Flexion-Extension Rhythm in the Lumbosacral Spine : Spine (original) (raw)

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Lin, Ruey-Mo MD*; Yu, Chih-Yin MD†; Chang, Zeu-Jen MD†; Lee, Chang-Cheng BS; Su, Fong-Chin PhD§

*Department of Orthopedics

†Department of Radiology

‡private family practice, National Cheng-Kung University Medical College, Tainan, Taiwan

§Institute of Biomedical Engineering, National Cheng Kung University, Tainan.

Abstract

Study Design and Objectives

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 0o from the lordotic position; the translations changed from slightly retrolisthetic to zero displacement. Using L3-L4 as a baseline for calaculating the intervertebral differences in flexion, all of the rotational differences were less than 1.5o, except at L5-S1, which remained 5o. 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.