LCD L39958: Intervertebral Disc Repair

This is a non-coverage policy for all intervertebral disc injections (intradiscal/interdiscal) for management of chronic low back pain.

Low back pain secondary to degenerative disc disease is the most prevalent musculoskeletal complaint among the adult population, affecting up to 80% of people and costing the United States (U.S.) healthcare system between $19.6 and $118.8 billion per year. 1 Degenerative disc disease can lead to changes in the spinal vertebrae that can destabilize the anterior spinal column and cause radiculopathy due to nerve compression. The normal intervertebral disc serves as a "shock absorber" between each vertebra. The intervertebral disc consists of a gelatinous mucoid center and the nucleus pulposus (NP) that is covered by the annulus fibrosus, a band of fibrous tissue. When an individual is upright, weight causes the nucleus of each vertebra to expand, but the annulus fibrosis holds it in place. A degenerative cascade is often initiated by an imbalance between catabolic and anabolic processes in the intervertebral disc, influenced by genetic, nutritional and mechanical factors. 2 As the degeneration cascade progresses, production of pro-inflammatory molecules such as tumor necrosis factor (TNF)–α and interleukins increases. Furthermore, endplate calcification impairs nutrient flow and exacerbates the hypoxic acidic environment. Together, nutrient deprivation and inflammatory environment accelerates the cell death within NP. As a consequence of extracellular matrix degradation, neoinnervation and neovascularization take place. Ultimately, this degenerative process results in loss of elasticity as fibrosis and dehydration of the NP worsen. There is loss of disc height, formation of osseous spurs, and, eventually, extrusion of nucleus tissue. 3 Due to its low blood supply, an intervertebral disc has difficulty repairing itself after an injury or age-related dehydration, thus the continuing loss of cushioning function. 4

Conservative management of back pain is the first-line treatment for most patients. Nonsteroidal anti-inflammatory drugs or other analgesics are used for symptom relief. Duloxetine or tramadol are recommended second-line pharmacologic therapies by the American College of Physicians. 5 Additionally, modification of activity in conjunction with some form of exercise therapy is frequently prescribed early in the course of symptoms. For patients with persistent non-radicular back pain, guidelines recommend interdisciplinary rehabilitation, which is defined as an integrated approach using physical rehabilitation in conjunction with a psychological or psychosocial intervention. Opioids may also be prescribed. Invasive procedures include spine fusion and recently, spinal arthroplasty. 4 Spinal fusion is a procedure that unites 2 or more vertebral bodies together. The goal is to restrict spinal motion and remove the degenerated disc (the presumed pain generator) in order to relieve symptoms. However, fusion alters the normal mechanics of the spine and is associated with an increase in long-term degenerative changes in adjacent spine segments. Practice guidelines from the American Pain Society recommend that surgery be presented as an option to patients with persistent (>1 year) disabling non radicular low back pain with discussion of its risks and benefits and with interdisciplinary rehabilitation discussed as similarly effective. 6 Shared decision-making with regard to surgery should take into account that most patients who undergo surgery will have some residual symptoms.

Although existing surgical treatments may provide better pain relief than nonsurgical interventions, 7 they do not address the biology of disc degeneration. Most patients respond to conservative management and surgical interventions well initially, yet a sizable number of patients continue to suffer from chronic low back pain. Moreover, these treatments are limited to relieving symptoms, with no attempt to restore the disc’s structure. Artificial disc replacement is a newer alternative to fusion. A theoretic advantage of lumbar disc replacement compared with fusion is that a prosthetic disc could help preserve normal range of motion and spine mechanics. This could reduce the long-term degenerative changes in adjacent vertebral segments that have been observed following spinal fusion. However, the evidence suggests that the efficacy of this approach is similar to that of spinal fusion. These early trials have reported on small sample sizes and clinical applications that are limited by the strict inclusion criteria and/or lack of durability. A key limitation of existing evidence for the role of lumbar disc replacement is the lack of longer-term follow-up to assess efficacy and failure rates necessitating device removal and potential conversion to a fusion procedure. Guidelines from the American Pain Society found insufficient supporting evidence regarding long-term benefits and harms of disc replacement to recommend the procedure. 8

Regardless of treatment (disc replacement, fusion, or nonsurgical), few patients report complete symptom resolution. Because of the high prevalence of long-term discogenic pain, regenerative biological therapies, including gene therapies, growth factors, cellular-based injections, and tissue-engineered constructs, have attracted significant attention in light of their potential to directly address the degenerative process. Several clinical trials have evaluated both autologous and allogeneic human cellular/tissue therapies in patients with painful degenerative disc disease and have reported various improvements in pain and function. This LCD reviews the evidence for agents that are administered via intradiscal injection for management of chronic low back pain. Management via these injections means the injectate is meant to rehydrate, repair, or supplement the disc.