The prevalence of atypical bilateral trigger thumb in children: a systematic review and meta-analysis

Abstract

Background

Trigger thumb is a common hand condition in children, and the necessity of observing a period before surgery is debated due to factors such as the metachronism of bilateral lesions, inconsistent severity, and rates of spontaneous resolution. The exact prevalence of bilateral lesions in these cases remains uncertain. Understanding these rates could help avoid unnecessary surgeries and reduce anesthetic exposure. This systematic review defines atypical bilateral trigger thumb as either metachronous or exhibiting inconsistent bilateral lesions. Its aim is to estimate the overall prevalence of atypical pediatric bilateral trigger thumb and determine the optimal observation duration to prevent unwarranted surgeries.

Methods

This study followed the PRISMA guidelines and registered in the PROSPERO. The PubMed, Embase, and Cochrane Library databases were searched for all relevant studies up to August 2025. The Joanna Briggs Institute’s quality assessment checklist was utilized to evaluate study quality. A random-effects meta-analysis was employed to synthesize prevalence rates from individual studies. Sensitivity and subgroup analyses were conducted to identify sources of heterogeneity and compare prevalence estimates.

Results

A total of five studies were included for the final analysis, with 1240 pediatric trigger thumbs. Our final meta-analysis showed that the pooled prevalence estimate of atypical pediatric bilateral trigger thumb was determined to be 5.9% (95% CI 2.7– 12.3). Significant heterogeneity was observed across the studies included in this analysis (I² = 85%; P < 0.001). Subgroup analyses showed that the pooled prevalence of metachronisim and inconsistent degree was 3.4% (95% CI 2.5– 4.8, p < 0.001) and 10.7% (95% CI 3.1– 30.7, p = 0.002), respectively. Three studies reported the age at the first visit ranged from 20.1 to 31 months, while the period of metachronism spanned from 12 to 18 months.

Conclusion

Our study demonstrates that some cases of pediatric trigger thumb exhibit bilateral metachronism and varying degrees of severity, supporting a period of 12 to 18 months of observation before surgical intervention to minimize the risk of unnecessary or secondary procedures. Given the limited evidence in this systematic review and meta-analysis, it is imperative that future research includes rigorously designed, large-sample randomized controlled trials to strengthen the evidence base.

Trial registration

PROSPERO (CRD42024562483).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-026-09553-y.

Background

Research findings indicate that the prevalence of pediatric trigger thumb (PTT) ranges from 0 to 3.3 per 1,000 live births [1, 2]. Notably, 25% to 30% of diagnosed cases exhibit bilateral symptoms [3]. Typically, toddlers are identified with pediatric trigger thumb between the ages of 6 and 24 months [4]. The exact etiology of pediatric trigger thumb remains uncertain, although some researchers suggest a combination of congenital and acquired factors may play a role [2, 5, 6]. The primary concern is a developmental mismatch between the flexor pollicis longus tendon and its surrounding sheath [7, 8].

Historically, surgical release of the A1 pulley has been the standard treatment for pediatric trigger thumb that is locked in flexion [9, 10]. However, a recent systematic review on the rate of spontaneous resolution in pediatric trigger thumb has confirmed the effectiveness of a watchful waiting approach, thereby providing evidence in support of conservative management [11]. Additionally, observations reveal a metachronous relationship in trigger thumb cases, where in symptoms on both sides do not appear simultaneously [12]. Discrepancies in symptom severity between the two thumbs—ranging from intermittent locking to complete flexion locking—have been documented [13]. For the purposes of this study, atypical bilateral trigger thumb is defined as presenting either metachronously or with inconsistent degrees of bilateral lesions. Considering the natural history of pediatric trigger thumb, which includes a spontaneous resolution rate of 43.5% [11], surgeons might contemplate delaying surgical intervention in cases of atypical bilateral trigger thumb due to potential future requirements for a second procedure and the associated risks of anesthesia [14].

However, the precise prevalence of atypical bilateral trigger thumb and the optimal observation duration to avoid unnecessary surgery remain unclear. No systematic review or meta-analysis has comprehensively assessed the prevalence of atypical bilateral trigger thumb. Such insights could be crucial in minimizing the need for subsequent surgical interventions and reducing anesthetic exposure. This information is vital for both parents and surgeons, facilitating informed decision-making regarding whether to pursue a period of observation or immediate surgical intervention for atypical bilateral trigger thumb [15–17]. The aim of this review is to conduct a thorough analysis of the existing literature on the prevalence of atypical bilateral trigger thumb in children and to determine the optimal observation duration to prevent unwarranted surgeries, utilizing both qualitative and quantitative research methodologies.

Methods

Research design and method

This study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines throughout its protocols. The systematic process of searching, assessing eligibility, evaluating quality, extracting data, and analyzing data was rigorously executed based on a predesigned protocol. Moreover, the study protocol was duly registered on the International Prospective Register of Systematic Reviews (PROSPERO) prior to the commencement of data extraction (Registration CRD42024562483).

Data source and selection process

The literature search was conducted on August, 2025, utilizing three major databases: PubMed, Embase, and The Cochrane Library. The search strategy employed a combination of MeSH terms and keywords, specifically targeting the following phrases: “trigger finger” or “trigger thumb” and “child” or “infant” or “newborn” or “pediatric”. To ensure comprehensive coverage, additional relevant studies were identified by thoroughly reviewing the reference lists of the selected eligible studies.

