You are in: eMedicine Specialties > Orthopedic Surgery > HAND AND UPPER EXTREMITY Trigger ThumbArticle Last Updated: Oct 23, 2003AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: David R Steinberg, MD, Director of Hand Fellowship, Associate Professor, Department of Orthopedic Surgery, University of Pennsylvania Health System David R Steinberg is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Medical Association, and American Society for Surgery of the Hand Editors: Joseph E Sheppard, MD, Director of Hand and Upper Extremity, Associate Professor, Department of Orthopedic Surgery, University of Arizona; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Michael Yaszemski, MD, PhD, Associate Professor, Departments of Orthopedic Surgery and Bioengineering, Mayo Foundation, Mayo Medical School; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Harris Gellman, MD, Consulting Surgeon, Broward Hand Center, Voluntary Clinical Professor of Orthopedic Surgery and Plastic Surgery, Departments of Orthopedic Surgery and Surgery, University of Miami School of Medicine Author and Editor Disclosure Synonyms and related keywords: trigger finger, tenosynovitis, stenosing tenosynovitis, stenosing tendovaginitis, thumb pain, locked thumb, idiopathic trigger thumb, congenital trigger thumb INTRODUCTIONSection 2 of 12
  Painful triggering or locking of the thumb is a common malady that can significantly interfere with hand function and the performance of routine activities. Much less frequently, a similar condition may occur in children. The condition in children has been referred to as congenital trigger thumb, although it usually presents sometime after infancy. ProblemTriggering of the thumb occurs when focal degenerative changes within the flexor pollicis longus (FPL) tendon lead to a localized swelling that limits tendon excursion within the tendon sheath. FrequencyIn adults, triggering most commonly occurs in the thumb, long finger, and ring finger. Idiopathic trigger thumb is 4 times more likely to develop in women than in men, usually affects women in the fifth and sixth decades of life, and is often bilateral. Trigger digits in the pediatric population occur almost exclusively in the thumb. EtiologyTrigger thumb usually occurs idiopathically. It develops more frequently in individuals with diabetes and in patients with osteoarthritis. Trigger thumb is more likely to occur in an individual with any condition that causes proliferation of the tenosynovium, such as inflammatory arthritis, gout, or chronic infection (eg, fungus or atypical mycobacteria). Certain people appear more prone to tenosynovitic conditions; patients with trigger thumb are more likely to develop carpal tunnel syndrome and de Quervain disease. The roles of overuse and trauma in trigger thumb are controversial, although the condition does have a predilection for the dominant hand. PathophysiologyTriggering normally occurs when localized swelling of the flexor tendon at the level of the metacarpophalangeal (MP) joint causes the tendon to get caught under the A1 pulley of the flexor tendon sheath. With greater constriction, the tendon nodule often suddenly sticks proximal to the sheath, causing the thumb to lock in flexion. Occasionally, the nodule may catch within the sheath, locking the digit in extension. Thickening and histologic changes occur within the A1 pulley; occasionally, a ganglion develops on the tendon sheath. Trigger thumb in patients with rheumatoid arthritis or chronic infection is due to diffuse proliferation of tenosynovium within the tendon sheath. This process can extend distal to the MP joint and, when severe, cause stiffness rather than intermittent triggering. ClinicalPatients initially present with painful clicking of the finger or popping of the proximal interphalangeal (PIP) joint. They may complain of morning stiffness of the fingers without frank triggering. More advanced involvement leads to locking, usually in flexion (occasionally in extension), which must be released by passive manipulation with the other hand. Long-standing cases may result in a stiff finger with diminished tendon excursion. In these cases, the physician must be suspicious of a trigger thumb based on history, as triggering may not be demonstrable when tendon gliding is decreased. Examination reveals a tender nodule over the distal palm that moves with flexion and extension of the finger. The physician may appreciate crepitus or clicking. The patient may be able to demonstrate active locking or snapping of the interphalangeal (IP) joint; this should not be confused with subluxation of the finger. Children with trigger thumb rarely complain of pain. They usually are brought in for evaluation when aged 1-4 years, when the parent first notices a flexed posture of the thumb IP joint. These children often demonstrate bilateral fixed flexion contractures of the thumb by the time they present to the physician. INDICATIONSSection 3 of 12
Consider surgical release of the A1 pulley in the symptomatic patient in whom nonsurgical measures have failed. Conservative treatment is not appropriate in the patient who presents with a locked digit that cannot be passively extended; the thumb fixed in flexion requires surgical correction. RELEVANT ANATOMYSection 4 of 12
