Is lumbar facet joint tropism developmental or secondary to degeneration? An international, large-scale multicenter study by the AOSpine Asia Pacific Research Collaboration Consortium

published_or_final_versio

Critical values of facet joint angulation and tropism in the development of lumbar degenerative spondylolisthesis: an international, large-scale multicenter study by the AOSpine Asia Pacific Research Collaboration Consortium

published_or_final_versio

An international, large-scale multi-center study assessing the role of facet joint angulation and tropism with the development of lumbar degenerative spondylolisthesis - A study from the AOSAP Research Collaboration Consortium

Session: Free Papers Lumbar Spine 2: abstract no. 39935INTRODUCTION: Degenerative spondylolisthesis (DS) mainly occurs at L4-L5. The phenotype and critical values of facet joint (FJ) angulation and tropism (FJs angulation asymmetry) in relation to DS remain controversial. The study addressed the role of FJ angulation and tropism in relation to L4-L5 DS in the Asia Pacific region. METHODS: An international cross-sectional study was performed in 33 institutions of single level DS. Imaging assessment consisted of identifying the DS level and left/right L4-L5 FJ angulations. Patients were stratified to those without (Group A) or with L4-L5 DS (Group B). ROC and multivariate analyses were performed, assessing the FJ angulation profile and tropism in relation to DS. RESULTS: The study included 349 patients (63% females; mean age: 61.8 years). Group B had greater sagittal FJ angulation than Group A (p<0.001). 58 degrees or greater significantly increased the risk of DS (unilateral FJ: OR:2.5; 95% CI:1.2-5.5; bilateral FJ: OR:5.9; 95% CI:2.7-13.2; p<0.001). FJ tropism was found to be relevant between 16-24 degrees angulation difference (OR:5.6; 95% CI:1.2-26.1). CONCLUSIONS: To the authors’ knowledge, this is one of the largest studies to address the role of FJ angulation and tropism in relation to L4-L5 DS. Greater FJ angulation was associated with DS, with a critical value of ≥58 degrees increasing DS risk for unilateral and bilateral facet involvement. Specific FJT ranges were related to DS. This study further broadens the understanding of the phenotype of facet joint orientation in relation to DS

Lumbar facet joint orientation in degenerative spondylolisthesis: the role of ethnic variation in the Asia Pacific

Program schedule A020Scientific session: Deformity surger

Facet Joint Tropism and Degenerative Spondylolisthesis—A Study from the AOSAP Research Collaboration

The abstract can be viewed at http://www.spineresearchforum.org/WFSR_2014_Thieme_AbstractBook_with_Cover.pdfConference theme: The Intervertebral Disc - from Degeneration to Therapeutic Motion PreservationShort Talk SessionIntroduction Degenerative spondylolisthesis (dSpl) is translation of the vertebral body in relation to adjacent levels, mainly attributed to degenerative changes of the intervertebral disc and facet joint complexes, and primarily occurs at L4-L5. Studies have suggested that more sagittal oriented facet joints at L4-L5 are associated with dSpl. However, the role of facet joint tropism (i.e., asymmetry between facet joint orientations) in L4-L5 dSpl remains inconclusive, in particular, in an Asian population and possibly attributed to nonstandardized definitions of tropism. As such, the following study addressed the role of facet joint tropism in relation to L4-L5 dSpl in the Asia Pacific region. Materials and Methods A multinational, multiethnic cross-sectional image-based study was performed in 34 institutions in the Asia Pacific region. Lateral standing radiographs and axial MRIs and/or CT scans were obtained for patients diagnosed with lumbar dSpl. Imaging assessment consisted of the following: magnitude of slip displacement, level of spondylolisthesis, and left/right L4- L5 facet joint angulations were noted on image assessment. Patients with single level dSpl were included. Patients were further stratified into those presenting with (Group A) or without (Group B) L4-L5 dSpl. Facet joint tropismwas defined as 7 degrees difference (Grogan et al 1997) between left and right facet joints and also assessed on receiver operating characteristics (ROC) curve analysis to identify critical values for multivariate analysis. Gender, age, weight/height (body mass index [BMI]), and ethnicity were also noted. Results The study included 351 patients (36.9% males and 63.1% females) with a mean age of 61.8 years (range: 24-90 years). The mean BMIwas 25.6 kg/m2 (range: 15.4-43.9 kg/m2). There were 267 patients (76.1%) in Group A and 84 individuals (23.9%) in Group B (control). Sex type (p ¼ 0.295) and BMI (p ¼ 0.227) did not significantly differ between groups, but elevated age was more pronounced with L4-L5 dSpl (p ¼ 0.001). There was a statistically significant difference between right and left L4-L5 facet joint angulations between Group A (right mean: 57.5 degrees; left mean: 55.4 degrees) and Group B (right mean: 48.4 degrees; left mean: 46.5 degrees) (p < 0.001). Based on facet joint tropism of 7 degrees difference between facet angulations, there was no statistically significant difference between groups. ROC analysis identified high sensitivity and specificity of facet joint angulation difference of 15 degrees or greater associated with dSpl. Based on ageadjusted multivariate analysis, facet joint tropism with a critical value of 15 degrees or greater angulation difference noted an odds ratio of 2.34 (95% CI: 1.17-4.67; p ¼ 0.016) associated with dSpl. Slippage was noted with increased facet joint tropism, but the effects could not be discerned. Conclusion Greater sagittal FJ orientationwas associated with dSpl, aswas joint tropism. A critical value of 15 degrees FJ angle difference produced a twofold increased likelihood of dSpl. Our study broadens the understanding of FJ morphology and its role in degenerative sagittal plane instability. Acknowledgments This study was funded by AOSpine Asia Pacific. Disclosure of Interest None declare