Fusion Rates of Lateral Lumbar Interbody Fusion Using Recombinant Human Bone Morphogenetic Protein-2.

STUDY DESIGN: Retrospective observational case series. OBJECTIVES: Lateral lumbar interbody fusion (LLIF) has been widely performed with recombinant human bone morphogenetic protein-2 (rhBMP-2), but the fusion rates using this graft alternative have not been well studied. We aimed to evaluate fusion rates in 1- and 2-level LLIF with rhBMP-2 and their relationship with fixation, as well as rates of BMP-related complications. METHODS: Institutional review board (IRB)-approved spine registry cohort of 93 patients who underwent LLIF with rhBMP-2 (71 one-level cases and 22 two-level cases). Minimum 1-year clinical follow-up and computed tomography (CT) scan for fusion assessment. Postoperative CT scans were used to evaluate the rate of fusion in all patients. Instrumentation and complications were collected from chart and imaging review. RESULTS: Average age was 65 years (67% female). For 1-level cases, 92% (65/71) had complete fusion and 8% (6/71) had either incomplete or indeterminate fusion. Three of the 6 patients who had incomplete or indeterminate fusion had bilateral pedicle screw instrumentation, 1 patient had unilateral posterior fixation, and 2 had no fixation. In 2-level cases, 86% (19/22) had complete fusion and 14% (3/22) had either incomplete or indeterminate fusion. The 3 patients who had incomplete or indeterminate fusion did not have fixation. CONCLUSION: Interbody fusion rates with rhBMP-2 via LLIF was 92% in 1-level cases and 86% in 2-level cases, indicating that rhBMP-2 may be used as a viable graft alternative to allograft options for LLIF. Higher rates of pseudarthrosis occurred when not using fixation.

Effect of Anatomic Variability and Level of Approach on Perioperative Vascular Complications With Anterior Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: The study aim was to determine the prevalence of vascular complications associated with anterior lumbar interbody fusion (ALIF) as a function of anatomic variation and the number of levels fused. SUMMARY OF BACKGROUND DATA: ALIF often requires mobilization of the great vessels, particularly when exposing levels above L5-S1. The exposure can be more challenging in the setting of spondylolisthesis or transitional anatomy. METHODS: This retrospective review of prospectively collected data from our spine database identified 204 patients who had undergone single level (n = 142) or multilevel (n = 62) ALIF from 2008 to 2013 with minimum 6-month follow-up. Average age was 58 years; 57% were female. Preoperative radiographic assessment for spondylolisthesis and transitional anatomy was performed. Body mass index, estimated blood loss, and levels of ALIF were recorded. Intraoperative vascular injury, postoperative deep venous thrombosis, and pulmonary embolism events were noted. RESULTS: Eleven patients experienced postoperative thromboembolic events and were more likely to have had intraoperative vascular injury compared with patients who did not develop a vascular complication (36% and 5%, respectively; P = 0.004). Estimated blood loss was significantly higher in patients with spondylolisthesis when compared to patients without spondylolisthesis (520 cc vs. 103 cc, respectively; P = 0.017) or transitional anatomy (347 cc vs. 262 cc, respectively; P = 0.022). Patients undergoing multilevel ALIF had significantly higher blood loss than patients undergoing a single level procedure (684 cc vs. 107 cc; P < 0.001). Patient characteristics, blood loss, anatomic variation, and level of approach were not associated with the development of postoperative thromboembolic complications. CONCLUSION: Performing ALIF in the setting of spondylolisthesis or transitional anatomy resulted in higher blood loss. Patients undergoing multilevel rather than single level ALIF experienced greater blood loss. Because patients with intraoperative vascular injury had increased likelihood of postoperative thromboembolic event, thrombosis prophylaxis should be considered in these patients. LEVEL OF EVIDENCE: 4.

Vascular complications of exposure for anterior lumbar interbody fusion.

OBJECTIVE: The purpose of this study is to document the incidence of vascular complications during anterior lumbar interbody fusion (ALIF) in 212 consecutive patients treated at the Scripps Clinic and determine what factors adversely affected outcome. METHODS: We reviewed the prospectively maintained database of all ALIF procedures performed at Scripps Clinic between August 2004 and June 2009. All procedures were performed by a spine surgeon in conjunction with a vascular surgeon who performed the exposure portion of the operation, and protected the vessels from injury during the instrumentation phase of the operation. RESULTS: Two hundred twelve ALIF operations were identified. The mean age of the patients was 53.8 years, and 120 (56.6%) were female. The mean body mass index (BMI) was 29.6 (range, 18.1 to 47.8). Twenty-two (10.4%) operations were performed at the L4-5 disc space, 149 (70.3%) at L5-S1, and 41 (19.3%) involved L4-L5 with L5-S1. The mean estimated blood loss (EBL) was 143 milliliters. There was a significant direct correlation between increasing BMI and EBL (P = .018). Thirteen (6.1%) vascular injuries occurred of which five were major (38.5%). One major arterial injury (0.5%) occurred and required arterial thrombectomy and stent placement. Four of the major vascular injuries were venous in nature and required a multi-suture repair. The remaining eight injuries (61.5%) were venous, the majority of which required a suture repair. There were no mortalities. There was an increase risk of vascular injury when both L4-L5 and L5-S1 were exposed (P = .003) and with the male gender (P = .013). Calcification of the aorto-iliac system did not exert an effect on EBL or vascular injury. In four cases, the surgeon was unable to expose the appropriate disc levels. CONCLUSIONS: Anterior exposure of the spine for ALIF can be performed safely with a team approach that includes a vascular surgeon. Preoperative evaluation by a vascular surgeon is advisable. Patients with increased BMI and bi-level exposures should be approached with caution.