The Fingers & Repetitive Strain Injuries

Anatomy

The fingers have no actual muscles in them. Rather, the movement of bending the fingers is caused by the muscles in the forearm contracting and pulling on the tendon (the long, rope-like structure that connects muscle to bone) that attach to the fingers. These muscles start at the inside edge of the elbow.

The muscles that straighten the large knuckles of the hand are also forearm muscles that start at the outside edge of the elbow.

There are small muscles within the hand (palm area) that straighten the finger tips and provide fine motor control.

Trigger Finger

The tendons that bend the fingers run through a pulley system within the finger itself. The pulley system is necessary to hold the tendon close to the bones and prevent bowstringing of the tendon. This system maximizes the efficiency, motion, and strength of grip.

Unfortunately, one of the most common repetitive hand injuries occurs within this pulley system. Over the front of the palm, at about the level of where the large knuckles bend, the tendon passes underneath a ligament bridge. If the tendon becomes swollen and inflamed, it does not pass smoothly underneath this ligament. The resulting friction may cause the tendon to “hitch”, get caught, snap, and feel as if it is not working effortlessly. The finger may also “lock” when the swollen tendon pops through the tightness but is unable to pass back underneath. If this happens often enough, or if the finger is painful or the swelling tight enough, the finger can actually begin to contract at the joint and it may become physically stiff. The palm area at the site of this inflammation can also become quite tender and painful. This triggering can occur in any of the fingers and the thumb.

Arthritis

Other than trigger finger, the most commonly occurring, non-traumatic injuries that occur in the hand tend to be arthritic in nature. Osteoarthritis is caused by wear and tear on the joints. This type of arthritis is not necessarily caused by actual age, but by the mileage (physical stressors) put on the hands over the years. That said, there does seem to be a genetic predisposition towards developing osteoarthritis. Although not directly a repetitive strain injury, arthritic joints can become inflamed and painful with work activity.

Heberden’s nodules are calcifications caused by arthritis at the top joint of the fingers. Bouchard’s nodules are calcifications caused by arthritis at the middle joints of the fingers. These nodules can enlarge the joints and make them painful and unstable. Once the fingers have had joint changes due to the arthritic process, the joint cannot return to its normal state.

With arthritis, the goal is to prevent joint changes by using the hands more gently or in a supportive way. Joint protection techniques, energy conservation techniques, and the use of adaptive equipment are all prevention methods that are associated with the attempt at preventing arthritic joint changes.

Below are some ergonomic techniques that will help prevent the overuse activities that can cause inflammation or trigger finger and the physical stressors that can promote osteoarthritis.

Ergonomics

Avoid sustained gripping or pinching activity. 

  • Use a larger grip if possible;  for example, use pens with a larger barrel such as the Dr. Grip; or use kitchen utensils designed with the Good Grip handles – these are comfortable to use and take the stress off the hands.
  • Do not hold/squeeze the mouse with any force.
  • Rather than holding a book, place it on a surface (such as a bean-bag lap tray) and use the palms to hold it open; or use a weighted book mark to hold it open for you.
  • Use specially designed ergonomic tools with larger and softer grips; check industry catalogs for equipment specific to your type of occupation/work.
  • Use electric tools and gadgets (e.g., can opener) rather than manual tools

Avoid repetitive gripping (opening and closing the hand).

  • Use the lightest touch possible to activate the keyboard.
  • Use rotary scissors or self-opening scissors.
  • Open bottles/jars using the flat palm of the hand rather than a large, finger grip hold.

Pacing Activity

  • If unable to avoid the above activities, take frequent micro-breaks.
  • If possible, rotate activities throughout the day so that you are not performing any one type of hand-intensive activity for any length of time.
  • Do not go home after performing heavy or repetitive work and immediately perform leisure or housework activity that uses similar motions.
  • Use a cold pack for 10 minutes after any activity that causes pain.

Joint Protection and Energy Conservation

The general principles of Joint Protection and Energy Conservation are to avoid a sustained position, use leverage versus a grip when possible, use the largest joint possible for the activity, respect pain, and balance work and rest. Visit Hand Health Resources for detailed information on tendon and joint protection principles.

Exercises

Stretch often.

