Wrist Problems

Wrist Problems

Some Anatomy

The wrist is a complex joint and can perform many different movements. These include:

Flexion: bending the palm surface towards the wrist.
Extension: raising the back of the hand.
Supination: turning the wrist into a palm up position.
Pronation: turning the wrist into a palm down position.
Ulnar deviation (flexion): bending the wrist to the little finger, or ulnar bone, side. With the right hand this is the movement you use when hitting the Enter key.
Radial deviation (flexion): bending the wrist to the thumb, or radial bone, side.

Go to the Wrist Movements Page for more details on these wrist movements.

How do Computers Contribute to Wrist Pain and Repetitive Strain Disorders?

Keyboarding or typing requires that the wrists be held in the following positions:

Pronation: In order to type the wrists are held at the extreme range of pronation.
Extension: In order for the fingers to reach the keys the wrists must be held in extension.
Ulnar/Radial Deciation (Flexion): In order to press the Enter or Backspace key the operator must ulnar deviate the right wrist. To press the Escape or Tab key they must ulnar deviate the left wrist.

These postures are maintained for long periods of time while the fingers make rapid movements around the keyboard.

Carpal Tunnel syndrome

The carpal tunnel is formed by a ligament (called the transverse carpal ligament) that attaches to the carpal bones of the wrist. This tunnel is important because many nerves, blood vessels, and tendons pass through it on the way to the hand. Irritation, due to excessive, repetitive, or awkward movements, can result in swelling of the tendons within the carpal tunnel. This swelling puts pressure on the nerves, as they squeeze through the tunnel, causing a number of problems. This is known as the Carpal Tunnel Syndrome.

Problems caused within this carpal tunnel are often felt in the hand and fingers, rather than the wrist itself. Symptoms of problems within the carpal tunnel, known as Carpal Tunnel Syndrome can include:

Tingling in the fingers.
Clumsiness, such as dropping things.
Weakness, such as difficulty picking up and holding things.
Numbness in the fingers or palm.
Pain in the fingers, hand or wrist.

While Carpal Tunnel Syndrome gets the most press it is by no means the only repetitive strain syndrome associated with the wrist. Other syndromes include:

Intersection Syndrome

Intersection Syndrome is a painful condition that affects the thumb side of the forearm.
This is where two muscles cross over - or intersect - two underlying wrist tendons.
The upper muscle group tendons connect with the thumb to pull it away from the hand - and the lower set of tendons bends back, or extends, the wrist.
Cause: Irritation of the two tendons (tenosynovitis).
Symptoms: Swelling and redness may occur over the area where the two tendons rub against one another - at the intersection point. Pain can spread down to the thumb or back up along the thumb side of the forearm. Movement may be restricted. Intersection Syndrome can be confused with DeQuervain’s Tenosynovitis.

DeQuervain’s Tenosynovitis

Pain on the side of the wrist and forearm just above the thumb
Cause: The two tendons that pull the thumb out and back from the hand are causing this discomfort. These two tendons run in a tunnel on the side of the wrist just above the thumb. When these tendons become inflammed they have difficulty moving through the tunnel, which causes pain.
Symptoms: Pain at the base of the thumb that may also radiate up towards the elbow.

Guyon’s Canal Syndrome

As it crosses the wrist, the ulnar nerve and artery run through the tunnel known as Guyon's canal. This tunnel is formed by two bones, the pisiform and hamate, and the ligament that connects them.
Cause: Nerve compression affecting the ulnar nerve as it passes through Guyon’s canal. Similar to carpal tunnel syndrome, but involves a completely different nerve. Sometimes both conditions can be causing a problem in the same hand. The hamate bone has a small spur that sticks out for attachment of ligaments in the wrist. This spur is called the hook of the hamate bone and can be broken off, which could cause Guyon’s Canal Syndrome.
Symptoms: A feeling of pins and needles in the ring and little finger, starting in the early morning before waking. This progresses to a burning pain of the wrist and hand, followed by decreased sensation and eventually clumsiness in the hand.

Important Note: Sleeping Position

How you sleep can be a contributing factor to wrist discomfort. Some people sleep with their wrist flexed (bent) which contributes to compression of the carpal tunnel.

The subject in this image is sleeping on their left hand, with the wrist flexed. The contents of the carpal tunnel are subjected to prolonged compression.

