Lumbar juxta-facet joint cysts in association with facet joint orientation, -tropism and -arthritis: A case–control study

• Facet-joint cysts occurrence associates with joint orientation, -tropism and -arthritis.
• Thirty-six patients and match paired controls mean age of 67.19 ± 10.3 years had a mean JFC size of 9.26 ± 4.8 mm.
• 75% of JFC occurred mostly in the segment L4–L5 and on the left side (61%).
• Compared to controls JFC significantly associates with arthritis and coronally orientated FJ.
• Within a single patient, cysts locate in asymmetric segments in the more sagittally orientated FJ.

ObjectiveTo assess the association between juxta-facet-joint cysts (JFC) occurrence at the lumbar spine and Facet Joint (FJ) orientation, -tropism and -arthritis.MethodsStudy group, 36 consecutive patients with JFC and the same number of controls, with degenerative diseases without JFC were match paired for demographics and spine segment. Parameter assessment was by T2-weighted axial MRI scans. JFC diagnosis was confirmed histopathologically. Group comparison was by Student's t-test for continuous variables and X2 for categorical variables.ResultsNineteen female and 17 male patients, aged between 45 and 85 years (mean 67.19 ± 10.3 years) had a mean JFC size of 9.26 ± 4.8 mm occurring most frequently in the segment L4–L5 (75% n = 25) and on the left side (61%). Mean FJ orientation of the study group was significantly more coronal compared to controls (left side 42° vs 36°, p < 0.02*, 95% confidence interval: 0.9–11.5 and right side 43° vs 37°, p < 0.02*, 95% confidence interval: 0.6–10.6 respectively). However, individual intersegmental analysis for study group patients showed the JFC bearing side to be significantly more sagittally oriented 40° ± 11.2° compared to 45° ± 13.2° for the side without FJC (p < 0.03*, 95% confidence interval: 8.1–1.7). 50% of the study group showed FJ asymmetry compared to 30% in controls, with a trend for FJ tropism (p < 0.07). Severe (grade 3) FJ arthritis was significantly more predominant in the study group 23/33 (p < 0.001*) as compared to controls.ConclusionsCompared to a control group, JFC occurrence is associated with significant higher rates of arthritis and coronally orientated FJ. At intersegment comparison within the same patient cysts located in more sagittally orientated FJ and the asymmetric segments show a trend for FJ tropism.