  • A great stretch for the hand and forearm is to put your arm out in front of you with the palm down then pull the wrist back as if you are saying “stop”. Gently increase the stretch by pulling the wrist and fingers back with the other hand. Hold for 30 seconds.
  • You can also open your hand and spread your fingers open as widely as you can.
  • Gently pull each finger back using the other hand.
  • A great stretch for the smaller muscles within the palm area of the hand – make a hook fist (try to touch the fingers to the very top edge of the palm as if you are holding a briefcase or a grocery bag; the large knuckle should be straight and the two end knuckles of the fingers are hooked into a fist). Maintaining the hook, gently push the large knuckle back into more extension using the other hand.
  • If having hand/finger pain, do not exercise the hand by using grippers or squeezing a ball. Rather, use a rubber band placed at the tip of the fingers for light resistance as you open the hand. This works the opposite muscle groups and creates balance, rather than stressing muscles that are already over-worked.

Neutral Position

  • There is a natural, soft curve to the fingers.
  • Many people are tense sleepers who tend to make a tight fist at night. Try to sleep with the fingers mostly straight. If needed, use a splint such as the Pil-O-Splint to keep the fingers from fisting in the night.
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Typing Style – Repetitive Injuries are NOT just about the Keyboard

The goal of ergonomics is to reduce the force, repetitiveness or awkwardness of activities so that the body performs tasks most efficiently and with the least amount of stress. Many excellent resources are available that describe ergonomic modifications for the office environment. Because of this information, most people now have some general knowledge of the healthiest location for the keyboard and monitor. Less commonly known is that typing style can be the cause of injuries.

TYPING STYLES

In their book Repetitive Strain Injury: A Computer User’s Guide, Dr. Emil Pascarelli and Deborah Quilter describe a variety of typing techniques that can lead to painful symptoms and repetitive injuries. Even the best and most expensive ergonomic keyboard will not eliminate pain caused by the following typing methods.

Resters – Resters lean the base of the hand upon the desk or the wrist rest. This can be harmful for the following reasons: 1) It places point pressure against the carpal tunnel; 2) It isolates the small muscles of the hands and forces them to do the work of the larger shoulder and elbow muscles; and 3) It can promote wrist postures that are not neutral.

Leaners – Leaners type by placing their elbows on the desk or chair arms. This puts pressure on the ulnar nerve, the superficial nerve at the elbow.

Loungers – loungers slump in their chairs leading to compression of the spine and low back pain. Lounging also promotes forward head and rounded shoulder posture.

Clackers or Pounders – Pounders hit the keys with excessive force potentially leading to pain and tingling in the finger tips and finger joints.

Pressers – Pressers hold down keys (for example, while scrolling) with excessive force placing pressure on the small joints in the fingers.

Pointers – Pointers are hunt-and-peckers who hold their arms poised in midair. Pointers are at risk from awkward positioning if they hold their fingers stiffly rather than in a relaxed position or if the keyboard is not positioned correctly.

Thumb or Pinkie Extenders – Extenders hold one finger stiffly out while the others perform the work. This separation causes excessive strain on the tendons of the fingers.

Grippers – Grippers hold tightly to the mouse or use too much force when clicking.

TYPING-STYLE ERGONOMICS

The following typing tips describe work-style modifications that will help prevent injuries and maximize the benefit of that ergonomic keyboard.

  • When typing, keep the fingers relaxed and slightly curled as if they are resting over a large ball.
  • Tap lightly with the finger tips rather than with the pulp of the finger.
  • Keep fingernails short – longer nails require that the fingers be tensely extended so that the key can be tapped with the pulp of the finger.
  • Keep the thumb relaxed – not held stiffly over the space bar.
  • Use the lightest touch possible on the keys.
  • Don’t stretch the fingers to reach keys that are far from the home row. Move fingers closer to the key by moving the whole arm.
  • Don’t stretch the fingers wide to activate a two-key command with one hand. Use one finger from each hand to activate these commands.
  • Maintain a neutral wrist position.
  • The mouse should be held loosely. Control of the mouse should come from the larger muscles of the elbow and shoulder, not from wrist motion.
  • Don’t rest the wrist on the table or wrist rest. Use the wrist rest as a guide that the wrist slides over.
  • Don’t lean on the elbow when typing, talking, contemplating, or holding the phone.
  • Pad any sharp edges that the forearm rests against.
  • The keyboard and mouse should be positioned so that the arms are at the sides (do not reach forward or out to the sides to activate either), shoulders relaxed, elbows opened up slightly more than 90 degrees.

Repetitive Strain Injury: A Computer User’s Guide offers more tips and exercises to help correct typing styles. Find it at Amazon.com.