Mini Anterior Lumbar Interbody Fusion: One Year Follow up for a Novel Device

Abstract

Introduction This study is a prospective cohort observational trial, to evaluate the ROI-A (Radiolucent Open Implant-ALIF) and VerteBRIDGE plate construct, in the treatment of symptomatic lumbar degenerative disc disease. The principal advantage of anterior approach is that the risks associated with exploration of the spinal canal through a posterior approach can be avoided and damage to the muscles of the back is eliminated. The anterior approach offers superior visualization of the disc space itself, and can be done without disruption of the otherwise healthy posterior elements. The Mini ALIF retroperitoneal approach facilitates rapid patient recovery. Materials and Methods The ROI-A (Radiolucent Open Implant-ALIF) is made from PEEK (Polyetheretherketone), a medical grade plastic, and two metallic anchoring plates, marketed as VerteBridge, which provide both stability at the site of desired bony fusion and fixation of the implant to the vertebrae adjacent to the interbody device. Inclusion Criteria: 18 patients between the ages 31 and 65 years of age; Disc disease between L2-S1; Patients may have up to grade I spondylolisthesis or retrolesthesis at the involved site; Maximum two diseased vertebral motion segments to be instrumented; Has had no more than two previous non-fusion surgeries to the lumbar soine at the same level(s); Has failed to respond to an appropriate attempt at conservative treatment. Exclusion Criteria: More than two vertebral motion segments involved; Prior anterior, retroperitoneal approach; Has had previous anterior instrumented fusion at the proposed operative level; Higher than grade I spondylolisthesis or retrolisthesis at the involved level(s); Has reported active malignancy, localized or systemic infection; Morbid obesity, as defined by NIH Clinical Guidelines Body Mass Index (BMI > 40); Patients with a diagnosis of osteoporosis, osteopenia, Paget's or other metabolic bone disease; Patients who smoke more than 1 pack per day; Has an active workers compensation claim relative to the involved part. Outcome Measures: Subjects are evaluated clinically pre-operatively, 6 weeks and 12 months post op by the pain questionnaire (VAS), and function questionnaire (ODI); The radiological measures included the segmental lordosis, integrity of the construct, and presence of bridging bone; Fusion success is defined as presence of bridging bone, and postoperative intervertebral motion at 12 months which is less than 5 degrees, via manual radiographic angular measurements (Cobb Method) of the implanted level(s) on flexion and extension radiographs at the 12 month follow up visit. Results The VAS has improved from an average of 9 preop to an average of 2 postop. ODI score has reduced an average 30 points from preop measurement. 83% (15 patients) went on bony fusion at the radiological assessment 12 month post op. None of the patients underwent revision, removal of implant, supplemented fixation, or re-operation. One patient developed mechanical ileus for 48 hours postop, resolved with NG tube. Conclusion Mini anterior inter-body fusion is a valid option when treating degenerative/discogenic back pain, the ROI-A implant is a safe and simple, with satisfactory results up to 12 month, according to our pilot study.