Facet Joint Morphology and Tropism in Adolescents : Association with Lumbar Disc Herniation and Spondylolysis

Study Design: Cross-sectional, observational.
Objective: To investigate the incidence of bidirectional lumbar facet tropism and its relationship with lumbar spine disease in adolescents.
Summary of Background Data: There is limited information on facet joint asymmetry in the sagittal plane in adolescents.
Materials and Methods: The orientation of all lumbar facet joints was measured in the bidirectional planes on computed tomographic images for 191 patients with low back pain. The patients were divided into four groups according to age (<15 or ≥15 years) and sex. The facet joint angle and tropism rate were compared among the groups. Facet tropism was defined as a difference in bilateral angle of >10° in the axial plane and >5° in the sagittal plane. The association of facet tropism with disease was investigated further by analyzing facet joint orientation and the incidence of facet tropism in 116 patients with single-level lumbar disease.
Results: Facet tropism was observed in 8.7% of axial views and 7.5% of sagittal views. The incidence of axial facet tropism was significantly higher in male patients aged ≥15 years, especially at L4/5. Facet joint morphology in the axial plane was more coronal at L3/4 and L4/5 in male patients ≥15 years than in those <15 years. Facet joint morphology in the sagittal plane was unchanged at around 15 years of age in both sexes. Axial facet tropism was found at L4/5 in 55.6% of patients with herniated nucleus pulposus. There was a significant difference in sagittal facet orientation in patients with spondylolysis at L5. The facet angle was significant larger in patients with L5 spondylolysis at L3/4 and L4/5.
Conclusion: The facet tropism rate in adolescents is similar in the axial and sagittal planes. Facet tropism and specific morphology may be related to lumbar disc herniation and spondylolysis in this age group.

There is limited information on the incidence of facet tropism in adolescents. Our findings suggest that facet tropism occurs at a similar rate in the axial and sagittal planes in adolescents. Facet tropism and distinctive facet orientation could be involved in lumbar disc herniation and spondylolysis in adolescents.

内容要旨・審査要旨・論文本文の公開
本論文は，著者Yoshihiro Ishihamaの学位論文として提出され，学位審査・授与の対象となっている。
論文本文は2025-07-15以降公開予定
This is a non-final version of an article published in final form in Ishihama Y, Tezuka F, Manabe H, Morimoto M, Yamashita K, Sakai T, Sairyo K. Facet Joint Morphology and Tropism in Adolescents: Association with Lumbar Disc Herniation and Spondylolysis. Spine (Phila Pa 1976). 2024 July 15. doi: 10.1097/BRS.0000000000004818. Epub ahead of print. PMID: 37661834.