Published 4/1/2016
Terry Stanton

Study: Shorter Time Between Injections for Trigger Finger Predictive of Need for Surgical Release

Study data indicate that patients who received a second steroid injection for stenosing tenosynovitis—commonly known as trigger finger—within 6 months of the first injection had a significantly higher likelihood of requiring surgical release than patients who received a second injection after 6 months.

The study, presented at the 2016 AAOS Annual Meeting by Charles Ekstein, MD, also found that patients who had closely spaced initial injections had a greater likelihood of developing the condition in another finger.

According to Dr. Ekstein, stenosing tenosynovitis is among the most common hand conditions, with a lifetime risk of trigger finger between 2 and 3 percent for any individual, but up to 10 percent in patients with diabetes. Patients with carpal tunnel syndrome, de Quervain's disease, hypothyroidism, and rheumatoid arthritis also appear to have a higher incidence of trigger finger.

Study methods
Dr. Ekstein and colleagues at North Shore–Long Island Jewish Medical Center conducted a retrospective review of medical records of 551 patients, seen by two board-certified hand surgeons in a single practice, who had a second corticosteroid injection in at least one finger. A total of 349 fingers in these individuals had two or more injections. They hypothesized that the period of time between a first and second steroid injection for trigger finger would not increase the likelihood that the finger would require surgery or that the patient would develop the condition in other fingers.

"We conducted this study primarily because no one had really looked at the second injection as a starting point for investigation," Dr. Ekstein commented. "There's plenty of research out there looking at success of injections, associated conditions, and cost-effectiveness of different regimens, but nothing that really examined what happens after you give that second injection. We wanted to see if that second injection had more meaning, especially with respect to its timing, rather than just recording that a second injection was done preceding surgery."

If patients returned at any point with recurrent symptoms in the same finger, they were offered a second injection. Typically, if the second injection failed to completely resolve the trigger finger in the affected digit, they were offered surgical release of the A1 pulley. Some patients opted to wait longer or refused surgery, accruing more than two injections to the same finger. Patients were evaluated postoperatively within 2 weeks, and then on an as-needed basis.

Surprising results
The median length of time between the first and second injection was 5.5 months. In patients who had two injections on the same finger within 6 months, 34 percent required surgery within 6 months of the second injection and 60 percent required surgery by 1 year (Fig. 1). Also, in patients who had 2 injections on the same finger within 6 months, 14 percent developed triggering in another finger within 1 year, and 39 percent developed stenosing tenosynovitis in another finger within 2 years. In patients whose injections were greater than 6 months apart, 8 percent developed another trigger within 1 year, and 24 percent developed the condition within 2 years. All results were statistically significant, according to the study authors.

"The results were surprising," Dr. Ekstein said. "Our hypothesis was that the time between the first and second injection wouldn't really matter, but as it turned out, it significantly impacted the future of that particular affected finger," he said. "There was a clear increase in both the likelihood of surgery and the chance to develop other triggers if the patient came back quickly to the office."

Dr. Ekstein said that the results—showing that if patients come back to the office within 6 months, they have a 60 percent chance of requiring surgery on that particular finger, and a 40 percent chance if they come back after 6 months—yield important information that can be conveyed to patients.

"For instance," he said, "imagine a patient who has received an injection for a trigger finger, and he or she returns at some point within 6 months. We can then say, 'Well, we can try a second injection, and it's the standard of care, but because you came back within 6 months, your chance of eventually needing surgery on this finger is 60 percent. Do you just want to get the surgery now?'

"This is kind of a simplification," he said, "but the idea being that there are some more aggressive patients out there, and this study really helps surgeons feel OK with potentially operating earlier and saving that particular patient the pain of another injection, or of having the trigger recur after that second injection."

Study limitations
Limitations of the study include the fact that data collection is from a retrospective chart review, and that there is a possibility of patient recall bias, particularly with regard to the duration of symptoms prior to arriving in the office. "For instance," the authors write, "patients would occasionally remember a past injection, but not recall which finger was affected. In addition, some patients received injections by outside physicians, either before beginning care in our office, or in the middle of an episode of care. We cannot control for the injection technique or corticosteroid used in these outside injections. However, we feel that the above concerns are diminished by the fact that there were so few of these outside injections within our time frame. Less than 1 percent of injections within 2 years were done by a surgeon other than the authors."

Also, the defined time period of the study, January 2007 to December 2014, may be a limitation. "For those patients who received their first steroid injection within 2 years of the end of the study, if they were not seen again before Dec. 31, 2014, they were counted as a success of the injection. Our study would not capture whether these patients returned with a failure of the injection or required surgery in 2015 or beyond," the authors noted.

Dr. Ekstein's coauthors are Kate W. Nellans, MD, MPH; Sara Merwin, MPH; Nina Kohn, MA, MBA; and Lewis B. Lane, MD.

Conflict of interest information for the authors can be found at www.aaos.org/disclosure

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org