From the Department of Orthopaedics and Rehabilitation, University of New Mexico School of Medicine, Albuquerque, New Mexico, U.SA.
Abstract: (4294 Views)
The cadaver spine motion segment behavior under torsional load was evaluated
with the disc intact, with partial anterior discectomy and with spacer insertion. The
results of this study explain how anterior lumbar discectomy and interbody fusion
(ALIF) affects the torsional stability of the motion segment.
The pseudarthrosis rate of the anterior lumbar discectomy and interbody
fusion (ALIF) is known to vary with leveL Therefore fifteen fresh human
cadaveric degenerated discs at L3-4, L4-5, and L5-S1 levels were loaded in
torsion: intact after anterior discectomy and, after spacer interposition and
removaL
Torsional rigidity of intactL5-S 1 was greater than L3-4 (41 %) orL4-5 (53%).
Anterior discectomy significantly decreased the torsional rigidity compared to
intact: L3-4 (73%) L4-5 (48%) and L5-S1 (55%). Interpositioning of spacer
partially restored the torsional stability compared to discectomy: L3-4 (22%) L4-
5 (18%) and L5-S1 (38%).
In conclusion, L5-S 1 degenerated discs are rotationally more stable than L3-
4 or L4-5. Anterior discectomy significantly increases torsional flexibility. Spacer
interposition partially restores the disc's torsional stability which is most prominent
at the L5-S 1 leveL Increased rotational flexibility seems related to pseudarthrosis
rate.