Lumbar spinal stenosis is a common cause of low back and leg pain and disability in adults, and it is often caused by spondylolisthesis (spinal slippage).^[1] Patients who do not improve after 3-6 months of nonoperative therapy (eg, physical therapy, pain management, acupuncture, or chiropractic) may consider surgical decompression as an option.^[2]

Spinal decompression surgery (laminectomy) removes the compressive structures, including hypertrophic ligamentum flavum and lumbar facet joint osteophytes.

The goals of surgical treatment are to alleviate neural compression (decompression) and, in selected patients with a deformity or instability, to stabilize the spine (fusion), so as to prevent further spinal compression and recurrent symptoms.^[3-8]

Image courtesy of Wikimedia Commons.

Preparation

The patient is appropriately positioned, and anatomic landmarks are marked in preparation for incision. In this slide, the patient's head is to the right.

Image courtesy of Anne Vinsel, MS, MFA.

Retraction

The incision is made, retractors are in position, and the spinous process and paraspinal muscles are exposed.

Image courtesy of Anne Vinsel, MS, MFA.

Dissection

Tissue planes are dissected along the spinous process and the laminae. Moving the paraspinal muscles laterally provides visualization of the laminae, thereby enabling exposure of the central canal and neural elements.

Image courtesy of Anne Vinsel, MS, MFA.

Placement of Pedicle Screws

In selected patients (eg, those with a deformity or spondylolisthesis), a spinal fusion with instrumentation is required. Spinal pedicle screws with connecting rods provide direct fixation into the vertebrae and increase spinal stability, thereby improving the chances of successful fusion. A successful spinal fusion requires osseous growth of the vertebrae and the bone graft together.

Image courtesy of Anne Vinsel, MS, MFA.

Intraoperative Fluoroscopy

Pedicle screws are localized by means of intraoperative fluoroscopy. The fluoroscopic image in the slide shows that the pedicle screws are in proper position.

Image courtesy of Anne Vinsel, MS, MFA.

Triggered Electromyography (EMG)

Intraoperative pedicle screw electrical stimulation is performed to confirm that the screws are not compressing or in contact with the neural elements. This facilitates identification and removal of the compression.

Image courtesy of Anne Vinsel, MS, MFA.

EMG Tracing

The intraoperative EMG monitor tracing in the slide shows no abnormal nerve response to screw stimulation, thus verifying that the pedicle screw is not in contact with the nerve.

Image courtesy of Anne Vinsel, MS, MFA.

Decompression

Decompression of the central canal and the neural structures is begun with the rongeur, and the L4 spinous process is removed.

Image courtesy of Anne Vinsel, MS, MFA.

Decompression

With retractors in place, it can be seen that the L4 spinous process has been removed.

Image courtesy of Anne Vinsel, MS, MFA.

Confirmation of Screw Placement

Visual inspection of the incision shows that the L4 and L5 pedicle screws are in position laterally and outside the canal.

Image courtesy of Anne Vinsel, MS, MFA.

Rod Placement

After decompression is complete, rods are placed into the pedicle screws to stabilize the spine, and set screws are tightened. Bone graft is placed laterally along the transverse process to allow an osseous fusion.

Image courtesy of Anne Vinsel, MS, MFA.

Bone Grafting

Successful spinal fusion also requires bone grafting. The autograft bone provides a source for bone-forming cells (osteogenesis), a means of stimulating bone growth (osteoinduction), and a structure on which new bone can grow (osteoconduction).

Bone graft sources vary, depending on the patient and the surgeon's preference. The historical gold standard is autogenous bone graft from the iliac crest. As a result of the limitations of this type of graft, newer biologics are being used in combination with alternative bone grafts (eg, local autograft bone obtained during decompression).

In this case, the surgeon used a combination of local bone graft and recombinant human bone morphogenetic protein-2 (rhBMP-2) for the posterior fusion (an off-label use of the product).

Image courtesy of Anne Vinsel, MS, MFA.

Closure

The retractors are removed and the decompression confirmed. The muscles are then brought back together, and the fascia is closed.

Image courtesy of Anne Vinsel, MS, MFA.

Closure

The cutaneous layers of the incision are sutured closed.

Image courtesy of Anne Vinsel, MS, MFA.

Postoperative Radiography

An upright lateral postoperative radiograph shows the rod and pedicle screws in good position.

Patients tend to experience resolution of their leg symptoms immediately after surgery and are encouraged to ambulate. The incision typically heals over the following 2-3 weeks, and the incisional pain continually improves. The main concern at this point is to be alert for new pain or weakness. In addition, any fever, drainage from the wound, or worsening symptoms should be discussed with the surgical team.

Image courtesy of Anne Vinsel, MS, MFA.