Flexion-extension radiographs for detecting lower lumbar spinal instability : Standing vs lateral decubitus views
Boonsin Buranapanitkit, Asst. Prof., D. of Orthopaedic Surgery and Physical Medicine,
F. of Medicine, PSU.
Pharkpoom Rattanakij, Wachira General Hospital, Phuket
Corresponding e-mail : bboonsin@ratree.psu.ac.th
Published : Songkla Med J 2000, 18(4) : 273-277
Key words : radiograph, lower lumbar spinal instability
Lower lumbar spinal instability is a common cause of low back pain. However, diagnosis and treatment of this condition are still controversial. In general, lateral flexion-extension views in a standing position are used to detect lower lumbar instability. In this study we analyzed radiographs
of patients who were suspected of having lower lumbar spinal instability by comparing parameters
such as range of motion, slip angle and percentage of slip between flexion-extension radiographs with standing and lateral decubitus views. Correlation among all parameters was also defined. Thirty-five patients with an average age of 47.2 years (range 23-70) were included in this study. There were no statistically significant differences regarding slip angle and percentage of slip in both L4-L5 and L5-
S1, levels between standing and decubitus views. Range of motion of L4-L5 level in lateral decubitus view showed a statistically significant difference from that in standing views (p=.002). Correlation among all parameters showed that range of motion was strongly correlated with slip angle in both
L4-L5 and L5-S1 levels. Slip angle correlated with percentage of slip at L4-L5 level in decubitus view, while percentage of slip at L4-L5 was correlated with range of motion in standing view. This study implies that lateral decubitus flexion-extension radiograph can be used to detect lower lumbar spinal instability, especially with patients who cannot stand and perform normal flexion and extension of
their backs.
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