Reprinted from the ACJ - May, 2000
Get ready, big words ahead!
Musculoskeletal Disorders (MSD); injuries affecting muscles, nerves, tendons and bones, account for one third of occupational injuries each year. Granted they aren't as exciting as explosions, falls, or shipping an employee overseas, but they are more common. Of the MSD, Carpal Tunnel Syndrome (CTS) is the most common. CTS is a catch all phrase for repetitive motion injuries involving the fingers, wrist and forearm area. Hands are wonderful things, that's why we use them so much. But continual or excessive strain of the muscles and ligaments of the wrist is the major culprit causing CTS. Pinching, picking pulling or twisting at the wrist for hours and hours can cause the muscles and ligaments to swell. These muscles and ligaments, along with nerves (specifically the median nerve) travel through small openings in the wrist bones and then up the arm, where they attach. The wrist bones are referred to as the Carpus area and these small openings through the bones are the Carpal Tunnel (please turn on vehicle headlights).
As the muscles and company swell in response to overuse they get tighter and tighter in the tunnel. Think of pulling a rope through a washer. Now soak the rope in water, so it swells, and then try to pull it through. That rubbing on the edges is the same as in your wrist. Be careful not to pull on the rope to long or hard or you may develop CTS from the demo. The tighter the passage in your wrist becomes, the more pressure builds on the nerves, resulting in more pain and less movement. Eventually it can make picking up a penny an excruciating exercise (not just because it is not worth the time to bend over for a penny).
The first sign of CTS is a tingling, numbness or shooting pain in your fingers, wrist or forearm not caused by being caught in a piece of machinery. Often this pain occurs hours after working. Sometimes at night while resting. Drifting off on the couch and awakening with your arm `asleep' doesn't count.
CTS doesn't normally go away without a change in either the causal work procedure, or the arm itself, or both. You must reduce the strain on the wrist area or expect more of the same. Since working with your wrist in a `bent' position, coupled with repetitive finger activity is the cause, sufferers often wear a wrist brace to keep the Carpal openings aligned with the arm and hand. This both reduces the nerve rubbing on the edges of the tunnel and allows the person to go straight from work to bowling league. Aspirin and Ibuprofen can help reduce the swelling and some of the pain. In severe cases Corticosteriods are injected to reduce swelling. Extreme cases (realize that 50% of untreated CTS cases reach this state) require surgery to open up the Carpal openings and alleviate the problem.
That sounds painful and expensive so let's try to be proactive and avoid the condition. How? Proper equipment set up and proper technique. In the office adjust the keyboards and desks such that your lower arm extends as straight as possible through the wrist to your hands when working. Computer operators are prime candidates for CTS. In the shop, support heavy hand tools, such as air wrenches and those N-20 tip torches, with counter weights. Setup work benches to keep your forearms parallel to the floor. Learn to turn wrenches from the arm and not the wrist. Better yet, hold the wrench still and spin the car.
If you have not been afflicted as of yet, routinely stretch your forearms, wrist and fingers by pulling back slowly on your fingers and wrist several times a day. Taking breaks and stretching is the preferred rehabilitation method as well. If possible don't let new guys (or old guys learning new tricks) over strain. Slowly increase the repetitive procedures over a week or two to develop the muscles and loosen up the ligaments without injury. This may seem like a waste of time, but not when compared to having your best shop guy, wearing wrist braces and pouring coffee in the waiting area, entertaining the customers with tales of high games and picking up the 7-10 split. Remember, it's all in the wrist.
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
JOHNSON MANUFACTURING COMPANY
114 Lost Grove Road / PO Box 96 / Princeton, Iowa 52768-0096
Phone 563-289-5123 or Fax 563-289-3825