Six-Year Outcomes of Anterior Lumbar Interbody Arthrodesis with Use of Interbody Fusion Cages and Recombinant Human Bone Morphogenetic Protein-2

BACKGROUND: Twenty-four-month outcomes have been reported for patients with degenerative lumbar disc disease who were treated with stand-alone anterior lumbar interbody arthrodesis with use of dual tapered interbody fusion cages and recombinant human bone morphogenetic protein-2. This report represents an update of the clinical and radiographic results of this treatment at six years. METHODS: Two hundred and seventy-seven patients with single-level degenerative disc disease with up to grade-I spondylolisthesis were enrolled in two prospective, multicenter, U.S. Food and Drug Administration-approved investigational device exemption studies and were treated with an open or a laparoscopic surgical procedure. The patients received recombinant human bone morphogenetic protein-2 on an absorbable collagen sponge with lumbar fusion cage implants. One hundred and forty-six patients completed the six-year clinical follow-up evaluations, and 130 patients had complete radiographic follow-up at six years. Outcomes were determined with use of well-established clinical outcome measurements (Oswestry Disability Index, Short Form-36, and back and leg pain scores) and radiographic assessments. RESULTS: At six years, 128 (98%) of the 130 patients treated with recombinant human bone morphogenetic protein-2 and stand-alone fusion cages had a fusion. The second surgery rate was 6.7% (eighteen patients) prior to two years and 3.7% (seven patients) from two to six years. A worst-case scenario analysis, which includes all second surgical procedures due to pseudarthrosis, resulted in a fusion rate at seventy-two months of 91% (128 of 141). Significant improvements in the Oswestry Disability Index scores, Short Form-36 health survey physical component summary scores, and back and leg pain scores were achieved by six weeks in both the open and laparoscopic groups and were sustained at six years (p < 0.001). The percentage of patients who were working at six months (63%) was higher than the percentage who had been working preoperatively (52%), and this improvement was sustained at six years (68%). CONCLUSIONS: The use of dual tapered threaded fusion cages and recombinant human bone morphogenetic protein-2 on an absorbable collagen sponge obtained and maintained intervertebral spinal fusion, improved clinical outcomes, and reduced pain after anterior lumbar interbody arthrodesis in patients with degenerative lumbar disc disease.