The Wrist & Repetitive Strain Injuries

The wrist joins the hand to the forearm. It is able to move forward and back, side-to-side, and in circular movements. This variety of motion allows the hand to reach objects and function in a wide range of motion. In addition, a strong and stable wrist is important during grip activities.The wrist is a complex joint where the two long bones of the forearm meet the eight small carpal bones of the wrist. These carpal bones are essentially arranged in two rows of 4 bones. The eight small wrist bones then meet the five long finger bones in the palm of the hand. Most of the muscles that move the wrist, fingers and thumb are located in the forearm. The tendons (the cords that connect muscle to bone) that bend and straighten the wrist and the fingers must cross through the wrist joint on their way from the elbow towards the hand.Many of the repetitive strain injuries associated with computer work occur at the wrist. In fact, according to the National Occupation Research Agenda for Musculoskeletal Disorders, the most frequently reported upper-extremity musculoskeletal disorders affect the hand and wrist region.

Carpal Tunnel Syndrome is the most commonly diagnosed nerve injury in the arm. The nerves are the power cords for the arms, providing strength to the muscles and sensation to areas of skin. Carpal tunnel syndrome is the compression of the median nerve as the wrist as it passes from the neck to the fingers. Carpal Tunnel Syndrome can cause pain at the base of the hand and in the bulky muscles in the palm right below where the thumb meets the palm. Also, people often say they feel as if they have a tight band around their wrists. Numbness in the thumb, index and middle fingers is common. The pain may feel as if it is traveling up the arm and into the shoulder and neck

Pain where the thumb meets the wrist may be caused by a tendinitis of the muscles that pull the thumb back (as if you were hitchhiking). People who type tensely are prone to developing this tendinitis as they hold their thumbs over the keyboard with tension. Pain at the base of the thumb can also be caused by arthritis in the joint where the long palm bone meets one of the tiny wrist bones of the thumb.

Tendinitis of the wrist and finger flexors (the bending/closing muscles) and extensors (the straightning muscles) and benign ganglion cysts also occur fairly frequently at the wrist.

RSI Prevention

  • Maintain a neutral wrist position.
    • The wrist should be flat in relationship to the forearm; it should not be bent forward or back.
    • For each 15 degrees that the wrist is out of alignment, the pressure on the median nerve increases.
    • The middle finger should be in alignment with the forearm, not angled toward the thumb or the small finger.
    • Wrist supports can provide proper positioning during the night.
    • Do not fight against a wrist support. It is better to remove the brace and perform activities carefully than to wear a brace that prevents necessary movement.
    • Softer, neoprene braces without the rigidity provide support but also allow for some movement and may be a better choice is the task requires wrist movement.
    • Using a wrist brace can cause the body to compensate for loss of motion by moving the elbows differently. Monitor for a shift in pain symptoms in other body areas.
  • Ergonomics
    • Using a split keyboard can align the wrists into a more neutral position.
    • Try a negative tilt of the keyboard where the row of keys closest to you is slightly higher than the row farthest away.
    • The keyboard height should allow the wrists to be neutral while the shoulders are relaxed and the elbows are open slightly greater than 90 degrees.
    • Use the upper arm to manipulate the mouse. Do not activate the mouse by using side-to-side movements of the wrist.
    • The mouse should be located by the keyboard. Do not reach forward to activate the mouse positioned on a different level than the keyboard or positioned out of easy reach.
    • Keep the fingers and thumb relaxed on the keyboard. Use only the minimum necessary force to activate the keys. Do not float the fingers stiffly over the keyboard.
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Smartphone Ergonomics

Since their inception, the push has been to make computers smaller, smarter and more portable. Functions that once took banks of computer hardware are now performed on electronic gadgets that fit in the palm of our hand.1973 heralded the birth of hand held computers with the first programmable calculator. Within 2 years, a primitive and portable computer organizer was developed with a calculator, alarm clock and scheduling feature. The first “palmtop” with DOS was developed in the mid 1980s. John Sculley of Apple Computer officially coined the term PDA (personal digital assistant) in 1992 when he introduced the Apple Newton. The mass market appeal of these small devices was realized with the introduction of the Palm Pilot in 1996. About the same time, the first “smartphone” (a combination of cellular phone and PDA) was developed. The popular BlackBerry was introduced in 1999. Currently, 2.14 billion people worldwide subscribe to mobile phone service (en.wikipedia.org/wiki/mobile_phone).

