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.