58. rhBMP-2 in short segment thoracolumbar fusion augmented with transforaminal lumbar interbody fusion: does dosage matter?

Abstract

BACKGROUND CONTEXT Some studies identify complications associated with off-label use of rhBMP-2 in the setting of transforaminal lumbar interbody fusion (TLIF). The dose-related efficacy of rhBMP-2 in the setting of short segment fusion has not been thoroughly investigated. PURPOSE In the setting of short-segment thoracolumbar fusion augmented with TLIF, to determine the effect of increasing dosages of rhBMP-2 on postoperative clinical and radiographic outcomes. STUDY DESIGN/SETTING Retrospective cohort study of prospectively collected data from a single surgical practice. PATIENT SAMPLE TLIF with rhBMP-2 was performed in 516 consecutive adults who underwent primary or revision short segment open posterior instrumented fusion. Patients who received any amount of rhBMP-2 for posterolateral fusion were excluded from this study. OUTCOME MEASURES Complications including seroma, infection, and revision surgery that occurred within 2 years of the index surgery were all recorded. Preoperative VAS-BP, VAS-LP, and ODI were collected. They were additionally recorded at 6 weeks, 3 months, 6 months, 1 year, and at 2 years. METHODS The sample was divided into 3 cohorts based on dosages of rhBMP-2 utilized (0 mg, 2 mg, 4 mg). Complication rates were compared between the 3 groups. Radiographic union was assessed based off of flexion and extension films. All patients had a minimum of 2-year clinical and radiographic follow-up. No industry funding was received for this study. RESULTS Mean age of patients was 78.6 (sd = 33.0). The mean number of levels fused was 2.31 (sd=1.08). There were no differences in baseline demographics, comorbidity burden, tobacco use, and number of levels fused between cohorts. At an average of 5 years of follow-up, there were a total of 27 (5.2%) non-unions and no statistically significant differences in nonunion rates amongst cohorts: 0 mg - 6.5%; 2 mg - 5.9%, 4 mg - 4.1%; p=0.577. There were no differences in overall perioperative complications appreciated between the cohorts including postoperative seromas and infections. At the two-year postoperative visit, no significant differences in VAS-BP, VAS-LP, or ODI were appreciated between cohorts; all cohorts experienced significant improvement in pain and function from preoperative baseline. CONCLUSIONS This is the largest prospectively collected data series comparing BMP to local autograft in the setting of TLIF to date. Clinical outcomes, including rates of non-union, are no different when using local autograft vs increasing dosages of rhBMP-2. Furthermore, with use of our current BMP technique, complications rates are acceptably minimal. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.