Mechanical effects of Botox treatment on isolated muscle: Assessment of theoretical paralyzation patterns via finite element modeling

The aim of this paper is to investigate the mechanical effects of Botox application to muscle pathologies such as spasticity on isolated muscle model via finite element analysis. In order to determine the effect of paralyzation location three cases are chosen: Proximal half passive, middle half passive and distal half passive. Whole muscle active and whole muscle passive cases are also studied for comparison. Strain and stress distributions and length-force relationships of these cases are compared. Length-force relationship showed that at low lengths, compared to active whole muscle distal half paralyzed cased showed force reduction up to 15% than other two cases whereas at high lengths no distinct differences were seen. This result may be significant for spastic muscles since they are active al low lengths. Distal half passive case also showed higher strain distributions and lower stress values. We can state that the effects of Botox at low length are the results of (1) passive parts of the muscle due to Botox application show less shortening (2) active parts of partially active cases show more shortening compared to completely active muscle.