Artificial disc replacement
2009
ADR is increasingly used as an alternative for patients with sufficiently healthy vertebral body and plates.
Vicky Joseph describres her experience of this surgery
Things went from bad to worse and I was virtually unable to sit, stand or walk; I even had to eat in a kneeling position.
During a brisk walk in January 2000, I developed a tremendous ache in my right hip and groin. Anxious to get back to walking I saw a chiropractor who diagnosed a strained sacroiliac joint and advised me to “take it easy for a couple of weeks”. I took it easy but the pain got worse and moved to my back as well. So I went to a sports injury specialist who ordered an MRI, found nothing more than ‘some minor degeneration normal for my age’ (45) and referred me for physiotherapy which didn’t help. Things went from bad to worse and I was virtually unable to sit, stand or walk; I even had to eat in a kneeling position. No position gave me relief and I frequently felt as if someone had plunged a knife into my side.
The following five years were nothing less than a nightmare that I thought would never end. I saw osteopaths, neurologists, rheumatologists, orthopaedic surgeons and several pain specialists, acupuncturists, homeopaths, Pilates and Alexander technique teachers, faith healers and even a ‘psychic surgeon’. It wasn’t until March 2005, after a chance encounter on an Internet pain forum led me to a specialist back clinic in Munich, Germany(1), that I finally got a diagnosis, and not until the autumn that my life began the slow journey back to normality.
Diagnosis
In Munich, yet another MRI (my sixth) amazingly showed a possible cause for my undiagnosed pain – a ruptured disc at L5-S1. An excruciating discography confirmed that the disc was a pain generator and the doctor, Dutch surgeon Dr Willem Zeegers called me back into his office to discuss my options. There were three –
- do nothing,
- try a minimally invasive procedure that allegedly had a 50% chance of success or
- have the damaged disc removed and replaced with an artificial one.
Dr Zeegers tried to persuade me to do nothing which, after an outburst of tears, I realised was to test my resolve to go ahead. In fact I did have the minimally invasive procedure the following month but it didn’t help and my husband accompanied me to Munich for the artificial disc replacement (ADR) surgery.
The surgery
The first artificial disc replacement implant, consisting of a steel ball inserted between the vertebrae to maintain space mobility, was introduced in Sweden in the early 1960s and used in more than 100 patients(2). Although research to develop a safe, reliable and long lasting implant with the ability to mimic the movement of the human spine has been ongoing for over 40 years(3), ADR surgery has only recently become available in the UK and the USA. In Munich, however, Dr Zeegers had been replacing discs since 1989 and, by the time I saw him, had conducted over 1500 operations.
Traditionally the treatment for people who have found no relief for chronic back pain through conservative treatment, like physical therapy, medication or manual manipulation, has been spinal fusion surgery. This permanent locking of two or more spinal vertebrae together so they cannot move except as a single unit is still considered the gold standard surgical treatment. However, for a number of reasons, ADR is increasingly used as an alternative for patients with sufficiently healthy vertebral body end plates. It is considered superior to fusion as it reduces the potential for accelerated degeneration of the discs above and below the fused level and helps to preserve flexibility, motion and near normal distribution of stress along the spine and to restore predegenerative disc height.
Advantages
Apparently, about 22% of fusion patients report problems with the adjacent segment within five years of their surgery whereas reports of such problems after ADR surgeries are less than 1%.(4) Another advantage of ADR surgery over fusion is that no bone graft is taken from the hip which can result in a very painful healing process. There are, of course, some conditions that may prevent a patient from receiving a disc replacement and these include spondylolisthesis, osteoporosis, vertebral body fracture, allergy to the materials in the device, tumours, infection, morbid obesity, significant changes of the facet joints, chronic steroid use or auto-immune problems. Because the operation is done through the abdomen a patient who has had previous abdominal surgery may also be excluded.
Today, there are a variety of different artificial discs either on the market and under development and the National Institute for Clinical Excellence approved the surgery in the UK in 2004(5). Artificial discs are typically made of bio-compatible materials such as stainless steel, titanium alloy, cobalt chrome, ceramic or other biomaterials such as polyethylene or polyurethane, either alone or in combination. Implants come in a range of sizes to accommodate different patient anatomies and are generally comprised of two ‘plates’ which are fixed to the vertebrae plus a smooth, usually curved moving inner part which provides motion by the surfaces sliding across each other.
