Techniques in Managing Spondylolisthesis
Nickalus R. Khan
Kevin T. Foley
Spondylolisthesis can be classically described as isthmic (spondylolytic), degenerative, traumatic, or pathologic. This chapter will focus on the treatment and management of adult lumbar degenerative spondylolisthesis (DS). DS of the lumbar spine is a condition in which a cephalad vertebra translates anteriorly without disruption of the posterior elements. DS often occurs in conjunction with facet hypertrophy and thickening of the ligamentum flavum, which can lead to spinal stenosis and neurogenic claudication. This combination of pathologies can be successfully treated with surgical intervention.1 Although decompression alone can alleviate the symptoms of neurogenic claudication, patients with DS are often treated with decompression and fusion.2,3 The combination of arthrodesis and decompression has been shown to achieve superior outcomes in patients with DS.4,5 The number of DS patients in the United States receiving decompression alone has decreased from 12% to 4% between 1999 and 2011, and the rates of interbody fusion for DS have increased from 14% to 37%. Surgical approaches to interbody fusion for this disorder include open posterior lumbar interbody fusion (PLIF) and open transforaminal lumbar interbody fusion (TLIF). Since the initial description of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) in 2002, the technique has gained significant popularity in the treatment of lumbar degenerative disease.6, 7, 8 Theoretically, the use of a paramedian, muscle-sparing approach and percutaneous screw/rod placement result in less tissue damage while allowing the application of time-tested principles of lumbar decompression, fusion, and internal fixation. Additionally, minimally invasive surgical (MIS) posterior lumbar surgery minimizes injury to the tendinous attachments of the multifidus muscle and maintains the integrity of the dorsolumbar fascia. Proponents of the technique cite decreased operative blood loss, decreased postoperative narcotic requirements, and shorter hospital stays while maintaining similar patient-reported and radiographic outcomes compared with standard open transforaminal lumbar interbody fusion (O-TLIF).
The focus of this chapter will be on minimally invasive techniques for managing lumbar DS.
OPERATIVE TECHNIQUES IN MANAGING SPONDYLOLISTHESIS
Typically, our patients are positioned prone on a Jackson spinal surgery table. All pressure points are appropriately padded. A midline mark is drawn on the dorsal skin surface.
Minimally Invasive Approach
Parallel lines are drawn 3.5 cm from the midline on either side of the midline mark. Bilateral 1-inch incisions are made on these lines at the level of the appropriate disk space, following fluoroscopic disk space localization using 22 gauge spinal needles (an imaginary line coaxial with the needle and extending from the needle tip should bifurcate the disk space). The incisions are carried only into the subcutaneous tissues. The MI-TLIF approach is performed on the side that is most responsible for the patient’s symptoms. If the patient has bilateral radicular pain or neurogenic claudication, a bilateral decompression is performed via the unilateral approach or via the contralateral incision.
Next, pedicle screw localization and K-wire placement are performed. Jamshidi needles are advanced through the 1-inch skin incisions to entry points at the junctions of the transverse processes and facets, at the lateral fluoroscopic borders of the pedicles. The needles are advanced through the pedicles under anteroposterior and lateral fluoroscopic guidance until they reach the midportions of the vertebral bodies. Kirschner wires (K-wires) are inserted through the needles and the needles are withdrawn. The K-wires are temporarily deflected superiorly and inferiorly (above and below the incisions) and are attached to the drapes using hemostats.
After pedicle localization, our attention is turned to performing the decompression. A K-wire is inserted through the 1-inch incision and is directed toward the disk space. The K-wire is advanced only until it penetrates the fascia. An initial dilator is then inserted over the K-wire and through the fascia and the K-wire is withdrawn. The initial dilator is docked on the inferior portion of the cephalad lamina (e.g., on L4 for a L4-L5 surgery), just superior to the laminar edge. These landmarks can be palpated with the tip of the dilator, which can also be used for a focal subperiosteal dissection. The surgical approach lies in the intermuscular plane between the multifidus and longissimus muscles. Sequential dilation is then performed and a 22 mm diameter tubular retractor of appropriate length is inserted over the final dilator, followed by removal of the dilators and attachment of the tubular retractor to an articulated arm connected to the operating room table (Figs. 39.1 and 39.2).
Figure 39.2 Anteroposterior fluoroscopic view of correctly localized pedicles using K-wires and correct placement of a 22 mm diameter tubular retractor.
Figure 39.3 Diagram showing the planned bony cut starting at the laminar edge medial to the facet joint and extending superiorly and laterally through the pars interarticularis (the boundaries of the properly placed tubular retractor can be used as a cutting template).
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