SCI Forum Reports
Prevention of Overuse Injuries
February 6, 1996
"The main muscles used in pushing a wheelchair are the shoulder depressors," said Anthony J. Margherita, MD, a physiatrist at Harborview Medical Center and assistant professor of rehabilitation medicine at the UW. He demonstrated a downward-pushing motion with both of his arms and said, "All of that strength is in front. That sets people up for shoulder problems, particularly rotator cuff problems. The earliest I've ever seen a person develop rotator cuff problems was within two months of injury. By 10 to 15 years after injury, it's very common."
The rotator cuff is a system of four tendons that blend together to help stabilize and move the shoulder. Damage to the rotator cuff can cause shoulder weakness, and severe damage can make it difficult to raise the arm or move it out to the side.
"When your arm is moving forward, the natural tendency is for your shoulder bone, the humerus, to go in the direction of motion," Margherita said. Muscles in the back are needed to counteract this tendency. If those muscles fail, the humerus goes forward, reducing the space in which the rotator cuff can do its job and compressing it against the cartilege.
Treating shoulder problems involves three steps, Margherita said. The first is to avoid using the injured shoulder as much as possible. The second is acute treatment with antiinflammatory medications to reduce swelling and pain while the damage heals. The third step is to prevent or delay future problems by doing exercises to strengthen the back muscles that stabilize the shoulder.
Other common sites for overuse injury are the elbow and wrist. Elbow problems often have to do with wrist extension, and the key to prevention is to reduce weight bearing in a straight-armed position with the hand bent back (this often occurs during transfers). Treatment for elbow problems usually involves resting and stabilizing the affected joint.
Injuries to the wrist can involve ligaments, tendons, bones or nerves, though nerve injuries such as carpal tunnel syndrome are perhaps the most talked-about. "Carpal tunnel syndrome is a specific injury to the median nerve. It can occur when the wrist is in the extended position or when it's in a flexed position," Margherita said, explaining that repeated pressure on the nerve as it passes through a narrow channel in the bones of the wrist causes the nerve to become inflamed. "It can occur from pushing your chair."
Treatment for carpal tunnel syndrome usually involves splinting the wrist in the neutral position to prevent further damage and allow the nerve to heal. Severe cases may require surgery to relieve pressure on the median nerve.
The ulnar nerve passes over the elbow and through the wrist, and may develop problems from driving a power wheelchair or from the position of the hand on an arm rest. In such cases, changing position may be all that's needed to provide relief, Margherita said.
"There are a few things that are critical to good shoulder health after SCI. First, balance is very important. If you're using a manual chair, balance (in muscle development) is key. If you've got it in front, you've got to have it in the back. The exercises are not that complicated.
"Second, as much as you can, change position and modify your techniques when you do develop symptoms. Use a sliding board to do car transfers, even though you really could make it. Don't hang your body off of your arms.
"Third, if you can, avoid some of those pressure areas that cause you to run into potential problems with your wrists."