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The Fingers & Repetitive Strain Injuries


Repetitive Strain Injuries (RSIs) from computer use or desk work can cause headaches, eyestrain, and pain through the neck, shoulders, arms and back. "The Fingers" is part of a series that takes a closer look at the mechanism of injury and specific injury prevention techniques for particular pain areas.

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.


Avoid repetitive gripping (opening and closing the hand).


Pacing Activity

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.

Neutral Position


Marji Hajic is an Occupational Therapist and a Certified Hand Therapist practicing in Santa Barbara, California. For more information on hand and upper extremity injuries, prevention and recovery, visit Hand Health Resources.


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