Evaluating the Potential Risks and Consequences of Artificial Disc Replacement

For artificial disc replacement and anterior spinal fusion, the spine is approached from the front, with an incision near the belly button. Complications associated with this approach to the spine include injury to the major blood vessels that bring blood to and from the legs with significant bleeding, injury to the tubes which move urine from the kidneys to the bladder (ureters), and injury to the small or large intestines.

In males, an additional potential complication called "retrograde ejaculation" exists, occurring in 2 to 5 % of males. With this complication, patients have normal erections and penile sensation and feel normal orgasms, but do not ejaculate. Instead, with orgasm, the semen moves into the bladder and is later urinated out. This makes having children by natural means difficult if not impossible, and males who are possibly interested in having children in the future are encouraged to bank sperm for later use if needed.
These risks are all significantly higher with revision anterior approaches to the spine.

What are the Potential Complications Associated with the Artificial Disc Implants?

Early implant complications include migration of the metal endplates or the central plastic core. This is an uncommon occurrence, and is usually related to problems with initial implant positioning or unrecognized instability of the spine. If this occurs, immediate revision with replacement of the components or conversion to a spinal fusion is the treatment of choice. Rarely, the implant can fracture the vertebra upon insertion or the vertebra can fracture in the postoperative period. If this occurs, brace immobilization may suffice or revision surgery with possible conversion to a spinal fusion may be needed.

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Late complications may include:

  • Collapse of the implant into the bone (subsidence), which may limit implant movement.
  • Eventually, the implant may wear out, and require revision or conversion to a fusion. Longer-term (10-20 years following surgery) studies from Europe indicate that wearing out of the artificial disc implant is uncommon.
  • Late infection is a very rare complication, with only 2 to 3 cases reported in the medical literature. Treatment with antibiotics may suffice, but removal of the implant and conversion to fusion may be needed.

Which is Better, Artificial Disc Replacement or Spinal Fusion?

The potential benefits of artificial disc replacement, including retained mobility and limiting stress on the adjacent discs, must be weighed against the potential for wearing out of the implant over time and the unknown future of the mobile facet joints and other possibilities.

Nothing can replace a full and frank discussion of all the surgical and non-operative options with your surgeon, or multiple surgeons, as well as discussing the risks of any spinal fusion or artificial disc procedure recommended.

Consider also the experience of the surgeon with artificial disc replacement and anterior spinal surgery in general when choosing a surgeon. Few surgeons may have vast experience with total disc replacement at this point in time, but the surgeon should be experienced with anterior spinal surgery in general (including an experienced access surgeon as part of the team) before performing artificial disc procedures.

Does Artificial Disc Replacement Provide Better Relief of Pain than Spinal Fusion?

The clinical studies which have provided evidence for the benefit of the Charite and Prodisc lumbar disc implant are called ‘non-inferiority’ studies. That means, as requested by the FDA, the studies were designed to show only that artificial disc replacement is not less effective than spinal fusion. This type of study requires fewer patients than trying to prove that artificial disc replacement is in fact superior to spinal fusion. The data provided by these studies do support the claim that artificial discs provide results that are not inferior to fusion surgery, but it cannot yet be determined that artificial disc replacement provides a better result.