EDITOR’S CHOICE Relationship of Carpal Tunnel Release and New Onset Trigger Finger Dafang Zhang, MD, *† Jamie Collins, PhD, *† Brandon E. Earp, MD, *† Philip Blazar, MD*† Purpose Carpal tunnel syndrome and trigger finger (TF) frequently present concomitantly; some studies suggest that carpal tunnel release (CTR) is a risk factor for the development of ipsilateral TF in the postoperative period. The primary objective of this study was to elucidate the relationship between CTR and the subsequent development of TF. Methods A retrospective study was conducted of 1,386 hands in 1,140 patients who under- went primary CTR at a tertiary referral center from July 2008 to June 2013. After exclusion of cases in which contralateral CTR was performed within the first postoperative year after ipsilateral CTR, conditional logistic regression was performed in 906 hands in 890 patients to determine the association between CTR and TF in the first postoperative year in the operative hand compared with the contralateral hand. Conditional logistic regression and Poisson regression were performed in 1,386 hands in 1,140 patients to examine the association be- tween CTR and TF in the year before surgery compared with the year after surgery. Multi- variable regression analysis was used to determine associated risk factors. Results Of 1,386 hands, a new TF was seen in 147 (10.6%) within 1 year before CTR and 81 (5.8%) within 1 year after CTR. The occurrence of postoperative TF was associated with 2.5 times higher odds in the operative hand compared with the contralateral hand in the conditional logistic regression model of 906 cases. However, the incidence of TF was associated with 0.5 times lower odds during the year after CTR compared with the year before CTR in both con- ditional logistic regression and Poisson regression models of 1,386 cases. Increased body mass index is statistically associated with TF after CTR, but the attributable risk is negligible. Conclusions There is a predisposition for these 2 common hand pathologies to present in the same hand; however, patients can be counseled that CTR does not cause new incidence of TF in the operative hand. (J Hand Surg Am. 2019;44(1):28e34. Copyright Ó 2019 by the American Society for Surgery of the Hand. All rights reserved.) Type of study/level of evidence Prognostic IV. Key words Carpal tunnel syndrome, carpal tunnel release, trigger finger, postoperative trig- gering, new onset triggering. T HE ASSOCIATION BETWEEN CARPAL tunnel syndrome (CTS) and trigger finger (TF), or stenosing flexor tenosynovitis, is incompletely character- ized. Prior studies have shown that these 2 common hand pathologies frequently present concomitantly. 1e3 Other studies go further to suggest that carpal tunnel release (CTR) is a risk factor for the development of ipsilateral TF in the postoperative period. 4,5 The primary objective of this study was to elucidate the relationship between CTR and the development of TF. Our null hypotheses were that (1) there would be From the *Department of Orthopaedic Surgery, Brigham and Women’s Hospital; and †Harvard Medical School, Boston, MA. Received for publication March 12, 2018; accepted in revised form October 3, 2018. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Dafang Zhang, MD, Department of Orthopedic Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115; e-mail: dzhang9@partners. org. 0363-5023/19/4401-0005$36.00/0 https://doi.org/10.1016/j.jhsa.2018.10.003 28 r Ó 2019 ASSH r Published by Elsevier, Inc. All rights reserved.