David W. Polly, Jr. and Jürgen Harms

Goals of Surgical Treatment

Achieve a solid, pain-free arthrodesis with optimal sagittal alignment and minimal tissue disruption.

Diagnosis/Indications for Surgery

1. One- or two-level spinal fusion below T10

2. Spondylolisthesis

3. Spinal instability

4. Failed discectomy

5. Discogenic low back pain

Contraindications

1. Patient who is not a surgical candidate

2. Previous anterior discectomy

3. Possibly current active infection

4. Conjoined nerve root

Advantages

1. Improved biomechanics (6 to 18 times stiffer than posterior pedicle screws only)

2. Improved biology (greater area for fusion than intertransverse process fusion)

3. Improved sagittal contour

4. Less dural mobilization than conventional posterior lumbar interbody fusion (PLIF)

Disadvantages

1. Potential dorsal root ganglion irritation

2. Technically more demanding than posterolateral fusion

Procedure

Fusion Levels

As indicated by the diagnosis.

Patient Positioning

1. The patient is positioned prone with the abdomen decompressed to minimize epidural bleeding.

2. Options include placing the patient with the lumbar spine flexed for screw placement, discectomy, and interbody graft placement, and then extending the patient for compression and restoration of normal sagittal contour. If this is done, the table is jackknifed for the initial part and then flattened out or reverse jackknifed for the compression.

3. The patient can be placed on a Jackson spinal table with the hips extended. This makes the distraction slightly more difficult, but then anteroposterior (AP) and lateral fluoroscopy can be used. Compression for lordosis is then easily applied.

4. Some surgeons use a radiolucent Wilson frame flexed for the initial part and then flattened out for the final compression.

Surgical Technique/Exposure Secrets

1. A slightly longer incision is helpful.

2. Have a retractor that opens up wider than usual for a typical decompression operation. A “sprung” Gelpi-type retractor is useful to give adequate retraction and not interfere with pedicle screw placement.

3. After routine exposure, place the pedicle screws and then resect the facet joints. At this point distract across the segment (preferably between the spinous processes). Distraction on the screws may cause them to fail if the bone quality is poor. Use the screws to hold the distraction rather than to obtain the distraction.

4. Resect the facet joint completely on one side. We are right handed and prefer to resect the left facet. Resect it in line with the superior border of the subjacent pedicle and with the inferior border of the suprajacent pedicle. Resect the facet capsule as it blends with the ligamentum flavum.

5. Control the epidural veins. A cottonoid can be used to sweep the contents cephalad, and this can minimize dissection of the microenvironment of the dorsal root ganglion.