[Dynamec changls in dimension of cross-sectional areas of lumbar canal and dural sac: an experimental study].

The variation in the cross-sectional areas (CSA) of lumbar canal and dural sac under extension and flexion was studied by using CT scans in ten human cadaver lumbar spine specimens. CSA at different levels or same level in varying positions were distinctive. CSA in flexion position was increased, while in extension position reduced. Dynamic changes of CSA of canal (CSAC) at L4,5,L5-S1 were very significant (P < 0.01), and those of CSA of dural a (CSADS) at all levels but L5-S1 were significant (P < 0.05). It was considered that dynamic changes of CSAC at intervertebral levels were determined by the range of lumbar motions, but those of CSADS were influenced by changes of canal and biomechanical factors of intracanal soft-tissue and changes of dural sac length. Measurement of CSADS was more significant than that of CSAC.