In a piece of electronic equipment the size of the palm of our hand, we now have the ability to make phone calls, take pictures and videos, access calendars and address books, check email, surf the web, perform office tasks and develop business documents with mobile versions of word processors and spreadsheets, locate areas of interest and avoid traffic jams with GPS, play games, and entertain ourselves with music and video downloads.

The following ergonomic and safety tips will keep you healthy and pain-free when using your handheld device.

“BlackBerry Thumb”

Text-messaging and miniature or keyboard functions can take their toll on the thumbs. “BlackBerry Thumb” is a commonly used term to describe a painful and debilitating tendonitis of the thumb tendons caused by repetitive use.

    • Limit your typing time to no more than 10-15 minute sessions.
  • Stretch often.
    • Turn your palms up.
    • Open the thumbs wide as if you are hitch-hiking.
    • Using your other hand, gently push the thumb back until you feel a nice stretch.
  • Use a portable keyboard attachment when possible.
  • If using a stylus, use one with a larger grip handle.
  • Support your arms on pillows while typing.
  • Hold a pencil and use the eraser to push the keys to give your thumbs a break.
  • If your thumbs feel sore, use cold packs after typing. Take a break from using your thumb keyboard. Seek medical attention if the pain does not go away.

A Quick Comparison of Carpal, Cubital and Radial Tunnel Nerve Compressions

Three peripheral nerves provide power and sensation to the hand and arm.  The following is a quick comparison of the most common sources of pain caused by compression syndromes of these nerves.

nerve paths

Carpal Tunnel Syndrome

  • Nerve Affected:  Median
  • Location of Compression:   Wrist
  • Numbness and/or Tingling:  Usually in the Thumb, Index, Middle & Half of Ring Fingers
  • Pain:
    • Usually in the Thumb, Index & Middle Fingers
    • A band of pain around the wrist
    • Pain in the muscles at the base of the thumb
    • Pain radiates up the forearm
  • Likely Cause (activity related):
    • Frequent gripping/squeezing/holding of tools
    • Gripping or pinching tools or objects for a period of time
    • Finger movement with the wrist held at an awkward angle
  • Prevention:
    • Avoid sustained or repetitive grip and pinch
    • Maintain the wrist in a neutral (straight) position with activity
    • Avoid leaning on or putting pressure against the front of the wrist of the base of the hand
  • Splinting:   A wrist brace that  holds the wrist in the neutral (straight) position at night

Cubital Tunnel Syndrome

  • Nerve Affected:  Ulnar
  • Location of Compression:   Elbow
  • Numbness and/or Tingling:  Usually in the Ring & Small Fingers
  • Pain:
    • Usually in the Ring & Small Fingers
    • Pain in the hand muscles on the small finger side of the hand
    • Pain radiates up the forearm and into the elbow along the small finger side
  • Likely Cause:
    • Leaning on the elbow or pressure against the forearm along the small finger border
    • Frequently bending and straightening the elbow, such as when pulling a lever
    • Holding the elbow bent for long periods of time, such as when sleeping or holding a phone to the ear
    • Forceful elbow extension (straightening) activities, such as rowing, gym activity, push-ups
  • Prevention:
    • Avoid leaning on the elbow or putting pressure on the forearm muscles
    • Avoid holding the elbow bent more than 90 degrees for any length of time
    • Avoid repetitively bending and straightening the elbow
    • Avoid repetitive or forceful elbow extension activities
  • Splinting:   A soft pad or elbow support that holds the elbow in a mostly straight position at night

Radial Tunnel Syndrome

  • Nerve Affected:  Radial
  • Location of Compression:   Muscles on the back of the forearm near the elbow
  • Numbness and/or Tingling:  Uncommon
  • Pain:
    • Usually in the elbow and forearm muscles
    • Pain may radiate down the arm into the wrist and the back of the hand
    • Pain may radiate up the arm towards the shoulder
  • Likely Cause:
    • Computer mouse activity, swiveling the wrist and forceful mouse “clicking”
    • Holding the fingers tensely extended over the computer keyboard
    • Forcefully bending the wrist forward and back
    • Repetitive twisting movements, such as when using a screwdriver
    • Carrying or lifting heavy objects, particularly with the forearm pronated (palm rotated down)
  • Prevention:
    • Maintain the wrist in a neutral position while using the computer mouse
    • Don’t hit the keys or click the mouse forcefully and keep the fingers relaxed over the keys and mouse
    • Avoid repetitive and forceful wrist movements or twisting movements
    • Avoid heavy lifting, especially with the palm facing down, such as carrying a suitcase or heavy briefcase
  • Splinting:   A wrist splint that holds the wrist neutral may be helpful when performing stressful activities

