Sublaminar wiring techniques became popularized in the 1980s with the introduction of the Luque rectangle method of segmental spinal instrumentation for deformity correction. In contrast to the hook-distraction rod methods that predated the Luque construct, this method allowed for multilevel segmental deformity correction. Moreover, this method is able to distribute biomechanical loads over a much larger surface and hence reduce the risk of hardware failure. While the introduction of pedicle screw fixation has largely replaced sublaminar wiring techniques due to a decreased risk of neurologic injury with the former, it remains a highly adaptable, inexpensive, and expeditious means of instrumentation in the thoracolumbar spine. In this chapter, we review the patient selection, preoperative evaluation, operative technique, postoperative management, and potential complications associated with sublaminar wiring techniques.
36.2 Patient Selection
Although used primarily for the correction of spinal deformity, in general, sublaminar wiring can be an effective strategy for any patients with thoracolumbar traumatic injuries, tumor, or degenerative conditions. Sublaminar wiring allows for fixation to the rod construct at multiple, variable levels; this facilitates correction of complex spinal deformities in both the sagittal and coronal plane, as well as reduction of translational injuries involving the vertebral column. Additionally, sublaminar wiring techniques may be used in hybrid constructs to primary instrumentation (i.e., pedicle screw fixation), which allows for greater distribution of biomechanical forces and is particularly useful in patients with abnormal or small pedicles.
Because of the need to develop a clear plane within the epidural space to pass wires and cables without resultant neurologic injury, patients with severe stenosis from degenerative disease or malignancy are not ideal candidates for this method. Furthermore, patients who had had prior surgery may have significant adhesions or scarring and are at greater risk for dural tears or neurologic injury during the passage of wiring. Additionally, patients with prior laminectomy defects encompassing the levels for desired instrumentation (i.e., those patients with postlaminectomy instability or deformity) are not ideal candidates for sublaminar wiring, primarily because of the decreased laminar surface area for wire-bone interface. Similarly, patients with severely compromised bone quality may not be suitable for sublaminar wiring given the need the need for strong wire–bone contact when securing construct in place.
36.3 Preoperative Preparation
Patients under consideration for sublaminar wiring should undergo thorough history and physical examination. In particular, signs and symptoms of neurologic compression that could complicate sublaminar wire passage should be elicited. Furthermore, a thorough surgical history of prior spinal procedures should also be obtained for similar reasons. If there is any concern for anatomical compression of the neural elements, magnetic resonance imaging or computed tomography (CT) myelography should be performed to evaluate the spinal canal. Moreover, CT will provide detailed imaging regarding the patient’s bone quality, an important assessment when considering sublaminar wiring for patients. Patients with a history of or evidence on CT imaging of osteoporosis can also undergo dual-energy X-ray absorptiometry (DEXA) scanning to evaluate the degree of disease.
In general, typical preoperative laboratory tests, including a complete blood count with platelet levels and baseline hemoglobin and hematocrit levels, coagulation profile, and type and screen should be obtained in preparation for surgery. Significant blood loss can occur during the exposure and preparation of the sublaminar space for wire passage; therefore, blood products should be placed on hold for the operating room. Finally, patients should be medically fit for surgery. In particular, in the case of spine trauma, the patient should have all other life-threatening injuries addressed and should be hemodynamically stable at the time of surgery.
36.4 Operative Procedure
After being placed under general endotracheal anesthesia and baseline neurophysiologic assessments are obtained, the patient is positioned prone on the operating room table, preferably an open, radiolucent Jackson table. The patient is prepared and draped widely to incorporate additional levels cephalad and caudal if extension of construct is necessary; the iliac crests are also included in the preparation for harvesting autograft for use in fusion, if desired. A midline incision is made, and using monopolar electrocautery, the spinous processes and lamina are exposed; if a posterolateral fusion is desired, the dissection should be carried out laterally to the transverse processes. Once the exposure is complete, any decompression, tumor debulking, or anterior column reconstruction should be performed ( ▶ Fig. 36.1).
Fig. 36.1 Thoracolumbar spine after decompressive laminectomies. Anteroposterior view. Decompression, tumor debulking, and anterior column reconstruction should occur before sublaminar wiring.
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