Introduction: Traditional treatments for AIS realign curves with instrumentation that often spans 8-10 spinal motion segments to achieve desired correction, balance and fusion. The risk of developing adjacent segment disease suggests that limiting fusion levels may have clinical benefits.
Methods: 21 consecutive female AIS patients (Lenke 1A/1B) were prospectively studied at 4 institutions with a novel Heim joint pedicle screw and L shaped screw rod-connection construct allowing for torsional and angular correction with maintenance of mobility. Arthrodesis was limited to the short apical curve region. Instrumentation spanned fused and unfused segments with motion of unfused vertebral segments maintained. Concave rods were removed at maturity. Radiographic data was collected pre and post-op as well as post-removal. The devices are not commercially available at this time.
Results: At time of this abstract, all 21 patients are beyond 2Y post index and 15 of 21 patients had the stabilizing rod and Heim screws electively removed. Data was available for 21 patients at 1Y, 18 at 2Y post-index procedure and 13 post-removal. Average age at surgery: 14.2Y(11-17Y). The main thoracic Cobb angle improved from 56.1(±8.0)° pre-operatively to 20.8(±7.8)° at 1Y and 21.3(±8.4)° at 2Y post-index resulting in instrumented main thoracic Cobb angle improvements of 62.2(±15.9)% and 61.0(±16.4)% respectively. A total of 10.5(±1) levels were stabilized with 5.0(±0.5) levels fused and a screw density of 0.97(0.15). In the vertebral motion segments that were stabilized but not fused, motion was 26(±6)°pre-operatively compared to 10(±4)° at 1Y. There were no reported screw or rod failures. Following removal, main thoracic Cobb angle measured 30.0(±6.4)°for a 45.5(±12.9)% improvement from baseline.
Conclusions: This surgical technique and technology adopts accepted treatment methods in an innovative way to obtain acceptable correction with less fusion, lower implant density, and preservation of motion segments in AIS patients with minimal reported complications.
Patient Care: Lower implant density will help with cost and safety while short apical fusion will delay adjacent segment disease onset
Learning Objectives: Scoliosis treatment may be performed with lower density of implants, and fusion of only the apical levels in hopes of delaying adjacent segment disease