The space through which flexor tendons travel down the fingers is very narrow. As the flexor tendons traverse the palm & enter the digits they pass through tunnels formed by fibrous tissue rings that surround the tendon & are connected to the underlying bones. These fibrous tunnels keep the tendons close to the bone & prevent bowstringing during normal motion. If any inflammation occurs around the tendon it cannot slide up & down this narrow space. The tendon becomes caught in the tunnel or sticks to the tunnel sidewalls. Hence, the clicking sensation sometimes accompanied by pain on motion progressing to the digit being stuck or locked in a flexed position in more severe cases. This process sets up a vicious circle where sticking to the tunnel sidewalls creates a more severe disease process or more inflammation. There can be significant pain on attempting to extend or straighten the finger. Rarely, the finger can become locked in an extended position. The inflammation is a result of repetitive work trauma as with the chronic use of tools such as screwdrivers, scissors, typewriters, etc. The majority of these cases resolve with splinting or alteration in the use of work tools. Persistent or severe triggering is treated with a single steroid injection that cures over 70% of cases. The problem is many physicians give the shot improperly & miss the tunnel or inject directly into the tendon rather than around it. Uncommonly another injection is required 4 to 6 weeks later. Should the problem then recurr or be resistent to steroid therapy a surgery release procedure is required. You should have this problem evaluated by a qualified physician as soon as possible at it can become incapacitating.
I prefer not to give more than 2 injections & recommend surgery if there is no response to steroid injection or if the problem returns after resolving. Of course, some changes have to be made in hand activities after response to steroid injection in order to prevent recurrence.