STUDY DESIGN: Retrospective
radiographic review of consecutive patients with universally applied standard. OBJECTIVES: To define
MRI findings at the
facet joints that may suggest abnormal
sagittal plane translation seen on standing lateral flexion-extension (SLFE)
radiographs. SUMMARY OF BACKGROUND DATA:
MRI findings, including
facet joint orientation,
facet joint osteoarthritis, and the presence of
synovial cysts, have all been linked with degenerative
spondylolisthesis (DS).
MRI can also detect
facet joint effusion; however, there has not been a study specifically addressing the association of
facet fluid signal to degenerative
spondylolisthesis (DS). METHODS:
MRI and SLFE films of all patients seen at a single institution for an
orthopedic spine consultation over a 2-year period were analyzed. The presence of
facet effusions,
synovial cysts, increased
intensity within the
interspinous ligament, degenerative changes at the
facets, and
anterior sagittal plane translation were all recorded. The data were analyzed to determine if there was a significant association between the presence of DS and the following:
facet effusion, degenerative changes of the
facets,
synovial cysts, increased signal in the
interspinous ligament, age, and gender. RESULTS: There were 139 patients without DS at (NegDS) and 54 with DS (PosDS) on SLFE films at L4-L5 (n = 193). PosDS patients were more likely to be older (P < 0.0001), female (P = 0.0042), have
synovial cysts (P < 0.0001), have higher
osteoarthritis grade (P < 0.0001), and have larger
facet effusion size (P < 0.0001). For both groups,
facet joint effusions were also found to be significantly larger in patients with Grade 2 or less
osteoarthritis, than in patients with Grade 3
osteoarthritis. Twenty-two percent of the listheses were not detectable on supine
MRI. CONCLUSION: Large (> 1.5 mm)
facet effusions are highly predictive of degenerative
spondylolisthesis at L4-L5 in the absence of measurable
anterolisthesis on supine
MRI. A clinically measurable
facet effusion (> or = 1 mm) suggests the need for SLFE films to diagnose degenerative
spondylolisthesis that can be missed with supine positioning on
MRI.
