Purpose: Dorsal decompression has become accepted as the standard surgical treatment for spinal stenosis. However, no consensus has been reached to date concerning the extent of resectioning required or the ensuing functional impairment of the segment. As a result, a discussion is now underway on the necessity of employing various additional methods for instrumented stabilisation. The aim of this biomechanical in vitro study is to objectify the functional impact of various defined decompression techniques.
Methods: With the aid of a universal spine tester, the increasing defect situations following left hemifacetectomy, bilateral hemifacetectomy, left hemilaminotomy and laminectomy of the functional spinal unit L4/5 were assessed. A three-dimensional motion analysis was performed on six human lumbar spine specimens under the loading conditions flexion/extension, left/right bending and right/left rotation.
Results: The results showed an increase in both the neutral zone and the range of motion under all the loading components. No significant differences were observed in coupled motions following decompression.
Conclusions: Laminectomy leads to a distinct instability and the question arises of how much additive stability achieved by instrumented stabilization will be adequate.