Effects of tensioning the lumbar fasciae on segmental stiffness during flexion and extension: Young Investigator Award winner.
METHODS
Biomechanical study of unembalmed human lumbar segments.


OBJECTIVE
To investigate the effects of tensioning the lumbar fasciae (transversus abdominis [TrA]) aponeurosis) on segment stiffness during flexion and extension.


BACKGROUND
Animal and human studies suggest that TrA may influence intersegmental movement via tension in the middle and posterior layers of lumbar fasciae (MLF, PLF).


METHODS
Compressive flexion and extension moments were applied to 17 lumbar segments from 9 unembalmed cadavers with 20 N lateral tension of the TrA aponeurosis during: 1) "static" tests: load was compared when fascial tension was applied during static compressive loads into flexion-extension; 2) "cyclic loading" tests: load, axial displacement, and stiffness were compared during repeated compressive loading cycles into flexion-extension. After testing, the PLF was incised to determine the tension transmitted by each layer.


RESULTS
At all segments and loads (<200 N), fascial tension increased resistance to flexion loads by approximately 9.5 N. In 15 of 17, fascial tension decreased resistance to extension by approximately 6.6 N. Fascial tension during cyclic flexion loading decreased axial displacement by 26% at the onset of loading (0-2 N) and 2% at 450 N (13 of 17). During extension loading, fascial tension increased displacement at the onset of loading (10 of 17) by approximately 23% and slightly (1%) decreased displacement at 450 N. Segment stiffness was increased by 6 N/mm in flexion (44% at 25 N) and decreased by 2 N/mm (8% at 25 N) in extension. More than 85% of tension was transmitted through the MLF.


CONCLUSIONS
Tension on the lumbar fasciae simulating moderate contraction of TrA affects segmental stiffness, particularly toward the neutral zone.
Barker
Priscilla J
PJ
Department of Anatomy & Cell Biology, University of Melbourne, Victoria, Australia. p.barker@unimelb.edu.au
Guggenheimer
Katharine T
KT
Grkovic
Ivica
I
Briggs
Christopher A
CA
Jones
Daniel C
DC
Thomas
C David L
CD
Hodges
Paul W
PW
D001696:Biomechanical Phenomena; D005205:Fascia / Q000502:physiology*; D006801:Humans; D008023:Ligaments, Articular / Q000502:physiology*; D008159:Lumbar Vertebrae / Q000502:physiology*; D018583:Pliability; D016059:Range of Motion, Articular / Q000502:physiology; D013718:Tensile Strength / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology