Marshal D. Peris and William F. Donaldson

Posterior Approach Goals

Gain access to the cervical and thoracic spine for purposes of decompression, fusion, and instrumentation.

Diagnosis

X-ray, magnetic resonance imaging (MRI), computed tomography (CT) scans, and clinical assessment can be used.

Indications

1. Posterior cord compression

2. Instability without anterior cord compression

3. Trauma without anterior cord compression

4. Kyphosis usually in conjunction with anterior surgery

5. Following anterior decompression for infection, tumor, or trauma to supplement stability

Contraindications

1. Medical instability

2. Skin problems over the proposed surgical site (skin infection, ulcer, and necrosis)

3. Ongoing or systemic infection (relative)

Advantages

1. Large exposure of the entire posterior spine

2. Improved stability from instrumentation techniques

3. Improved correction of deformity

4. Relatively safe approach surgically

Disadvantages

1. Risk of increased blood loss due to muscle dissection

2. Risk of neurologic injury using instrumentation

3. Risk of dural tears and neurologic injury performing decompression

4. Risk of infection from large exposure

5. Higher incidence of postoperative back pain from muscular dissection

6. Cannot completely access the vertebral bodies or disc spaces

Procedure

Positioning

Prone with chest rolls or chest and pelvic pads on a radiolucent table. Skull pins or traction may be necessary.

Approach

1. Midline incision carried down to dorsal fascia.

2. Subperiosteal dissection of paraspinal musculature off the spinous processes.

3. Blunt dissection with Cobb elevator of musculature off the lamina.

4. Dissection with electrocautery around facet joints and transverse processes.

5. If laminectomy is to be performed, use a 3-0 curved curet to define the lower border of the lamina to be removed. Then use a Kerrison to remove lamina centrally and laterally, protecting the dura/cord at all times.

6. If using instrumentation requiring sublaminar hooks or wires, a window of ligamentum flavum is removed and a small laminotomy is made at each level required.

7. If using pedicle screw systems, a laminotomy needs to be performed to feel the pedicle at each level. Guide wires are placed in the pedicles and anteroposterior (AP) and lateral radiographs or fluoroscopy is used to ensure correct positioning.

8. If using plates and screws in the cervical spine, the screws should be started just medial to the lateral mass and directed 25 to 30 degrees superiorly and laterally. This may need to be altered to parallel the plane of the facet joint and to stay out of the foramen or canal.

Instrumentation

1. Pedicle screws

2. Luque rectangle and sublaminar wires

3. Lateral mass plates connecting with rods

4. Hooks and rod system with sublaminar wires

Pitfalls