The focus of this week’s upper extremity column will be the overuse of injuries of the hand and wrist. The wrist is a very complex area with several bones, muscles, tendons, nerves and ligaments, which can become injured or overused.
One of the most common wrist problems seen in orthopaedic practice is carpal tunnel syndrome. Much time and effort has been used in describing this syndrome. Briefly, carpal tunnel syndrome (CTS) occurs when the median nerve, which runs through the wrist through a bony canal called the carpal tunnel, becomes entrapped and compressed. The carpal tunnel is formed on three sides by the small carpal bones of the wrist and on the fourth (palmar) side by several fibrous structures. None of the walls of the carpal tunnel are flexible at all. If the tendons that share the carpal tunnel with the median nerve become overused, the inflammatory material that accumulates within the tunnel can compress the median nerve. Of all of the structures that pass through the carpal tunnel, the median nerve is the most sensitive to entrapment.
The symptoms of median nerve entrapment and hence CTS include pain, tingling and numbness on the palmar side of the hand over the thumb, index and long fingers. The pain and parethesia are usually worse when the wrist is being overused and at night. Sometimes one will wake up with the hand asleep. People who work with their hands doing repetitive motions are most at risk for CTS. Clerical workers, dentists, dental hygienists and people who work with computers are especially at risk.
Treatment for CTS often begins with a trial of conservative therapy. This could include using wrist braces to keep the wrist in a position, which allows the room within the carpal tunnel to be maximized. Oral anti-inflammatory medicines may also be tried and physical therapy is an option. Occasionally, an orthopaedic surgeon may opt to place a steroid injection into the carpal tunnel to try to decrease the inflammation within the tunnel. The definitive treatment for carpal tunnel syndrome is to undergo a surgical carpal tunnel release. This requires the fourth, non-bony wall of the carpal tunnel to be surgically dissected and the median nerve to be freed from its inflammatory sarcophagus.
Another common overuse problem around the wrist is called DeQuervain’s tenosynovitis. This involves an inflammation of the sheaths that envelop two of the tendons that function to pull the thumb back. Much like the carpal tunnel syndrome, it is common in people who either recreationally or occupationally use their wrist in a repetitive fashion.
Symptoms of DeQuervain’s tenosynovitis are usually linked to pain on the thumb side of the wrist, which is often worse with thumb extension or wrist deviation. This is an overuse syndrome and not usually the product of a traumatic event.
Treatment for DeQuervain’s is a trial of immobilization of the thumb, oral medicines, and physical therapy. If that fails, it may be necessary to inject the first extensor compartment where the two effected tendons are located. This will often break the cycle of inflammation and pain. If conservative therapy fails, it may be necessary to dissect those tendons from their sheath in order to break the inflammation, and release the constriction. This is the definitive treatment for DeQuervain’s tenosynovitis.
Also in the category of overuse and inflammatory conditions is trigger finger. Triggering occurs when the flexor tendon of the finger or thumb becomes entrapped while coursing through a pulley. Pulleys exist in the hand to give a mechanical advantage to the flexor tendon by preventing bow stringing. If a small amount of inflammatory tissue develops in the tendon it can become difficult for the tendon to pass through the pulley. The condition is analogous to a knot in a rope being pulled through a pulley.
Trigger finger can develop in anyone but is somewhat more common in people who use their hands a lot in their line of work. Treatment involves one of only two things. The first and least invasive is an injection around the pulley at the site of triggering phenomenon. This is successful in a fairly large percentage of the time. If the injection fails, the only treatment option left is to perform a surgical trigger finger release. This allows the tendon to course through the hand unimpeded. This will stop the clicking or catching.