presence or absence of SNs was scored. The SNs were further classified into SN of primarily developmental cause (SNd) and SN of primarily acquired cause (SNa) according to their image features by two independent readers. Lumbar degeneration of patients with SNs and 150 controls without SNs was evaluated using an existed grading system. Interreader agreement, epidemiologic features of SN subtypes and their association with lumbar degeneration were analyzed.

Results: A total of 2262 patients (45 ± 16 years, 1534 men) were included. Four hundred and forty patients (440/2262, 19%) had 975 SNs, 446 were classified as SNd, and 529 were classified as SNa. The prevalence of SNa increased with age (from 3 to 52%, p < 0.001), while the prevalence of SNd was similar among age groups (from 7 to 10%, p = 0.230). Sex difference was not observed for both SNa (p = 0.585) and SNd (p = 0.167). The most commonly affected lumbar level was L4 and L5 for SNa and L2 for SNd. SNa was independently associated with higher lumbar degeneration scores (p < 0.001) while SNd was not (p = 0.297). The interreader κ value was 0.67.

Conclusion: The SN subtypes differ in their predilected lumbar levels, the relationship with age and lumbar degeneration and should be analyzed as different entities.