The flexor anatomy of the thumb differs from that of the fingers. The FPL is a single tendon within the flexor sheath that inserts onto the base of the distal phalanx. The fibro-osseous sheath is comprised of 2 annular pulleys (A1 and A2) that arise from the palmar plates of the MP and IP joints, respectively. The oblique pulley, which originates from and inserts onto the proximal phalanx, is the most important pulley from a biomechanical perspective. The oblique pulley is approximately 10 mm in length, blending with a portion of the adductor pollicis insertion. The digital nerves and arteries run parallel to the tendon sheath distally. At the level of the MP flexion crease, they lie just deep to the skin. Proximal to the A1 pulley, the radial digital nerve of the thumb crosses obliquely over the sheath. CONTRAINDICATIONSSection 5 of 12
Other conditions whose presentation may overlap with trigger thumb include osteoarthritis, partial laceration of FPL tendon, or a tendon tumor. A locked MP joint or more distal tendon nodule may be confused with idiopathic triggering in the fingers but not in the thumb. The congenital trigger thumb must be differentiated from fracture, dislocation, congenital absence of the extensor, and, less commonly, cerebral palsy or arthrogryposis. WORKUPSection 6 of 12
Lab Studies
Imaging Studies
Histologic FindingsTensile and shearing stresses in the tendons and peritendinous tissues may lead to thickening, adhesions, and cellular proliferation in both the tendon and tendon sheath. Studies of surgical specimens have demonstrated a thickening of the A1 pulley with fibrocartilaginous changes within its inner surface. This fibrocartilage metaplasia consists of an increased number of chondrocytes and extracellular matrix. Similar changes occur on the adjacent surface of the flexor tendon. Evaluation of the nodule in the pediatric trigger thumb usually reveals noninflammatory fibrosis. TREATMENTSection 7 of 12
Medical therapyConservative treatment of trigger thumb is aimed toward the irritation surrounding the tendon through immobilization and anti-inflammatory medication. This includes oral nonsteroidal anti-inflammatory drugs, steroid injection, and judicious use of a hand-based splint that prevents motion of the MP and IP joints of the thumb (each maintained in 15° of flexion). The splint most commonly is worn at night and prevents the excessive flexing and locking that occurs during sleep. Patients with severe symptoms may need to wear the splint for daytime activities as well. The splint should not be worn for more than 10-14 days on a constant basis; after that period, wean the patient from the splint to avoid permanent stiffness. Patients with a history of triggering for more than 4-6 months or who present with locking are less likely to respond to medical treatment. Most patients who improve with corticosteroid injection do so after the first injection; some may require a second or even third injection after an appropriate interval. Preoperative detailsSurgical decompression of the trigger thumb is performed best under tourniquet using local anesthesia with or without additional intravenous sedation. Loupe magnification greatly assists in visualization of important structures. Intraoperative details
Postoperative detailsEncourage active motion as soon as the patient is comfortable. Unless the patient develops a prominent tender scar or a stiff thumb due to adhesions, formal hand therapy is rarely required. COMPLICATIONSSection 8 of 12
If the surgeon maintains a careful surgical technique, the incidence of complications should be low. The most common complication reported after trigger thumb surgery is transection of a digital nerve. The radial digital nerve is injured more frequently due to its superficial location and oblique course over the flexor sheath. Adhesions and subsequent stiffness may develop with excessive handling of the tendon or delayed postoperative mobilization. Flexor tendon sheath infection is a rare but potentially devastating complication of A1 release. Compared to trigger thumb surgery, painful scars are more likely to occur after trigger finger surgery. OUTCOME AND PROGNOSISSection 9 of 12
Idiopathic Splinting alone may lead to resolution in 50% of individuals with trigger thumb. Corticosteroid injection may be successful in as many as 90% of thumbs, although it may require as many as 3 treatments. Surgical release of the A1 pulley results in more than 95% relief of symptoms, with approximately a 3% recurrence rate. Congenital Triggering may resolve spontaneously in as many as 30% of cases. If patients are not treated by the time they are aged 4 years, many are left with permanent flexion contractures. Surgical release of the A1 pulley prior to this age leads to excellent results. FUTURE AND CONTROVERSIESSection 10 of 12
While referred to as congenital trigger thumb, recent studies have called into question the natural history of this process in the pediatric population. For this condition to occur in newborns and infants is actually unusual; congenital trigger thumb appears to develop in young children sometime during the first few years of life. Percutaneous release of the A1 pulley has been advocated for some individuals with trigger finger. This procedure should not be attempted in persons with trigger thumbs due to the significant risk of iatrogenic digital nerve injury. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Article Last Updated: Oct 23, 2003 | ||||||||||||||||||||||||||
