A laminotomy is performed using a posterior approach, so the patient will, once general anaesthetic has taken hold, be turned onto their front in order for the surgeon to have full access to their back. If the procedure is being performed on the cervical spine then a brace or clamp may be used to ensure that the patient’s head remains stationary during the procedure. The area above the vertebral level being operated on is swabbed and sterilized and (if the patient has not had a general anaesthetic) a local anaesthetic will be injected into the area of the spine to be operated on. The surgeon will make a small incision (around 18mm or so) in the back above the affected vertebrae and insert a series of tubular retractors with gradually-increasing diameters to gently ease the tissues aside and gain visual access to the ligamentum flavum. In an open procedure the surgeon will use retractors to pull the skin and muscle away from the spine, sometimes cutting the muscles and hold them out of the way during the procedure.
For some patients, calcification of the ligamentum flavum itself can be the root cause of the spinal stenosis and nerve compression. These ligaments are often cut during a laminotomy to allow the spine to relax and decompress. The surgeon will then be able to visualize the laminae and excise a section according to the site of stenosis. The portion removed may be in the center, or to one side, but a laminotomy does not remove a whole segment of the lamina as in a laminectomy, in order to preserve spinal stability. If a laminoplasty is to be performed then the surgeon will score down one side of the lamina and retract that section to create a hinge-like structure. Metal instrumentation may be introduced to connect the outer edge of the lamina to the spinal column, depending on the degree of cutting that has occurred. These bridging and retaining plates are made of titanium and are used to keep the lamina ‘door’ open as it heals into its new position.
Watch this short animation of a Laminotomy
In both laminotomy and laminoplasty the newly created space at the back of the spine can allow the spinal cord, spinal nerves, and blood vessels to relax and undergo decompression. It may be difficult in some circumstances for a surgeon to observe the level of decompression achieved by this surgery, which is a clear disadvantage of the procedures in comparison to a laminectomy.
If the surgeon has visual access, via endoscope, to osteophtyes, fragmented discs, or herniated disc material, then they will usually attempt to remove this in order to achieve further decompression of the spine. Advances in minimal access procedures have now made this possible whereas, in previous years, a laminectomy would have to have been performed in order to access the discs and bone spurs.
Closing up the incision
Once all the offending material has been removed, and any instrumentation put in place as necessary, the surgeon will often use a fluoroscope to assess the level of decompression achieved before removing the retractors and suturing the muscles if an open procedure has been performed. The incision will then be closed up and a surgical dressing will be applied before the patient is taken to recovery and monitored as they come round from the anaesthetic.
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