Possible Solutions

The handshake position is considered to be the position of least stress on the wrist. Consequently, manufacturers have developed mouse and keyboard alternatives that position the wrist in a handshake position, such as a vertical mouse, or somewhere between full pronation and the handshake position.


Handshake position	Handshake position while using a vertical mouse

Before proceding to change your keyboard and mouse, consider your posture. Making improvements in posture can help you deal with problems in other areas, such as your wrist.

How are you sitting; what is the height of your desk?
Do you have to perch on the edge of your chair, or are you slouching?
Are you twisting your neck to read a document?
Are you twising your neck to hold the telephone while you type?

These and other issues should be considered when addressing wrist problems.

Mouse:
- Change the hand you are using to operate the mouse, or alternate between hands.
- Vertical mice are operated with your wrist in the "handshake" position, not in full pronation. This can reduce joint and muscle strain at the elbow. An example of a vertical mouse:
  
  3M Ergonomic Mouse
  
  3M Ergonomic Mouse + Bakker Elkhuizen S-Board 840 Compact Multimedia Keyboard
- Contoured mice can reduce elbow stress as they do not require you to hold your wrist in full pronation. They are operated the same as a standard mouse. An example of a contoured mouse:
  
  Goldtouch Ergonomic Mouse
  
  KeyOvation Goldtouch Ergonomic Mouse + A4 Tech Slightly Compact Multimedia 'A' Style Slanted Keycap Keyboard
- Roller-style mice are stationary mice that do not require a static grip (static grip means that the mouse must be pinched between thumb and fourth digit while it is being operated).
  
  Contour Design RollerMouse Free 2
  
  Contour Design RollerMouse Free 2 + Standard keyboard
- Touchpads are another form of stationary mice.
  
  Cirque Easy Cat Touchpad
  
  Cirque Smart Cat Pro Touchpad Mouse + KeyOvation Goldtouch Go! Travel keyboard
- Trackballs are also stationary mice.
  
  Kensington Orbit Mouse
  
  Kensington Orbit Mouse + Kinesis Freestyle keyboard (with V3 accessory)
- A mouse operated by a different part of your body, such as a head-operated mouse, may work, although head-operated mice are not for everybody.
  
  NaturalPoint SmartNav 4

Keyboard
- Adjustable keyboards help to reduce pronation and wrist extension by adjustable vertical tenting and keyboard splay.
  
  Kinesis Freestyle Keyboard with VIP Accessory
  
  Kinesis Freestyle keyboard (with V3 accessory) + Evoluent VerticalMouse 4 (small)
  
  KeyOvation Goldtouch Adjustable Keyboard
  
  KeyOvation Goldtouch Adjustable keyboard + KeyOvation Goldtouch Ergonomic Mouse
- Fixed-split keyboards help to reduce pronation and wrist extension, but the tenting and splay are fixed.
  
  Microsoft Natural Ergo Keyboard 4000
  
  Microsoft Natural Ergo Keyboard 4000 + Evoluent VerticalMouse 4 (small)
  
  Smartfish Technologies Compact Ergomotion Keyboard
  
  Smartfish Technologies Compact Ergomotion Keyboard + Cirque Smart Cat Touchpad
- Contoured keyboards have keys in one of two depressions, helping to eliminate ulnar deviation and wrist extension.
  
  Kinesis Advantage Contour Keyboard
  
  Kinesis Advantage Contour Keyboard + Kensington Slimblade Trackball
- 'A' Style Slanted Keycap Keyboards have keys that are slanted, helping to reduce ulnar deviation.
  
  A4Tech 'A' Style Slanted Keycap Keyboard
  
  A4Tech Left Handed 'A' Style Keyboard + HumanScale SwitchMouse
  
  A4Tech 'A' Style Slanted Keycap Keyboard + MouseTrapper Advance
- For right-handed mouse users a keyboard with the numeric keypad on the left reduces the amount of reaching for the mouse.
  
  Evoluent Mouse Friendly Compact Keyboard
  
  Evoluent Mouse Friendly Compact Keyboard + Designer Appliances Air02Bic
- For those who do not require a numeric keypad, another solution is to use a compact keyboard. Because these keyboards do not have a numeric keypad, the mouse can be positioned closer to the midline.
  
  Evoluent Essentials Keyboard
  
  Evoluent Essentials Keyboard + Posturite Penguin Ambidextrous Vertical Mouse