Flexion-extension rhythm in the lumbosacral spine.
OBJECTIVE
This study was conducted to depict the qualitative and quantitative changes of intervertebral rotation and translation from L1-L2 to L5-S1 during flexion, standing, and extension using dynamic lumbosacral radiographs.


METHODS
A radiopaque ruler was placed on the back of each subject for the normalization of translational value. Eighty-nine volunteers were examined.


RESULTS
From extension to flexion, all of the intervertebral rotations approached 0 degree from the lordotic position; the translations changed from slightly retro-listhetic to zero displacement. Using L3-L4 as a baseline for calculating the intervertebral differences in flexion, all of the rotational differences were less than 1.5 degrees, except at L5-S1, which remained 5 degrees. The mean translational difference was less than 0.6 mm, except at L5-S1, where it remained 1.5 mm.


CONCLUSIONS
The amount of total flexibility was level-dependent and its frequency distribution is important. Qualitative rhythmic changes from extension to flexion and quantitative values of intervertebral difference in flexion help define the normal flexibility more accurately.
Lin
R M
RM
Department of Orthopedics, National Cheng-Kung University Medical College, Tainan, Taiwan.
Yu
C Y
CY
Chang
Z J
ZJ
Lee
C C
CC
Su
F C
FC
D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D011187:Posture / Q000502:physiology; D011446:Prospective Studies; D011859:Radiography; D012399:Rotation; D012447:Sacrum / Q000000981:diagnostic imaging / Q000502:physiology*