Despite my willingness to go through any procedure, no matter how ghastly, to get rid of the pain, squeamishness prevented me from doing much research about the different discs before my surgery. My question to Dr Zeegers about which disc he would use received the response that he would decide when he saw the size of my vertebrae. Unlike many American doctors, he had no commercial interest in any particular product nor was he restricted by any government regulatory body – he was free to use whichever disc he thought best for me. So when I came round from the operation I discovered that I had an Activ L (left), an advanced version of Pro Disc, an ultra-high molecular weight polyethylene which is attached through a keel and spikes on each endplate. Physiologically it matches the range of motion in flexion, extension, axial rotation, and lateral bending of a normal spine6. Unusually for me I don’t know every last detail about its pros and cons but I trusted Dr Zeegers totally and I like the word ‘active’!
Disadvantages
It must be said that ADR is not without its critics. It has been argued that ADR at L5-S1 is rarely indicated because there is no significant functional motion. Adjacent segment degeneration has been shown to be equal between disc replacement and fusion at this level. It has also been argued that artificial joints produce wear debris and an inflammatory response which escalates over time where this is not a problem with fusion. According to critics of ADR, current studies indicate a high long term failure rate and only a little benefit over fusion for protecting the adjacent segment.
Dr Zeegers’ early patients have had their artificial discs for the best part of 20 years
This suggests that the short-term benefit of lumbar ADR for motion preservation may not be worth the risk of long-term problems. Clearly we don’t yet know how long these prostheses will last and how well they will function in the long term although Dr Zeegers’ early patients have had their artificial discs for the best part of 20 years.
In addition it has been claimed that revision surgery, if necessary, can be life threatening as the anterior part of the spine lies behind large vessels and intra-abdominal structures which make it difficult to reach after the first operation is performed7. Unsurprisingly experienced ADR surgeons like Dr Zeegers dispute this. For me, having had the surgery and having got my life back, I live for today and choose to remain hopeful that the disc will either outlive me or, by the time it needs replacing, advances in surgery will make it much safer.
Recovery
Although artificial discs are revolutionary in material and design, there is little disagreement that the techniques to install them are routine and safe. And recovery and after-care are much like that for other anterior approaches to lumbar spine surgery. It is claimed that in some cases recovery is faster than for a traditional fusion surgery and there is less pain and fewer complications in general. My recovery from the surgery went fairly routinely although the immediate aftermath was, I confess, extremely painful. I was in hospital for four nights, in a hotel for a further three and flew home to London exactly one week later wearing my very expensive custom-made rigid corset which I was not to remove, except for sleeping, for six weeks.
Of course having surgery abroad has its drawbacks, most of all the lack of visitors and having nothing to watch except CNN. But everyone except the cleaners spoke English and I got by in German. The nursing was excellent, the clinic absolutely spotless and the food fantastic. Today there are a number of British surgeons who are experienced at ADR but three years ago it seemed a safer bet to go to Germany and they had, after all, found out what was causing my problem where countless British doctors had failed.
I have to say that the short term results of the surgery were not as good as I had hoped and it took many months of physiotherapy and Pilates type exercises before the pain really began to subside. The best part of six years in chronic pain can change the way in which you use your body and it can take time to ‘unravel’ the problems, to unlearn bad habits, correct poor posture and start to use the muscles ‘correctly’.
Today I have intermittent pain but even my worse days are nothing like before the surgery. I am leading a ‘normal’ life and although I have decided not to return to the tennis court or to wind surfing, I cycle regularly, can walk for three or four hours without problem and have been skiing several times. I always sit at the end of the row in the cinema or theatre and don’t much enjoy wandering around museums and art galleries any more but I’m grateful every day to have my life back – and my husband is still doing the supermarket shopping. Every cloud…..!
References
1. www.atos-muenchen.de/info
2. http://www.prestigedisc.com/
3. http://www.europeanmedicaltourist.com/spinesurgery/
4. http://www.spineuniverse.com/
5. www.nice.org.uk/Guidance/IPG100
6. http://www.spine-health.com/treatment/
7. http://www.espine.com/artificial-disc.htm