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The purpose of this study was to assess whether there is a universal pattern of movement of the finger joints while performing a cylinder grip. A sensor glove was used to record the finger joint motion of 48 participants. Our observations showed that when examining the fingers, flexion motion began either at the metacarpophalangeal (MP) or proximal interphalangeal (PIP) joints, with the distal interphalangeal (DIP) joints always last to move ( p = 0.0052). The sequence of the joints at the end of the gripping motion was different than at the beginning. Here, the only statistically significant observation was that the DIP joints fully flexed only once the MP joints had flexed fully. Apart from that, it was completely variable which joint reached its final position first or last. The analysis also revealed that synchronization of four identical joints (i.e. the four PIP joints) was significantly higher than synchronization of the 12 finger joints. Although synchronization was already high at the beginning of the flexion motion, it increased significantly by the time the joints completed their movement.

The purpose of this study was to analyse motion patterns of the finger joints dynamically while making a fist. 10 subjects were examined using the TUB-sensor glove, which was equipped with 14 joint angle sensors. The median time it takes the finger joints to complete flexion until reaching the state of a closed fist ranges between 0.5 to 1.0 s. A specific pattern can be seen for every finger. The PIP and DIP joints appear to be linked, with the DIP trailing the PIP joint. At the thumb the IP is trailing the MCP joint. The MCP joint shows more variation at the beginning of flexion: while in some cases it initiates movement in a finger, in other cases its flexion falls behind the PIP joint movements. The completion of flexion is achieved by the MCP joints, with the PIP and DIP joints reaching their end of motion first. The range of motion (ROM) at the MCP joints shows a finger-dependent median of 79-97°. At the PIP joints the median lies between 87° and 90°, at the DIP joints between 52° and 68°. At the thumb it is 21° for the MCP and 24° for the IP joint. The linkage between PIP and DIP joints can also be seen when analysing the ROM. The coupling ratio amounts to 0.77 at the index finger, 0.75 at the middle and ring finger and 0.57 at the small finger.

The present study analyses force distribution patterns during primary grips. 10 subjects were examined using the TUB-sensor glove, which was equipped with 10 pressure sensors. 5 proximal sensors at the MCP joints and 5 distal sensors at the DIP joints were attached palmarly. 9 different gripping motions were examined: the cylinder grip using 4 different objects, the pinch grip and 4 different kinds of precision grips. The force distribution patterns can be clearly divided into 2 groups. On the one hand there are the "power grips", in which the force is distributed over the proximal and distal sensors. On the other hand there are the "precision grips", which only show a force distribution at the distal sensors. Therefore Napier's concept of the existence of primarily 2 gripping patterns, which is based on visual analysis, can be verified objectively. For the "power grips" the force distribution is shifted further distally with increasing size of the objects. In conclusion, their distribution pattern shifts towards the pattern of the "precision grips". At the small finger the distal sensor is already dominant during the "power grips" of smaller objects. The thumb plays a subordinate role during the "power grip" of smaller objects, since these grips are similar to the "closing fist motion" and the objects can be held between the fingers and the palm of the hand. However, with increasing object sizes the thumb gains more importance, since its opposing movement is now required to accomplish the grip.