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Large compressive preloads decrease lumbar motion segment flexibility
Author(s) -
Janevic J.,
AshtonMiller J. A.,
Schultz A. B.
Publication year - 1991
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.1100090211
Subject(s) - preload , torsion (gastropod) , flexibility (engineering) , lumbar , shear force , structural engineering , trunk , materials science , lumbar spine , orthodontics , anatomy , mathematics , medicine , engineering , surgery , hemodynamics , anesthesia , biology , ecology , statistics
The bending, shear, and torsion flexibilities of 13 intact adult lumbar motion segments (from 11 men, two women, 48–83 years of age) were compared under three different compressive preloads, 0, 2,200, and 4,400 N. Test forces and moments up to 160 N and 16 Nm were applied at the center of the upper end plate of the intact disc. A compressive preload of 2,200 N resulted in a significant decrease in motion segment flexibilities in all seven test directions (p < 0.06) when compared with results obtained with no preload; the preload decreased flexibility 2.6, 4.5, and 6.1 times in bending, axial torsion, and shear, respectively. These results suggest that studies of internal trunk load‐sharing between active and passive tissues during strenuous tasks, which engender large spine compressive loads, should take these changes in spine passive resistance into consideration.