DR BISWAJIT DUTTA BARUAH

Consultant orthopaedic surgeon, KIMS Oman Hospital

Texting thumb refers to a repetitive strain injury (RSI) or overuse injury caused by frequent use of the thumb in operating smartphones and mobile devices. The medical term for the condition is De Quervain’s tenosynovitis named after the Swiss surgeon Fritz de Quervain, who first described the condition in 1895.

On the back of the thumb lie two tendons that connect the muscles in the forearm to the bones that make up the thumb. The tendons are covered by a sheath of tissue (tenosynovium) that secretes an oily material (synovial fluid) for lubricating the tendons. The rope-like tendons also pass through tunnels at the region of the wrist whose roof is made of a thick fibrous sheath (extensor retinaculum).

Most patients present with pain along the base of the thumb mostly along the tendons extending, at times, up to the level of the wrist. Pain is usually not present all the time, but aggravates with certain activities. However the pain is sharp and disabling at the time of occurrence. Some doctors feel that the thumb does not possess the dexterity of the other four fingers, and is not particularly well suited for high-speed typing. This puts a strain on the tendons that run through the thumb leading to pain.

A second group of people in whom it is common are women who are pregnant or who have recently delivered a baby. Repetitive strain is likely when a mother has to wash, feed, clothe or even just pick up the baby, explaining why it is common in them. The occurrence in pregnancy, however, questions this hypothesis.

A second likely explanation is fluid retention which is common in pregnancy. Examination of tissue under the microscope (histopathological examination) has revealed degenerative changes in the tissues surrounding the tendons including collection of jelly-like substances (myxoid deposits). It is commonly accepted that the condition is more degenerative than inflammatory.

Activities that incite pain

Pain is felt acutely in activities of daily living that involve a clenched fist and thumb. Activities that incite pain are wringing clothes, opening a bottle cap, hammering a nail, gripping a pen or golf club.

A visit to the orthopedic surgeon becomes necessary when the pain is worsening. The surgeon will take a history and proceed to examine the wrist and thumb. He may perform the Finkelstein's test - a clinical test to confirm the diagnosis.

As the tendons pass close to the wrist bone (radial styloid process), most patients feel that the bone is the source of pain. However, bone is not involved in this condition and x-rays are unnecessary. In a much older person, arthritis of the thumb joints (CMC joint) may mimic the pain of tenosynovitis. In such a situation xray will be helpful in detecting arthritic changes in the joint. Ultrasound can help confirm the condition.

Treatment options

It is important to understand that, in almost all cases, the condition is self limiting and will resolve with time. In persons with continued pain, the surgeon may prescribe anti-inflammatories.

In pregnant women, this may not be appropriate, and likely the surgeon will prescribe paracetamol instead. Applying ice to the area and avoiding

the repetitive movements will make it easier on the patient.

Splinting the thumb can be helpful in resting the tendons and restrict use of the thumb. Ultrasound can also be useful for treatment purposes.

Other physical therapies in the form of deep tissue massage, exercises to stretch the thumb muscles and strengthening exercises by the physiotherapist can help alleviate pain. If pain still persists, steroid injection may be helpful for short time relief from pain.

Last option

Surgery will be resorted to when non-operative measures fail to relieve pain. Postoperative care is usually limited with light dressing.

Patients are advised light activities, and within two weeks after removal of sutures (stitches), they are able to resume their day to day activities. RSI patients may continue to experience mild swelling and tenderness at the surgical site for a few months.