This study provides insights into the characteristics, congenital comorbidities, and developmental outcomes of children with trigger thumbs. The incidence was 0.64%, with no significant demographic differences in birth weight, breastfeeding habits, or income levels between the affected and control groups. Notably, children with trigger thumb have greater odds of developing musculoskeletal malformations, lens malformations, or circulatory system conditions. Despite these associations, developmental assessments using GEE showed no significant delays in gross motor, fine motor, cognitive, language, social, or self-help skills. These results indicate that although pediatric trigger thumb is linked to certain congenital malformations, it does not adversely affect the overall developmental milestones during early childhood, emphasizing the need for comprehensive care and monitoring.
Our study revealed a trigger thumb incidence of 6 per 1,000 births in this cohort, which is slightly greater than the previously reported range of 1–3 per 1,000 births [6, 19–22]. This discrepancy may be due to underestimation in previous studies with limited sample sizes, overestimation in our study due to the inclusion of cases that mimic trigger thumb, and ethnic variations, as seen in the higher rates among Hispanic populations [23]. A Japanese study reported an incidence of 3.3 cases per 1,000 births [6], and their method of postal questionnaires to parents one year after birth might have underestimated the true prevalence. Further research is warranted to investigate these potential explanations and to establish a more accurate understanding of trigger thumb incidence across different populations.
The mean time to diagnosis of trigger thumb was 31.3 months, which is similar to or slightly earlier than the previously reported age [2, 19, 24]. Generally, pediatric patients visit clinics with an abnormally flexed thumb and/or an inability to extend the thumb, which is often noticed by their parents or caregivers at approximately age 2 years [19]. Improved medical accessibility and government pediatric health checkup programs may facilitate earlier diagnosis. In Korea, all children aged 4 months to 6 years are required to undergo pediatric health examinations, which may lead to earlier diagnosis.
More than half of the patients in this study were managed non-surgically. The 32.6% rate of surgical treatment for pediatric trigger thumbs was lower than that previously reported [2]. In the US, national health claims data showed a 49% rate of surgical treatment for trigger thumb [2]. The low surgical rate in our study may be due to the early diagnosis of less severe cases, which could be managed with observation or conservative treatment. The outcomes of nonsurgical treatment vary; an observational US study reported spontaneous resolution in approximately one-third of patients [4]. However, for patients with > 30° interphalangeal joint flexion and contracture at diagnosis, surgical treatment is more likely [4]. In another prospective follow-up study, the spontaneous resolution rate was estimated to be greater than 75% after at least 5 years of follow-up [25]. Given the high rate of spontaneous recovery [5, 26], early detection and supportive care in our study may explain the lower rate of surgical intervention.
Our study found that children with trigger thumb had a higher prevalence of musculoskeletal, lens, and circulatory system malformations. This association may be attributed to genetic, environmental, or physiological factors. Pediatric trigger thumb, although not diagnosed at birth, has been reported in twins and siblings, suggesting a congenital or genetic link [5, 8, 27–31]. Specific genetic mutations may cause both trigger finger and congenital malformations owing to their impact on musculoskeletal and connective tissue development. Environmental stressors or toxins during critical stages of fetal development can also result in malformations in various body systems, including the lens and circulatory system. These systems are particularly sensitive during early gestation, and disruptions can lead to malformations. Moreover, the trigger thumb itself may indicate abnormalities in specific physiological processes during fetal development, potentially leading to other developmental abnormalities. Mechanical stress or abnormal growth patterns associated with the development of trigger finger can result in systemic malformations. These findings suggest that the association between pediatric trigger finger and concurrent malformations is multifaceted and involves genetic, environmental, and physiological influences, warranting further research to clarify the causal pathways involved.
One point to consider here is the high likelihood of developing musculoskeletal system disorders (ICD-10 codes Q65-79). This could be due to misdiagnosis, as the trigger thumb is often mistaken for a congenital abnormality of the musculoskeletal system, although the actual co-occurrence rate is not high. Some primary care physicians are unfamiliar with this condition and may miscode it as a musculoskeletal malformation. To further clarify this issue and gain a more accurate understanding of the comorbidities associated with pediatric trigger thumb, a more detailed analysis of the lower-level codes within the Q65-79 category is required.
Our study found no significant association between trigger thumb and developmental delay. Despite the presence of trigger thumb and associated congenital malformations, affected children generally achieve developmental milestones at a rate comparable to that of their peers. This lack of association can be attributed to the fact that the trigger thumb primarily affects the tendons and does not disrupt the neurological or muscular systems critical for overall development. These findings highlight the importance of distinguishing between congenital physical abnormalities and their effects on development. Although it is crucial to monitor and manage trigger finger and its associated conditions, parents and healthcare providers can be reassured that the condition alone is unlikely to hinder a child’s development. Further research should continue to monitor developmental outcomes in children with trigger finger to confirm these findings and explore any long-term effects.
In this study, a large sample exceeding 2,000,000 children, including those with trigger thumb and a matched control group, provided a robust and representative dataset. Employing GEE accounted for correlations and was adjusted for multiple confounders, thus enhancing the reliability of the findings. The inclusion of confounding factors, such as sex, birth weight, prematurity, breastfeeding, and socioeconomic status, strengthened the validity of the conclusions. Additionally, a detailed analysis of specific congenital malformations associated with trigger thumbs offers valuable insights into their broader health implications.
However, this study had some limitations. First, the initial diagnostic code for congenital malformations of the trigger thumb and comorbidities could have been incorrectly recorded due to incomplete diagnostic work-up, potentially overestimating the prevalence in patients with trigger thumbs. Second, the health claims data lacked detailed information, making it difficult to discriminate trigger thumb from trigger finger and to analyze laterality and bilateral cases. Third, this study only included patients who visited clinics, potentially excluding subclinical or undiagnosed patients. Finally, the follow-up period ending in 2018 may have missed some children who later underwent surgery.