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Risk Factors and Sources of Injury > Trigger Finger          
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Image of Hand Showing Interphalangeal and

              Carpal JointsTrigger Finger

What is Trigger Finger?

Trigger Finger refers to inflammation caused by inflammation in the tendon sheaths in the interphalangeal joints in the fingers (i.e. the parts of the fingers which allow them to curl and flex).    This inflammation results in 'bumps' in these sheaths (or tenosynovium) which prevents them from acting as lubricants for the smooth application of tendons to open and close the fingers (and grasp objects).

Why is Trigger Finger a Risk Factor?

When an individual is required to press a mouse button or a key on a keyboard, this is an action which requires the articulation of the finger and use of tendons to press down on the button or key.  If the tendon sheaths are inflamed, the use of these tendons will cause them to thicken and the more frequent the movement, the more serious the risk factor will be.  Unfortunately, repetitive movements are inherent in modern computer usage of either the keyboard and the mouse, making trigger finger a very real risk factor for computer users.

How Much Trigger Finger Related Inflammation is 'ok' and not a Risk Factor?

For most individuals, once the movement or dexterity of the fingers is affected, that is an indication that the inflammation is severe enough to be a cause for concern and worth addressing.

What are the Symptoms of Trigger Finger?

The symptoms of Trigger Finger include pain which is usually more pronounced during movement (i.e. when one flexes the fingers).  In addition there may be a snap or click-like sensation as the tendons move around the inflamed areas where the bumps are located.  In severe cases, the symptoms can mimic arthritis often found in seniors in that the fingers will become partially or completely immobile in a partially curled, 'claw-like' position.  

How can the Choice of Mouse Help to Reduce Trigger Finger?

Mice which reduce or eliminate the amount of force or movement required to press the buttons will generally provide benefits to individuals suffering from Trigger Finger.  Touchpads will virtually eliminate movement from the act of mousing, and eliminate the force required from clicking as one can tap to click.  Other types of pointing devices such as Assistive Devices take away the possibility of clicking, by using a different paradigm for mousing and removing the cause (buttons pressed by the fingers) from the action of mousing.

How can the Choice of Keyboard Help to Reduce Trigger Finger?

Keyboards offer a wide variety of keyswitches and selecting one which is full travel, tactile and low force is ideal for individuals suffering from Trigger Finger.  Full-travel tactile keyswitches of 3.5 mm or longer typically provide 'stopping distance' after the point of actuation which prevents the problem of 'bottoming out' at the end of a keystroke, and the resulting strain on the joints in the fingers.  Tactile keyswitches provide feedback which allow the user to exert only as much force as is required to actuate the keyswitch, and not exert more muscle effort than is required.  Low force keyswitches also assist in reducing the amount of effort associated with typing. 
What Other Strategies can be used to Reduce Trigger Finger?

An excellent strategy which will assist in Load Balancing would be to use Footswitches to move repetitive tasks from the fingers to the feet.


Last edited December 16th, 2013

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