INTRODUCTION: It's often to encounter the synovial proliferation induced by the osteoarthritis of the facet joints on surgical approach for lumbar spinal canal stenosis (LSCS). The foregoing research indicated that hydrops of the facet joint might participate in the symptom formation of compressive nerve lesion in LSCS. The purpose of this study was to investigate the significance of the synovitis of the facet joint (SFJ) in LSCS.
METHODS: The subjects consisted of 26 patients (mean age 70 years) with LSCS and 8 patients (mean age 69 years) with lumbar spondylosis (SP) as the control. All patient underwent Gd enhanced MRI (1.5T) which could detect the SFJ in LSCS. Relation between the clinical symptoms and the SFJ was analyzed.
RESULTS: The distribution of the SFJ on MR image was 0% at L1/2, L2/3, L3/4 and L5/S, 13% at L4/5 in SP and 13% at L1/2, 20% at L2/3, 10% at L3/4, 73% at L4/5, and 7% at L5/S in LSCS. There was a remarkable difference between SP and LSCS. The frequency of the SFJ was in 46% (12/26 levels, 23 in L4/5, 3 in L3/4) for the symptomatic level and in 10% (10/104 levels) for the asymptomatic level. Especially, the SFJ at the symptomatic level was in 73% (8/11 cases) for cauda equina lesion and in 27% (4/15 cases) for radicular lesion. There was a statistical difference between them.
DISCUSSION: It has been reported that the synovial fluid of the facet joints include a large amount of the inflammatory cytokines which possible induce the chemical neuritis. This study showed that the SFJ produced in almost all the facet joints at the responsible intervertebral level for the cauda equina lesion. The SFJ plays an important role in the mechanism producing cauda equina lesion in LSCS.