Research has shown that tension in hands may result in tension in the deep neck muscles which again may result in restricted blood flow in arms and hands, a serious cause of Repetitive Strain Injury (RSI).
Expensive treatment, sick leave and social security expenditures due to RSI related complaints as a result of working with all available types of computer mouse initiated the design of the alternative called The Horse.
The Horse was developed by prof. Chris J. Snijders and Paul C. Helder from within the Department of Biomedical Physics and Technology of Erasmus MC, the Erasmus university hospital of Rotterdam in cooperation with Maastricht Instruments, a sub section of the medical faculty of the University of Maastricht.
It has been shown that the use of the currently available computer mouse is one of the causes of RSI, a serious type of complaint which causes discomfort and pain with the user. RSI is a significant social burden i.e. cost with developed economies. According to Statistics Netherlands the Dutch centre for statistics, in 2000 23% of the working population suffered from RSI related complaints. Moreover, the Dutch Minister of Social Affairs informed Parliament by means of an official letter that costs involved are estimated at 2 billion Euro per annum for The Netherlands only.
The primary design misconception of the conventional mouse has been proven to be a major cause of RSI.
This due to the necessity of continuous stretching of the hand and hovering of the fingers above the buttons to prevent inadvertent switching. As a result of this exertion excessive tension in the deep neck muscles may occur.
The team consisting of prof. C.J. Snijders and Mr. P.C. Helder of Erasmus MC, University Medical Centre Rotterdam, the Netherlands, in cooperation with the design team of Maastricht Instruments, a sub section of the medical faculty of the the University of Maastricht, have studied the concept of the conventional computer mouse of which billions are used on a global scale. Over a period of five years this team has come up with a major and significant design change. The aim of the design change is to prevent unnecessary tensions which occur as a result of the use of the current conventional mouse. During the studies it was noted that no significant difference with respect to the load on the tendons occurs when one compares the various types of computer mouse. This in view of the misconception which is part and parcel of these products.
The adapted computer mouse developed by the team, however, allows for the hand to be relaxed between and during click actions. Between click actions the finger extensor muscle activity is low or absent and during clicking activity, extensor and flexor activity is equal or lower than when using the conventional mouse or even other ergonomic mice. The latter have recently been evaluated by the team, this on request of a major Dutch insurance company. Only The Horse was able to realize maximum muscle relaxation.
Although the above sounds plain and simple, until now the industry has not been able to provide a suitable solution for the complaints as described as RSI.
Background of development
Tension in the lower arm reduces significantly by proper support of the desired places of the hand. To assess the effect of the adapted computer mouse under operational circumstances in the office environment, a field study was executed over a period of 6 months while a final evaluation based on multiple choice questions took place after 1 year. This next to fundamental research with Erasmus MC.
The aim of the studies was to establish if daily use of an adapted mouse would result in less complaints with clients i.e. patients.
Adapted design called “The Horse”
To demonstrate unnecessary tensions the conventional mouse was compared with the adapted mouse which acts like a saddle for the hand and is therefore called The Horse. This concept allows for the three middle fingers to adopt a flexed position to relax the tendons. A major part of these fingers rests in a more or less vertical position, thumb and little finger are supported at a lower level at the sides of the hand.
Only a minor contraction of the muscles of the fingers is required to operate switches and scroll wheel. Arms and hands remain in a relaxed position. This contrary to a conventional computer mouse which requires continuous lifting of the fingers and thus unnecessary muscle action.