General Indications and Contraindications

Introduction

This chapter provides an overview of the contemporary literature on lumbar interbody fusion (LIF) instrumentation based on the Spine Patient Outcome Research Trial, Swedish Spinal Stenosis Study, and a recent New England Journal of Medicine article on clinical outcomes. Preoperative factors influencing the surgical outcome are discussed, along with five basic tenets of LIF based on: (1) presence and extent of concurrent listhesis at the level of fusion, (2) need for unilateral versus bilateral foraminal decompression, (3) presence of central canal stenosis, (4) loss of coronal and sagittal balance, and (5) the history of prior surgery at the same level or adjacent levels with or without instrumentations. We also discuss the complications of some original LIF approaches with relevant illustrations depicting the successful use of alternate LIF approaches to correct them. The chapter also portrays the synergistic role of novel techniques and technologies that can make modern LIF procedures safer, more feasible, and more efficacious. These LIF techniques require a lot of expertise and can often be hard to do well, especially in reoperations. These operations are very equipment dependent, and it is important to be familiar with all the common LIF techniques in clinical practice and their individual benefits and complications. Clear understanding about the various LIF approaches can equip the spine surgeon especially when dealing with a complication needing implant retrieval from a distinct approach that was performed by another surgeon.

Background

The first recorded surgical attempt at fusion of the spinal column was in 1891, when Hadra attempted cervical interspinous wiring to treat subluxation caused by Potts spine. However, it took another two decades before the first reports of surgery in the lumbosacral spine emerged in 1911, when Russell Hibbs and Fred Albee reported on their techniques of spinal fusion to treat tuberculosis. Hibbs used “feathered” (morselized) laminae and spinal processes, which were placed into decorticated facet joints to create the world’s first dynamic stabilization. Albee, on the other hand, used tibial grafts between the spinous processes to stimulate fusion. The rationale behind the “posterior fusion” surgery was to prevent deformity, improve stability, and reduce pain. The next major step in development of spinal surgery occurred when Watkins reported the posterolateral intertransverse fusion in 1953.

In 1962 Harrington reported on his series of scoliosis surgery using sublaminar hooks and rods, and the era of spinal instrumentation began. Advances in metallurgy and surgical techniques led to the development of transpedicular, translaminar, corticopedicular, and facet screw systems as well as myriad types of interbody cages made of titanium, polyetheretherketone, and so forth, with variations such as trabecular mesh. Spinal technology grew closely following the prosthetic joint technology; for example, the lessons of enhanced biomechanical pull-out strength and migration resistance offered by porous coating of hip implant (first application of Plasmapore coating of titanium hip prosthesis) in 1986 slowly made its way to the lumbar spine market in 2012 (as the first Plasmapore-coated polyetheretherketone lumbar implant). Continuous improvisation of novel technologies, designs, navigation, and robotics make LIF an ever-evolving area of spine surgery.

Other revolutionizing factors included various osteoinductive and osteoconductive materials being used in bone fusion. A significant step forward was made with the development of recombinant human bone morphogenetic protein (rhBMP). BMPs comprise a group of osteoinductive cytokines that belong to the transforming growth factor beta (TGF-β) superfamily. BMP-2 had been approved by the US Food and Drug Administration (FDA) in 2002 for anterior lumbar interbody fusion (ALIF) based on a pivotal study by Burkus et al. Since its introduction into clinical use, BMP had an immense surge in popularity as spinal surgeons started using osteobiologicals in large numbers to avoid the graft site complications associated with iliac crest grafts. This, in turn, led to reports of many serious complications following off-label use in posterior surgeries, as well as in ALIF. Carragee et al. reported a higher reoperation rate in patients treated with rhBMP-2, mainly to correct graft subsidence. They, among other researchers, found that as many as 20% to 70% of patients had suffered some complications that could be attributed to BMP, including endplate resorption, retrograde ejaculation, seroma formation, bone overgrowth, osteolysis, and an increased risk of cancer. The Yale University Open Data Access study was conducted against this background to assess the safety and utility of BMP-2 and found that the incidence of retrograde ejaculation and neurologic complications were equal in both autograft and BMP-augmented ALIF surgeries. It also demonstrated a small increased relative risk of malignancy with the use of rhBMP-2 in posterolateral lumbar surgeries. However, the absolute risk was very low and therefore clinically insignificant. No difference was found between rhBMP-2 and iliac crest graft, but there was a higher rate of ectopic bone formation in these procedures. Based on these findings, judicious use of BMP is now advocated in posterior lumbar surgeries. In transforaminal lumbar interbody fusion (TLIF), a high risk of postoperative radiculitis has been reported; hence, the use of BMP in these cases is not encouraged. The use of bone marrow aspiration from the exposed lumbar vertebral bodies during the surgery, and then using this aspirate as graft material has been recently reported. This overcomes the graft site complications as well as the problems associated with the use of BMP-2. Further research is ongoing about the use of growth differentiation factor 5, also known as BMP-14, as an osteogenetic material.