56: Posterior Surgical Treatment for Scheuermann’s Kyphosis

Posterior Surgical Treatment for Scheuermann’s Kyphosis

Daniel J. Hedequist

Indications

Progressive kyphosis greater than 75°

Intractable back pain

Objectionable appearance to the patient

Neurologic signs or symptoms

Pitfalls

• Patient misperceptions

• Curves amendable to bracing

• Medical comorbidities

Controversies

• Need for anterior release and fusion

Examination/Imaging

Standing posteroanterior (PA) and lateral 36-inch radiographs are obtained. Figure 1 shows standing radiographs of a patient with kyphosis in PA (Fig. 1A) and lateral (Fig. 1B) views.

FIGURE 1

A lateral radiograph in hyperextesion with a bolster under the kyphotic apex is also obtained.

Magnetic resonance imaging is done to assess for any possible thoracic disk herniations.

Treatment Options

• Open/thoracoscopic anterior release and fusion with posterior fusion and instrumentation

Surgical Anatomy

Posterior-only treatment for Scheuermann’s kyphosis requires an understanding of the posterior anatomic structures of the spine as well as the variations in pedicle anatomy.

Intimate knowledge of the posterior structures allows for the surgeon to easily perform Ponte osteotomies (foramina to foramina) over the apex of the curve.

Positioning

The patient may be placed prone on a standard radiolucent spinal operating frame.

• The abdomen must be kept free, and bolsters are placed at the chest and iliac crest regions.

• The arms are flexed at the elbows and placed forward with the axilla remaining free of any compression.

• The head needs to be placed in a standard headrest with access at the cervicothoracic junction.

The patient must have appropriate somatosensory and motor evoked potential monitoring in place.

Pearls

• A Mayfield headrest in order to control access to the cervicothoracic junction

• Armrests placed to facilitate surgeon access to the cervicothoracic junction

Pitfalls

• Poor proximal thoracic spine access secondary to head position

• Poor proximal access secondary to inadequate draping

Equipment

• Motor and sensory evoked potential monitoring

• Radiolucent operating frame to confirm location and screw placement

Portals/Exposures

The exposure of the thoracic and lumbar spine entails standard techniques.

Hypotensive anesthesia is useful, taking care to keep the mean arterial pressures in the 65- to 70-mm Hg range.

Subperiosteal dissection is necessary in order to obtain adequate bone for fusion as well as clear anatomic landmarks for pedicle screw placement.

Exposure is done with Cobb elevators and electrocautery, taking care to expose out to the tips of the spinous processes.

Pearls

• Mean arterial pressure 65–70 mm Hg

• Judicious electrocautery

• Preservation of junctional interspinous ligaments

Pitfalls

• Inadequate exposure at proximal and distal ends

• Excessive soft tissue remaining on spine

Procedure

Step 1

Pedicle screw placement begins distally in the lumbar spine, taking care to include the lumbar vertebra that is centered over the sacral spine in the lateral view.

The use of fixed or variable screws will lead to reliable results in correcting kyphosis. The use of reduction screws at the distal levels may help capture the rods more easily, and may aid in rod capture proximally as well.

Standard lumbar screw placement is performed, taking care to place as large a diameter of screw as possible, with the length of screws typically ranging from 40 to 50 mm.

Thoracic screw placement is done after facetectomies at each corresponding level.

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Tags: Operative Techniques Pediatric Orthopaedic Surgery

Jun 7, 2016 | Posted by admin in ORTHOPEDIC | Comments Off

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