Modeling of interaction between a three-fingered surgical grasper and human spleen

The aim of this study was to develop a more sophisticated model of the spleen tissue and investigate its interactions with a three-fingered laparoscopic grasper. The spleen tissue, modeled as a hyper viscoelastic material, was subjected to external loadings, imposed by rigid grasping jaws. The tissue deformation as well as the sliding occurrence between tissue and jaws was investigated using nonlinear finite element method. Results indicated that a grasping configuration which aimed a sufficiently large piece of spleen with small radius of curvature was more successful for effective grasping. The trends and magnitudes of the tool-tissue interaction forces obtained during effective and ineffective grasping were quite different. A force with progressively increasing trend toward a high magnitude was found to be indicative of effective and safe grasping. This finding might be used to predict the effectiveness of different grasping configurations and sliding thresholds during spleen and other soft organs surgery.