Shock wave treatment shows dose-dependent enhancement of bone mass and bone strength after fracture of the femur

Abstract

Shock wave treatment is believed to improve bone healing after fracture. The purpose of this study was to evaluate the effect of shock wave treatment on bone mass and bone strength after fracture of the femur in a rabbit model. A standardized closed fracture of the right femur was created with a three-point bending method in 24 New Zealand white rabbits. Animals were randomly divided into three groups: (1) control (no shock wave treatment), (2) low-energy (shock wave treatment at 0.18 mJ/mm 2 energy flux density with 2000 impulses), and (3) high-energy (shock wave treatment at 0.47 mJ/mm 2 energy flux density with 4000 impulses). Bone mass (bone mineral density (BMD), callus formation, ash and calcium contents) and bone strength (peak load, peak stress and modulus of elasticity) were assessed at 12 and 24 weeks after shock wave treatment. While the BMD values of the high-energy group were significantly higher than the control group ( P = 0.021), the BMD values between the low-energy and control groups were not statistically significant ( P = 0.358). The high-energy group showed significantly more callus formation ( P < 0.001), higher ash content ( P < 0.001) and calcium content ( P = 0.003) than the control and low-energy groups. With regard to bone strength, the high-energy group showed significantly higher peak load ( P = 0.012), peak stress ( P = 0.015) and modulus of elasticity ( P = 0.011) than the low-energy and control groups. Overall, the effect of shock wave treatment on bone mass and bone strength appears to be dose dependent in acute fracture healing in rabbits.