A comparative biomechanical study of spinal fixation using Cotrel-Dubousset instrumentation.
A biomechanical study was performed comparing the stiffness and stability of Cotrel-Dubousset (CD) spinal instrumentation with that of segmentally wired Harrington distraction rods and segmentally wired Luque rods under conditions of single-level instability. The axial and torsional stiffness coefficients of each system were determined on a customized geometric spine simulator fashioned from stainless steel. The relative stability of each instrumentation system was then compared by mounting the fixation systems on bovine thoracic spines from 12-week-old calves, destabilized by anterior vertebrectomy to create simulated two column instability. Thirteen spines were tested. Each specimen was tested under axial and torsional loading conditions while monitoring with a personal computer-based data acquisition system was performed. The stability of first- and second-level CD instrumentation was tested on the bovine specimens. First-level CD instrumentation involved double-hook fixation one level above and below the level of instability. Second-level CD instrumentation involved fixation two levels above and below the level of instability without fixation at the intermediate level. In axial loading, double-level wired Harrington distraction rods, double-level wired Luque rods, and first-level CD rods were 26.5%, 18.4%, and 21.5%, respectively, as stable as second-level CD instrumentation. In torsion, double-level Harrington, double-level Luque, and second-level CD rods were 13%, 64%, and 34%, respectively, as stable as first level CD instrumentation. Locking hooks, double-hook configurations, and stabilizing transverse traction devices of the CD contributed to its greater stability.(ABSTRACT TRUNCATED AT 250 WORDS)
Farcy
J P
JP
Department of Orthopaedic Surgery, Helen Hayes Hospital, West Haverstraw, New York.
Weidenbaum
M
M
Michelsen
C B
CB
Hoeltzel
D A
DA
Athanasiou
K A
KA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D005592:Fracture Fixation / Q000295:instrumentation*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008875:Middle Aged; D009984:Orthopedic Fixation Devices; D013124:Spinal Injuries / Q000601:surgery*