[Growth modulation in operative treatment of juvenile scoliosis by USS paediatric].

OBJECTIVE

Growth modulation in operative treatment of juvenile scoliosis can be done by USS paediatric instrumentation to control spinal growth in patients of small stature with juvenile scoliosis. The double-rod system has to be distracted every 4-6 months. The system is used in young patients too tall for VEPTR (vertical expandable prosthetic titanium rib) instrumentation. The system with a very low profile allows reduced soft-tissue pressure saving soft tissue from atrophy or the development of pseudocysts above the screws. With this procedure controlled growth with growth modulation of the spine is possible and final spondylodesis can be done later.

INDICATIONS

Congenital, idiopathic and neuromuscular scolioses. Children, who are too tall and big for a VEPTR instrumentation. Cobb angle > 40 degrees or progression > 10 degrees during brace therapy.

CONTRAINDICATIONS

Adults. Dysplastic pedicles with vertebral anomalies. Arthrogryposis.

SURGICAL TECHNIQUE

The patient should be positioned prone, lying flat on the table. Median skin incision with subperiosteal preparation of the paraspinal muscles is done to expose the vertebrae. Next, the pedicle is prepared with a tap, and the USS paediatric pedicle screw system with its very low profile is inserted under fluoroscopic control in anterior-posterior and lateral view. In the upper thoracic spine the authors use screws 4.2 mm in diameter, in the lower thoracic spine 5-mm screws, and in the lumbar spine 6-mm screws. Measurement of the rod length and insertion of the rod are performed. When spinal growth for > 4 years is expected, distraction of the double-rod system by the use of two dominos is done on the concave and convex side of the curve to modulate spinal growth. When spinal growth for 2-4 years is expected, distraction is done just at the concave side of the curve. For correction of the curve, either segmental correction or classic derotation by the Cotrel-Dubousset technique can be performed.

POSTOPERATIVE MANAGEMENT

Postoperative on block rotation. Mobilization of the patient on day 2 after surgery with a rigid brace. Individual rigid custom-made plaster brace for 3-8 months. During postoperative recovery, muscular efforts should be reduced for 6 months after first implantation. Distraction of the system is necessary every 4-6 months to modulate spinal growth.

RESULTS

From 2004 to 2008, 26 patients (15 girls, eleven boys) with a mean age of 9 years (6-13 years) were treated using this technique. Follow-up examinations were performed 3, 6, 12, and 24 months after surgery. The mean follow-up was 26 months (6-40 months). At first implantation of the scoliosis instrumentation, just little scoliosis correction was done depending on the quality of bone. At every distraction, an average correction of the Cobb angle of 5 degrees was reached. The Cobb angle could be reduced from 71 degrees to 34 degrees on average. Fusion rate in the cranial and caudal part was evaluated by X-ray. 5-mm rods have a reduced stiffness of 50% compared to USS 6-mm rods. Average spinal growth was about 5.6 cm (4.0-8.1 cm) over a period of 3.2 +/- 1.2 years. During 2-year follow-up, rod or pedicle screw breakage, dislocation, or loosening of the Cobb angle did not occur.