Linda P. D’Andrea, JahanGir Asghar, James T. Guille, and Randal R. Betz

Description

Vertebral stapling is a method of regulating spinal curvature development in the young patient with a coronal plane deformity. This can be accomplished using traditional or minimal access approaches.

Expectations

Ideally, a surgeon with experience in anterior spine surgery, especially using minimally invasive techniques, should be able to perform this procedure. It may be helpful to enlist the assistance of a general or thoracic surgeon with experience in thoracoscopic and minimally invasive techniques. With the use of these techniques, scoliotic vertebrae from T2 to L4 can be stapled, while limiting the total scar length.

Indications

Patients who have at least 1 year of growth remaining, have a scoliosis deformity that would be considered for brace treatment, or may have failed or refused bracing are ideal candidates for the stapling procedure. Lenke 1, 3, 5, and 6 scoliosis curves are ideal for treatment with vertebral stapling.

Contraindications

Medical contraindications are the same as for any anterior spine or chest procedure and include systemic infection, active respiratory disease such as uncontrolled asthma, or conditions with increased anesthetic risk. Significantly compromised pulmonary function may be a relative contraindication.

We do not perform vertebral stapling for curves over 45 degrees, or in those whose curves do not correct to less than 20 degrees on bending films, because prior experience has yielded poor results. In children <8 years old with larger curves, it still may be desirable to perform stapling because of the ability to avoid early fusion and the potential for correction with continued growth, especially if a posterior growth device is added.

Kyphosis greater than 40 degrees is also a relative contraindication, because of the potential for the creation of hyperkyphosis with growth.

Special Considerations

When performing thoracoscopic vertebral body stapling in small children (weighing under 50 lb), it may be difficult for the anesthesiologist to obtain or maintain single-lung ventilation. The child’s airway size may not be compatible with the limited sizes of endotracheal tubes available. In these cases, the use of carbon dioxide (CO₂) insufflations for the thoracoscopic portion or two minithoracotomies may be used. If using CO₂, it is important to maintain the intrathoracic pressures at 7 to 10 mm Hg. Higher pressures can produce adverse hemodynamic effects (e.g., tachycardia, hypotension).

An important principle of insertion is to have the tines of the staples parallel and adjacent to the vertebral body end plates. In order for there to be actual correction of the scoliosis by modulation of the vertebral body growth, the patient should have at least 1 year of growth remaining.

Staple tine deployment usually occurs over 5 minutes. The staples should be placed in the inserter, with the tines straightened, and immersed in the sterile ice bath until the moment of insertion. Using flexible or rigid portal sleeves or a nasal speculum to maintain open portals allows for quick passage of the staples while protecting the skin and muscle. If tine deployment is occurring as the staple is being driven into the body, it is essential that the surgeon stop, as the tines may curl enough to penetrate the disk space. If this occurs, the staple should be removed, re-iced, and then reinserted.

Tips, Pearls, and Lessons Learned

Although the patient is in the lateral decubitus position, often the flexible, main thoracic curve reduces. To further reduce the curve while placing the staples, lateral pressure to the apical ribs can be applied. The dull staple trial may also be used to push at the apex of the convexity, further reducing the curve prior to staple impaction. This may be important, because evaluation of data from patients who have already undergone the procedure suggests that patients who had the greatest correction at the time of surgery (curve <20 degrees on first erect radiograph) maintained that correction best.

Previously, patients were told to wear a noncorrecting thoracolumbosacral orthosis (TLSO) for a brief time after surgery, but over the last 4 years we have found that this is usually not necessary. In a very active child with stapling of a lumbar curve, we will request that the child wear a lumbosacral corset for 6 to 8 weeks post-surgery. All patients are asked to restrict activities for 4 to 6 weeks to allow for skin and muscles incised during the surgery to heal. Only two staples of 1400 have partially moved with normal activities or vigorous participation in sports (including gymnastics) or dancing.

Key Procedural Steps

1. The thoracic and lumbar spine are accessible with minimally invasive techniques.
   
   
   
   1. One-lung ventilation or CO₂ insufflation for thoracic visualization
      
   2. Minimal flank incisions and nerve stimulation in lumbar surgery
      
   3. Staple insertion aided by biplanar fluoroscopy
   
   
2. Curve reduction prior to staple insertion
   
   
   
   1. Positioning on operating table
      
   2. Indirect pressure on same-level ribs
      
   3. Direct pressure with staple trial instrument
   
   
3. Placement of vertebral body staples
   
   
   
   1. Parallel to the body’s apophyses
      
   2. Slightly anterior to rib heads
      
   3. Use of sterile ice bath
      
   4. Fluoroscopic verification of placement

The recommended guideline for choosing levels is to include all vertebrae that lie within the Cobb angle of the curve. The levels that may be safely stapled include T2 to L4. If the vertebrae are small, sometimes only a single two-prong staple can be placed in the upper thoracic spine.

Under general anesthesia, patients are placed in the lateral decubitus position with the convex side of the scoliosis curve in the up position. The table is not flexed, and only a small axillary roll is placed.