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The Effect of Electrical Stimulation on Lumbar Spinal Fusion in Older Patients: A Randomized, Controlled, Multi-Center Trial: Part 2: Fusion Rates

Andersen, Thomas MD, PhD*; Christensen, Finn B. MD, PhD, DMSc*; Egund, Niels MD, DMSc; Ernst, Carsten MD; Fruensgaard, Søren MD§; Østergaard, Jørgen MD; Andersen, Jens Langer MD, DMSc; Rasmussen, Sten MD; Niedermann, Bent MD*; Høy, Kristian MD*; Helmig, Peter MD, PhD*; Holm, Randi MD*; Lindblad, Bent Erling MD, PhD*; Hansen, Ebbe Stender MD, DMSc*; Bünger, Cody MD, DMSc*

doi: 10.1097/BRS.0b013e3181b02c59
Randomized Trial

Study Design. Randomized, controlled, multi-center trial.

Objective. To investigate the effect of direct current (DC) electrical stimulation on fusion rates after lumbar spinal fusion in patients older than 60 years.

Summary of Background Data. Older patients have increased complication rates after spinal fusion surgery. Treatments which have the possibility of enhancing functional outcome and fusion rates without lengthening the procedure could prove beneficial. DC-stimulation of spinal fusion has proven effective in increasing fusion rates in younger and “high risk” patients, but little information exist on the effect in older patients.

Methods. A randomized clinical trial comprising 5 orthopedic centers. The study included a total of 107 patients randomized to uninstrumented posterolateral lumbar spinal fusion with or without DC-stimulation. Fusion rate was assessed at 2 year follow-up using thin slice CT. Functional outcome was assessed using Dallas Pain Questionnaire and Low Back Pain Rating Scale pain index.

Results. Available follow-up after 2 years was 89% (84 of 95 patients). Fusion rates were surprisingly low. DC-stimulation had no effect on fusion rate: 35% versus 36% in controls. Other factors associated with low fusion rates were female gender (32% vs. 42% in males, P = 0.050) and smoking (21% vs. 42% in nonsmokers, P = 0.079). Patients who achieved a solid fusion as determined by CT had superior functional outcome and pain scores at their latest follow-up.

Conclusion. Thin slice CT revealed very high nonunion rates after uninstrumented spinal fusion in older patients. DC-stimulation was not effective in increasing fusion rates in this patient population. The achievement of a solid fusion was associated with superior functional outcome.

A multi-center, randomized trial comparing uninstrumented posterolateral fusion with and without direct current-stimulation in patients older than 60 years. Fusion rates were low and not affected by direct current-stimulation. Presence of a solid fusion was associated with superior functional outcome at follow-up.

From the *Orthopaedic Department E, Spine Section, †Department of Radiology, Aarhus University Hospital, Aarhus, Denmark; ‡Orthopaedic Department, Esbjerg County Hospital, Esbjerg, Denmark; §Orthopaedic Department, Holstebro County Hospital, Holstebro, Denmark; ¶Orthopaedic Department, Viborg County Hospital, Viborg, Denmark; and ∥Orthopaedic Department, Vejle County Hospital, Vejle, Denmark.

Acknowledgment date: November 9, 2008. Revision date: April 20, 2009. Acceptance date: May 22, 2009.

The device(s)/drug(s) that is/are the subject of this manuscript is/are not FDA-approved for this indication and is/are not commercially available in the United States.

Corporate/Industry and federal funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

The study was approved by the regional ethical committees (case number): 20000262, 2000/149mc, M-2200–00, 20000235.

Address correspondence and reprint requests to Thomas Andersen, MD, PhD, Orthopaedic Research Laboratory, Building 1A, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C; E-mail:

© 2009 Lippincott Williams & Wilkins, Inc.