INTRODUCTION: The optimal fusion method in older patients has been debated. Some studies suggest achievement of solid fusion results in better clinical outcomes. Use of direct current electrical stimulation (DC‐stimulation), could be one way to achieve this. The aim of the present study was to assess the effect of DC‐stimulation on long term functional outcome after uninstrumented spinal fusion in elderly patients and to evaluate the importance of achieving solid fusion.
METHODS: 4‐8 year follow‐up on a multi‐centre randomized clinical comparing DC‐stimulation to a control group in older patients undergoing uninstrumented spinal fusion using allograft. 74 patients (76% of original sample) consisting of 26 males and 48 women, with a mean age at follow‐up of 76 years (range 65‐89 years) completed the long term follow‐up. Mailed versions of Dallas Pain Questionnaire (DPQ), Low Back Pain Rating Scale pain index (LBPRS) and SF‐36 as well as self reported amount of pain medication was used as outcome measures. Fusion was assessed at two years using thin slice CT‐scanning.
RESULTS: No difference between the control and the DC‐stimulated group could be demonstrated in any of the outcome parameters. This could not be attributed to difference in dropouts between the two groups. Improvement from preoperative DPQ scores at long term follow‐up was still significant in two out of four categories in the DC‐stimulated group but not in the control group. Patients who were solid fused had better scores in the physical function (p=0.09) and bodily pain (p=0.06) subscales of the SF‐36 as well as a significant better physical component summary score (p=0.03).
DISCUSSION: No additional benefit of DC‐stimulation to uninstrumented fusion in patients older than 60 years could be proven. Patients who obtained a solid fusion had superior results compared to patients with a non‐union. This study received unrestricted support from Biomet/EBI of 180.000 DKr.