Trigger finger is a relatively common pathology in pediatric orthopedics, which is characterized by achieving full extension of the thumb. Occasionally, the flexion-extension movement of the interphalangeal joint of the thumb can be performed with an audible and sometimes painful click, a situation that eventually causes discomfort and discomfort in the child when picking up objects.
Causes of spring thumb
The cause of spring thumb is unknown. Apparently, one of the “pulleys” that support the tendon that moves the tip of the finger is somewhat narrow, a fact that produces a thickening of the tendon (nodule) that finally prevents the fluidity of the movement.
This pathology usually occurs after the first year of age, and is caused by a discrepancy between the size of the thumb flexor pollicis longus tendon and a reflection pulley located at the base of the finger. The reflection or pulley bands serve to ensure that the tendon has proper function and does not separate from its path parallel to the bone. When the tendon is thicker than the size of the pulley, it rubs inside the pulley, becomes inflamed and ends up producing more thickening and more difficulty of passage, with the so-called Notta’s nodule. At the moment in which the thickened area of the tendon passes to one side and to the other of the pulley in the finger movements, the protrusion occurs (Figure 1).
Spring thumb: diagnosis and treatment
The diagnosis consists of noticing early on when a protrusion or click is noticed when the child bends and/or stretches the finger. If the process does not resolve spontaneously, the finger will remain blocked with the tip of the thumb in a flexed position, producing pain due to forced extension.
Mostly, the solution is a surgical intervention, and the process consists of opening the pulley, which allows the complete recovery of the finger mobility.
Once the child reaches the age of one year and the size of the hand structures allows it, the time for safe surgery arrives. The surgical intervention is performed by making a longitudinal cut in the reflection pulley to free the tendon and it is verified that the finger can move freely without the tendon being trapped. All this is performed under general anesthesia, and the base of the thumb can also be locally anesthetized so that it does not hurt during the postoperative period.
Normally, the results of the intervention are excellent and the child recovers mobility immediately and without pain. However, in a small percentage of cases it has been seen that it can recur despite performing the technique properly.
It is noteworthy that, sometimes, this process is bilateral affecting both thumbs and does not have to coincide simultaneously, so we will have to perform two surgeries and not act prophylactically.
For more information consult with the traumatologist.