Differences in Flare Reaction Incidence and Intensity Following Trigger Finger Injections

Corticosteroid injections are effective non-surgical approach to treating trigger finger (stenosing tenosynovitis) with success rates reported as high as 92% after just one injection [1]. Among their side effects is a post-injection flare of increased pain that is attributed to crystal-induced synovitis. Reports of these flares in the literature have been rare. Recent evidence their incidence can be as high as 33%. The investigators feel it is a more common clinical issue than traditionally reported and it would be beneficial to control and reduce their incidence if possible.

Two common corticosteroids used for trigger finger treatment are betamethasone and methylprednisolone. Both injections are effective in treating trigger finger and the decision of which to use in treatment is currently a matter of the current practice and physician preference. There is no literature comparing the side effects, specifically flare reactions between these two treatments. The goal through this randomized trial is to see whether there is a difference between these two corticosteroids in inducing flare reactions and if there are any differences in the peak level of pain and their duration.

This is a double-blinded randomized trial enrolling patients into one of the two treatment groups. The volume of the doses will be standardized to 1 cc of either methylprednisolone (40 mg) or betamethasone (6 mg). Patients, who meet the inclusion criteria, will be instructed to complete a visual analog scale (VAS) of their pain (1-10) prior to the injection, during the injection and once a day for the following 7 days after the injection. The investigators estimate that a minimum of 30 patients in each group will be needed to achieve a minimum of 80% power and 0.05 significance. The incidence, intensity, time to peak and time to resolution of the flare reactions (defined as a 2-point increase from pre-injection pain) will be assessed and compared between the two groups. Findings indicating a statistically significant difference in the incidence and/or intensity of the flare reactions would be clinically significant and would be evidence supporting the switch of current practice to one corticosteroid over the other.

Inclusion criteria

• Single trigger injection
• First time for the digit
• No prior surgery on digit

Exclusion criteria

• Current oral steroid use
• Rheumatoid arthritis
• More than one single digit involved
• Previous injection in same digit
• Prior surgery on same digit
• Other injections in the same clinic on the same day