The lay term “trigger finger” is an apt description of this condition, medically known as stenosing tenosynovitis. One or more fingers, usually on the dominant hand, become painfully locked in a bent (flexed) position. The affected finger has to be straightened manually, when it suddenly “pops” back into place with a painful clicking sensation, much like pulling the trigger of a gun. The ring finger is most commonly affected, followed by the thumb.
Some unfortunate individuals develop trigger finger in multiple digits. Around 3 per cent of the general population is affected, but the prevalence rises to nearly 10 per cent in people with diabetes. Although trigger finger is not dangerous, it can be disabling, interfering with daily activities.
The tendons that bend our fingers are enclosed within protective sheaths and lubricated by synovial fluid. These tendons glide smoothly through a series of fibrous pulleys, much like a rope passing through the rings of a pulley system. With ageing and repeated use, the tendon may become thickened or develop small nodules. The pulley through which it passes may also become narrowed. As a result, the tendon catches while moving, producing the characteristic locking and clicking.
In many patients, no obvious cause can be identified. Although repetitive strain has long been suspected, studies have not shown a higher incidence among people who perform repetitive manual work or frequently use vibrating or pressing tools.
Certain medical conditions increase the risk. Trigger finger is particularly common in people with diabetes. The likelihood of developing the condition increases with the duration of diabetes rather than the degree of blood sugar control. It is also seen more frequently in people with hypothyroidism and rheumatoid arthritis.
Patients often report waking with stiffness in the affected hand. Initially, the finger may lock but can be straightened with little discomfort. As the condition progresses, both locking and straightening become increasingly painful. A tender nodule may be felt in the palm at the base of the affected finger. Eventually, many people avoid using their hands because of the pain. Prolonged disuse may result in stiffness and permanent contractures.
The diagnosis is usually straightforward and is based on history and physical examination. X-rays are generally unnecessary. Imaging studies such as an ultrasound or MRI may be required if there is a history of trauma or an atypical presentation. Blood tests can detect underlying conditions such as diabetes, hypothyroidism or rheumatoid arthritis.
In the early stages, simple measures often provide relief. Soaking the hand in warm water for about 10 minutes, morning and evening, followed by repeatedly squeezing a soft rubber ball about 20 times, may help maintain tendon movement. Non-steroidal anti-inflammatory drugs such as ibuprofen can reduce pain and inflammation.
Wearing a splint at night to keep the affected finger in a neutral position is particularly useful for people whose symptoms are worse on waking. Splinting relieves symptoms in about 65 per cent of patients, especially when treatment is started early. However, it is less effective in severe or long-standing cases.
If conservative treatment fails, a corticosteroid injection into the tendon sheath is the next step. This is most successful when symptoms have been present for less than six months, only one finger is affected and the patient does not have diabetes.
When symptoms persist despite splinting and steroid injections, surgery may be required. The procedure is simple and involves releasing the constricted pulley so that the tendon can glide freely again. Most patients regain full movement and can resume normal activities within a few weeks.
The writer has a family practice at Vellore and is the author of Staying Healthy in Modern India. If you have any questions on health issues, please write to yourhealthgm@yahoo.co.in