Steroid injection of a trigger finger

History
A very common hand condition.
Caused by a nodule over the flexor tendon, which catches at the entrance of the flexor pulleys (A1 pulley).
Patients initially complain of a painful click at the base of the finger or thumb on the palm, which ultimately leads to the finger being “stuck” in a flexed position at the PIP Jt, most commonly in the morning. They have to push it out straight, which is painful..
Trigger finger is more common in diabetics, who often have multiple fingers affected.

Examination
Often a painful nodule can be felt under the distal palmer crease, which moves when the finger moves.

Differential diagnosis

• Pseudo triggering. This is a problem of the MCP joint on the dorsum of the hand. The extensor tendons falls into the ulna sided gutter, causing the finger to lock. This is at the MCP joint and not the PIP Joint, and the pain is dorsally. Beware this diagnosis especially in the elderly.
• Tenosynovitis.  Triggering can also be a manifestation of flexor tendon sheath inflammation, especially in the Rheumatoid patient.

Investigations
There are no specific investigations needed for simple trigger finger.
If however there is a concern that there may be tenosynovitis, then an ultrasound scan can be helpful.

Treatment

• If minimal problems associated. then it can be treated conservatively.
• The mainstay of treatment is a steroid injection. This is curative in around 80% of patients with up to 2 injections. Less if the finger is permanently locked and in diabetic patients.
• If injections have failed, or if the patient is not keen on injections, then referral for surgical release is indicated.

When to refer
If you are happy to carry out injections, then I think this should be the first treatment option in symptomatic trigger finger. If this fails then refer on. If the injection works fully or partly and then the triggering returns, than a second injection is warranted if clinically required.

Injections 
Please refer to section on steroid injections for further information.

What’s the Evidence ?
Marks et al  JHS 1989. 84% success rate of trigger fingers and 92% trigger thumbs after single injection of Kenalog at 3.5 yrs

How to Inject

• Better outcome in women, worse outcome in IDDM and multiple fingers
• Blue needle
• 1ml Lignocaine and 10-20mgs Kenalog
• Distal palmer crease
• 45 degrees
• Aim for metacarpal head