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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Trigger Finger – Repetitive Strain Finger Pain

Mouse and keyboard use can cause finger pain. One common cause of finger pain is called trigger finger. Trigger finger is a swelling of the tendon or tendon sheath in the palm of the hand of the tendons that bend the fingers. This swelling prevents the tendon from gliding smoothly through the sheath and the “pulley” (ligament) which holds the tendon to the bone. Trigger finger occurs most frequently in the middle finger and the ring finger, but it can occur in any finger or the thumb.SYMPTOMS

  • A locking, snapping, popping or catching sensation in the finger while making a fist.
  • This “triggering” of the finger can be quite painful at times.
  • The finger may “lock” into a bent position.
  • There will most likely be pain or tenderness in the palm of the hand over the site of the pulley which holds the tendon close to the bone.
  • There may be joint stiffness and pain in the affected finger.

OCCUPATIONAL CAUSES

  • Repetitively gripping or bending and straightening the fingers (e.g. – mouse clicking)
  • Sustained gripping (e.g. – squeezing the mouse forcefully or holding a pen in a “death grip”)
  • Using tools that have handles with sharp or hard edges

ERGONOMICS

  • Avoid repetitive grasping and releasing of objects. Modify the activity if you are unable to avoid it. Look for ergonomic mice or larger barreled pens. Change your typing style so that your fingers are relaxed on the keyboard and mouse.
  • Avoid sustained grasp.
  • Keep the fingers relaxed over the keyboard. Do not plant your wrist down on the wrist rest while typing as this causes excessive and stressful finger movements to reach all the keys. Rather, the wrist should glide over the wrist rest, allowing the fingers to be positioned over the keys in a relaxed manner.
  • Purchase tools with padded, comfortable handles.
  • Handles should have some texture for easier holding. Slippery surfaces require more forceful grasping.
  • Minimize repetition. Periodically rest the hands during repetitive or stressful activity. Stretch frequently during repetitive activity.
  • Slow down!
  • Use the lightest grip possible (on tools, pens, the mouse, the steering wheel, etc.) that still allows you to maintain good control.
  • Use the least amount of force necessary during the activity.
  • Use the appropriate tool for the job.
  • Use ergonomically designed tools if available (modified or padded handles, larger grips with good traction, handles with modified designs).
  • Make sure that tools are in good condition and that cutting edges are sharp (reduces the force needed to use the tool).
  • Alternate work activities so the hands are not performing any one task repetitively for any length of time.

And It Hurts…Here…Because? Ergonomic Recommendations

The location of where you are experiencing pain while working at a desk or on a computer can often give clues as to what needs to be adjusted during an ergonomic intervention.  Here is a quick guide of worksite and work-method recommendations that may help when you are feeling pain in a specific area.

Finger Pain – May indicate arthritic joints, a trigger finger, or strain from overuse.  Avoid squeezing the mouse too hard or pounding the keyboard.  Keep a light touch when typing.  Hold your pen lightly when writing.

Thumb Pain– May indicate a trigger thumb or DeQuervain’s Tenosynovitis.  Often occurs from either squeezing the mouse too hard or from tensing the thumb (as if hitch-hiking) over the keyboard keys.  Keep the thumbs relaxed using only the minimal amount of force needed to control the mouse.  When typing, keep the thumbs relaxed and just hovering over the keyboard.  Don’t pound the space bar.  Also, when writing, use a larger-barreled pen and don’t squeeze the pen too tightly.  Keep the thumb tip relaxed and only slightly bent – it is common for people write with their thumb tips bent at an extreme angle.

Wrist Pain or Pain at the Base of the Hand/Thumb– May indicate a tendinitis where the wrist muscles attach (flexor or extensor tendinitis), DeQuervain’s Tenosynovitis, or Carpal Tunnel Syndrome.  These are often caused by swiveling the mouse in or by poor wrist positioning.  Keep the wrist neutral (flat – not bent forward or back or angled side-to-side; the middle finger should be in a parallel line with the forearm).  Initiate small movements to control the mouse from the elbow and shoulder.   Don’t squeeze the mouse too tightly – use only the minimal amount of force necessary to control it.  Check your keyboard size and fit.  Pain over the small finger side of the wrist is often caused by the outward angulation of the wrist required to rest your hand on the home keys.  Using an ergonomic split keyboard is a quick-and-easy way to provide neutral wrist positioning.

Elbow Pain – May indicate an inflammation where the forearm muscles attach into the upper arm bone at the elbow – Medial or Lateral Epicondylitis.  Can also be caused by several nerve compression syndromes that occur near the elbow – Cubital Tunnel Syndrome, Radial Tunnel Syndrome.  Check out the positioning of the keyboard height and mouse location.  When working at a computer, your ear, shoulder and elbow should be stacked in a vertical alignment.  If your elbow is not relaxed at your side, you may need to change positioning by lowering the keyboard surface or getting in closer to your desk.  The elbow should not be bent at more than a 90 degree angle while using the computer.  A mouse that positions the arm in a more neutral “hand-shake” position may also be helpful.  Don’t swivel the mouse from the wrist.  Also, keep the hand relaxed on the mouse and use only the smallest amount of force necessary to activate the mouse click.  Don’t hold the index finger stiffly over the mouse (as if pointing) and don’t pound the mouse buttons, especially with a straight finger.  Rather, keep the index finger slightly bent and lightly touching the mouse.

Shoulder Pain – Often caused by reaching forward for long periods of time for the keyboard or mouse.  When working at a computer, your ear, shoulder and elbow should be stacked in a vertical alignment.  If your elbow is not relaxed at your side, you may be reaching forward causing strain on the arm muscles.  It takes work to hold the arm in this position for long periods of time even if the work itself is not too forceful.  To keep the upper arm muscles more relaxed, you may need to lower the keyboard surface or get in closer to your desk.  Check your chair.  Are you sitting back in the char?  Does it provide proper lumbar support and seat depth?  Look at the arm rest height.  You may need to lower the arm rests in order to keep the shoulders relaxed.

Neck Pain, Eye-Strain & Headaches – Often caused by poor positioning of the monitor.  Position the monitor directly in front of the keyboard so you are not twisting the body while using the computer.  Check out the height and distance of the monitor.  It may need to be adjusted so that you can clearly see the monitor print without tipping the head forward or back.  Avoid using bifocals while on the computer.  If you work extensively from copy, keep the copy in front of the monitor or directly to each side.  Use a tray that holds the copy close to monitor height to avoid repetitively looking up-and-down from the copy to the monitor.  Use a phone headset to avoid cradling the phone between the shoulder and the ear if you need to type and talk at the same time.