Abstract
Introduction: Extracorporeal shock wave therapy (ESWT) covers a multitude of different indications in modern orthopedics, however, bacterial infections are still considered as contraindications. The goal of the present study was to determine the effect of ESWT on growth of clinically relevant bacteria in orthopedic and trauma surgery.
Methods: Standardised suspensions of a methicillin sensitive and a methicillin resistant strain of Staphylococcus aureus, and reference strains of Staphylococcus epidermidis, Pseudomonas aeruginosa and Enterococ-cus faecalis were subjected to 4000 impulses of high-energy shock waves with an energy flux density (EFD) of 0.96 mJ/mm2 and a frequency of 2 Hz. Furthermore, corresponding suspensions of S. aureus ATCC 25923 were exposed to different impulse rates of shock waves (1000 to 6000 impulses) and to different EFDs up to a maximum of 0.96 mJ/mm2 (2 Hz) to evaluate the influence of shock wave parameters. Subsequently, viable bacteria were quantified by culture and compared with an untreated control.
Results: A highly significant antibacterial effect of the ESWT was demonstrated for all bacterial strains with a reduction of growth to values between 1,1% and 29,7% (P < 0.01). Reference strains of S. aureus and S. epidermidis reacted most sensitive whereas E. faecium demonstrated highest resistance against high-energy shock waves. After applying different energy levels to S. aureus, a significant bactericidal effect was observed only with a minimum threshold EFD of 0.59 mJ/mm2 (P < 0.05). A threshold impulse rate of more than 1000 impulses could be defined to reduce bacterial growth of S. aureus (P < 0.05). Further elevation of energy and impulse rate exponentially increased bacterial killing.
Conclusions: ESWT proved to exert significant antibacterial effect in an energy-dependent manner. The results suggest that infections are not necessarily contraindications to shock wave therapy and could even represent a new indication for ESWT. However, clinical relevance should be assessed in vivo in an animal model.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
