Trigger finger, also known as stenosing tenosynovitis, is a disorder characterized by catching or locking of the involved finger in full or near full flexion, typically with force. There may be tenderness in the

palm of the hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the Koala#Characteristics and adaptations, koala (which ...

near the last skin crease (distal palmar crease). The name "trigger finger" may refer to the motion of "catching" like a trigger on a gun. The

ring finger The ring finger, third finger, fourth finger, leech finger, or annulary is the fourth digit of the human hand, located between the middle finger and the little finger. Sometimes the term ring finger only refers to the fourth digit of a left-han ...

and

thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...

are most commonly affected. The problem is generally idiopathic (no known cause). There may be an association with

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

. The pathophysiology is enlargement of the

flexor A flexor is a muscle that flexes a joint. In anatomy, flexion (from the Latin verb ''flectere'', to bend) is a joint movement that decreases the angle between the bones that converge at the joint. For example, one’s elbow joint flexes when one ...

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

and the A1 pulley of the

tendon sheath A tendon sheath is a layer of synovial membrane around a tendon. It permits the tendon to stretch and not adhere to the surrounding fascia. It has two layers: * synovial sheath A synovial sheath is one of the two membranes of a tendon sheath wh ...

. While often referred to as a type of

stenosing tenosynovitis Trigger finger, also known as stenosing tenosynovitis, is a disorder characterized by catching or locking of the involved finger in full or near full flexion, typically with force. There may be tenderness in the palm of the hand near the last ...

(which implies

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

) the pathology is mucoid degeneration. Mucoid degeneration is when fibrous tissue such as tendon has less organized collagen, more abundant extra-cellular matrix, and changes in the cells (fibrocytes) to act and look more like cartilage cells (chondroid metaplasia). Diagnosis is typically based on symptoms and signs after excluding other possible causes. Trigger digits can resolve without treatment. Treatment options that are disease modifying include

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

injections and surgery. Splinting immobilization of the finger may or may not be disease modifying.

Signs and symptoms

Symptoms include catching or locking of the involved finger when it is forcefully flexed. There may be tenderness in the palm of the hand near the last skin crease (distal palmar crease). Often a nodule can be felt in this area. There is some evidence that idiopathic trigger finger behaves differently in people with

Causes

It is important to distinguish association and causation. The vast majority of trigger digits are

idiopathic An idiopathic disease is any disease with an unknown cause or mechanism of apparent wikt:spontaneous, spontaneous origin. From Ancient Greek, Greek ἴδιος ''idios'' "one's own" and πάθος ''pathos'' "suffering", ''idiopathy'' means approxi ...

, meaning there is no known cause. However, recent publications indicate that diabetes and high blood sugar levels increases the risk of developing trigger finger. Some speculate that repetitive forceful use of a digit leads to narrowing of the fibrous digital sheath in which it runs, but there is little scientific data to support this theory. The relationship of trigger finger to work activities is debatable and there are arguments for and against a relationship to hand use with no experimental evidence supporting a relationship.

Diagnosis

Diagnosis is made on interview and physical examination. More than one finger may be affected at a time. It is most common in the thumb and ring finger. The triggering more often occurs while gripping an object firmly or during sleep when the palm of the subject’s hand remains closed for an extended period of time. Upon waking, the affected person may have to force the triggered fingers open with their other hand. In some, this can be a daily occurrence.

Treatment

Post-operative photo of trigger finger release surgery

Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involv ...

injections can cure trigger digits. Treatment consists of injection of a corticosteroid such as

methylprednisolone Methylprednisolone (Depo-Medrol, Medrol, Solu-Medrol) is a synthetic glucocorticoid, primarily prescribed for its anti-inflammatory and immunosuppressive effects. It is either used at low doses for chronic illnesses or used concomitantly at high ...

often combined with a local anesthetic (

lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia. When used for local anaesthesia or in nerve blocks, lidoca ...

) at the A1 pulley in the palm. The infiltration of the affected site is straightforward using standard anatomic landmarks. There is evidence that the steroid does not need to enter the sheath. The role of sonographic guidance is therefore debatable. Injection of the tendon sheath with a corticosteroid is effective over weeks to months in more than half of people. Steroid injection is not effective in people with Type 1 diabetes. If triggering persists 2 months after injection, a second injection can be considered. Most specialists recommend no more than 3 injections because corticosteroids can weaken the tendon and there is a possibility of tendon rupture. Triggering is predictably resolved by a relatively simple surgical procedure under local anesthesia. The surgeon will cut the sheath that is restricting the tendon. The patient should be awake in order to confirm adequate release. On occasion, triggering does not resolve until a slip of the FDS (Flexor digitorum superficialis) tendon is resected. One study suggests that the most cost-effective treatment is up to two corticosteroid injections followed by open release of the first annular pulley. Choosing surgery immediately is an option and can be affordable if done in the office under local anesthesia.

Surgery

Trigger digits can be released percutaneously using a needle. This is not used for the thumb where the digital reves are at greater risk.

References

External links

Video of Trigger Finger Release Surgery on YouTube

American Academy of Orthopaedic Surgeons information on trigger finger

Information from the Mayo Clinic
{{DEFAULTSORT:Trigger Finger Ailments of unknown cause Fingers Inflammations Disorders of synovium and tendon Wikipedia medicine articles ready to translate