Intervertebral disc arthroplasty

Artificial disc replacement (ADR), or total disc replacement (TDR), is a type of arthroplasty. It is a surgical procedure in which degenerated intervertebral discs in the spinal column are replaced with artificial devices in the lumbar (lower) or cervical (upper) spine. The procedure is used to treat chronic, severe low back pain and cervical pain resulting from degenerative disc disease. Cervical disc replacement is also an alternative intervention for symptomatic disc herniation with associated arm and hand symptoms.

Artificial disc replacement has been developed as an alternative to spinal fusion, with the goal of pain reduction or elimination, while still allowing motion throughout the spine. Another possible benefit is the prevention of premature breakdown in adjacent levels of the spine, a potential risk in fusion surgeries.

Regulation

United States

Four artificial discs have been approved by the FDA for use in the US: the Charite, manufactured by DePuy for use in the lumbar spine; and the ProDisc, manufactured by Synthes for use in the lumbar spine and cervical spine. The Prestige Cervical disc replacement is manufactured by Medtronics. These three designs are FDA approved for one-level applications, after clinical trials were said to show patient improvement in motion and pain equivalent to spinal fusion. Two-level disc replacement surgery was considered experimental in the United States, but has been performed in Europe for many years. This past year The Mobi-c Disc manufactured by LDR was approved in the United States and has FDA approval for one or two level cervical disc reconstruction.

While these four discs have received FDA approval, some insurance companies in the United States do not cover the surgery, still classifying it as experimental. Effective August 14, 2007, the Centers for Medicare & Medicaid Services (CMS) will not cover Lumbar Artificial Disc Replacement (LADR) for patients over the age of 60, on a national basis. Individual localities regulate the use of the procedure in patients 60 and under.^[1] Since Depuy merged with Synthes it is no longer supporting the Charite device in the United States.

The Maverick, manufactured by Medtronic, has been prevented from entering the US market due to patent infringement litigation, ongoing as of September, 2010.^[2]

History

The first reported human clinical effort to replace the disc involved implantation of metallic spheres within the intervertebral space. The devices and results were not met with acceptance within the spine surgical field though some early surgeons reported good clinical results with improved function and decreased pain. Ferstrom in Sweden, Harmon in the United States and Mckenzie in Canada all reported on their surgical reconstruction of the lumbar disc with various metallic spheres.

Artificial disc surgery is still relatively new in the United States, but has been used in Europe for more than 15 years. In Europe there area multiple manufactures and designs available for both lumbar (lower back) and cervical (neck) application.

The first device approved for use in the United States was the Charite artificial disc. Invented at Charite University Hospital in Berlin in the mid-1980s by the East German scientist, two-time Olympic champion in women's artistic gymnastics Karin Büttner-Janz and Kurt Schellnack,^[3] the disc received FDA approval in the United States in October 2004, following a four-year clinical trial. One of the worldwide practicing artificial disk replacement is the pioneer drs.Willem Zeegers since 1989. Drs. Willem Zeegers stopped with the Carité and is performing the lumbar Activ L artificial disc replacement (company Aesculap)since 2005.

The first surgeon to perform a Charite artificial disc surgery in the United States was Scott Blumenthal, M.D., a spine surgeon at Texas Back Institute in Plano, Texas. Blumenthal served as principal investigator for the Charite study in the US, after visiting drs.Willem Zeegers in the Netherlands, who showed him his experience with the Charité artificial disc implantation in the neighties. Drs Zeegers was involved in the evolutionary development of the Activ L instrumentation and Activ L implant design.

Dr. Rudolf Bertagnoli helped to develop Pro Disc and its surgical technique in Europe and has taught more than 2,500 surgeons how to perform the procedure.

Controversy

The New York Times, January 2008, raised concerns relating to the transparency of research being carried out by investors in Prodisc.^[4] Questions have been raised about the accuracy of that article.^[5]

A statement issued by The American Association of Orthopaedic Surgeons (AAOS) recommends caution in using the new devices, as the studies behind their approval were not designed to show their superiority, only that they produced results equivalent to existing treatments. The data shows that artificial disc replacement patients, when compared to spinal fusion patients, have a shorter recuperation period following surgery, but research also shows that spinal fusion patients show no better outcomes than patients undergoing physical therapy.^[6]

The AAOS also states that disc replacement requires a high level of technical skill for accurate placement, and has a significant level of risk if revision surgery is needed.^[7]

Members of AAOS and the American Association of Neurological Surgeons joined together as the Association for Ethics in Spine Surgery, formed to raise awareness of the ties between physicians and device manufacturers.

There are several class-action lawsuits pending^[8] against the Charite Artificial Disc, and reports of complications with the Pro Disc Artificial Disc implant when used in certain surgical situations.^[9][10]

References

External links

• Non-Profit International Patient Community for Artificial Disc Replacement
• Artificial disc replacement with the modular type SB Charité III: 2-year results in 50 prospectively studied patients.