Posterolateral inter-transverse lumbar fusion in a mouse model

Area of Science:

• Orthopaedic Surgery
• Biomedical Engineering
• Animal Models

Background:

• Spinal fusion is a common procedure, with existing models in canines, lapines, and rodents.
• Murine models for spinal fusion are underutilized despite the availability of genetically modified strains.

Purpose of the Study:

• To develop an efficient and minimally invasive mouse model for spinal fusion.
• To determine the optimal dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) for achieving spinal fusion mass.

Main Methods:

• A novel surgical approach for posterolateral lumbar spine fusion in mice was designed using MicroCT comparisons with human spines.
• Phase 1 evaluated decortication alone versus rhBMP-2 with decortication in mice.
• Phase 2 involved a dose-response study of rhBMP-2 (0-5 μg) in collagen sponges.

Main Results:

• The midline surgical approach was rapid, reproducible, and analogous to human procedures.
• Decortication alone did not induce bone formation; rhBMP-2 addition was necessary.
• 0.5 μg of rhBMP-2 per sponge was identified as the minimum effective dose for bridging lumbar vertebrae.

Conclusions:

• A safe, efficient, and reproducible mouse model for lumbar spine fusion was established.
• The technique mimics human surgical procedures and is suitable for genetically modified mouse studies.
• This model facilitates research into spinal fusion mechanisms and genetic factors.