Posterior midline access to the thoracolumbar spine
1. Skin incision
The skin and subcutaneous tissue is infiltrated with a 1:500,000 epinephrine solution to achieve hemostasis.
A midline skin incision is made centred over the involved segment. The length of the incision depends on the number of levels to be instrumented. For a short segment fixation, one level above and below the affected vertebra is exposed.
It is necessary to confirm the correct level of the approach with fluoroscopy.
For a long segment fixation, two segments above and below the fractured vertebra is exposed.
The dissection is carried down in the midline through the subcutaneous tissue and the fascia to the tips of the spinous processes. Self-retaining retractors are used to expose the surgical field.
The paraspinal muscles are elevated subperiosteally from the underlying laminae, in distal to proximal direction, using a Cobb elevator. Dissection is done along the spinous process and lamina.
Review preoperative images to verify whether the tumor invades the lamina. In such cases, exposure of the posterior elements should be performed with great care and the use of Cobb elevators should be avoided.
The use of a subperiosteal dissection minimizes bleeding and muscle damage.
In the thoracic region, the dissection is usually taken to the tips of the transverse processes.
In the lumbar spine, the dissection is limited to the facet joints. The extent of dissection will depend upon the need and type of fusion planned.
Note: during exposure, care is taken not to injure the facet joint capsule if a nonfusion technique is planned.
Alternatively, if the surgeon plans for a fusion, the facet capsule is excised and the joint cartilage surfaces are denuded for fusion.
Localizing x-ray or image intensifier check of spinal level should be obtained once exposure is completed.
For patients undergoing metastatic spine tumor surgery, intrawound vancomycin can be applied to decrease the risk of postoperative wound complications.
For patients undergoing revision metastatic spine tumor surgery and/or with history of radiation, plastic surgery should perform the soft tissue reconstruction to decrease the risk of wound complications.
Drains are usually inserted via a separate stab incision.
Once the surgical fixation and decompression have been performed, tight closure of the muscle and fascial layer is performed with continuous or interrupted sutures.