ISSLS prize winner: microstructure and mechanical disruption of the lumbar disc annulus: part I: a microscopic investigation of the translamellar bridging network.
METHODS
Microstructural investigation of interlamellar connectivity.


OBJECTIVE
To reveal the macro and micro structure of the translamellar bridging network in the lumbar annulus.


BACKGROUND
Contrary to the view that there is minimal interconnection between lamellar sheets, experimental data reveal a significant contribution to the material behavior of the annulus from interactions between fiber populations of alternating lamellae. Recent microstructural studies indicate a localized rather than a homogeneous or dispersed mode of interconnectivity between lamellae.


METHODS
Anterior segments of ovine lumbar discs in 2 age groups were sectioned along the oblique fiber angle. A 3-dimensional picture of the translamellar bridging network is developed using structural information obtained from fully hydrated unstained serial sections imaged by differential interference contrast optics.


RESULTS
A high level of connectivity between apparently disparate bridging elements was revealed. The extended form of the bridging network is that of occasional substantial radial connections spanning many lamellae with a subsidiary fine branching network. The fibrous bridging network is highly integrated with the lamellae architecture via a collagen-based system of interconnectivity.


CONCLUSIONS
This study demonstrates a far greater complexity to the interlamellar architecture of the disc annulus than has previously been recognized. Our findings are clearly relevant to disc biomechanics. Significant degrading of the translamellar bridging network may result in annular weakening leading potentially to disc failure. Most importantly this work opens the way to a much clearer understanding of the microanatomy of the disc wall.
Schollum
Meredith L
ML
Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.
Robertson
Peter A
PA
Broom
Neil D
ND
D000818:Animals; D001363:Awards and Prizes; D001696:Biomechanical Phenomena / Q000502:physiology; D003094:Collagen / Q000502:physiology; D004195:Disease Models, Animal; D005260:Female; D007403:Intervertebral Disc / Q000737:chemistry / Q000166:cytology / Q000473:pathology* / Q000502:physiology*; D007405:Intervertebral Disc Displacement / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000737:chemistry / Q000166:cytology / Q000473:pathology* / Q000502:physiology*; D008853:Microscopy; D012756:Sheep
D003094:Collagen