REFINE Study: A Study In a Novel Interspinous Fusion Device In Subjects With Low Back Pain

INTRODUCTION This study will evaluate the effectiveness and safety of the use of Aurora Spine ZIP™ MIS Interspinous Fusion System and bone graft material in single-level fusion in patients with chronic low back pain that present with degenerative disc disease (DDD) with concurrent neurogenic claudication. Devices included in study are the Aurora Spine ZIP™ MIS Interspinous Fusion System and bone graft material. The device is a bilateral locking plate system which attaches to the spinous processes of the posterior noncervical spine (T1-S1) from an interlaminar approach. The implants have superior and inferior spinous process articulations and a central bone graft chamber. The Aurora Spine ZIP™ is used to treat DDD (defined as back pain of discogenic origin with degeneration of the disc confirmed by history and radiographic studies), spondylolisthesis, trauma (i.e., fracture or dislocation), and/or tumor. The studied indication is lumbar degenerative disease resulting in back pain with lower extremity symptoms and neurogenic claudication. Degenerative disc disease is a common condition of the aging spine, and may contribute to a variety of painful symptoms, including radiculopathy, neurogenic claudication, and back pain. There are a number of mechanical sequelae that result from these degenerative processes of the intervertebral disc, which may manifest in the anterior, middle, and posterior columns of the spine. Symptoms of degenerative disc disease have traditionally been treated with a variety of conservative (pain medications, physical therapy, epidural steroid injections) and invasive (surgical decompression and/or fusion) options(1,2). Interspinous spacers (ISS) have been proven to be effective for neurogenic claudication with 5 year outcome data and robust clinical experience (3). More invasive treatment options for lumbar spinal stenosis include decompressive laminectomies and a variety of approaches to lumbar fusion. Direct comparison of two year results of ISS and decompressive laminectomies found ISS offers a less invasive treatment that reduces the potential for comorbidities, necessity for future operations, and is less disruptive to the spinal anatomy providing greater options for future surgical interventions with equivalent clinical outcomes (4). The landmark multicenter SPORT trial compared decompressive laminectomy to conservative non-operative care in patients with spinal stenosis with neurogenic claudication and found that the surgical group had significantly greater improvement in pain and function at four-year follow-up (5). A meta-analysis of lumbar fusions for degenerative diseases looked at patient reported outcomes from 65 studies including disability, pain scores, and patient satisfaction. Fusion has been shown to be evidenced for spondylolisthesis, and patients who were randomly assigned to fusion care were 4 times as likely to be satisfied, attained 34% greater pain relief and saw a 40% improvement of preoperative disability when compared to those who received non-operative care (2). Evidence for fusion for stenosis without spondylolisthesis is limited in this meta-analysis, however this did not distinguish among fusion approaches. Fusion did provide greater relief than non-operative care in patients with chronic low back pain without clinically significant stenosis or spondylolisthesis (2). Five randomized control trials reported results with fusion between 16-18% improved in terms of back and leg pain as compared to non-operative care (2). Anterior interbody fusion (ABF) and posterolateral fusion with pedicle screws (PLF) in patients with discogenic low back pain resulted in a significant decrease in VAS pain scores, with greatest relief following ABF, compared to conservative treatment (6). 3 STUDY PURPOSE The purpose of this study is to evaluate the effectiveness and safety of the use of Aurora Spine ZIP™ MIS Interspinous Fusion System and bone graft material in single-level fusion in patients with chronic low back pain that present with degenerative disc disease with concurrent neurogenic claudication.