Trigger finger (TF) is a condition involving the flexor tendon sheath, which leads to abnormal gliding of tendon and narrowing of the first annular (A1) pulley causing pain and locking of finger during flexion. The subject experiences painful flexion and difficulty in straightening of digits. It is one of the most common problems of hands and wrist, which leads to pain, dysfunction and disability, if not treated.
The patient may complain of clicking which may further develop into catching or popping pain. This may get normalized by manual palpation of digits. Stiffness and pain of the metacarpophalangeal joint in the morning which generally eases along the day, is a common complaint .
Pain is present in the distal aspect of the palm and at the proximal end of the digit involved. A painful, swollen nodule can be palpated near the metacarpophalangeal joint, arising due to inflammation or bunching of the fibrous tissue from trauma. At a time, one or more digits can be involved.
Conservative release technique
“Graston technique” is the latest technique used in the treatment; this differs from the conventional approach, and aims at re-establishing the extensor strength of the digits by palpation and control of pain using cryotherapy. The second approach is splinting technique; which is done in patients not willing for corticosteroid injections. It involves reducing the friction caused by movement of flexor tendons by immobilizing or splinting them .
Involves corticosteroid injections at the area of thickening of the sheath. It is done under strict aseptic conditions where the steroid injection is given within the tendon sheath and the patient is encouraged to move the digits. A different technique is also used in which the biaxial injection is given at the level of mid proximal phalanx which is less painful .
When the conservative or conventional approach doesn’t work or in the case of a locked TF, surgical technique is opted in which a full sectioning of the A1 pulley is done. Other technique is “Kapandji enlargement plasty” of A1 pulley in which A1 pulley is surgically enlarged. Patient feels early symptomatic relief by this technique. Latest technique is accucision or TRF (Trigger finger release), a microinvasive surgery for TF. Complications of these techniques include digital nerve and artery injury. In some cases infections, bowstring, bleeding, tendon rupture, atrophy of subcutaneous fat can occur .
Prognosis of TF is good in most cases following splinting or surgery or both. Corticosteroid injections are beneficial in patients having symptoms for a short time (less than 4 months). In most cases conservative approach, along with digital palpation and cryotherapy works.
Surgical release is proved beneficial in the patients with symptoms for prolonged duration (more than 4 months). Patients are generally cured and recurrence is seen rarely .
Etiology of the condition is mostly unknown. One of the causes is using of hand held tools and repeating motions. Activities involving prolonged stress and exertion of the pulleys can lead to trigger finger. Systemic conditions like diabetes mellitus or rheumatoid arthritis may also lead to the tendon sheath inflammation.
Acute or chronic infections, either localized or systemic, may in some cases involve the tenosynovium. Few autoimmune diseases may cause changes in the structure of tendons and pulleys. Collagen vascular diseases like sarcoidosis, amyloidosis and hypothyroidism may act as an underlying factor .
Trigger finger is a relatively common problem of the hand and wrist region and is over six times more common in women than men. It commonly affects the person during fifth and sixth decade of life. TF occurs commonly in patients with systemic diseases like diabetes, carpel tunnel syndrome, autoimmune disorders, De Quervain disease, renal diseases, hypothyroidism, and amyloidosis. The sequence of digit involvement includes thumb, middle, index and little fingers .
Trigger finger arises due to repetitive movements, pressure, stress and inflammation of the tendon sheath leading to accumulation of inflammatory exudates which results in pain during movement. Histological studies have shown accumulation of inflammatory cell infiltrate in extracellular matrix in some cases, and the appearance of chondrocytes also restrict the tendon sheath movement. Repetitive forceful movements also add to the accumulation of collagen type 3 in some areas, thus contributing to the inability of movement .
If the trigger finger is not treated for long time, it results in fibrous metaplasia of the tendon sheath.
Prevention can be done by avoiding repetitive movements and over exertions of fingers. Any of the tasks involving forceful flexion movements for longer durations should be avoided. Persistent pain and inflammation in the digits indicates the diagnosis of TF, where immediate medical attention is required. In case of excessive use or forceful flexion for longer period of time, adequate rest between works should be given to the hands and digits.
In trigger finger (TF) or stenosing tenosynovitis, the pathology lies in the tendon sheath and not the synovial lining, so it is more appropriately referred as "Tendovaginitis”. Tendon sheaths comprising of annular and cruciform pulleys form the pulley system that helps in the movement, and in force distribution of the flexor tendons during different motions. Among all the pulleys A1, A2, and A3, the first annular (A1) pulley which is located near the head of metacarpal, bears the most of stress and is responsible for many actions. It is affceted the most amongst all pulleys .