|
Arthritis is one of the leading causes of lost work time and disability. Therapists can extend their clients' careers and reduce the risk of work-related disability with ergonomic training. To this end, therapists should work to minimize strain to damaged or changing structures, reduce pain and avoid positions that can exacerbate known deformities.
For instance, synovitis often creates inflammation of the dorsal wrist. As the synovium thickens it weakens surrounding structures such as tendons, stretches supportive ligaments, destroys articular cartilage and invades the bone. It's important to minimize forces and friction within the synovial sheaths to reduce the chances of tendon rupture, especially during flare-ups. As rheumatoid arthritis (RA) progresses, the carpal ligaments become overstretched and the wrist deviates radially, the carpus supinates on the radius, the ulna subluxes dorsally and the fingers deviate ulnarly to assume a Z-shaped deformity.
Movement Control
Most workers plant their wrists on a desk or wrist rest while typing and using a mouse. These actions can result in sustained wrist extension, which creates a sharp angle for the tendons as they pass through the extensor compartments of the wrist. The friction increases strain on these weakened structures with each keystroke or movement. The best ways to correct these problems is through education and implementing changes to maintain a neutral wrist.
For example, tilting the front of the keyboard down away from the user (negative tilt) can straighten the wrist. This negative slant is accomplished with an adjustable keyboard tray. If a client can't break the habit of wrist extension, wrist rests can serve as a positional aide.
If the user's wrists deviate ulnarly during typing, he should acquire a split keyboard. Keyboards that eliminate or move the numeric pad to the left side can minimize reaching for the mouse and reduce the angle of the wrist and ulnar deviation forces of the fingers.
A standard mouse puts the wrist in full pronation, which increases tension and wrist strain. Instead, suggest a mouse that's large enough to support the whole hand and keep the wrist in a partially pronated position.
During periods of exacerbation the wrist should be resting with a soft or rigid splint. This short period of restricted movement helps maintain a neutral wrist. As inflammation enters remission and a client weans from the splint, make sure he's left with a work set-up that encourages optimal wrist posture.
Another way to minimize strain is to limit motion at the wrist. Work technique is crucial in these instances. Many workers rest the palm on a mouse pad and navigate with the mouse through wrist motion. This creates static muscle contraction in the weakened tendons, encourages repetitive motion and increases strain on carpal ligaments.
Teach clients to move the hand up, so the palm is supported on the mouse and the fingers can relax onto the buttons. While moving the mouse, they can keep the wrist still and move the whole arm with the larger, stronger joints. However, a client needs to minimize reach so the elbow can rest at his side.
A wrist splint aides retraining because a user must use joints other than the wrist.
For those who develop ankylosing at the wrist, it's beneficial to learn to minimize reach and use the entire arm to move.
Other ways to minimize wrist motion are by using keyboard shortcuts to minimize mouse clicks, paging up and down and pressing arrow keys instead of the scroll wheel.
Tenosynovial sheath inflammation in the volar wrist can create compression on the median nerve in the carpal tunnel. If workers with a known history of RA present with carpal tunnel syndrome, you should distinguish if it's unrelated or secondary to active RA.
Using a second mouse or trackball to the left of a keyboard allows a client to spread work to both hands. If the user's job requires detailed mouse movements where this option isn't feasible, a second mouse can help with functions such as e-mail or searching the Internet.
Pinpointing the Problem
As the collateral ligaments of the metacarpophalangeal (MCP) joints weaken, the metacarpal heads sublux volarly. Avoid a vertical mouse, since it can encourage a lumbrical grasp.
Don't encourage increasing lumbrical use and volar shear forces at the MCPs, given the propensity to sublux in this direction. A better solution is using a mouse large enough to provide support for the whole hand to rest. This position provides gentle support to the volar MCPs and doesn't engage the lumbrical muscles. Trackballs can encourage a lighter touch and eliminate sustained grasp of a mouse.
The interphalangeal joints are a common site of osteoarthritis (OA). Any increased force can worsen osteophyte formation and reduce movement to make typing difficult. Keyboards that require less force for activation and teaching a user to type lightly can decrease forces at these joints.
Also, tell clients to listen to the sound of their keystrokes. If coworkers can hear typing several desks away, then a person is typing with too much force.
|