A new musculoskeletal AnyBody™ detailed hand model

Lucas Engelhardt,Maximilian Melzner,Linda Havelkova,Pavel Fiala,Patrik Christen,Sebastian Dendorfer,Ulrich Simon

doi:10.1080/10255842.2020.1851367

Abstract

Musculoskeletal research questions regarding the prevention or rehabilitation of the hand can be addressed using inverse dynamics simulations when experiments are not possible. To date, no complete human hand model implemented in a holistic human body model has been fully developed. The aim of this work was to develop, implement, and validate a fully detailed hand model using the AnyBody Modelling System (AMS) (AnyBody, Aalborg, Denmark). To achieve this, a consistent multiple cadaver dataset, including all extrinsic and intrinsic muscles, served as a basis. Various obstacle methods were implemented to obtain with the correct alignment of the muscle paths together with the full range of motion of the fingers. These included tori, cylinders, and spherical ellipsoids. The origin points of the lumbrical muscles within the tendon of the flexor digitorum profundus added a unique feature to the model. Furthermore, the possibility of an entire patient-specific scaling based on the hand length and width were implemented in the model. For model validation, experimental datasets from the literature were used, which included the comparison of numerically calculated moment arms of the wrist, thumb, and index finger muscles. In general, the results displayed good comparability of the model and experimental data. However, the extrinsic muscles showed higher accordance than the intrinsic ones. Nevertheless, the results showed, that the proposed developed inverse dynamics hand model offers opportunities in a broad field of applications, where the muscles and joint forces of the forearm play a crucial role.

Highlights

The human hand is a highly developed and sophisticated grasping organ containing 27 bones with 36 articulations and 39 active muscles (Hirt et al 2017)
The mean moment arms along the range of motion (ROM) for all muscles and joints are summarized in Table 3 for a better comparability
The current study presented the development of a musculoskeletal hand model using the AnyBody Modelling System (AMS) framework, that is capable of kinematics as well as inverse dynamics predictions, based on a consistent anatomical dataset

Summary

Introduction

The human hand is a highly developed and sophisticated grasping organ containing 27 bones with 36 articulations and 39 active muscles (Hirt et al 2017). This contributes to a wide range of motion (ROM) (31 degrees of freedom – DOF) while possessing sensitive haptic properties. To address various malfunctions because of to disorders of the musculoskeletal system, the inverse dynamics modelling approach is an increasingly applied method With this method, the complex dynamic force distribution in all hand structures can be analyzed in numerous kinds of tasks for physiological as well as for pathological simulations. Mechanical loads within the hand do affect muscle activities and forces in the surrounding joints and lead to balancing forces in the entire body

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Conclusion