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.
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.
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.
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.
- 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.
- 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.
- 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.