SURGICAL STRATEGY FOR THORACOLUMBAR SCOLIOSIS OR PREDOMINANTLY LUMBAR DOUBLE CURVATURE SCOLIOSIS WITH A CLOSED ILIOLUMBAR ANGLE

Abstract

Purpose of the study: The surgical technique for thoracolumbar scoliosis and T11-L3 lumbar scoliosis with a lumbosacral counter curvature (neutral L4) does not raise any particular problem in terms of the length of the instrumentation and the choice of the vertebral bodies to include in the fusion. The strategy is however more difficult to establish when the iliolumbar angle is closed and L4 is included in the curvature.

Material and methods: We report 11 cases of type II scoliosis, all in girls aged 15.5 years on average (range 12–18 years). These girls presented an imbalanced trunk with lumbar asymmetry. Mean lumbar curvature was 51° (range 41–72°), and, for patients with a double curvature, the mean thoracic counter curvature was 28° (range 21–45°). Lateral lumbar displacement was 4.2 cm (3–4.9 cm), and in double curvatures the thoracic displacement was 3.1 cm (1.7–4.2 cm). Mean lumbar lordosis was −41° (range −38° to −46°). Mean thoracic kyphosis was +13° (range −2° to +22°). Anterior instrumentation was used for all curvatures. For six patients, five levels, from T11 to L3 were instrumented and in five patients, four levels from T12 to L3. For the double scoliosis cases, in situ rod bending was necessary to balance the lumbar curvature with the thoracic curvature.

Results: Mean follow-up was 42 months (range 14–79). One revision was required for rupture of a corporeal screw with L4–L5 nonunion. Trunk imbalance was corrected in all patients. The iliolumbar angle was opened with a mean L3–L4 inclination of 11° (range 0–18°). Mean Cobb angle was 22° in the lumbar region (range 17–30°). For the double curvatures, the mean residual thoracic curvature was 27.6° (range 17–44°). Mean residual lateral displacement was 0.2 cm in the lumbar region (range 0–0.3 cm) and 0.8 cm (range 0.3–2.2 cm) in the thoracic region. Mean thoracic kyphosis was 13° (range +10–25°). Mean lumbar lordosis was −51° (range −49° to +44°).

Discussion: In the literature, a posterior approach has been proposed for curvatures with a closed iliolumbar angle and inclusion of L4. The assembly includes L4 and often L5, extending as high as T5–T6 in the cases with double curvatures. We have chosen a completely different strategy and propose short anterior instrumentation. The spinal balance obtained appears to be as good with a better functional result due to the preservation of spinal motion and posterior muscle function. Longer follow-up will be necessary to assess the effect on the discs above and below the fusion.