| ULNAR
DEVIATION ERGONOMICS |
|
Ulnar deviation refers to hands that
are forced to "splay out", into unnatural postures or un-ergonomic
positions as illustrated in figures 1 and 2. Severe Ulnar deviation
increases the friction between the tendons and the surrounding components
of the carpal tunnel--sometimes contributing to Carpal Tunnel Syndrome (CTS). This ongoing
posture may also cause the ulnar nerve to be stretched in the elbow possibly
contributing to a condition known at cubital tunnel syndrome.
Persons
who are overweight (figure 1) experience even greater angles of ulnar
deviation as they must attempt to compensate for their greater body mass. Our
experience shows that persons who have discomfort in conjunction with
intensive data entry tasks, in general, find relief with our ergonomic
keyboard products. To be fair, there are many other risk factors
associated with Carpal Tunnel Syndrome; and repetitive stress type injuries
are difficult to trace back to one single cause; however, eliminating
as many risk factors as possible, including awkward postures, is good
ergonomics and usually leads to a reduction in symptoms. |
| WRIST PRONATION
ERGONOMICS |
|
The figures to the left contrast awkward versus natural
or more ergonomic posture. Wrist pronation is associated with discomfort
for workers who must maintain fixed posture while performing intensive
data entry tasks.
Sustained
pronation strains the forearm muscles and creates a situation where blood
flow is usually reduced. Additionally the median nerve may come under
pressure over long periods of time. Good ergonomics always dictates
that no muscle or muscle group be statically contracted over long periods
of time.
The
figures of three hand positions to the lower left depict various
degrees of pronation as they relate to keyboard products we sell. "POOR"
means, that in terms of reducing pronation, palms keying in the standard
flat posture are not as desirable as other less pronated postures. |
