Fracture models in the lumbar sheep spine: a biomechanical investigation.
The purpose of this study was to find out if a limited resection of the cranial vertebral body leaving the posterior wall intact is a sufficient model for AO type 3 fractures, or if additional resection of the posterior wall is necessary. In six, fresh-frozen, lumbar sheep spine specimens, the segmental stability was tested in three motion planes in a spine tester. First, the intact specimens were tested. Then, partial resection of the intervertebral disc L3/4 and resection of the cranial vertebral body of L4 was performed, leaving the posterior wall intact. This defect was tested without instrumentation and with a ventral monosegmental interlocking plate mounted. Then, the defect was extended to a total cranial resection, including the posterior wall, and the tests were subsequently repeated. The stability of both types of defects under the different conditions was compared. Without instrumentation, the total cranial resection showed significantly more ROM in flexion/extension and axial rotation than partial cranial resection. With the ventral interlocking plate mounted, the instability in total cranial resection was significantly higher in flexion/extension, with the relative relation even being increased. In axial rotation and lateral bending, the differences were equalized by the mounted plate. From a biomechanical point of view, total cranial resection including the posterior wall should be preferred as a sheep spine fracture model for AO type 3 fractures.
Heineck
Jan
J
Klinik für Unfall-u. Wiederherstellungschirurgie, Universitätsklinik Carl Gustav Carus der Technischen Universität Dresden, Dresden, Germany. jan.heineck@uniklinikum-dresden.de
Haupt
Cornelius
C
Werner
Karin
K
Rammelt
Stefan
S
Zwipp
Hans
H
Wilke
Hans-Joachim
HJ
D000818:Animals; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D005260:Female; D008159:Lumbar Vertebrae / Q000293:injuries*; D016059:Range of Motion, Articular; D012756:Sheep; D016103:Spinal Fractures / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed