Anterior Vertebral Body Stapling for the Treatment of Idiopathic Scoliosis

Abstract

The standard of care for moderate idiopathic scoliosis (20°–45°) typically involves observation and bracing to prevent further curve progression. However, several studies suggest that bracing is only effective when worn >12 h a day and may create psychosocial stresses resulting in limited compliance (Rahman et al., J Pediatr Orthop 25(4):420–422, 2005; Katz et al., J Bone Joint Surg Am 92(6):1343–1352, 2010; Helfenstein et al., Spine (Phila Pa 1976) 31(3):339–344, 2006; Weinstein et al., N Engl J Med 369(16):1512–1521, 2013; Misterska et al., Spine (Phila Pa 1976) 37(14):1218–1223, 2012; Cheung et al., Int Orthop 31:507–511, 2007; Misterska et al., Med Sci Monit 17(2):CR83–CR90, 2011). Furthermore, in patients with juvenile idiopathic scoliosis with curves between 20° and 30° at the onset of puberty, it has been shown that there is a 75% risk of requiring a spinal fusion, and in curves >30°, there is a 100% risk of fusion (Dimeglio et al., J Pediatr Orthop 31(1 Suppl):S28-S36, 2011). In a subset of skeletally immature patients with progressive idiopathic scoliosis and significant growth remaining, surgical spinal growth modulation is an alternative to bracing for the treatment of moderate idiopathic scoliosis. Spinal growth modulation relies upon the Hueter-Volkmann principle to slow growth on the convexity of the curve and allow growth on the concavity of the curve, resulting in gradual correction of the deformity. Several devices are currently utilized including vertebral body stapling (VBS) and vertebral body tethering (VBT). The potential advantages of these techniques are curve correction through a minimally invasive thoracoscopic or a mini-open retroperitoneal approach, a quicker recovery, and preservation of motion.

Vertebral body stapling in published series worked best for patients with idiopathic scoliosis with thoracic curves 25°–35° and lumbar curves 25°–45°. These patients should be at least 8 years of age but still skeletally immature (girls less than 13 years, boys less than 15 years) with at least 1 year of growth remaining (Risser 0–1, Sanders digital stage ≤4). Other considerations are curve flexibility with side bending correction to <20°, minimal rotation with correction on clinical exam or X-ray, and a true sagittal kyphosis <40°. VBT may be more suitable than VBS for curves 35°–75° or curves that do not bend below 20°. Postoperative nighttime bracing is recommended for VBS if the curve is >20° on the first erect radiograph. Most complications are related to the approach including atelectasis, pain at the site of the chest tube, and pneumothorax. Device-related complications are rare, If the VBS does not prevent curve progression and the curve progresses beyond 50 degrees then the staples do not need to be removed nor do they preclude use of standard pedicle screw fixation for a posterior spianl fusion. At this time, none of the devices for spinal growth modulation have been approved by the United States Food and Drug Administration for use in idiopathic scoliosis; however, early clinical results are promising.