Deviation When Using the Keyboard
What is Ulnar Deviation?
If one looks at the width of the shoulders of an adult and the
width of the spacing of the hands when placed on the home row of
a standard conventional keyboard, it is clear that the shoulders
are wider. To compensate for this, people are forced to
bend their wrists outward (in the direction of the fifth finger)
to type comfortably forming a 90° angle between the home row
keys and their hands, and this bend is called ulnar
Ideally the hands should be in alignment with the forearm, so
that a straight line can be drawn through the center of the
forearm, your wrist, and through the third (middle) finger, with
no 'bend' or lateral deviation at the wrist. The use of a thumb
can also be a cause of ulnar deviation
as it is
shorter than the other digits, and as such people often rotate
their hands outwards in order to make it easier for their thumb
to reach keys.
Why is Ulnar Deviation a Risk Factor?
When adopting this position, blood flow is constricted through
the wrist and this posture also requires sustained muscle
tension which further reduces blood flow to the muscles. The
median nerve runs through the carpal tunnel in the wrist, and
when adopting a position of ulnar deviation
span of this tunnel is compressed and pressure on this nerve can
lead to Carpal
How Much Ulnar Deviation is 'ok' and not a Risk Factor?
Every individual has different degrees of strength, dexterity,
endurance and fatigue rates in the muscles in their hands.
For most individuals, a small amount of deviation will not cause
any numbness, pain or discomfort. However, maintaining a
position which is non-neutral for extended periods of time may
become more problematic, and with many individuals spending most
of their working day on their keyboard, even a small amount of ulnar
can pose a risk factor.
What are the Symptoms of 'too much' Ulnar Deviation?
Symptoms to look for which indicate that the ulnar
in their workday has become a problem
include pain, numbness or tingling in the fingers and weakness
in the hand and fingers.
How can the Choice of Keyboard Help to Reduce Ulnar
which adjust so that they 'split' or
'splay' and Separated
can eliminate ulnar deviation
allowing the hand of the user to be perpendicular to the
orientation of the keyboard without the need to bend their
wrists outwards. Also, since repetitive muscle use can
cause inflammation and pressure on the median nerve
with keyboards which require higher force to press keys or more
movement), keyboards which minimize range of movement and have a
can help reduce pressure on the median nerve
What Other Strategies can be used to Reduce Ulnar Deviation?
Often individuals will adopt positions of ulnar deviation
while they are asleep without being conscious of this
movement. The wearing of a wrist brace or support while
sleeping can prevent accidental adoption of a position of ulnar
when one is supposed to be at rest.
To reduce awkward reach associated with multi-key combination
keystrokes, a potential solution is to use Footswitches
for the modifier keys (CTRL, ALT, SHIFT).