Surgery: what about cervical and disc prostheses?

For twenty years now, disc prostheses have been offered to patients to relieve crippling neck or lumbar pain.

But this is an option of last resort with very specific indications.

For Professor Serge Perrot, rheumatologist and head of the pain center at Cochin Hospital,

.

Eventually, in fact, the pain may reappear and prove to be much more difficult to treat than before if the intervention has affected or stretched the nerves.

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In a certain number of cases, hernias, linked to deterioration of the discs, compress the nerves and become a source of pain.

A so-called "conservative" treatment is always recommended as first-line treatment: the disc is, in fact, preserved, and spontaneous healing is encouraged, while relieving the patient with analgesics, anti-inflammatories, a neck brace or a belt lumbar, and teaching him to strengthen his back.

But if the pain persists after several months and proves to be very debilitating, surgery may be considered.

Limited indications

It is then a question of decompressing the nerves, then of removing the damaged disc, and finally, of fusing the vertebrae concerned – which happens, moreover, in cases of spontaneous healing.

To obtain this “arthrodesis”, a metal, carbon or plastic cage is used.

Positioned in place of the disc, it is filled with natural or synthetic bone responsible for sticking the vertebrae together.

This intervention has a serious consequence: it prevents the mobility of the joint.

However,

explains Professor Perrot.

In other words, the intervention can displace the problem.

And it is mainly to avoid it and favor mobility that the first disc prostheses were developed.

Their invention dates back to the early 1960s: inspired by the movements of the hip and the knee, the team of Swedish surgeon Ulf Fernström places small stainless steel balls between the vertebrae.

But the results are disastrous.

And it was not until the 1980s that new attempts proved more successful, with prostheses generally comprising two plates – fixed in each of the vertebrae – and a spherical core embedded in one of them.

Several models have emerged, with differences in their materials and their freedom of movement (translation and rotation).

Their indications are in principle very limited.

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According to the recommendations of the High Authority for Health (HAS), the fitting of a disc prosthesis is possible for

only one disc can be replaced.

In addition, the list of contraindications is impressive: excessive compression, obesity, osteoporosis, scoliosis, slipping of vertebrae, local infectious history, degenerative lesions of the joints, unfavorable psychological conditions, etc.

comments Professor François Rannou, rheumatologist at Cochin Hospital and researcher at Inserm.

In its 2007 opinion, the HAS indicates that they represent between 1 and 5% of patients under 60 consulting for chronic low back pain.

The restrictions are also important concerning cervical prostheses, which the HAS does not consider justified if there is no compression of the nerve roots, or even of the spinal cord.

And here again, only patients under 60 years of age, who have tried conservative treatment for more than six weeks, and whose joint remains more or less mobile, are concerned.

There are still many contraindications: excessively advanced osteoarthritis, damaged posterior joints, history of infection, trauma that may have caused hypermobility or deformity, osteoporosis or bone fragility.

Finally, when it comes to replacing cervical and lumbar discs, the question arises of the interest of the gesture compared to other solutions.

But this is where the shoe pinches,

Lumbar prostheses in debate

For the Federal Center for Expertise in Health Care (KCE, Belgium), no significant difference was demonstrated

.

The same would apply to the installation of lumbar disc prostheses.

However, the debate is open.

In a bulletin from the National Academy of Medicine, Professor Patrick Topiano (CHU de la Timone, Marseille) and his collaborators believe that

They nevertheless point out that

.

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In practice, such trials would require significant funding.

But with the evolution of technologies, a prosthesis, of which one would have possibly demonstrated the interest, would not have any more ten years later.

It therefore remains to stick to the indications, by appreciating the patient's condition as well as possible:

says Professor François Rannou.

Good to know

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and cervical hernias are the leading cause of back surgery, accounting for 40% of operations.

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must be carried out by a spinal surgeon (at least 50% of his activity) and a vascular surgeon must be present or ready to intervene if necessary.

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in disc prostheses, we can list: stainless steel alloys including carbon, chromium, iron and nickel;

titanium and titanium alloys;

cobalt alloys;

alumina or zirconium;

polyethylenes.