Bone morphogenetic protein-2 expression in spinal fusion masses enhanced by extracorporeal shock wave treatment: a rabbit experiment.

PURPOSE

Extracorporeal shock wave (ESW) has been introduced to enhance spinal fusion. This study was conducted to assess the effect of ESW on bone morphogenetic protein-2 (BMP-2) expression in a spinal fusion experiment.

METHODS

Twelve rabbits underwent fusion at bilateral L5-6 intertransverse spaces. They were evenly divided into two groups. In the study group, bilateral L5 and L6 transverse processes were treated with 1,000 impulses of ESW at 14 kV at 12 weeks. In the control group, the rabbits did not receive ESW treatment. All rabbits were sacrificed at 16 weeks, and their lumbar spines were harvested for radiographic and molecular biological study.

RESULTS

In the study group (n = 6), the radiographs showed good fusion in all six rabbits, while in the control group (n = 6), good fusion was found only in three rabbits (50%). Although more rabbits in the study group had a good fusion result, the inter-group difference was not statistically significant (P = 0.182). In the molecular biological examination, the mean value of the normalized expression of BMP-2 mRNA in the fusion masses of the study group was 90 ± 8.4 while that of the control group was 77.33 ± 6.74. Statistical analysis showed the study group had a significantly higher BMP-2 mRNA expression in the fusion masses than the control group (P = 0.018).

CONCLUSIONS

The current study showed that ESW treatment enhances BMP-2 mRNA expression in spinal fusion masses.