Trigger finger or ‘stenosing tenosynovitis’ is among the top five causes of disability in the hand. It presents with pain and locking of the fingers and is due to pathology of the tendons and tendon sheath. Interestingly it commonly affects two very different age groups, children under eight and adults(more common) in the fifth and sixth decade. While in children there is a 90% incidence of the thumb being involved, the adult group can have the thumb or the ring finger affected. As you read onwards this article highlights the presentation, pathophysiology, causes and treatment options available.
- the classic complaint in trigger finger is locking of a finger in a flexed position and a subsequent difficulty in achieving a full straightening or extension, this eventually releases with a snap or has to be forced open passively resulting in pain in the distal palm and the digit
- milder cases may present with a discomfort and stiffness in moving the digits particularly after periods of rest or uneven finger movements
- multiple digits may be affected in individuals with diabetes or rheumatoid arthritis
- some patients may have a painful node at the base of the finger without any snapping or triggering
- some patients may report swelling of the digit
- on examination a tender palpable node is often felt at the distal palmar crease
Normally the flexor tendons slide back and forth within a tendon sheath. Think of the sheath as tunnel within which the tendon glides to move the fingers. Thickening of this tendon sheath along with some tendon thickening results in a narrowed tunnel for excursion. A nodule might develop in the tendon which ultimately leads to a block in movement. With forceful attempts to straighten the finger this node passes through the point of restriction resulting in a ‘snap.’ The commonest site for this is at the metacarpophalyngeal joint or at the distal palmar crease of the hand, because this is the site of high local forces and maximal tendon excursion.
- overuse of the hands from work or recreational activities
- occupations involving repetitive finger movements and compressive forces at the distal palmar crease eg: long hours of grasping a steering wheel or use of pistol gripped power tools
- direct injury resulting in microtrauma to the tendon sheath
- partial tendon lacerations
- contributing factors can be an associated medical condition such as rheumatoid arthritis, diabetes, hypothyroidism, amyloidoses, gout
- it commonly coexists with other hand disorders such as carpal tunnel syndrome, deQuervains tenosynovitis, dupuytrens contracture
For more severe cases that do not respond to the above conservative management, other treatment options are:
- steroid injection
- percutaneous trigger finger release
- surgery; success rates vary from 60% to 97%, complication rates are high. Complications include long term scar tenderness, inadequate release, nerve damage and infection.