What happens in the finger
The flexor tendons run along the palmar side of the finger in a dense canal where they are held in place by annular ligaments. The most loaded of them is located at the base of the finger at the level of the head of the metacarpal bone. With constant stress, the tendon sheath becomes inflamed and thickens, forming a nodule. While the nodule is small, it slips under the ligament with a click, and with further thickening it gets stuck, and the finger is fixed bent. Over time, the ligament becomes denser, the canal narrows even more, and the process becomes self-sustaining.
- Stage 1 - pain and tender nodule without clicking
- Stage 2 - clicking during active extension
- Stage 3 - the finger is extended only with the help of the second hand
- Stage 4 - persistent flexion contracture
Causes and risk factors
In most cases, this is the result of chronic overload: prolonged gripping of a tool, working with scissors, a screwdriver, a sewing machine, heavy bags. But for a significant proportion of patients, the first place is not the load, but metabolism. In diabetes, the tendon sheaths thicken due to glycation of collagen, so a trigger finger is often the first reason to check your blood sugar. A separate form is congenital clicking thumb in children, which is discovered in the first years of life.
- Monotonous work with a strong hand grip
- Diabetes mellitus and prediabetes
- Hypothyroidism
- Rheumatoid arthritis
- Amyloidosis during dialysis
- Congenital form in children
Symptoms
The first to appear is discomfort and a painful point on the palm at the base of the finger, which is easy to feel. In the morning the finger straightens worse, and in the evening after work the complaints intensify. Later, a characteristic click is added, and then episodes of blocking. The pain can radiate into the finger itself, causing patients to mistakenly look for a problem in the joint. Over a long period of time, the finger stops straightening completely, even passively.
- Dense painful nodule on the palm
- Clicking sound when flexing and extending
- Morning stiffness of the finger
- Locking the finger in a bent position
- Pain in the finger when grasping objects
- Swelling of the base of the finger
Diagnostics
The diagnosis is usually obvious upon examination: the doctor asks to clench and unclench the hand several times and palpates the nodule at the level of the head of the metacarpal bone. Ultrasound helps to see thickening of the tendon and ligament, assess the presence of fluid in the sheath, and rule out rupture. X-rays of the hand are prescribed if arthrosis or the consequences of injury are suspected. Since the disease is closely related to metabolism, it is reasonable to check glucose levels, and in case of multiple lesions, thyroid function and rheumatological indicators.
- Examination and palpation of the palm
- Ultrasound of the tendon and annular ligament
- X-ray of the hand for injury and arthrosis
- Blood glucose, if necessary HbA1c
- MRI of the hand in unclear cases
- Rheumatological tests for lesions of several fingers
Treatment and prognosis
At an early stage, it is often enough to reduce the load and fix the finger in an extended position with a night splint for several weeks. Exercises for soft sliding of tendons, ultrasound and phonophoresis are added. If the clicking persists, the doctor may inject a glucocorticoid into the tendon sheath area - this method is effective, but works less well in diabetes. In case of persistent blockage and contracture, a minor operation is performed: dissection of the annular ligament through an incision or percutaneously. The finger begins to move immediately, relapses are rare. The decision about blockade or surgery is made by the doctor.
- Reducing the load and changing the working grip
- Night splint for 4–6 weeks
- Tendon gliding exercises
- Ultrasound, phonophoresis, laser therapy
- Glucocorticoid injection as prescribed by a doctor
- Dissection of the annular ligament with persistent blockage
- Controlling blood sugar in diabetes