Artificial disc replacement surgery

The goal of the CHARITÉ Artificial Disc procedure is to restore the intervertebral disc height and neuroforaminal height while restoring physiologic motion (similar to that of a healthy disc) in that segment of the spine. The surgery requires complete removal of the unhealthy disc in order to implant the new artificial disc.

The CHARITÉ Artificial Disc surgery is approached from the front, with a relatively small incision in the abdomen (usually below the belly button).

The abdominal organs are then gently moved to the side so that the surgeon can visualize the spine while protecting important anatomic structures. This part of the surgery is usually done by a general surgeon or vascular surgeon with the appropriate skills.

The spine surgeon then removes the patient’s collapsed, degenerated disc.

The CHARITÉ Artificial Disc is then implanted - first the two endplates, then the core in the middle, using specialized instruments. The two endplates (made of a cobalt chromium alloy) are pressed into the vertebrae above and below the disc space, and teeth along the border of the endplate grip the vertebral bone. A polyethylene core is then placed between the endplates (see Figure 3).

The artificial disc is designed to be held in place by the spinal ligaments and the remaining part of the annulus of the disc as well as the compressive force of the spine. Bending X-rays of patients after the surgery show that the motion of the artificial disc (flexion, extension, side bending and rotation) can closely approximate the normal motion of a healthy disc.

After the disc replacement surgery, it has been reported in the European experience and in the U.S. clinical trials that patients can typically expect:

Return to daily function soon after surgery, usually without the need for prolonged postoperative bracing
Rehabilitation usually starts about four days after surgery
Hospital stay of about 1 to 4 days
Unlike spinal fusion, bone graft is not used so there is no potential for pain or discomfort from the bone donor site (in the patient’s hip).

Potential risks and complications
In general, the risks of the CHARITÉ Artificial Disc replacement include:

The risks of general anesthesia
The risks of an anterior retroperitoneal (from the front of the abdomen but staying outside the intestinal sac) approach to the spine. Similar to the reported complications of anterior retroperitoneal BAK fusion, these operative complications include vascular injury, retrograde ejaculation in males, infection.
Allergic reaction to the implant materials
Bladder problems
Bleeding (may require a blood transfusion)
Implants that break or move or otherwise malfunction (which may require revision surgery)
Post-surgery pain or discomfort
Slow movements of the intestines
Spinal cord or nerve damage
Spinal fluid leak
Problems with the incision healing

Because artificial disc replacement is a major surgery in and around the spine and major vascular structures, there is also a risk of death or paralysis. In addition, as with any type of spine fusion surgery for chronic low back pain there is a risk that the patient will still have low back pain after the surgery.

All of the above risks can be substantially mitigated by ensuring the diagnosis is accurate, the patient is an appropriate candidate for the surgery, and the spine surgeon is appropriately trained and experienced in doing the CHARITÉ Artificial Disc procedure.

Finally, in addition to the known risks listed above, there are also unknown risks due to the fact that the CHARITÉ Artificial Disc is still a relatively new technology and procedure. For example, it is not yet known how well the disc implant will hold up over time. Because most of the candidates for disc replacement are in there 30’s and 40’s, the disc will need to withstand a great deal of force and wear and tear. Over time, more will become known about the potential limits of the disc and if and/or when replacement surgery will be needed for patients.