Pulsed electromagnetic fields: an adjunct to interbody spinal fusion surgery in the high risk patient

Lumbar fusion success rates are unpredictable. Turner, reporting on 82 published studies, cites a fusion success rate that ranged from 16% to 93%, mean 66%. Spinal fusion can be compromised by a number of risk factors that have been identified which tend toward a poorer prognosis. These risk factors include smoking, graft type (autograft vs. allograft), and number of fusion levels. Brown reports a statistically different, 32% decrease in spinal fusion healing in smokers as compared to nonsmokers. Allograft has been reported to significantly lower success rate in posterolateral fusions. Autograft is the preferred graft material because it is both tissue compatible and contains viable bone cells. If these bone cells can continue to be viable during the bridging process, the fusion healing process should be enhanced. Allograft bone does not have any viable bone cells within its matrix and may be rejected due to tissue incompatibility issues. Wilkinson reported that each additional fusion level decreased the possibility of spinal fusion success by approximately 20%. Surgeons are attempting various treatment regimens and adjunctive procedures to increase the odds of fusion for these high risk patients. One method is through the adjunctive use of electrical stimulation by pulsed electromagnetic fields (PEMFs) following a spinal fusion procedure. PEMFs is an inductive method of generating an electric potential at the fusion site. A pulsing magnetic field surrounding the fusion site through a dual coil system creates an electronegative potential along the fusion site. This negative potential is very similar to the natural property that bone has of healing itself. This technology has proven useful in treating the nonunion of long bone and it seemed reasonable to attempt to improve fusion success rates in spinal fusions given the relative safety of PEMFs and the success noted so far in long bones. The purpose of this paper is to demonstrate the safety and efficacy of PEMFs in treating spinal fusion patients with one or more high risk factors regardless of the presence/absence of fixation.