A straight handled knife puts strain on a worker's wrists
Workers who regularly use straight-handled knives in their jobs are in danger from more than just accidental cuts. Straight-handled knives force the wrist into an unnatural position which can lead to pain and numbness in the wrist and hands. OSHA has a number of guidelines for using straight-handled knives in the poultry and grocery industries, and those recommendations apply equally well to workers in other industries.
Carpal Tunnel Syndrome
Although wrists bend, they aren't meant to stay bent for long periods of time. When people work with bent wrists, the tendons move back and forth over the bones and ligaments. The tendon becomes inflamed and swollen which can be very painful. The tendon may become so swollen that it compresses the median nerve, causing numbness and pain in the hands. In some cases, permanent disability can result.
Dangers of Straight-Handled Knives
Workers who use straight-handled knives are forced to keep their wrists bent and put significant pressure on wrist tendons because of the hand and finger pressure involved in the job. This may be aggravated if the worker must grip the knife handle tightly because he is wearing gloves, if he is working in a cold environment in which the hands may become numb, or if the knife is dull or if the material is difficult to cut into.
Bent-Handled Knives
OSHA recommends employers switch workers over to knives with bent handles. This allows employees to keep wrists straight when working, reducing strain on wrist tendons. The ideal degree of bend will depend on the work being done but typically runs 30 to 45 degrees. Some tasks might call for an upright knife with a blade mounted at a 90-degree angle at the bottom of the handle. Companies should consider custom-designed knives for special jobs if none of the off-the-shelf solutions will work.
Other Options
OSHA has other recommendations for cases where bent handles are not a practical option. Tilting the work surface even a few degrees will reduce the strain on a worker's wrist. Knives with rough handles are easier to hold so workers can use a gentler grip and get better knife control. Loop handles allow workers to flex their hands in between cuts without putting the knife down. Workers should also be encouraged to take regular breaks during which they shake their hands and flex their fingers.
Keep Blades Sharp
A major source of wrist strain when using any type of knife occurs when the blade is not properly sharpened. Knives in regular use should be sharpened every day or even several times a day if they see heavy service. Knives used daily should be sharpened at each use. Train workers in proper sharpening techniques, since using a sharpener incorrectly is dangerous and will make the blade duller rather than sharper. Blades should be professionally sharpened about once a year.
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