In vitro biomechanical comparison of the flexion/extension mobility of the canine lumbosacral junction before and after dorsal laminectomy and partial discectomy.

The purpose of this canine cadaver study was to evaluate the range of flexion and extension of the canine lumbosacral spine before and after dorsal laminectomy and partial discectomy. Using a cantilever biomechanical system, a 3Nm bending moment was applied to flex and extend the lumbosacral segment. Motion in L7 (total range of motion [ROM] and neutral zone motion [NZ]) was recorded via a rotational potentiometer. There was a significant increase in NZ and ROM after the decompressive procedures (NZ before decompression 6.0±1.2°; NZ after decompression 7.6±2.1°; ROM before decompression 32.8±6.4°; ROM after decompression 40.2±5.6°). It is unknown whether dorsal laminectomy and partial discectomy will induce the same increased motion in clinical cases. Dogs with lumbosacral subluxation, active dogs with little radiographic degenerative changes and working dogs could benefit from lumbosacral stabilization. This cadaver study demonstrated that dorsal laminectomy and partial discectomy at the lumbosacral junction does lead to significant spinal instability.