Disc Replacement

The concept of disc replacement is to place an artificial device into the disc space to replace a damaged or painful disc and at the same time allowing the mobility of the spine to be maintained. There are at present three disc replacement devices which are in common surgical practice.

A disc replacement in the lumbar spine is inserted through the abdomen. This is for the technical reason that the lumbar spine disc replacements have to be physically large enough to support the vertebra bodies and, because of this size, cannot be inserted through the back via a traditional spinal operation approach. Incisions in the abdomen vary in size and position depending upon the disc to be replaced. These scars are tending to become smaller as improved operative techniques are developed, nonetheless it will seem odd to some patients that an operation on your back is carried out through the front of the body! The length of time for the operation is around 90 minutes and consists of a careful dissection to the spine and in some areas mobilising the blood vessels which are in the way. The disc itself is then entirely removed and the vertebra above and below prepared to accept the implant. This generally consists of two metal plates containing a plastic liner in a similar way to joint replacement surgery in the knee or hip. The implants are press fitted into place and no cement is used, unlike joint replacement surgery in the lower limb.

The risks and complications of these sorts of procedures tend to be vascular i.e. injury to blood vessels. Another possible complication for a man in a replacement of the lowest disc at L5/S1, is a possibility of retrograde ejaculation. This means that semen is not ejected outwards in the normal process of an orgasm but is directed back into the bladder. This can render a man sterile. The other risks of this sort of surgery are the more usual ones of infection and deep vein thrombosis guarded against by the use of antibiotics and TED stockings. Nerve injury, although possible, is relatively rare.

Post-operatively patients are mobilised in a similar way to any form of spinal surgery and very rarely is there any requirement for a support brace as muscular control is usually adequate. Following disc replacement follow up x-rays are taken over a period of 6 to 12 months to ensure that the implant does not displace.

Disc replacements are mainly for patients who have pain emanating from their lumbar intervertebral discs only. One of the occasional failures of the technique is that although a disc has been replaced, back pain may continue owing to problems in the facet joints. It is therefore useful to ascertain, prior to considering such surgery, how much pain is coming from the facet joint by using injections and spinal probing to determine the pain source.

Usual hospitalisation time for a disc replacement is about 7 days with a recovery period of about 6 weeks during which time increasingly more activities can be undertaken. During the first 6 weeks after surgery the wound will be healing and there will be an improvement in physical stamina.

In the cervical spine disc replacement surgery is also possible. The incision in the cervical spine for a disc replacement tends to be anterior; in other words through the front of the neck. The risks and complications for cervical disc surgery and cervical disc replacement are similar and are firstly from the anaesthetic itself. There is a small risk of nerve root injury and a small risk of cerebro spinal fluid leak leading to headache. This tends to be treated by bed rest. There is a risk of a hoarse voice if the nerve to the voice box is bruised or injured. More usual risks are those of infection or deep vein thrombosis which will be guarded against by the use of prophylactic antibiotics and by the use of TED. stockings. You will also be mobilised the day after the operation to further prevent deep vein thrombosis or clot formation.

In general disc replacement surgery has its place in both areas of the spine provided there are correct indications. It is best to keep an area of the spine mobile, as it reduces the stresses and strains on the levels above and below which otherwise would be increased with fusion.

At Spine-Works we currently do not carry out lumbar (back) disc replacement surgery. We feel that, although it makes intellectual sense, the surgery is relatively complex and the current devices do not address all the areas of symptoms such as the facet joints. We are currently evaluating the potential of cervical (neck) disc replacements.

© Spineworks Ltd 2005/2006