Fortuna, RafaelSawatsky, AndrewHerzog, WalterVaz, Marco AurélioHart, David A.2018-10-092018-10-092015-07-16Fortuna, R., Vaz, M. A., Sawatsky, A., Hart, D. A., & Herzog, W. (2015). A clinically relevant BTX-A injection protocol leads to persistent weakness, contractile material loss, and an altered mRNA expression phenotype in rabbit quadriceps muscles. Journal of Biomechanics, 48(10), 1700–1706. https://doi.org/10.1016/j.jbiomech.2015.05.0181873-2380http://hdl.handle.net/1880/108808https://doi.org/10.11575/PRISM/43932Botulinum toxin type-A (BTX-A) injections have become a common treatment modality for patients suffering from muscle spasticity. Despite its benefits, BTX-A treatments have been associated with adverse effects on target muscles. Currently, application of BTX-A is largely based on clinical experience, and research quantifying muscle structure following BTX-A treatment has not been performed systematically. The purpose of this study was to evaluate strength, muscle mass, and contractile material six months following a single or repeated (2 and 3) BTX-A injections into the quadriceps femoris of New Zealand white rabbits. Twenty three skeletally mature rabbits were divided into four groups: experimental group rabbits received 1, 2, or 3 injections at intervals of 3 months (1-BTX-A, 2-BTX-A, 3-BTX-A, respectively) while control group rabbits received volume-matched saline injections. Knee extensor strength, quadriceps muscle mass, and quadriceps contractile material of the experimental group rabbits were expressed as a percentage change relative to the control group rabbits. One-way ANOVA was used to determine group differences in outcome measures (α=0.05). Muscle strength and contractile material were significantly reduced in experimental compared to control group rabbits but did not differ between experimental groups. Muscle mass was the same in experimental BTX-A and control group rabbits. We concluded from these results that muscle strength and contractile material do not fully recover within six months of BTX-A treatment.enUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.botulinum toxincerebral palsyfibrosismuscleweaknessatrophyspasticityjournal articlehttp://dx.doi.org/10.1016/j.jbiomech.2015.05.018