Bone Graft Options for Spine Fusion in Adolescent Patients with Idiopathic Scoliosis

Proximal junctional kyphosis and rates of fusion following posterior instrumentation and spinal fusion for adolescent idiopathic scoliosis

BACKGROUND

Proximal junctional kyphosis (PJK) can cause significant functional impairment and neural compression. Varying rates of PJK and pseudoarthrosis following posterior instrumentation and fusion for adolescent idiopathic scoliosis (AIS) are described with multiple biologic and biomechanical correlations attributed. This retrospective study aims to determine our rate of pseudoarthrosis and PJK in posterior spinal fusion for AIS, along with analysing the influence of autograft and allograft bone volume.

METHODS

Immediate and 12-month post-operative radiographs of 78 patients treated for AIS were analysed along with late complications to a minimum of 2 years. Proximal kyphosis was determined by measuring and comparing the angle between the upper instrumented vertebra and upper instrumented vertebra + 2 for both immediate and 12-month post-operative radiographs. Spinal fusion was determined using an accepted grading scale on the 12-month radiograph. These findings were correlated with known surgical variables in bone grafting technique.

RESULTS

There was one case of PJK and no cases of pseudoarthrosis. Three patients showed a defect in the fusion mass but were still suggestive of fusion. The rates of fusion and PJK were not significantly different when using different allograft volumes or incorporating autograft.

CONCLUSION

Relatively low rates of PJK following AIS correction were observed compared to the literature. Rates were not increased with the use of proximal autograft. The amount of allograft used did not affect fusion rates either.

Low-Intensity Pulsed Ultrasound-Induced Spinal Fusion is Coupled with Enhanced Calcitonin Gene-Related Peptide Expression in Rat Model

Low-intensity pulsed ultrasound (LIPUS) has been found to accelerate fracture healing. In this study, we analyzed the role of calcitonin gene-related peptide (CGRP) in a rat spinal fusion model treated with LIPUS. The results revealed that LIPUS significantly increases bone formation, and the process was coupled with elevated CGRP innervation. CGRP was located in fibrous tissue, closely surrounding the allograft and newly formed cartilage. The density of CGRP peaked at week 3 after surgery in both the control (non-LIPUS-treated) and LIPUS-treated groups. These results suggest that LIPUS might accelerate spinal fusion by promoting sensory nerve fiber innervation.