OBJECTIVE: To determine biomechanical flexion-extension forces in cadaveric canine lumbosacral specimens, before and after dorsal laminectomy with partial discectomy, and after dorsal pedicle screw-rod fixation of L7 and S1. STUDY DESIGN: Biomechanical cadaver study. ANIMALS: Cadaveric spine specimens without lumbosacral pathology from mature, intact Labrador retrievers (n=12). METHODS: Lumbosacral spine segments were subjected to a constant bending moment from L6 to S1 in a hydraulic 4-point bending materials testing machine. Force and displacement were recorded during each loading cycle constituting 1 complete flexion-extension cycle of the spine. Each spine segment had 3 series of recordings of 5 loading cycles each: (1) intact spine, (2) after surgical destabilization by dorsal laminectomy and partial discectomy, and (3) after surgical stabilization using dorsal pedicle screw-rod fixation. RESULTS: After dorsal laminectomy and partial discectomy, the neutral zone and range of motion were not different from those in the native spine specimen. After pedicle screw-rod fixation, the neutral zone and range of motion of the instrumented specimen significantly (P<.0001) decreased compared with the native specimen and the specimen after dorsal laminectomy. CONCLUSION: Dorsal laminectomy and partial discectomy does not lead to significant spinal instability in flexion and extension whereas pedicle screw and rod fixation effectively stabilizes the lumbosacral spine. CLINICAL RELEVANCE: Dorsal laminectomy and partial discectomy does not lead to significant spinal instability. Pedicle screw-rod fixation of L7 and S1 may be used to stabilize an unstable L7-S1 junction in dogs with degenerative lumbosacral stenosis.
OBJECTIVE: To determine biomechanical flexion-extension forces in cadaveric canine lumbosacral specimens, before and after dorsal laminectomy with partial discectomy, and after dorsal pedicle screw-rod fixation of L7 and S1. STUDY DESIGN: Biomechanical cadaver study. ANIMALS: Cadaveric spine specimens without lumbosacral pathology from mature, intact Labrador retrievers (n=12). METHODS: Lumbosacral spine segments were subjected to a constant bending moment from L6 to S1 in a hydraulic 4-point bending materials testing machine. Force and displacement were recorded during each loading cycle constituting 1 complete flexion-extension cycle of the spine. Each spine segment had 3 series of recordings of 5 loading cycles each: (1) intact spine, (2) after surgical destabilization by dorsal laminectomy and partial discectomy, and (3) after surgical stabilization using dorsal pedicle screw-rod fixation. RESULTS: After dorsal laminectomy and partial discectomy, the neutral zone and range of motion were not different from those in the native spine specimen. After pedicle screw-rod fixation, the neutral zone and range of motion of the instrumented specimen significantly (P<.0001) decreased compared with the native specimen and the specimen after dorsal laminectomy. CONCLUSION: Dorsal laminectomy and partial discectomy does not lead to significant spinal instability in flexion and extension whereas pedicle screw and rod fixation effectively stabilizes the lumbosacral spine. CLINICAL RELEVANCE: Dorsal laminectomy and partial discectomy does not lead to significant spinal instability. Pedicle screw-rod fixation of L7 and S1 may be used to stabilize an unstable L7-S1 junction in dogs with degenerative lumbosacral stenosis.
Authors: Lucas A Smolders; Idsart Kingma; Niklas Bergknut; Albert J van der Veen; Wouter J A Dhert; Herman A W Hazewinkel; Jaap H van Dieën; Björn P Meij Journal: Eur Spine J Date: 2012-04-11 Impact factor: 3.134
Authors: William Mark Erwin; Leroi DeSouza; Martha Funabashi; Greg Kawchuk; Muhammad Zia Karim; Sarah Kim; Stefanie Mӓdler; Ajay Matta; Xiaomei Wang; K Arne Mehrkens Journal: Arthritis Res Ther Date: 2015-09-05 Impact factor: 5.156