Idiopathic Scoliosis: Pre-op Planning

Pre-Op Planning and Anesthesia

Patients are selected based on progressive scoliosis. Clinical evaluation is performed for pelvic obliquity, waist crease, shoulder height difference, amount of rotation flexibility and sagittal balance. 36-inch P/A and lateral x-rays as well as lateral recumbent bending lateral films are obtained. Cobb angles are marked in standard fashion. Complete history and physicals are performed to rule out any associated anomalies.

General anesthesia is administered with a double lumen intubation technique in adults and children weighing more than 45kg. Children weighing less than 45kg may require selective intubation of the ventilated lung. Anesthesia has a major roll in the success of the procedure. It is imperative to have the lung completely collapsed. This depends on adequate one lung ventilation by an experienced anesthesiologist. The anesthesiologist must be well versed in fiberoptic intubation. General or thoracic surgeon assistance is recommended initially.

Patient Positioning
Once intubated, the patient is placed into the direct lateral decubitus position, with the arms at 90/90 and the concave side of the curve down. The hips and shoulders are taped to the operating table (Photo 1).

Photo 1

This will help ensure the patient is maintained in the correct position during the case. On occasion when the patient has been positioned the O2 saturation will drop. This will occur if the endotrachial tube advances during the turning of the patient with subsequent occlusion of the upper lobe of the lung. The anesthesiologist must readjust the tube, often fiberoptically.

Portal Placement
Proper portal placement is critical to the success of the procedure. A C-Arm and a straight metallic object, used as a marker, are utilized to identify the vertebral levels and portal sites. The superior and inferior portals are the most critical since the vertebrae at these levels are at the greatest angle in relation to the apex of the curve. The portal planes are visualized with a C-Arm in the P/A Plane being sure the end plates are parallel and well defined. The C-Arm must be rotated until it is parallel to the vertebral body end plates, not perpendicular to the table. (Figure 1)

Figure 1

The Marker is positioned posterior to the patient and aligned with every other vertebral body. (Photo 2)

Photo 2

Photo 3

Figure 2

Once these marks are made at all portal sights the C-Arm is rotated to the lateral position. The Marker end is placed on each line. (Photo 4)

Photo 4	Photo 5	Photo 6

The Marker position is adjusted until the C-Arm image shows the end of the Marker at the level of the rib head on the vertebrae (Photo 5). A cross mark is then placed on the previous line (Photo 6). This is the location of the center of the portals. This will also show the degree of rotation of the spine.