Factors Associated With Clinical Outcomes After Lumbar Interbody Fusion With a Porous Nitinol Implant

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: The aim of this study is to assess the association of demographic and perioperative factors with clinical outcomes of lumbar interbody fusion with a porous nitinol (TiNi) implant for degenerative disc disease. METHODS: Forty-one patients with degenerative lumbar disease were prospectively followed for a mean of 4.8 years. All patients were instrumented with porous TiNi interbody fusion devices. The Oswestry Disability Index (ODI) and return to work were used to assess clinical outcomes. Factors including age, body mass index, smoking status, insurance status, number of comorbidities, duration of surgery, estimated blood loss, number of levels fused, time since surgery, and preoperative ODI score were assessed. A multiple linear regression analysis was performed to look for demographic and perioperative factors associated with clinical outcome. RESULTS: All patients except one (98%) showed complete fusion on radiography at 1 year. Estimated blood loss and duration of surgery were significantly associated with higher postoperative ODI scores (P = .002 and P = .019, respectively). Smoking status, salary insurance status, age, body mass index, number of comorbidities, number of levels fused, time since surgery, and preoperative ODI score were not significantly associated with outcome. CONCLUSIONS: Porous nitinol permitted fusion rates similar to those reported in the literature for alternative fusion cages. Poor functional outcome of patients was strongly associated with intraoperative blood loss and duration of surgery. We believe that estimated blood loss should be carefully evaluated in studies of postoperative outcome, as it may affect midterm outcomes. LEVEL OF EVIDENCE: Level 3