Surgical Management of Scheuermann Kyphosis

Overview

The posterior-only treatment of Scheuermann kyphosis using segmental posterior shortening and instrumentation has been a treatment option for over 20 years. Early reports detail the poor results with posterior-only surgery, but these were primarily associated with Harrington compression instrumentation. This led to advocacy of a combined anteroposterior (AP) approach with anterior releases followed by posterior compression instrumentation and fusion. Loss of correction and pseudarthrosis have been reported. However, more recent studies have demonstrated excellent results with pedicle screw instrumentation in association with posterior-only resections and deformity correction. The anterior releases are associated with increased complication rates if performed in a staged fashion, but complication rates are similar between posterior-only surgery and anterior release followed by posterior spinal fusion if performed on the same day.

Indications and Contraindications

Indications

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Failure of nonoperative management of kyphosis or thoracic pain
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Progressive kyphosis or pain with thoracic deformity greater than 75 degrees or thoracolumbar deformity greater than 40 degrees
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Radiographic wedging of greater than 5 degrees at three levels consistent with the diagnosis

Contraindications

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Pregnancy
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Metal sensitivity
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Malnutrition
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Vitamin D deficiency

Operative Technique

Equipment

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Radiograph-compatible operating table
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Imaging system (fluoroscopy or navigation)
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Headlight system
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Retractor system
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Bone graft source
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Posterior instrumentation (implants), longitudinal rods, pedicle screws, and sublaminar, pedicle, and transverse process hooks (discretionary)
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Sublaminar wires (optional)
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Crosslink connectors
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Kerrison rongeur, 1 to 4 mm
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Midas burr
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Leksell rongeur
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Hemovac drain
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Jackson frame
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Spinal cord monitoring with some added somatosensory-evoked potentials (SSEPs) and motor-evoked potential (MEPs) with sphincter monitoring
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Cell Saver (Haemonetics, Braintree, MA) autotransfusion system

Patient Positioning

The patient is placed prone on the Jackson frame. With severe cases, appropriate padding may be required to safely position the patient initially. A mobile table that allows intraoperative repositioning may be helpful to aid in the reduction maneuver.

A slight reverse Trendelenburg position will keep the patient’s eyes from being in a dependent position to prevent facial, periorbital, and airway swelling. Additionally, this will aid in visualization in the upper thoracic spine. General endotracheal anesthesia is used, and arms are positioned at the patient’s side with the shoulders taped to allow access for any type of imaging modality to the cervicothoracic junction. This is particularly necessary if navigation is being used. Arms may be positioned in the abducted position, no more than 90 degrees, with the elbows well padded and the shoulders well supported. If navigation modalities are not being used, caution should be exercised with this positioning, because it may place the brachial plexus at risk; neurologic monitoring will be helpful in assessing the brachial plexus throughout the case. The entire back is prepped from the hairline to the buttocks and to the midaxillary lines.

Location of Incision

The incision extends from approximately overlying the spinous process of C7, and it is extended caudally to the rostral lumbar spine in the midline. With severe upper thoracic kyphosis, the rostral extent of the incision may need to extend into the subaxial cervical spine to allow for pedicle screw entry.

Local anesthetic with epinephrine may be injected subcutaneously along the incision site to assist with hemorrhage control. Care must be taken that the toxic dose, typically 3 mg/kg for amides without epinephrine, is not reached or exceeded.

Incision and Soft Tissue Dissection

The subcutaneous layer is divided, and hemostasis obtained. The deep fascia is divided in the midline along its connection to the spinous processes at the apex of the deformity. Great care must be taken rostrally not to damage the supraspinous and interspinous ligament complex in an attempt to limit the incidence of proximal junctional kyphosis ( Fig. 57-1 , down arrow ).

Exposure of the Vertebrae

Using a Cobb elevator and electric cautery, longitudinal muscles are exposed and elevated laterally out to the lateral border of the transverse processes and are held with self-retaining retractors ( Fig. 57-2 ).

A permanent radiopaque marker should be used for determining levels definitively. Methods include a needle placed into the spinous process; a clamp placed on the spinous process and a Woodson elevator placed under the lamina; or a curette placed into the pedicle. This will allow fluoroscopy, lateral radiography, or a three-dimensional imaging modality to be able to localize the desired level. It is important to note that severe deformity may preclude lateral radiography from definitively determining the level, and AP radiography may be necessary for level confirmation, particularly in the rostral thoracic spine.

Retractor Placement

Attention to the midline is important during the dissection so as to minimize bleeding. Self-retaining retractors are placed within the wound at the most proximal and distal aspects and are used to hold back the longitudinal musculature. Usually four retractors are necessary: two angled short retractors used at the ends of the incision and two longer straight retractors introduced over the end retractors and extended into the body of the wound. The retractors should retain longitudinal musculature laterally to allow better visualization of the transverse processes bilaterally, out to the most lateral aspect, from the top to the bottom of the operative field.

Rostral exposure should be limited to prevent excessive soft-tissue destruction in an attempt to limit proximal junctional kyphosis (see Fig. 57-1 ). The facets must be exposed with the capsule completely resected using curettes or electric cautery. Facets are then excised completely by the surgeon’s method of choice. If osteotomes are used for this, they must be sharp, and a high-speed burr may be useful in a more controlled resection of the facets. The spinous processes are resected, and local bone is used for grafting. Beginning in the midline, the ligamentum flavum is then excised with a Kerrison rongeur, proceeding laterally toward the facets. The remainder of the facets are resected with the Kerrison rongeur, and this resection is continued into the foramen at every level. Cephalad and caudad widening of the osteotomy is performed as indicated ( Figs. 57-3 and 57-4 ).