Comparative study of surface displacement in discs following chemonucleolysis and lasernucleotomy.
OBJECTIVE
Dynamic changes of the dorsolateral protrusion site have been postulated to play an important role in the therapeutic effect of lasernucleotomy and chemonucleolysis. Basic biomechanical effects of the anulus after lasernucleotomy and chemonucleolysis are investigated.


METHODS
This study evaluates the in vitro bulging of lumbar discs comparing lasernucleotomy and chemonucleolysis. The horizontal displacement at the ventral and dorsolateral surface of 20 cadaver discs were tested by application of a continuously increasing axial deformation before and after therapy. The increase in horizontal displacement due to this longitudinal deformation was measured.


RESULTS
Bulging was significantly lower at the puncture site of the chemonucleolysis needle as well as at that of the laser trocar. Significantly reduced bulging of the anulus was observed after chemonucleolysis. Slightly increased bulging was observed after lasernucleotomy in the total posterior region. There was a tendency to decreased stiffness after chemonucleolysis and a significantly decreased stiffness after lasernucleotomy.


CONCLUSIONS
The in vitro effect of lasernucleotomy seems to be based on reduction of the stiffness by distributing the load all over the anulus, whereas chemonucleolysis reduces bulging.
Department of Orthopaedics, University of Vienna, Austria.
H P
HP
Kutschera
W
W
Lack
M
M
Buchelt
R
R
Beer
D001696:Biomechanical Phenomena; D002102:Cadaver; D002917:Chymopapain / Q000008:administration & dosage; D004548:Elasticity; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000601:surgery*; D007404:Intervertebral Disc Chemolysis; D007405:Intervertebral Disc Displacement / Q000601:surgery* / Q000628:therapy*; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D008159:Lumbar Vertebrae / Q000601:surgery*; D015999:Multivariate Analysis; D013314:Stress, Mechanical
D002917:Chymopapain