What causes trigger finger

Dr. Bert Perey, MD, FRCPC, Orthopedic Surgeon

Duration: 2:54

Trigger Finger is a condition that causes pain, stiffness, and a sensation of locking or catching when a finger is moved. These symptoms can occur together or independently. The medical term for this condition is stenosing tenosynovitis. The ring finger and the thumb are the most commonly affected digits but it can occur in all digits.

Trigger Finger affects the flexor tendons to the digits. Flexor tendons are spaghetti-like structures that bend our digits. There are two flexor tendons for the index, long, ring, and little finger but there is only one flexor tendon for the thumb.

Each of the flexor tendons passes through a tunnel in the palm and the digit that allows it to glide smoothly as the finger bends and straightens. This tunnel is called the tendon sheath. The tendon sheath is formed by a series of pulleys that span the distal palm to the tip of the finger. The first pulley, named the A-1 Pulley, is a structure that causes the pathology in this condition. This pulley is located between the distal palm crease and the base of the finger; for the thumb, it is located under the palmar crease at the base of the thumb.

Trigger finger occurs when the A-1 Pulley becomes thickened, making it harder for the flexor tendon to glide through it as the finger bends. Over time, the flexor tendon may develop a small nodule, just proximal to the A-1 Pulley. This nodule can become stuck as it enters and exits the tunnel, causing a catching or snapping sensation, which is often painful. In more advance cases, the finger can become stuck in a bent position. Long-standing cases can lead to significant, and sometimes permanent, stiffness of the finger.

Trigger Finger is usually an idiopathic condition. This means that there are no defined causes for this problem and the etiology likely remains genetic. The average age of presentation is in the fifth decade of the life. The condition is more common in women. Trigger Finger can affect multiple fingers but most patients do not become symptomatic in more than one or two digits in their lifetime. Repetitive, heavy use of the hand, or trauma, can accelerate the onset of Trigger Finger. For most patients, however, there is no history of trauma or abnormal use. Trigger Finger is more common in patients with a history of Carpal Tunnel Syndrome.

Presenter: Dr. Bertrand Perey, Orthopaedic Surgeon, New Westminster, BC

Local Practitioners: Orthopaedic Surgeon