Investigational Research: Timeline, Trials, and Future Directions of Spinal Disc Arthroplasty.

Spinal disc arthroplasty (SDA) has been a rising alternative to fusion for the treatment of degenerative disc disease (DDD). This review aims to provide an overview of the timeline, approvals, and limitations of SDA through analysis of U.S. Food and Drug Administration (FDA)-approved trials. Clinical studies have shown more successful outcomes when comparing cervical disc arthroplasty (CDA) with anterior cervical decompression and fusion, with the key benefits of decreased risk of nerve root compression and adjacent disc disease. CDA is currently approved by the FDA for one- and two-level disc pathologies. However, there are no approved trials for three-level or more cervical pathologies. The FDA approved its usage for the treatment of one-level lumbar disc pathologies in 2007 and recently approved two-level disc pathologies in 2020. Thoracic SDA has not been approved by the FDA, and there are no currently occurring clinical trials. While multilevel SDA has been approved in the cervical and lumbar spine, it has not been approved in more than two adjacent vertebral levels. Based on these clinical studies, future research is needed to compare the success of SDA for three-level or more disc pathologies. There have been recent publications showing promising results, though no FDA-approved clinical trials exist. Furthermore, a hybrid construct has been a recent surgical method to treat multilevel DDD. In this approach, arthroplasty and fusion techniques are combined in alternating fashion at adjacent levels to treat two- and three-level disc disease. Hybrid arthroplasty compared with SDA is currently being studied in clinical trials. As such, long-term research with FDA-approved clinical trials is needed to understand the benefits and limitations of different approaches in the treatment of DDD.

Acute Refractory Hypocalcemia in a 51-Year-Old Male With a History of 1,1-Difluoroethane Inhalation.

Hypocalcemia is a common electrolyte derangement that is most associated with parathryoid hormone or vitamin D abnormalities. Less common causes that most providers are aware of include hyperphosphatemia, acute pancreatitis, chronic kidney disease, and sepsis. However, certain populations are at risk for less common, but no less dangerous, causes. One such cause is 1,1-difluoroethane, an organofluorine that is used as a propellant in aerosol sprays and is commonly abused. 1,1-Difluoroethane has been noted to cause severe hypocalcemia by accumulation of the metabolite fluorocitrate in tissues. Here, we present the case of a 51-year-old male with severe hypocalcemia and multiple rib fractures following a fall, with recent history of tibial fracture. The patient had a medical history of osteoporosis with numerous fractures and chronic steroid use. He admitted to using keyboard cleaner as an inhalant for the previous month, which was found to contain 1,1-difluoroethane. Previous case reports on 1,1-difluoroethane inhalation have not reported a patient with preexisting osteoporosis or refractory hypocalcemia.

The Impact of "Vaping" Electronic Cigarettes on Spine Health.

"Vaping" or the use of electronic cigarettes (e-cigarettes) has greatly increased within the past decade, with growing popularity among adolescents. E-cigarettes have many harmful effects on multiple organ systems, but more research is needed to fully understand the extent of possible risks. Our narrative literature review aims to provide comprehensive insight into the impact of e-cigarette use on spinal health with a specific focus on intervertebral disc (IVD) health, bone health, and spinal fusion. There are many metallic compounds and chemical flavoring additives within e-cigarette liquids that are associated with human toxicity. These chemical toxins have been linked to increased oxidative stress leading to systemic inflammation. E-cigarette carcinogens have shown to have a toxic effect on osteoblast cells, and long-term use may decrease bone mineral density and increase the future risk for osteoporosis. Additionally, nicotine in e-liquids negatively impacts IVD health by creating hypoxic environments that degenerate the IVD vasculature and cellular matrix. While studies have demonstrated the inhibitory effects of nicotine use on spinal fusions in animal models, the impact of e-cigarette use on spinal fusion operations in human patients is currently lacking. Future research should focus on the influence of e-cigarette use on spinal health, particularly in adolescents with long-term follow-up, as childhood is a critical time for bone growth and development. Additionally, studies exploring the effects of e-cigarettes on spinal surgery outcomes, such as spinal fusions, are sparse in the literature. Further prospective research studies with a focus on the variety of e-cigarette chemical toxins and flavoring agents is needed to assess the impact on spinal health.