As recently as 15 years ago, people who had spinal surgery faced long hospital stays and recovery running into months before they could return to normal activities. These days, patients can expect to leave hospital in as few as one or two days and return to even manual work in six weeks. Indeed, a number of these keyhole procedures can now be performed as day cases.

The advantages of minimally invasive spinal surgery are manifold:

• Less soft tissue dissection
• Less bleeding
• Lower complication rates
• Less post-operative pain 
• Shorter hospital stay. 

Keyhole surgery has the added benefit of reduced scarring and, because of short hospital stay, minimised risk of MRSA and other infections.

Chronic back pain affects about 13% of the population in Ireland and costs the Department of Social and Family Affairs E350 million in disability payments each year. 

Most people who develop chronic back pain usually improve and resume normal activities without recourse to surgery. Conservative treatments such as rest, physiotherapy and analgesia can prove very effective, however, for some patients the pain and disability will persist and possibly worsen.

A recent Europe-wide chronic pain study (PainSTORY, 2009) identified a surprisingly high number of chronic pain sufferers, many of whom had back pain, who were still struggling to find relief. 

By the end of the 12-month survey, 95% of patients undergoing conservative treatment reported being in moderate or severe pain, with 46% of this group suffering severe pain by the end of the year. The study concluded that for most patients, pain levels had not improved dramatically despite medical intervention for one year. 

Back pain: distinction of symptoms

Spine surgery is not the answer for most people with back pain – there are effective non-surgical treatments that should be fully explored before considering surgery – but for some patients who can’t find relief any other way, the last resort can seem the only option.

“You have to make a distinction between patients who have symptoms and signs of nerve root compression – typically sciatica – and those whose pain is chronic and confined to the back. In the former cases, investigation with MRI should be done relatively early, for example after as little as five weeks, because nerve root pain is very effectively treated with decompressive surgery, such as microdiscectomy, and long-term nerve root damage can be avoided,” said Mr Steven Young. Mr Young has been a consultant neurosurgeon at the National Neurosurgical Unit, Beaumont Hospital, for the past 20 years.

“In patients with chronic back pain, the situation is different: many people have chronic soft tissue and joint pain which is not amenable to surgery, but a small number have so-called discogenic pain or instability at a spinal segment which could respond well to minimally invasive fusion or possibly an intervertebral spacer.”

Patients with chronic back pain who might be helped by surgery have to be carefully selected and counselled, Mr Young added. They might have had multiple previous disc operations or have undergone conservative treatment for years. Depression, failed surgery and personal injury litigation are just some of the factors that could lead to a negative outcome. 

The Scottish-born surgeon, who is also owner and neurosurgeon at Spine Ireland in the Hermitage Medical Clinic, Dublin, explained that back pain which radiates into a limb and persists beyond a month or more is often due to a herniated disc or so-called ‘facet joint arthritis’, and should usually be investigated further when standard conservative treatments of rest and anti-inflammatory analgesics have failed.

“In the context of general practice, by far the most common conditions referred to me, around 90%, would be lumbar disc prolapse, lateral or central stenosis due to disc degeneration or discogenic pain.”

Modern disc surgery 

Disc degeneration is a term applied to a disc space that has undergone wear and tear mostly as a result of ageing, though it can also occur in younger patients, especially if they have been involved in contact sports such as Gaelic football or rugby, suffered injury or if they are just genetically predisposed to developing early deterioration in the spine.

“Typically, I would take a detailed history and examine the patient. Then, if indicated, they’d go for an MRI scan. Frequently nowadays patients will have already had MRI imaging. The MRI is by far the most effective way of showing whether or not someone’s back pain is amenable to minimally invasive surgery. 

“Traditionally, a surgical procedure called laminectomy was used to remove herniated disc material. This entailed removal of bone at the back of the spine and would often cause significant post-operative discomfort and even instability in the future. Now, accurate localisation by MRI scans and microscopic techniques have made it possible to approach discs through incisions only two to three centimetres in length with minimal disturbance to the underlying soft tissues,” said Mr Young.

Using an operative microscope and precision instruments, the muscle beneath need only be minimally retracted to one side exposing a natural gap between the vertebrae (the interlaminar space). This is covered by an elastic fibrous sheet called the ligamentum flavum. The surgeon cuts a window in this sheet to enter the spinal canal. The nerve root is usually clearly visible and is gently moved out of the way. The annular ring of the disc is then cut, and the offending disc fragment can be removed with fine instruments called rongeurs. Afterwards, time is taken to probe and irrigate the disc space to make sure there are no residual fragments.

“The huge benefit with minimally invasive surgery such as this is that you are disturbing the soft tissues, the muscle and normal tissues of the spine as little as you possibly can so that recovery time is rapid. 

“Most people are up and about the day of surgery and usually go home the next day. Indeed, a few cases we’ve done as day cases,” he said.

Controlled studies have proven that this procedure is safe, very successful, and cost-effective.

“We audit all our results and in general our success rate is the same as widely reported across the world, ie. about 80-85%.

