Posterior lumbar spine decompression surgery has been performed for over one hundred years. The most common indications for this type of surgery relates to degenerative lumbar spine disease. Degenerative changes affect the intervertebral discs, the lumbar facet joints, the ligamentum flavum and the lumbar vertebrae. The consequence of these changes leads to a relative or absolute reduction in the space available for the lumbar nerve roots. The resultant nerve compression can manifest either in the spinal canal or in the intervertebral exit foramina, or both, with compression of the traversing or exiting nerve roots respectively. Trauma, infection and tumours of the lumbar spine are also be managed with variations of these techniques. The surgical techniques, instruments, equipment and materials used have evolved considerably and the varied patient needs can be accommodated and addressed successfully.
The patient is positioned prone on a spine specific operating table with protective support for the head, torso and legs. The intended surgical levels and landmarks are marked immediately prior to surgery using pre-operative x-ray screening. A posterior midline incision is made spanning the intended surgical levels and the muscles of the lumbar spine are separated off the posterior components of the bony vertebrae.
The correct surgical level is confirmed with the assistance of intra-operative x-ray. The spinous processes and lamina of the vertebra are removed utilising a selection of instruments. The specific technique selected for this purpose depends on the patient’s spinal anatomy and the degree of decompression required. Typically, three components of spinal stenosis, or narrowing, are addressed with this surgery, namely central canal stenosis, lateral recess stenosis and foraminal stenosis. Particular care is taken to reduce the risk of an inadvertent spinal fluid leak. A high-powered surgical microscope is often used to ensure optimal surgical safety during the decompression of the neurological structures. Lumbar disc removal may also form a component of the decompression, depending on the extent and nature of lumbar disc degeneration. Improvement in the position and alignment of the lumbar vertebrae can be achieved by placing a spacer in the intervertebral disc space.
The need for lumbar fusion as an adjunct to the decompression depends on pre-operative assessment of spinal anatomy, alignment and dynamic stability along with the intra-operative assessment of the spinal stability following adequate decompression of the lumbar nerves. The fusion can be achieved in a number of different ways and usually requires the use of instrumentation (surgical implants). Lumbar pedicle screws are inserted in pairs in each vertebra utilising intra-operative x-ray to guide position and trajectory. The pairs of screws are then connected longitudinally with pre-contoured rods. Bone graft material is positioned to facilitate the bony fusion of the adjacent vertebrae that will be achieved over the course of the following months.
Once the surgeon is satisfied with the decompression of the nerve roots and haemostasis the retractors are removed and the posterior muscles are allowed to relax back into position over a small-bore wound drain. The muscle sheath is sutured to restore structural and functional integrity. The skin is closed with resorbable subcutaneous and sub-cuticular sutures and covered with an appropriate dressing.
Preparing for Surgery
Ensure that you know what surgical procedure you are having. It is important to understand the reasons for the operation as well as having a realistic expectation of the outcome. If you have any questions regarding your operation please do not hesitate to discuss these with Dr Crispin Thompson.
Ensure that you have received authorisation from your medical aid, including the authorisation number. Different medical aid providers and medical aid plans offer different levels of cover for surgical procedures. It is your responsibility to know what services are covered by your particular medical aid plan, including whether any co-payments are applicable.
Refrain from eating and drinking anything from 02h00 on the morning of your surgery, unless specifically instructed by one of our team members. Patient specific recommendations will be made depending on your specific circumstances.
Present yourself to the Mediclinic Milnerton reception area by 06h30 on the morning of surgery. You will be admitted onto the hospital administrative system by a member of the reception team before being shown to your bed on the ward. You will need to bring your identification document, your medical aid card and number and your authorisation number with you to the reception area.
Bring all your medication with you to the hospital so that the necessary in-hospital prescriptions can be accurately and appropriately formulated. The medication will need to be given to the ward nursing staff when you are admitted to the ward prior to surgery.
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