Disc degeneration affects the multidirectional flexibility of the lumbar spine.
METHODS
An in vitro biomechanical investigation using human lumbar cadaveric spine specimens was undertaken to determine any relationship between intervertebral disc degeneration and nonlinear multidirectional spinal flexibility.


BACKGROUND
Previous clinical and biomechanical studies have not established conclusively such a relationship.


METHODS
Forty-seven discs from 12 whole lumbar spine specimens were studied under the application of flexion-extension, axial rotation, and lateral bending pure moments. Three flexibility parameters were defined (neutral zone (NZ), range of motion (ROM), and neutral zone ratio (NZR = NZ/ROM)) and correlated with the macroscopic and radiographic degeneration.


CONCLUSIONS
In flexion-extension, the ROM decreased and NZR increased with degeneration. In axial rotation, NZ and NZR increased with degeneration. In lateral bending, the ROM significantly decreased and the NZR increased with degeneration. In all three loading directions, the NZR increased, indicating greater joint laxity with degeneration.
Mimura
M
M
Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut.
Panjabi
M M
MM
Oxland
T R
TR
Crisco
J J
JJ
Yamamoto
I
I
Vasavada
A
A
D000328:Adult; D001696:Biomechanical Phenomena; D003627:Data Interpretation, Statistical; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012399:Rotation; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*