The Wrist & Repetitive Strain Injuries | Hand Therapy & Occupational ...

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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Source: http://handtherapy.wordpress.com/2013/08/01/the-wrist-repetitive-strain-injuries/

Perry Hall High School