Alteration of bone metabolism and microarchitecture by intramuscular injections of botulinum toxin: A systematic review

Abstract

Intramuscular injections of botulinum toxin are frequently used as part of the treatment of spastic paresis or other neurological disorders. Their effects on bone modeling, remodeling and healing have received little clinical attention, in a context where clinician injectors are often confronted with an apparently excessive incidence of bone fractures in paretic patients repeatedly injected with botulinum toxin. We searched for English articles published between 1990 and 2017 in the Medline database. We used the MeSH term “bone” in association with “botulinum”. Studies were selected for further review after abstract reading if they provided data pertaining to the question of interest or when abstract information was insufficient to exclude them. Full-text articles of selected studies were then reviewed and included in the analysis if they provided relevant information for the review. Forty-four original articles were included in the analysis. Most were basic research studies using animal models. Injections of botulinum toxin increase bone resorption, inducing osteopenia, with a permanent alteration of bone structure. Evidence will be presented that supports the involvement, at least in part, of a non-mechanically induced mechanism for osteopenia. Bone development or bone healing are also altered by intramuscular injections of botulinum toxin. Intramuscular injections of botulinum toxin alter bone metabolism and structure. This may be highly relevant for clinicians using repeated botulinum toxin injections. Further research is necessary to evaluate and quantify the increased risk of fracture induced by multiple injections of botulinum toxin.