Anterior lumbar interbody fusion with LT-cages: the influence of workers compensation status on chronological clinical outcome

Abstract

Purpose of study: Workers compensation status is a predictor of clinical outcome in patients undergoing spinal fusion. The intent of this study was to examine the influence of workers compensation status on the chronological outcome of patients undergoing anterior lumbar interbody fusion (ALIF) with intervertebral fusion cages.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) as a bone graft substitute for 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. Workers compensation status was determined in all patients preoperatively.of findings: Of a total of 413 patients enrolled, 136 patients (33%) were receiving workers compensation at the time of surgery and 277 patients (77%) were not. Of these, 109 workers compensation and 215 noncompensation patients were seen at the 24-month follow-up point. Figs. 1 to 5 depict the clinical outcome at each of the follow-up periods (Figs. 1, 2, 3, 4, and 5).Relationship between findings and existing knowledge: We demonstrate a significant influence of workers compensation status on the chronological outcome of patients undergoing ALIF with intervertebral fusion cages.Overall significance of findings: There were no differences in the fusion rates between compensation and noncompensation patients at each of the evaluation periods. Oswestry, SF-36 physical component, SF-36 mental component and back pain scores were significantly better in the noncompensation patients at each follow-up period. Noncompensation patients continued to experience improvement in their Oswestry, SF-36 physical component and back pain scores between the 12-month and 24-month follow-up periods, whereas compensation patients reached maximum improvement at the 12-month follow-up period.Disclosures: Device or drug: rhBMP-2/absorbable collagen sponge, investigational device. Status: investigational.Conflict of interest: Harvinder Sandhu, grant research support, and, consultant.