Planning and positioning
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Preoperative evaluation includes a thorough neurologic history and examination with assessment of strength. A sensory examination should be conducted to rule out any dermatomal distribution of loss. Routine plain lateral, flexion, and extension lumbar spine films can show dynamic instability that may necessitate lumbar fusion as well as diskectomy. The diskectomy would allow for the treatment of radiculopathic leg pain but would be unable to treat mechanical back pain. Magnetic resonance imaging (MRI) without contrast enhancement of the lumbar spine can show focal neural foraminal stenosis that would allow the surgeon to focus on the level for diskectomy and foraminotomy.
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After being placed in a prone position, the patient is given a dose of preoperative antibiotics before the skin incision. Antibiotics and an intramuscular dose of ketorolac (Toradol) can be instilled at the end of the case.
FIGURE 71-1:
The patient is placed prone on chest rolls and a Wilson frame to hold the spine in flexion.
Procedure
Skin Incision
Fascial and Subfascial Dissection
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Bovie electrocautery can be used for subcutaneous dissection and for achieving hemostasis. The thoracolumbar fascia is identified after dissection through subcutaneous fat. A dry sponge raked along the fascia can identify the white tissue easily, and a periosteal elevator can be used to dissect off the subcutaneous fat from the fascia beneath. After placing a self-retaining retractor such as a Gelpi retractor, palpation to find the midline can be done.
Subperiosteal Dissection
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Bovie electrocautery on cut function can be used to cut through the fascia. For microdiskectomy, a paramedian facial incision can be done to ensure the midline ligamentous structures are not damaged by dissection. After minimal, one-sided exposure is completed rapidly, a localizing film should be done to assess the correct level.
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Subperiosteal dissection can also be done rapidly with an open dry sponge raked ventrally and laterally along the spinous process and lamina with a large periosteal dissector such as a Cobb elevator.
Hemilaminectomy
