Abstract
Introduction: 360 degree combined anterior and posterior fusion is an accepted surgical treatment for the management of discogenic back pain. Controversy exists to the optimal technique of posterior fixation. Proponents of translaminar screw fixation cite lower morbidity as a result of less dissection. Despite reports of high fusion rates with this technique, there are concerns over the biomechanical inferiority of this construct compared to pedicle screw fixation. Previous studies on translaminar screws have used only plain radiographs to assess fusion. The objective of this paper is to compare radiographic outcomes, using high definition CT scans, and clinical outcomes between these two methods of posterior fixation.
Methods: During 2001, 31 patients underwent combined anterior and posterior fusion by the two senior surgeons for the management of back pain. Anterior interbody fusion was performed using the Syncage in all patients. 16 patients underwent translaminar screw posterior fixation and 15 underwent pedicle screw posterior fixation. Fusion was assessed by high definition CT scan at one year postoperatively. Function was assessed with pre- and postoperative Low Back Outcome Score and visual analogue scores.
Results: Minimum follow-up was 12 months. The incidence of pseudarthrosis in the translaminar group was over 75% which was five times greater than that seen in the pedicle screw group (p = 0.01). There were trends towards greater improvements in the LBOS and VAS scores in the pedicle screw group and amongst those patients who achieved a successful fusion. There were two surgical complications in the translaminar screw group and one in the pedicle screw group.
Discussion: With the numbers that are available, there are no clinical differences between the two methods of fixation, although there were trends towards improved function and reduced pain in the pedicle screw group. Furthermore there does not appear to be any difference in regards to complications. However, translaminar screws are associated with a significantly higher rate of pseudarthrosis compared to pedicle screws.
The abstracts were prepared by Dr Robert Moore. Correspondence should be addressed to him at Spine Society of Australia, c/o the Adelaide Centre for Spinal Research, Institute of Medical and Veterinary Science, PO Box 14, Rundle Mall, Adelaide SA 500, Australia.
