What is a Total Disc Replacement?
Total disc replacement (TDR) refers to a surgical procedure that can be used to replace either a cervical disc (CDR) in the neck or lumbar disc (LDR) in the low back. In this article we will focus on the cervical disc replacement as it is much more commonly performed than the lumbar replacement. I will discuss lumbar disc replacement in the future so subscribe for further updates.
Cervical disc replacement was first approved by the U.S. Food and Drug administration (FDA) in 2007. Cervical disc replacement allows the patient to keep their natural neck motion after the procedure in comparison to the typical alternative procedure, the anterior cervical discectomy and fusion (ACDF). Cervical fusions are the gold standard to treat cervical disease but diminish motion in the neck. When one segment is fused we think it can cause some characteristic problems such as adjacent segment disease (aka wear and tear, aka disc degeneration at the levels above and below the diseased disc), which can occur in up to 25% of fusion cases. Cervical disc replacement reduces the rate of adjacent segment .
Who should get a cervical disc replacement? Cervical disc replacements are indicated for patients between 20-70 years of age who have failed conservative therapy for 6 weeks for the treatment of cervical radiculopathy (spine nerve compression) or cervical myelopathy (spinal cord compression). It can be used to treat up to two levels of disease but not three. If there is severe neck pain as the only source of symptoms, facet degeneration, disc height loss > 50%, or absence of motion, a cervical fusion procedure should be considered.
Are cervical disc replacements for everyone? The answer is that CDRs should only be used in select individuals. Cervical disc replacement can preserve but not recreate motion. Cervical disc replacement should not be performed in patients with instability in the spine (defined as abnormal shucking of the bones). If there is severe degeneration, deformity or circumferential compression of the spinal cord, CDR is also not a great option.
There are many different implant manufacturers, which are beyond the scope of this article to discuss. The two most commonly used implants are likely the Mobi-C produced by Zimmer Biomet and the Prodisc produced by Pristige.
What are some common things that can go wrong with a CDR? Complications are similar to cervical fusion in the short term as the access and implantation of the devices are similar (i.e through an anterior approach in the neck). In the short term patients may experience difficulty swallowing, or some hoarseness. Other issues specific to CDR include loosening of the components and auto-fusion. Auto fusion refers to the process of the disc arthroplasty fusing on its own. This can occur in 15% of cases and usually acts very similar to a cervical fusion so patients will still have a great outcome.
Overall the CDR represents an amazing technology which can help treat spinal disease without compromising neck motion.