9:43 Spinal fusion and smoking: is pseudarthrosis the cause for poorer clinical outcome?

Abstract

Purpose of study: Nicotine consumption by spinal fusion patients is associated with increased pseudarthrosis risk and poorer clinical outcome. This study examines the relationship between smoking and clinical outcome independent of fusion success.Methods used: Patients with symptomatic lumbar disc disease were enrolled in prospective studies to examine the efficacy of recombinant human bone morphogenic protein (rhBMP)-2 on an absorbable collagen sponge (InFuse; Medtronic, Minneapolis, MN) as a bone graft substitute for anterior lumbar interbody fusion (ALIF). All patients underwent single level ALIF with an LT-cage (Medtronic) containing either iliac crest autograft (control) or InFuse. Clinical outcome data were collected preoperatively, and at 1.5, 3, 6, 12 and 24 months after surgery. This included the Oswestry Disability Questionnaire Short Form (SF)-36 back profile and back pain questionnaires. Radiographic outcomes were assessed at 6, 12 and 24 months after surgery. Successful fusion required evidence of bridging trabecular bone on computed tomography scans and radiographs, and the presence of less than 50 of angular motion and less than 3 mm translation on flexion-extension radiographs, and no radiolucent lines covering more than 50% of the implant surface. Patients who had consumed nicotine by smoking within 6 months of surgery were identified as smokers. In order to exclude the effect of pseudarthrosis, we compared the outcome data between smokers and nonsmokers in the subgroup of patients who had achieved successful fusion.of findings: At 24 months after surgery, a total of 303 patients had achieved successful fusion: 211 nonsmokers (93.3% fusion rate) and 92 smokers (88.3% fusion rate). The following graphs depict the clinical outcome in these patients (Figs. 1, 2, 3, and 4) .Relationship between findings and existing knowledge: There is a significant relationship between smoking and clinical outcome independent of fusion success for ALIF procedure.Overall significance of findings: Independent of fusion outcome, there were differences in clinical outcome between smokers and nonsmokers. Nonsmoking patients with successful fusion had superior Oswestry scores (significant 6 and 12 months postoperative), superior SF-36 physical scores (significant 12 and 24 months postoperative), superior SF-36 mental scores (significant 6 and 12 months postoperative) and less back pain (significant 6 months postoperative) compared with smoking patients with successful fusion. The adverse effects of nicotine on osteogenesis and spinal fusion may not fully explain the poorer clinical outcome in patients who smoke.Disclosures: Device or drug: rhBMP-2 / absorbable collagen, investigational device. Status: investigational.Conflict of interest: Harvinder Sandhu, grant research support; Harvinder Sandhu, consultant for Medtronic Sofamor Danek.