Neuropathologic changes with experimental spinal instrumentation: transpedicular versus sublaminar fixation.
Fifty-six mature beagles underwent lumbar spine destabilization, followed by fusion using four techniques. Spinal cord neuropathologic analysis was carried out to determine the number of abnormalities within each group. Group I (n = 14) had posterolateral bone grafting without instrumentation. Group IIa (n = 14) had Cotrel-Dubousset (CD) pedicle screws and rods. Group IIb (n = 14) had Steffee pedicle screws and plates. Group III (n = 14) had sublaminar wires and rods. All of the animals remained clinically neurologically normal throughout the 6 months of the study. The incidence of moderate to severe neuropathologic changes was 21% in Group I, 18% in Group II, and 64% in Group III. Thus, a significantly higher percentage of neuropathologic abnormalities occurred with sublaminar instrumentation than with no instrumentation (p = 0.027), or with transpedicular instrumentation (p = 0.027). In this controlled animal study, the theoretical advantage of pedicle screws, which should not violate the spinal canal, over sublaminar devices, which must enter the canal, was confirmed.
Zdeblick
T A
TA
Department of Orthopedic Surgery, Johns Hopkins University, Baltimore, Maryland.
Becker
P S
PS
McAfee
P C
PC
Sutterlin
C E
CE
Coe
J D
JD
Gurr
K R
KR
D000818:Animals; D001863:Bone Screws; D016025:Bone Transplantation; D001864:Bone Wires; D004285:Dogs; D004867:Equipment Design; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000601:surgery; D009460:Neurologic Examination; D013116:Spinal Cord / Q000473:pathology; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods