Is facet joint tropism associated with spondylolysis and isthmic spondylolisthesis?
In brief
L4-L5 facet tropism appears in 66% with spondylolysis, versus 36% without
In CT scans from 358 patients, facet joint tropism at L4-L5 was more common in those with spondylolysis than in matched controls, and the same pattern appeared at other lumbar levels. The association does not show that asymmetry causes the condition; its presence at adjacent levels instead points to a broader anatomical trait.
- Journal
- European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society (Q1)
- Published
- 6 October 2026
- Study design
- Retrospective cohort
- Evidence level
- Level 3, Low (CEBM 3b)
- Authors
- Julio Urrutia, Hugo Demandes, Raul Zilleruelo, Christian Neumann
- PMID
- 42836972
- DOI
- 10.1007/s00586-026-10388-3
Why clinicians should know about it
- Picked for Anatomy (paper of the day, 8 October 2026): Facet joint tropism study, spinal anatomical variation
Abstract
PURPOSE: To evaluate the association between facet joint tropism (FJT) and spondylolysis, with or without isthmic spondylolisthesis (IS), in a large cohort of patients across a wide age range. METHODS: We retrospectively analyzed lumbar computed tomography scans from 358 patients (mean age 48.2 ± 20 years), including 191 patients with spondylolysis (137 with IS) and 167 age- and sex-matched controls without spondylolysis. Bilateral facet joint angles (FJA) were measured at L3-L4, L4-L5, and L5-S1. FJT was defined as a right-to-left FJA difference >6°. Absolute FJA differences and the prevalence of dichotomous FJT were compared between groups. Inter- and intra-observer agreement were assessed using intraclass correlation coefficients (ICC). RESULTS: Inter- and intra-observer agreement for FJA measurements were excellent (ICC = 0.88 for both). Patients with spondylolysis demonstrated more FJA asymmetry than controls at L3-L4 (5.8° versus 3.7%; p = 0.02), L4-L5 (6.6° versus 3.9°; p < 0.01), and L5-S1 (6.7° versus 4.5°; p < 0.01), with a higher prevalence of FJT at all levels (56% versus 38%, 66% versus 36%, and 68% versus 47%, respectively; all p < 0.01). Patients with IS also showed greater FJA asymmetry and more frequent FJT at L3-L4 and L4-L5, but not at L5-S1. CONCLUSION: Patients with spondylolysis, with or without IS, demonstrated significantly greater facet joint asymmetry and a higher prevalence of FJT than controls. The presence of FJT at adjacent levels suggests that it may represent a generalized anatomical characteristic rather than a purely local phenomenon.
Abstract as published, via PubMed.
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