gms | German Medical Science

Objective: Since establishment of microsurgical discectomy in the lumbar spine the majority of surgeons thought that normal anatomy could be saved by using this technique although its´ influence on the kinematic of the facet joint still has not been clarified. The purpose of the present in-vitro-trial was to examine changes in range of motion (ROM) across the facet joint due to microsurgical discectomy without facetotomy.

Methods: Using a spinal loading simulator we simulated physiological flexion, extension, and axial loading in 24 human lumbal functional spinal units (FSU´s). We measured the range of motion across the facet joint in 16 FSU´s before and after surgical intervention using a 3-D-motion measurement system and compared these findings with the results of 8 untreated specimens.

Results: Without discectomy, ROM in the facet joints of L2-L3 FSU´s increased between cycle 100 and cycle 10000 by 0.6% in mean and of L4-L5 by 29.2% in mean. With discectomy after 100 cycles, ROM in the facet joints of L4-L5 FSU´s increased between cycle 100 and cycle 10000 by 5.08% in mean and of L4-L5 by 13.8% in mean.

Conclusions: Despite protection of the facet joints discectomy leads to an increased ROM of the surrounding facet joints. Taken together microsurgical discectomy encompasses a broad set of anatomic changes to the surrounding joints which may result in degenerative changes of the facet joints cartilage and an increased laxity of its´ capsule.