Partial Disc Replacement Works Well for Some Patients
Whenever a new medical device comes on the market, doctors want to know when it can be used and what the results might be. Doctors in China are trying to answer these questions for the new prosthetic disc nucleus (PDN). The PDN replaces the inner portion of the disc (the nucleus), but it leaves the outer ring (annulus) intact. Disc herniation and degeneration are the two biggest reasons to use the PDN.

The PDN is made of a hydrogel core that absorbs fluid just like a real disc. Once it's inserted into the disc space, it expands. This lifts the vertebral bone, giving normal disc height. The implant gives patients good pain relief. Increasing the space between the bones takes the pressure off the spinal nerve root.

Researchers have been looking for a way to replace the discs with an artificial device for years. The first attempt was made in 1966 in Europe. The new PDN design was invented by Charles D. Ray of Germany in 1991. The authors of this study report that inserting the new PDN is a fairly simple operation. This is especially true when compared with spinal fusion or using a total artificial disc. They advise using it for single disc replacement.

They found that the PDN seems to work best for early, painful disc problems in the low back. Other treatment should be tried first, such as drugs, rest, and exercise. Anyone with a fracture, damaged joints, or disc space that's too narrow isn't a good candidate for the PDN. The annulus must be in good condition, too.

Most patients in this study had pain relief. X-rays show normal disc height with the PDN. Patients had good spinal motion and could return to work. When only a single PDN was implanted, no problems occured with shifting of the implant.
Dadi Jin, et al. Prosthetic Disc Nucleus (PDN) Replacement for Lumbar Disc Herniation. In Journal of Spinal Disorders & Techniques. August 2003. Vol. 16. No. 4. Pp. 331-337.