Tendons are thick fibrous cords which attach muscles to bones. They often glide in sleeve-like tubes called tendon sheaths. Most of the finger tendon muscles which flex the fingers start in the forearm. The tendons pass through the wrist in the carpal tunnel and go into the palm. Near the base of the large knuckles on the palm surface of the hand these tendons pass underneath a pulley-like ligament, and then into the fingers. When the finger muscles contract, such as when making a fist or holding a pencil, the tendons tighten causing the fingers to bend and grasp.
If a tendon in the palm becomes inflamed, thickened or grows a nodule it can become caught in the pulley near the base of the fingers.
Trigger finger causes a painful snapping or catching feeling when grasping things. The finger may actually lock down. Pain is experienced when grasping or pinching objects. There may be swelling and tenderness of the tendon as well. Usually it is limited to one or two fingers, or the thumb.
Trigger fingers seem to develop over time when the hand is used frequently to grasp hard objects with force (hammering, twisting or opening jars, or sporting activities such as tennis). The tendon becomes pinched between hard object on the outside and the knuckle bones underneath. Over time a nodule of scar tissue grows, and may enlarge to the point it catches under the pulley ligament. Diseases such as rheumatoid arthritis may also cause nodules in the tendons or tendinitis causing trigger fingers.
If the finger locks down when clenching a fist, trigger finger may be present. An experienced health care provider may be able to feel a nodule near the pulley ligament in the palm, and this area may be tender and swollen.
It is important to rest the tendon, and reduce direct pressure with hard objects. Gloves, and padded grips on tools or sports equipment will help to cushion the tendon. Sometime splinting the finger straight at night will provide additional tendon rest. If the painful finger locks frequently, a cortisone injection into the tendon sleeve is usually effective in reducing pain and locking caused by the nodule. For very large or stubborn cases, surgery may be necessary to stop the locking.