Evaluation of the modern luque trolley construct for treatment of early onset scoliosis using a gliding implant in an immature animal model

Abstract

STUDY DESIGN: Experimental animal study. OBJECTIVE: To determine biological compatibility, stability, and growth potential of the Trolley Gliding Vehicle (TGV) used in a novel surgical technique for guided spinal growth. SUMMARY OF BACKGROUND DATA: Current treatments for Early Onset Scoliosis (EOS) maintaining spinal growth consist of posteriorly based spinal constructs requiring repetitive lengthening. Such interventions have a high rate of complications. Using a muscle sparing technique, a modified dual growing rods construct and new sliding spinal anchors, we set out to test a Modern Luque Trolley construct in an immature animal model. METHODS: Six matched pairs of 3 month old lambs were randomized to an observation or surgical group and were followed for 9 months. The surgical group underwent implantation of a Modern Luque Trolley construct with the new TGV inserted in a minimally invasive transmuscular technique capturing the spine and the 2 overlapping rods on either side. Physical exams and imaging were conducted at routine intervals, with a subsequent necropsy. RESULTS: The spines of the study group grew 96% between the instrumented segments compared to the control group without evidence of implant failure. Forty-two % of the fixed anchors (pedicle screws) and 13.90% of the TGV were loose. All 6 animals had some heterotrophic bone formation tracking along the rods (<20%) mainly originating from the distal anchor point. We identified 19 unplanned spontaneous facet arthrodesis out of the 132 mobile facets found between the fixed proximal and distal anchors. An additional 10 facets spontaneously fused proximal to the most proximal instrumented implants. CONCLUSIONS: Implantation of a Modern Luque construct with Trolley gliding vehicle allows for spinal growth in a non-scoliotic animal model. Implant loosening was likely mechanical as no sign of reactive inflammatory reaction were found. Reducing heterotrophic ossification and spontaneous facet arthrodesis remains a challenge in managing immature spine.