Development of the two-dimensional biomechanical hand model for a guitar player

In this study, a two-dimensional biomechanical hand model predicting tendon loads in the fingers during guitar playing was developed. To estimate tendon forces, joint reaction forces, and force reactions against a given fingertip pressure (external force), a static hand model was developed based on the hand anatomy and static equilibrium conditions. Model inputs included 1) adopted existing anthropometry data, 2) fingertip pressures measured while playing the guitar, and 3) measured joint angles on the fingers. The hand model evaluated four chords: C, E, G7, and Am. G7 required the highest internal tendon force (41.0N), and Am (32.8N), E (30.3N), and C (26.6N) followed it. The index finger was mainly recruited for all four chords while the ring finger showed the worst efficiency, using the external force to internal tendon force ratio. Finally, the quick-and-dirty test showed the simulation result had strong correlation (R²= 65.1 %) with EMG result (C: 22.9%MVC, E: 22.1%, G7: 34.8%, and Am: 34.3%) on the FDP muscle, a main flexor of the finger.