Features Profiles
Health & Safety: hypothenar hammer syndrome

At one time or another you have probably used the heel of your hand as a tool to push, grind or even hammer something solid. Repetitive trauma to the fleshy part of the hand can lead to a serious condition called hypothenar hammer syndrome. A wide variety of activities can expose your hand to this type of harm.

Whether you are at work or tackling projects at home, or getting back into outdoor sports activities, learn to recognize the causes and symptoms and how to prevent harming yourself.

Hypothenar hammer syndrome is a condition of the hand in which the blood flow to the fingers is reduced. Hypothenar refers to the group of muscles that control the movement of the little finger. Some of these muscles make up the fleshy edge of the palm (hypothenar eminence).

It occurs when workers repeatedly use the palm of the hand (especially the hypothenar eminence) as a hammer to grind, push, and twist hard objects in either work or recreational activities. These activities can damage certain blood vessels of the hand, especially the ulnar artery. This artery goes through the fleshy area of the palm and supplies blood to the fingers. When the ulnar artery is damaged there is a reduction in the flow of blood to the fingers. Sometimes a single significant episode can cause the syndrome.

Workers at risk
Hypothenar hammer syndrome typically occurs in men with an average age of 40 years. Workers at risk include landscapers, bricklayers, auto mechanics, metal workers, lathe operators, miners, and machinists. Workers who use vibrating tools are also at risk.

This syndrome can also be caused from sports activities such as karate, basketball, baseball, mountain biking, golf, tennis, hockey, handball, volleyball, badminton, breakdancing, drumming, and weight lifting.  

Symptoms
The symptoms of hypothenar hammer syndrome are a pain at the hypothenar eminence and ring finger, pins and needles (paresthesia), loss of feeling, and difficulty holding heavy objects in the affected hand. The fingers become sensitive to cold and change colour.

Because this syndrome is relatively uncommon and unrecognized, the diagnosis is often missed or delayed. The diagnosis is based on symptoms, medical history and job history, and then confirmed with tests showing the obstruction of the blood vessels.

Treatment and prevention
Treating hypothenar hammer syndrome begins by avoiding those activities that caused the syndrome in the first place. Other treatments may include smoking cessation (smoking negatively affects blood circulation), the use of padded protective gloves, and avoiding the cold. Certain drugs will help to restore the blood flow. For some cases surgery may be necessary.

Be aware of the causes and symptoms of this syndrome. Some steps you can take to prevent hypothenar hammer syndrome are:

• Focus on improving work practices.
• Avoid using the palm of the hand as a hammer to pound, push or twist hard objects.
• Don’t grip tools such as impact wrenches, pliers, scissors and even vehicle gearshifts too tightly.
• Switch tasks regularly or rest your hands.
• Use padded protective gloves to avoid the excessive trauma to the heel of the hand while working or participating in activities that put pressure on the palm.

The Canadian Centre for Occupational Health and Safety (CCOHS)  promotes the total well-being – physical, psychosocial and mental health – of workers in Canada by providing information, training, education and management systems and solutions that support health and safety programs and the prevention of injury and illness.