The evidence of low-intensity pulsed ultrasound for in vitro, animal and human fracture healing.

BACKGROUND: Physical stimulation therapies are currently available to enhance fracture healing. SOURCES OF DATA: A search of PubMed, Medline, CINAHL, DH data and Embase databases was performed using the keywords 'ultrasound' and 'fracture healing'. AREAS OF AGREEMENT: The evidence in vitro and animal studies suggests that low-intensity pulsed ultrasound (LIPUS) produces significant osteoinductive effects, accelerating the healing process and improving the bone-bending strength. AREAS OF CONTROVERSY: The evidence in human trials is controversial in fresh, stress fractures and in limb lengthening. LIPUS is effective in delayed unions, in smokers and in diabetic population. GROWING POINTS: LIPUS is an alternative, less invasive form of treatment for complicated fractures, in patients with poor bone healing and may play a role in the management of large-scale bone defects producing substantial cost savings and decreasing associated disability. AREAS TIMELY FOR DEVELOPING RESEARCH: There is heterogeneity among in vitro, animal studies and their application to human studies. Further randomized controlled trials of high methodological quality are needed.