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Characteristics of Sagittal Vertebral
Alignment in Flexion Determined by Dynamic Radiographs of the Cervical
Spine
Ruey-Mo
Lin, MD*;
Kuen-Horng Tsai, PhD†;
Lee-Ping Chu, MS*;
Po-Quang Chang, MD‡
From the *Department of Orthopedics, National Cheng
Kung University, Tainan, Taiwan, the
†Department of Industrial Design, Da Yeh University, Changhua, Taiwan,
and the
‡Department of Orthopedics, College of Medicine, National Taiwan
University, Taipei, Taiwan.
SPINE
2001, February; 26(3):256-261
Study Design.
This study was conducted to depict the change patterns of intervertebral
motion of the cervical spine during flexion, upright, and extension
positions using dynamic radiographs. Special interest was focused
on the flexion position.
Objectives. To find reliable criteria for judging the normal intervertebral
flexibility based on a survey of the normal population.
Methods. The lateral dynamic radiographs of 75 normal subjects were
analyzed by digitization and computer calculation. The characteristics
of intervertebral positions were investigated using flexion radiographs.
Results. From extension to flexion, the angles of intervertebral angular
displacement changed from lordosis with different degrees to nearly
0°, which means the adjacent endplates are almost parallel, except
at C1–C2; the intervertebral translation changes from slightly retrolisthetic
to zero displacement. Using C2–C3 as a baseline to calculate the
intervertebral differences of angular displacement and translation
in flexion radiographs, nearly all the intervertebral differences
of angular displacement were less than 7°, and those of translation
were less than 0.06 mm.
Conclusions. Qualitative changes from extension to flexion and quantitative
values of intervertebral differences in flexion radiographs help
define the normal flexibility of the cervical spine more accurately.
Key words: cervical spine; flexion–extension radiograph; intervertebral
difference
Spine
2001 February;26(3):256-261
Copyright © 2001 Lippincott
Williams & Wilkins
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