Radial Tunnel Syndrome

As a certified hand therapist, I often treat people suffering from the symptoms of carpal tunnel syndrome (CTS). A less commonly known injury, but one that we are seeing more frequently in the clinic, is Radial Tunnel Syndrome (RTS). If you are experiencing an aching or burning sensation in the back of the forearm or over the back of the wrist or hand, you may have symptoms of RTS rather than CTS.

Anatomy

The radial nerve is one of three main peripheral nerves that provide sensation and power to the arm and hand (the other two are the median nerve and the ulnar nerve). The radial nerve leaves the spinal cord at the neck and travels down the arm and into the back side of the forearm. In the forearm it passes through the supinator muscle, the muscle that turns the palm up (such as when using a screwdriver).

The radial nerve is responsible for providing sensation to the back side of the forearm and the back of the hand. It is also responsible for providing power to the muscles that pull the wrist back and straighten the fingers at the large knuckle joint.

Causes of Radial Tunnel Syndrome

As the nerve travels down the arm, repetitive or forceful movements can cause friction at several sites along the nerve pathway as it passes through muscles and ligament bridges. Repetitive or forceful movements can also cause swelling in the tissues that surround the nerve. This compresses the nerve, pinching it and causing sensations of aching, burning, numbness and tingling.

Symptoms of Radial Tunnel Syndrome

Symptoms of RTS include an aching or burning pain over the back side of the forearm and/or into the back of the wrist. There may be tenderness over the back of the elbow and forearm close to the elbow. Pain may become worse with activities that require a lot of wrist movement (such as manipulating the mouse), finger movement (such as clicking the mouse), and palm up movements (such as using a screwdriver). With pressure against the tender area close to the elbow, you may experience a tingling or radiating pain. The arm may feel tired and heavy.  An aching pain may radiate down the arm into the hand or up into the shoulder.  The back of the hand, the index finger knuckle, and the muscular space between the index finger and the thumb may feel swollen.

Things to Help Prevent and Control Pain from RTS

If you are experiencing symptoms of RTS, here are a few things you might try to help you reverse the symptoms.

  • Rest as best as you can from the activities that are causing the problem.
  • A vertical mouse that places the forearm in a neutral position (the “handshake” position) may be helpful.
  • Do not swivel the mouse with wrist movement.
    • Keep the wrist neutral (straight and level, not bent forward or back or angled to either side) when typing and using the mouse.
    • Control the mouse by using the larger shoulder and elbow muscles to move it.
  • Keep the fingers relaxed on the keyboard and mouse.
    • Don’t forcefully straighten or lift the fingers while typing or clicking.
    • Use the least amount of pressure necessary to activate the keyboard and control the mouse.
  • Use a wrist brace to limit wrist movement and to help keep the muscles of the forearm relaxed.
  • Take frequent micro-breaks.
  • Use cold packs and hot packs.
    • A cold pack placed over the forearm muscles several times a day can help control swelling from overuse.
    • Hot packs can help improve flexibility.
    • Both can temporarily relieve pain.
  • Gently stretch the forearm muscles.
  • Avoid the following:
    • Heavy lift, grip or activities that twist the forearm.
    • Using a screwdriver   (Use electric tools whenever possible.)
    • Picking up luggage.
    • Weight-lifting.
  • Be careful of using tennis elbow straps that can place additional pressure on the radial nerve.
  • Seek medical attention if symptoms do not rapidly improve.

RTS is often confused with tennis elbow. Tennis elbow is an inflammation of the tendons as they attach on to the lateral epicondyle (the bony bump on the outside edge of the elbow). The tenderness associated with RTS is often a few inches farther down the forearm, more on the muscle than on the bone. A tendinitis pain is often sharper with activity and, unless it is a severe case, lessens with rest. Nerve pain, such as with RTS, can be more of an aching, burning pain that may become more severe after activity or at night. When seeking medical attention, be specific with your description of symptoms so that you can help your doctor diagnose the problem accurately.