Lumbar Spondylolisthesis

Lumbar spondylolisthesis

Spondylolisthesis occurs when one vertebra slips forward on the vertebra immediately below. About five percent of the population develop a spondylolisthesis at some point in their life.

There are four grades of severity, determined by the amount the upper vertebra has slipped in relation to the lower vertebra.

  1. grade 1 is a slip of less than 25 percent

  2. grade 2 is 25-50 percent

  3. grade 3 is 50-75 percent

  4. grade 4 is 75-100 percent

Most slips are grade 1 and are generally stable.

There are two major types of spondylolisthesis:


Degenerative spondylolisthesis usually occurs in older women, most often at the L4/5 level. It causes lower back pain and symptoms due to compression of the lumbar nerve roots, weakness, numbness, and tingling down one or both legs.

This type of slip is degeneration of the disc, which causes hypertrophy at the facet joints and is generally stable. Decompression can often be performed without the need for fusion.

Lytic or spondylotic listhesis

Isthmic spondylolisthesis usually occurs at L5/S1 and normally presents in the teenage years or 20s. It often appears in cricketers, when they sustain a stress fracture of the pars region of the L5 vertebra. It happens due to repetitive stress in the lumbar spine.

The fracture occurs through a thin portion of the vertebra between the two articular processes or joints. This part of the vertebra is called the pars or the pars inticularis.

Initial treatment is exercise and physiotherapy. Most patients will eventually require a posterior fusion with pedicle screws when the symptoms become significant. Surgery generally produces a cure.

Because fusion surgery can have long term ramifications, symptoms generally need to be significant before considering surgery.


Lumbar artificial disc replacement

Lumbar artificial discs are placed through the abdomen. They are mechanical devices that allow movement that mimics the normal function of a disc.

There are different types of artificial discs – e.g. Maverick, CHARITE and Prodisc-L.

Dr Steel believes preserving motion at a disc space places the additional vertebral joints under less stress compared with a fusion operation.

One of the issues that occur with fusion surgery is that people develop problems at the disc spaces next to the fusion. Dr Steel believes artificial disc replacements will minimise these problems with patients in the future.

Not all patients are suitable for an artificial disc replacement. In general, this procedure is appropriate for young patients who have primarily discogenic pain.

It is not suitable for elderly patients, osteoporotic patients, patients with facet joint disease, patients with sciatica or a collapsed and severely degenerate disc, or patients over 50 years.

Post operative care, advice and physiotherapy for a lumbar artificial disc replacement are essentially the same as for a microdiscectomy.


Anterior lumbar inter-body fusion

Anterior lumbar fusion or disc arthroplasty requires a cut through the lower abdomen. This is usually a horizontal incision, half way between the belly and the pubic area. The average incision is four to five centimetres long.

The abdominal contents are moved to the side, which exposes the front portion of the lumbar disc. A complete discectomy is performed back to the lumbar sacral nerve roots. The disc space is then filled with either a plastic cage, with artificial bone and bone graft.

If a disc replacement is used for younger patients the artificial disc is placed into the space where the normal disc has been removed.

The great advantage of anterior lumbar spine surgery is that there is less pain compared to posterior surgery. When operating through the abdomen it is surprising that no muscles are cut; they are separated to expose the front portion of the disc.

In contrast, posterior surgery requires muscles be peeled off the bone, even in minimally invasive endoscopic spine surgery.

After anterior surgery, patients remain in hospital for three to four nights. After posterior fusion operations they tend to remain in hospital for six to eight nights.

The disadvantage in anterior lumbar fusion surgery is that access to the nerve roots is more difficult. It is generally a procedure to treat back pain rather than a procedure to decompress nerves.

There are potential complications to the anterior lumbar exposure.



Injury to major blood vessels

There are major arteries and veins in front of the lumbar spine. The aorta and the inferior vena cava – the vein which delivers venous blood back to the heart – divide over the two lower vertebrae.

These vessels need to be dissected off the vertebra to expose the disc. For this reason, Dr Steel asks a vascular surgeon to perform the exposure. This minimises the risk of damage or injury to the blood vessels. 



On the front or side of the spine there is a pair of nerves called the sympathetictrunk. These do not supply any movement or feeling to the legs but they supply the skin of the legs, making the skin sweat and the blood vessels constrict.

Blood vessel constriction makes the skin cool and pale. Cutting a sympathetic trunk (called a sympathectomy) can result in a warm and dry leg.

For patients with extensive mid-lumbar dissection there is a small chance of developing a warm and dry leg.

This can also result in excessive sweating in the leg. However, it is unusual to see this complication when performing surgery at the L5/S1 or L4/5 levels.



Retrograde ejaculation

For males, another risk when exposing the L5/S1 disc is a condition known as retrograde ejaculation. There are small nerves in front of the L5/S1 disc that facilitate sperm being expelled from the penis.

By dissecting over the disc space, this may interfere with the valve action co-ordinating sperm to pass through the urethra. As a result, sperm may travel into the bladder.

The sensation of ejaculation is largely the same but it can impede conception. Fortunately, retrograde ejaculation happens in less than a few percent of cases and tends to resolve over time (a few months to a year), as these nerves do not control erection.



Special techniques

Dr Steel also performs lumbar decompression and fusion using a specialised minimally invasive technique in most cases. The aim is to reduce disruption to the normal tissues and allow a more rapid return to normal function.

Dr Steel uses much smaller exposures in minimally invasive spine surgery than in traditional spine surgery. The goals of the surgery remain the same – i.e. to decompress the affected nerves and spinal cord and to fuse or replace arthritic and painful joints.

Because of the inaccessibility of the spine, traditional spine operations involve exposing and pulling back skin, muscles and ligaments. This retraction can hamper recovery by causing pain and swelling.

Minimally invasive spine procedures require less exposure and retraction in order to conduct the surgery. Minimally invasive spine fusions allow surgeons to place titanium hardware through a narrow path that is created by separating muscles rather than cutting and retracting.