 “As with all operations it can never be 100% because you are dealing with the inevitable vagaries of a biological system, and often coincidental issues such as chronic depression or personal injury litigation will impact on results. However, if the scan correlates well with the clinical presentation in a previously well patient then you would certainly be searching for an explanation for a poor result,” Mr Young remarked.

A logical follow-on from straightforward microdiscectomy is minimally invasive fusion of the spine. This procedure may be indicated for patients with chronic severe pain arising from the disc itself, or who have excessive movement or slippage at a disc segment. 

Previously, this was an extensive operation carried out through a midline approach, but the relatively recent advent of mini-open lumbar interbody fusion via a paramedian route has significantly reduced muscle trauma and led to much more rapid recovery times.

“This procedure is commonly used in patients who have a severely degenerated disc and have a lot of chronic back pain. They may have had previous disc surgery and steps will usually have been taken to verify that the disc in question is responsible for the pain (discogram).

“After removing the disc, we replace it with an interbody cage and stabilise the spine with pedicle screws and rods while the bone fuses. At one time, lumbar spinal fusion was considered a very radical and major operation whereas now, with transcutaneous pedicle screw placement, the operation can be done in a much shorter time and with far less trauma to the muscle,” said Mr Young. 

The interbody cage is a hollow threaded titanium or carbon fibre cylinder filled with bone graft material. The cage replaces the problem disc while holding the two vertebrae in position until fusion occurs. 

A newer surgical option for the treatment of damaged lumbar discs is artificial disc replacement. This has been available in many countries for about 10 years and is currently in various phases of development and clinical trials in the US. 

With artificial disc replacement, pain relief is brought about by removal of the problematic disc and replacement with a prosthetic implant that maintains mobility. 

Unfortunately, though it sounds attractive, the exact indications for the procedure are not yet clear and it is perhaps telling that it has not been widely embraced. As a consequence, minimally invasive fusion surgery would still by far be more prevalent than artificial disc replacement in the lumbar spine

In the cervical spine, by contrast, artificial disc replacement seems better established, especially in the younger patient, and an increasing number are being requested and performed by Mr Young in the Hermitage Clinic.

“When a damaged disc is removed in the neck, traditionally surgeons would fuse the disc segment to maintain stability and keep the root canals patent, but the problem with that is by making a segment of the neck immobile you tend over time to put stress on adjacent discs leading to arthritis in the future, whereas with artificial disc replacement you retain mobility,” Mr Young pointed out. 

“This is a relatively new technique and it is thought to be of particular advantage in the younger patient with disc prolapse and little or no degenerative change.”

Pain treatments in the elderly

A common cause of back and leg pain in the elderly that may require surgery is central lumbar stenosis. This is basically a narrowing of the spinal canal through which the nerves pass, and is most commonly caused by degenerative arthritis and accumulation of bone over the years. 

If left untreated, progressive compression on the nerves can lead to claudication, similar to that seen in peripheral vascular disease, increasing weakness and loss of function of the legs.

“This is typically a condition of the elderly and can leave them, in extreme cases, unable to walk for more than a few hundred yards without stopping. In these cases, we can perform a lumbar decompression procedure through a small incision, removing some of the overgrown bone to open up the spinal canal and free the nerves. 

“It’s actually quite an effective and very satisfying procedure to carry out – even for people in their 70s and 80s. In many cases it can give them a new lease of life and keep them independent. Again hospital stay is rarely more than two or three days. 

“The idea that grossly impaired mobility in the elderly is something they have to put up with is a concept that we are trying to move away from,” stressed Mr Young. “I would certainly think there are a lot of patients, even in their 70s or 80s, who would benefit from this surgery who are otherwise confined to their living rooms and not very active at all.

“We are all living longer, and quality of life is as important at 80 for many as it is for those of 40. Our knowledge and technology is improving all the time, it’s important to be aware that there are many effective conventional and surgical options available to help with chronic back pain.”

Which type of surgeon to refer to – orthopaedic or neuro?

When considering spinal surgery, one of the most frequent initial questions is which surgeon is more appropriate? An orthopaedic surgeon or neurosurgeon? The truth is, probably either in most situations. 

Orthopaedic surgeons traditionally have been associated with the treatment of spinal trauma and deformity such as scoliosis, and neurosurgeons with the treatment of intradural tumours and vascular lesions. For degenerative conditions in Ireland, both orthopaedic and neurosurgeons have embraced discectomy, fusion and lumbar stenosis procedures.

The most important difference between any surgeons will be their level of experience – the number of cases seen and procedures performed. There is no doubt, and it applies to all surgery, that those surgeons who sub-specialise and do lots of cases will generally have the best results. So a more accurate question is not which type of surgeon, but what is their specific area of expertise, qualifications, practical experience and success rate in a particular type of surgery? 

“I know several excellent spinal orthopaedic surgeons and I know some neurosurgeons who don’t do a lot of spinal surgery. It’s down to how many cases people are doing and what their area of interest is. You can’t categorise it black or white. So it’s important to do your research and ask plenty of questions before selecting a spinal surgeon,” advised Mr Steven Young, a neurosurgeon at Beaumont Hospital and the Hermitage Clinic, Dublin.