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Internal deformations of intact and denucleated human lumbar discs subjected to compression, flexion, and extension loads
Author(s) -
Seroussi Richard E.,
Krag Martin H.,
Muller David L.,
Pope Malcolm H.
Publication year - 1989
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.1100070117
Subject(s) - extension (predicate logic) , compression (physics) , lumbar , anatomy , materials science , structural engineering , orthodontics , composite material , computer science , engineering , medicine , programming language
Three rows of six evenly spaced 0.5 mm metal beads were implanted midsagittally into the discs of ten L4–5 human lumbar motion segments. The intradiscal bead displacements in response to compression, flexion, and extension loads were obtained by digitizing the bead positions from sagittal plane radiographs taken before and during the load application. Each disc was denucleated and the loading process was repeated. For the intact discs, in compression, the intradiscal bead displacements were predominantly anterior. In flexion, the beads in the center of the disc moved posteriorly whereas the beads closer to the periphery of the disc moved anteriorly. In extension, the central beads moved anteriorly and the beads closer to the periphery of the disc moved posteriorly. After denucleation, the bead displacements for compression and flexion implied an inward bulging of the inner wall of the annulus, despite outward bulging of the disc surface. We hypothesize that the inward bulging causes radial tensile stresses within the disc, leading to disruption of adjacent layers of annulus.