Lumbar Microdiscectomy + Nucleus replacement
Who Needs It?
This is an operation performed to treat sciatica (leg pain). It is used when conservative methods of management such as rest, physiotherapy, anti-inflammatory drugs and blocks have failed to give adequate relief. Whether or not a patient is suitable for a microdiscectomy will depend upon the MRI scan or other investigations. If there is a large amount of the nucleus (centre) of the disc protruding, leaving little behind, it may be worth replacing the nucleus with a prosthetic device to prevent later collapse of the disc space.
The operation is performed under anaesthetic (usually a general anaesthetic, but an epidural can be used as an alternative) with the patient lying face down in the operating theatre. A small incision is made on the back, over the bad disc, which usually is only 2 - 3 cms in length and the spine is exposed by retracting the muscle slightly (only around 1.5 - 2 cms) and removing a small portion of the ligament (the ligamentum flavum). Then the surgeon can see the trapped nerve root using a microscope to obtain better vision and illumination and, and remove the bulging disc tissue below it. This frees up the nerve and allows the surgeon to empty any more disc material out of the disc space a needed. Alternatively, an approach can be made through the abdomen, to attack the disc in the same manner.
Once a thorough discectomy has been performed, a sizer is introduced into the disc space, to ensure that the device will fit - any necessary adjustments are made and the device is inserted into the disc space. One type of device allows the insertion of a ballon into the nucleus cavity created, which is then filled with a polymer to firm up in place. This then expands over 24 hours to provide support for the disc.
Outcome of Surgery
The aim of the operation is not to completely remove the disc, but to remove the parts which are trapping the nerve and causing the pain. The emptying of the disc space is always only partial. There is, therefore, the risk of further disc material coming out of the space at a later date, but this is a rare complication. Other potential complications include infection, which can lead to long term pain in the back if the disc itself is involved or nerve root damage which can lead to weakness or pain or both in the leg. These complications are rare and microdiscectomy remains a very good treatment for sciatica if other treatments have failed. Replacing the nucleus should prevent the potential problem of subsequent disc collapse leading to back pain.
Most people recover from the surgery over around six weeks. They are, however, mobile the day after the operation (or even later the same day) and usually out of hospital within 3 - 5 days. The mainstay of treatment post-operatively is physiotherapy, with exercises to strengthen the spine and return normal patterns of movement. Most patients progress slowly with these over a few weeks and may need to attend the physiotherapy gym 2 or 3 times after discharge from hospital.
Patients having the surgery under epidural anaesthetic are often home within 24 hours and usually feel able to return to work on light duties a few days after surgery.
Patients may return to sports after 6 weeks, but should avoid contact sports for up to 12 weeks. A clinic visit for review is usually arranged for 6 weeks post-operatively.
What are the risks of this operation?
(note figures vary)
|Nerve injury||Damage to the nerve whilst removing disc||<1|
|Fluid leak||Small tear in the nerve sheath allowing leakage of cerebrospinal fluid||<1 (But up to 10% if previous surgery|
|Infection||Contamination during surgery or, rarely, late infection via the blood||Approx 1|
|Recurrent disc||Persistence of small pieces of disc within the disc space - could come out later||1 - 2 (Literature suggests 6 -7)|
|Movement of the PDN||The device could slip backwards towards the spinal nerves if the patient mobilises too quickly or it has not fixed itself.||Low|
|With an anterior approach - organ injury||Retraction or surgical trauma to bowel, bladder, ureter, kidney.||Low|
|Wound pain||Surgery||All to some extent|
Click here to view pictures of the procedure.
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