Biomechanical flexion-extension forces in normal canine lumbosacral cadaver specimens before and after dorsal laminectomy-discectomy and pedicle screw-rod fixation.

Abstract

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: Björn P Meij, Niyada Suwankong, Albert J Van der Veen, Herman A W Hazewinkel
• Journal: Veterinary surgery : VS (Vet Surg) Vol. 36 Issue 8 Pg. 742-51 (Dec 2007) ISSN: 1532-950X [Electronic] United States
• PMID: 18067614 (Publication Type: Journal Article)

Chemical References

• Biocompatible Materials

Topics

• Animals
• Biocompatible Materials
• Biomechanical Phenomena
• Bone Screws (veterinary)
• Cadaver
• Diskectomy (methods, veterinary)
• Dogs
• Female
• Internal Fixators (veterinary)
• Laminectomy (methods, veterinary)
• Lumbosacral Region (physiology, surgery)
• Male
• Range of Motion, Articular
• Rotation
• Spinal Fusion (instrumentation, methods, veterinary)