Lateral epicondylosis is a tendon injury more commonly known as “tennis elbow.” However, in gaming, it is commonly called mouse elbow due to its prevalence in PC players.
Mouse elbow is an overuse strain that occurs in the extensor tendons of the wrist and fingers that attach to the outside (thumb side) of the elbow. The muscles involved are the extensor muscles that open the hand and bend back the wrist.
As the name suggests, PC gamers are more likely to experience this injury due to the use of the mouse.
Due to misuse and imbalance, the fiber orientation of the extensor tendons on the outside of the elbow become disrupted. This dysfunction is called a tendinosis, which is different than tendinitis—a common misnomer for this condition. We’ll discuss this difference in more detail below.
It’s important to know some basic anatomy of the wrist and elbow to understand mouse elbow.
To begin, the tendons affected in mouse elbow are collectively called the common extensor tendon. This tendon is made up of 4 individual muscles that converge in one spot—a projection on the outside of the humerus (arm bone) called the lateral epicondyle:
One additional muscle which may be involved attaches just above the common extensor tendon onto the supracondylar ridge of the humerus.
On their distal ends (further away from the body), each of these muscles attach to different parts of the hands or fingers, but the tendinosis occurs in the attachment at the elbow.
This injury is a tendinosis! It is NOT inflammatory in nature, and the term tendonitis is not appropriate! This is critical to determine the appropriate prevention & rehabilitation.
Mouse elbow occurs when there is at least one of two imbalances in muscle contraction. If one or both of these imbalances occur over time, degeneration of collagen (the protein found in connective tissue) occurs. This leads to the disruption of the tendon fiber orientation in the common extensor tendon.
The strong fibers of a tendon should line up parallel with one another. In tendinosis, these fibers will become jumbled or disorganized—commonly described as adhesion formation—causing pain and affecting the movement of the tendon and the elbow joint.
When concentric contractions occur too frequently without the counterbalance of eccentric contraction, collagen begins to degenerate from the chronic shortening. Eccentric contraction—the lengthening of a muscle & tendon under tension—helps maintain the tendon fiber orientation.
Eccentric contraction protects tendons from overuse injury!
When agonist muscle actions occur too frequently without the counterbalance of their antagonist, there is imbalance in the strength and tension on the joints involved. When strength and tension are not balanced, the muscles can be overworked and injury becomes more common.
If you’re affected by mouse elbow, you’re likely to experience the following symptoms:
Other common findings may include:
Note: Mouse elbow is considered an overuse tendinosis, and inflammation will not be present. Inflammation is categorized by pain with accompanying swelling, redness, and heat (feeling warm to the touch).
If you notice these signs of inflammation, you are experiencing something different than simple mouse elbow tendinosis. You should consult your doctor if you are concerned about these symptoms.
For gamers, mouse elbow is more common for PC users due to the position and action of the hands using a keyboard & mouse. Common risks for PC users include:
The most common mechanisms of injury for mouse elbow are imbalances. Therefore, balancing muscle contraction and activation is a simple, yet extremely effective preventative measure.
For all common gamer injuries including mouse elbow, we’ve created a comprehensive injury prevention program. Performing this exercise routine may help reduce your risk.
The lengthening phase of muscle contraction is the most important! For PC gamers, perform resisted extension exercises and stretches of the wrist and fingers and control the eccentric phase.
It is absolutely essential to perform the eccentric, or “down-phase” portion of these exercises slowly and under control!
On our injury prevention video, these exercises and stretches are:
Resisted finger extension
Weighted wrist extension
Post-facilitation stretch, wrist extensors
Balancing the muscle activity at any joint will help keep muscles healthy. For PC gamers, extension of the wrist & fingers is the strenuous action; therefore, it is important to perform flexion exercises and stretches for the wrists and fingers for balance.
On our injury prevention video, these exercises and stretches are:
Weighted wrist curl
Post-facilitation stretch, wrist flexors
In addition to these mouse elbow-specific preventative measures:
To effectively resolve mouse elbow, it is important to first identify and correct the initial cause. For example, if you’re not performing the eccentric action of the extensor muscles or exercising the flexor muscles, protocols may be ineffective because of the constant exacerbation.
In practice, rehabilitation protocols for tendinosis injuries are well-researched and highly effective. Treatment is described as a three step process.
The provider should use a firm surface (thumb pressure or a knuckle, for example) to apply moderate pressure to the common extensor tendon and scrape perpendicularly across the tendon. Unfortunately, this maneuver tends to be moderately painful.
This will loosen the tendon matrix and make it more malleable for the next part of the treatment.
Following cross-friction to loosen the tendon matrix, resistance must be added to lengthen the tendon under tension. This resistance should be moderate-to-significantly heavy in order to properly pull the tendon fibers taut.
For mouse elbow, this would involve holding a weight (dumbbell or other small, weighted object) in the palm of the hand with the wrist extended and elbow flexed. In a slow, controlled manner, allow the elbow to open and wrist to drop—pulling the tendon.
Using heat packs or other heat therapy (i.e. infrared laser) on the affected area should conclude this protocol. Generally, a heat pack should be used for 10-15 minutes.
Adding a damp towel between the heat pack and the affected area will increase its effectiveness by creating moisture that penetrates further into the body.
Generally, people think to ice their ailments to relieve the pain. However, ice relieves inflammation, and as previously discussed, inflammation is not the cause of pain.
Therefore, ice would not help this condition. In fact, icing the affected area may prolong the healing process.
Heating the area increases blood flow, thereby increasing oxygen and nutrients needed for recovery. For an overuse tendinosis, heat is more helpful than ice.
Following resolution, continuation of these protocols allows for prevention of this condition from reoccurring.
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