Application of extracorporeal shock wave treatment to enhance spinal fusion: a rabbit experiment

The Effects of the Exposure of Musculoskeletal Tissue to Extracorporeal Shock Waves

Extracorporeal shock wave therapy (ESWT) is a safe and effective treatment option for various pathologies of the musculoskeletal system. Many studies address the molecular and cellular mechanisms of action of ESWT. However, to date, no uniform concept could be established on this matter. In the present study, we perform a systematic review of the effects of exposure of musculoskeletal tissue to extracorporeal shock waves (ESWs) reported in the literature. The key results are as follows: (i) compared to the effects of many other forms of therapy, the clinical benefit of ESWT does not appear to be based on a single mechanism; (ii) different tissues respond to the same mechanical stimulus in different ways; (iii) just because a mechanism of action of ESWT is described in a study does not automatically mean that this mechanism is relevant to the observed clinical effect; (iv) focused ESWs and radial ESWs seem to act in a similar way; and (v) even the most sophisticated research into the effects of exposure of musculoskeletal tissue to ESWs cannot substitute clinical research in order to determine the optimum intensity, treatment frequency and localization of ESWT.

Effect of low-energy extracorporeal shock wave on vascular regeneration after spinal cord injury and the recovery of motor function

BACKGROUND

Latest studies show that low-energy extracorporeal shock wave therapy (ESWT) can upregulate levels of vascular endothelial growth factor (VEGF). VEGF can ease nervous tissue harm after spinal cord injury (SCI). This study aims to explore whether low-energy ESWT can promote expression of VEGF, protect nervous tissue after SCI, and improve motor function.

METHODS

Ninety adult female rats were divided into the following groups: Group A (simple laminectomy), Group B (laminectomy and low-energy ESWT), Group C (spinal cord injury), and Group D (spinal cord injury and low-energy ESWT). Impinger was used to cause thoracic spinal cord injury. Low-energy ESWT was applied as treatment after injury three times a week, for 3 weeks. After SCI, the Basso, Beattie, and Bresnahan (BBB) scale was used to evaluate motor function over a period of 42 days at different time points. Hematoxylin and eosin (HE) staining was used to evaluate nerve tissue injury. Neuronal nuclear antigen (NeuN) staining was also used to evaluate loss of neurons. Polymerase chain reaction was used to detect messenger RNA (mRNA) expression of VEGF and its receptor fms-like tyrosine kinase 1 (Flt-1). Immunostaining was used to evaluate VEGF protein expression level in myeloid tissue.

RESULTS

BBB scores of Groups A and B showed no significant result related to dyskinesia. HE and NeuN staining indicated that only using low-energy ESWT could not cause damage of nervous tissue in Group B. Recovery of motor function at 7, 35, and 42 days after SCI in Group D was better than that in Group C (P<0.05). Compared with Group C, number of NeuN-positive cells at 42 days after SCI increased significantly (P<0.05). The mRNA levels of VEGF and Flt-1 and VEGF expression at 7 days after SCI in Group D were significantly higher than those in Group C (P<0.05).

CONCLUSION

Low-energy ESWT promotes expression of VEGF, decreases secondary damage of nerve tissue, and improves recovery of motor function. It can be regarded as one mode of clinical routine adjunctive therapy for spinal injury.

Extracorporeal shock waves in articular cartilage defects in the rats

Thirty adult Sprague-Dawley rats were used to assess the nature of healing tissues in hyaline cartilage defects and to compare the healing in defects treated with shock waves, with those in defects without treatment. A 2 × 2 mm cartilage defect with exposed cancellous bone was created in a nonweight-bearing area of each medial femoral condyle. Each right knee defect was received extracorporeal shock waves (Swiss Dolorclast) of 500 impulses in 5 min at 2 bar (comparative to 0.09 mJ/mm(2)), and the left knee defects were assigned as controls. The rat groups were sacrificed at 6 and 12 weeks postsurgery. Sections from each knee were stained with hematoxylin-eosin to analyze synovial adhesion, synovial thickness, bone maturation, and chondroid metaplasia and with masson trichrome to analyze collagen fiber intensity. There was not a significant difference found between the study and control groups (P > 0.05). Extracorporeal shock waves did not effect healing of the chondral defects.

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.