Younger Age and Left Side Are Risk Factors for Contralateral Trigger Thumb in Children.

BACKGROUND: The metachronism of bilateral trigger thumb (TT) may lead to additional surgery under anesthesia. The aim of this study was to investigate the temporal development of bilateral TT, find risk factors for contralateral TT, and provide evidence for clinical practice. METHODS: A retrospective analysis was performed on children diagnosed with TT in our hospital from January 2016 to December 2019. Age at onset, laterality, sex, the interval time of onset of contralateral symptoms, age at the time of surgery, and preoperative and postoperative follow-up times were collected. The cases were divided into 3 groups: (1) the unilateral group, (2) the simultaneous bilateral group, and (3) the separate bilateral group. RESULTS: A total of 783 patients with 967 TTs were enrolled. There were 599 (76.5%) cases in the unilateral group, 157 (20.1%) cases in the simultaneous bilateral group, and 27 (3.4%) cases in the separate bilateral group. Seven (0.9%) patients underwent additional surgery on the contralateral side under anesthesia. Of these 7 patients, 6 (85.7%) had left-side onset and 5 (71.4%) patients developed bilateral TT by the age of 4. The mean age at the initial onset in the separate bilateral group was 20.1 months, and the mean age at diagnosis of the contralateral thumb was 33.6 months. Binary logistic regression analysis showed that age and side at initial onset had significant differences ( P =0.043 and 0.000, respectively). Receiver operating characteristic curve analysis showed that the cutoff value of age at initial onset was 16 months. CONCLUSIONS: There was a low incidence of metachronous bilateral TT with additional surgery for the contralateral thumb. Age and side at initial onset are risk factors for contralateral TT. LEVEL OF EVIDENCE: Level II; prognostic studies.