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Risk Factors and Sources of Injury > Trigger Finger or Stenosing Tenosynovitus       
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Image of Hand Showing Interphalangeal and
              Carpal JointsTrigger Finger or Stenosing Tenosynovitus

What is Trigger Finger or Stenosing Tenosynovitus?

Trigger Finger is condition 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 prevent 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?

Pressing a mouse button or a key on a keyboard is an action which requires the articulation of the finger and use of tendons. If the tendon sheaths are inflamed, using 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 using computers and tablets with both the keyboard and the mouse, which means trigger finger is a very real risk factor for computer and tablet users.

How Much Trigger Finger Related Inflammation is 'OK' and Not a Risk Factor?

Once a change in the movement, flexibility or dexterity of the fingers is noticeable, 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 the fingers are flexed), often initially at the base of the base of the fingers or thumb. 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 or Mitigate Trigger Finger?

Mice which reduce or eliminate the amount of force or movement required to press the buttons will generally provide benefits to those with Trigger Finger. Touchpads will virtually eliminate movement from the act of mousing, and practically eliminate the force required from clicking as only a light touch is required to generate clicks. 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?

Selecting a keyboard which has full travel, tactile and low force keyswitches is optimal 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. For more information on different types of keyswitches, review the Ergonomic Concept article Tactility on Keyboards - How to Evaluate "Soft" or "Light" Touch.
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. By moving the clicking action (left, middle and right click) from the fingers to the feet the fingers can be rested.


Last edited July 17th, 2018

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