Botulinum toxin A(Anterios, Inc.)

Dear EditorI read with great interest the article by Aydin et al. [1]entitled ‘‘Effects of botulinum toxin A on fracture healingin rats: an experimental study’’ and I congratulate theauthors on their interesting experiment. The authorsaddress an important area of investigation.I totally agree that the beneficial effects of botulinumtoxin A in fracture healing can be explained by a paralyticimmobilization effect, which may contribute to nonrigidfixation [1]. As you mentioned, this is also true of man-dibular condylar fractures, because mastication musclesaggravate the initial displacement. Injection of botulinumtoxin A into the mastication muscle induces immobiliza-tion of the muscle, leading to better fracture healing.As we know, angiogenesis is crucial for appropriatefracture healing. Although there has been some controversyover the effects of botulinum toxin A on angiogenesis,recent studies showed botulinum toxin A had little effecton angiogenesis [2, 3].Haubner et al. could not identify any effect of botulinumtoxin A on endothelial cells in respect of synthesis ofthe tested cytokines and growth factors. They concludethat their in-vitro study does not add evidence to suggesta significant therapeutic effect of botulinum toxinA injections on cutaneous wound healing beyondchemoimmobilization.Regarding dosage of botulinum toxin A, have theauthors performed a pilot study with different dosages? Ibelieve the dose of 8 units of botulinum toxin A is insuf-ficient to enable fracture healing.Without doubt, further studies are warranted to betterclarify the effect of botulinum toxin A on the fracture-healing process.