Q: Can you run me through a list of things that could go wrong with a cervical disc replacement? I'm looking into this for myself. I have a C5-C6 degenerated disc. Don't want a fusion but not sure how good these replacement parts are.

A: Before artificial disc replacements (also called cervical disc arthroplasty) were developed, patients with chronic neck pain and instability were treated with neck fusion. The fusion stopped motion at the diseased level and thus reduced pain. But the strain on the adjacent spinal levels contributed to further disc degeneration. This is considered a negative consequence of spinal fusion procedures.

Disc replacement preserves motion without putting increased stress on the spinal segments on either side of the disc replacement. Over the years, several companies have made different types of implants. The three major disc replacement devices currently on the market include: 1) BRYAN cervical disc, 2) ProDisc-C, and 3) Bristol Disc. Two of these products (BRYAN and Bristol Disc) are made by the same company (Medtronic).

Various studies have been done comparing the results of neck fusion versus disc replacement. The usual complications of surgery are always possible: infection, slow or poor wound healing, blood clot formation, and worse case scenario: death. The actual incidence of these events is very low.

Complications specific to disc replacement can include subsidence (implant sinks down into the bone), heterotropic ossification (bone formation in surrounding soft tissues), and postoperative dysphagia> (difficulty swallowing). There have been some reports of a decrease in cervical spine lordosis (natural neck curve). No one knows yet what the long-term (if any) consequences of this change might be.

Surgeons are actively seeking ways to reduce problems and complications while improving biomechanics of the spine. They recognize the need to properly implant the right sized implant. It takes a skilled surgeon to watch for and accommodate differences in individual anatomy when placing the implant.

Many changes have been made and suggested by surgeons who have expertise in this area. As a result, the design of the devices has also improved. We can expect to see continued improvements in surgical technique, implant design, and complications following surgery.

Reference: Xuesong Zhang, MD, et al. Randomized, Controlled, Multicenter, Clinical Trial Comparing BRYAN Cervical Disc Arthroplasty with Anterior Cervical Decompression and Fusion in China. In Spine. March 15, 2012. Vol. 37. No. 6. Pp. 433-438.