Extended use of a computer mouse can lead to multiple musculoskeletal issues such as neck, shoulder and forearm pain, including wrist pain and complications such as Repetitive Strain Injuries (RSIs) and inflammation of the tendons. 

Computer use, in general, can also lead to carpal tunnel, which in severe cases requires surgery to treat. Although little evidence states that an ergonomic computer mouse will reverse or treat carpal tunnel, John Hopkins Medicine acknowledged adjusting your computer setup may ease symptoms.

There are two primary wrist movements that are addressed in ergonomic mice, wrist flexion and wrist deviation. Wrist flexion, the motion of your wrist bending forward and backward, can lead to nerve complications such as inflammation and carpal tunnel. Over flexion of the wrist can put pressure on the median nerve within the carpal tunnel. This nerve runs under a ligament going across your wrist called the transverse carpal ligament.

Wrist deviation is the motion of your wrist bending from side to side. Radial deviation favors the radius, or inside bone of your arm, while ulnar deviation favors ulna, or the outside bone of your arm. This can lead to inflammation of the tendons and other symptoms that come with RSIs. Inflammation of the surrounding muscles and tendons of the wrist can also worsen carpal tunnel syndrome.

The average computer mouse found in stores has some benefits such as ease of understanding and efficiency in cursor use, though they often put the hand in positions of flexion and deviation. The fingers can commonly form a “claw-like” hand, especially if the mouse is too small for the user. Traditional mice can be improved with ergonomic features such as more material under the thumb for support.

Vertical computer mice position the hand in a neutral, “handshake” position. This decreases ulnar and radial deviation and forearm pronation, or twisting, as the user’s hand is on its side, roughly in line with the rest of the forearm. 

The fingers being in a more neutral hand position also experience less strain as they are not in a “claw-like” position and although there will be wrist flexion, it is more in the motion of moving the mouse rather than while stationary.

Some mice try to blend the vertical and traditional mouse by angling where the four fingers of the hand sit to reduce pronation of the forearm and wrist flexion although it is likely some pronation and flexion could occur.

Another common feature in ergonomic computer mice is a trackball acting as a cursor in place of moving the mouse itself. Keeping the mouse stationary reduces wrist flexion in vertical mice and wrist deviation in traditional mice. However, trackball usage does have an operational learning curve in contrast to moving the entire mouse. There is also strain placed on the specific finger operating the trackball.

Besides playing a part in reducing injury from long term computer use, investing in a low-friction, moveable wrist support for your mouse in addition to a keyboard pad can have a significant effect on the reduction of wrist injury as well as muscular and tendon inflammation. 

Proper posture also contributes to the prevention of musculoskeletal complications. Keeping your thighs and elbows parallel to the floor and your eyes either looking straight at the computer screen or slightly down, can reduce stress on your body. 

Although selecting the correct computer mouse for your needs is quite important to reduce the likelihood of RSIs, an important factor in computer usage health is taking breaks to walk around and letting your wrists heal to prevent overworking these muscles before symptoms occur.