I'm thinking about having a disc replacement at my L34 spine. How safe are these things?
Safety is a major concern for any company producing devices such as an artificial disc replacement (ADR). Joint wear and fatigue failure are two of the most common problems.

Each implant type is carefully tested in the laboratory and in animals before being used in humans. Even though there are 15,000 Charité ADRs successfully implanted in humans, the company (DePuy Spine, Johnson & Johnson) continues to test and retest these devices.

Most recently, six Charité ADRs were attached to machines and subjected to 10 million cycles of motion. Three implants were bent and extended over and over. The other three were subjected to repetitive side bending motion.

Testing for particle debris showed very minor wear. Motion early on in the life of the implant produced larger particles. Some light scratches were seen on the load-bearing surface of the device. These changes were hard to see and didn't cause any problems with motion later.

There is certainly room for more testing of these devices. Some patients have had an ADR for upwards of 10 years or more. Long-term results will be reported as time goes by. For now, the consensus of studies is that they are both safe and effective for the right patient.