This was an 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 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 aimed to test a modern Luque Trolley construct in an immature animal model.Materials and Methods:
Six matched pairs of 3-month-old lambs were randomized to an observation or a surgical group and were followed for 9 months. The surgical group was subjected to implantation of a modern Luque Trolley construct with the new TGV inserted using a minimally invasive transmuscular technique capturing the spine and the 2 overlapping rods on either side. Physical examinations and imaging were performed at routine intervals, with a subsequent necropsy.Results:
The spines of the study group grew 96% between the instrumented segments compared with the control group without evidence of implant failure. In total, 42% 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 TGV allows for spinal growth in a nonscoliotic animal model. Implant loosening was likely mechanical as no signs of reactive inflammatory reaction were found. Reduction of heterotrophic ossification and spontaneous facet arthrodesis remains a challenge in the management of immature spine.