Eligibility criteria and study selection

In this comprehensive review, we included studies that adhered to the following criteria: (Ⅰ) The study participants were children diagnosed with pediatric trigger thumb, aged up to 14 years, as well as reported at least 20 pediatric bilateral trigger thumbs; (Ⅱ) The study either reported the prevalence of atypical pediatric bilateral trigger thumb or provided sufficient data to calculate this prevalence; (Ⅲ) Atypical bilateral trigger thumb is defined as presenting either metachronously or with inconsistent degrees of bilateral lesions; (Ⅳ) The study was published in the English language. We excluded reviews, commentaries, case reports, and studies conducted on animal subjects. Additionally, letters to the editor, conference papers, books, editorials, gray literature, conference abstracts, non-indexed studies and notes were also excluded from our analysis.

Methods for data extraction and quality assessment

Two independent authors extracted pertinent data from the selected studies. The information collected from each study encompassed the following details: the name of the first author(s), the sample size, the year of publication, the age at the initial visit, metachronisim, inconsistent degree of bilateral lesions, as well as the number of atypical pediatric bilateral trigger thumb and their corresponding prevalence estimates.

All search results were aggregated and subsequently subjected to an independent eligibility screening by two of the authors. In instances of disagreement, a third author intervened during a meeting with the screening authors to mediate and resolve conflicts. This was achieved by attentively listening to the arguments presented and fostering discussions until a consensus was reached. The screening process entailed a review of the abstracts for each result. Following the initial screening and elimination of duplicates, the studies deemed potentially relevant were subjected to a thorough full-text review to ascertain their suitability for inclusion.

Eligible studies were evaluated for methodological quality by two independent reviewers using the Joanna Briggs Institute Quality Assessment Tool. This tool categorizes responses as ‘yes,’ ‘no,’ ‘not clear,’ and ‘not applicable.’ based on frequency scales. The total quality score for each study was determined by counting the positive responses, and any disagreements between reviewers were resolved through discussion. The appraisal results were presented both narratively and in tabular form. All studies that met the established quality threshold proceeded to data extraction and synthesis.

Data synthesis and analysis

In this research, all statistical analyses were performed utilizing the Comprehensive Meta-Analysis Software, version 3.0. The prevalence rates derived from the individual studies were amalgamated through the application of a random-effects meta-analysis model [18]. To evaluate the degree of heterogeneity between the studies, the I² statistic was employed [18]. The interpretation of the I² values is as follows: a value of 75% indicates high heterogeneity, 50% signifies medium heterogeneity, and 25% denotes low heterogeneity [19]. To assess potential sources of heterogeneity across the studies, we considered two key factors: metachronism of bilateral lesions and inconsistent degree of bilateral lesions. To evaluate the risk of publication bias, we employed Egger’s regression tests and funnel plots. For all statistical analyses, a P-value of 0.05 was established as the statistical significance. To further investigate the potential sources of heterogeneity among the studies included in our analysis, we conducted a leave-one-out sensitivity analysis.

Results

Identifcation of relevant studies

We initially identified 820 studies, excluding 229 duplicates, 359 titles, and 200 abstracts. This left 32 publications for further review, of which 5 were suitable for inclusion in our systematic review and meta-analysis (Fig. 1). No additional studies were identified by checking the references of the included papers. No relevant unpublished studies were obtained.

Fig. 1.

PRISMA flowchart of review search

Characteristics of included studies

The fundamental attributes of the studies encompassed in this systematic review and meta-analysis are delineated in Table 1. In total, 5 articles [8, 12, 13, 20, 21] were incorporated into the final analysis, encompassing 1240 cases of pediatric trigger thumb. Three studies reported the age at the first visit ranged from 20.1 to 31 months, while the period of metachronism spanned from 12 to 18 months. Two studies reported inconsistent degree of bilateral lesions. Among the three studies reporting on treatment modalities for atypical bilateral lesions, Lin et al. and Huang et al. described three and seven additional interventions, respectively.

Table 1.

The characteristics of included studies

Study name	Sample size	Prevalence, cases (n)	age at the first visit(months)	Metachronism(months)	Inconsistent degree of bilateral lesions	Treatment modalities for atypical bilateral lesions
Paaske BP 1995 [20]	58	19%,11	-	-	one side: trigger finger contralateral side: thickening, but no symptoms	-
Marek DJ 2011 [13]	173	6%,10	-	-	one side: trigger thumb contralateral side: locked	Ten simultaneous surgical interventions
Verma M 2013 [8]	28	7%,2	31	18(range:5–26)	-	-
Lin JS 2021 [12]	198	3%,5	24(range:8–37)	12(range:6–27)	-	Two simultaneous surgical interventions, Three additional interventions
Huang P 2023 [21]	783	3%,27	20.1(range:5–62)	13.5(range:1–36)	-	Seven additional interventions

Quality of included studies

Table 2 presents a detailed analysis of the quality and potential biases inherent in the studies included in this review. Drawing upon the Joanna Briggs Institute’s quality evaluation checklist, the articles selected for the final analysis exhibited a mean quality score of 7.4, with individual scores spanning from 5 to 9.

Table 2.

Qualities of included studies

Study name	Response
	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	Q9	Total
Paaske BP 1995 [20]	N	Y	N	Y	Y	Y	Y	Y	U	6
Marek DJ 2011 [13]	Y	Y	Y	Y	Y	Y	Y	Y	U	8
Verma M 2013 [8]	N	Y	N	Y	N	Y	Y	Y	U	5
Lin JS 2021 [12]	Y	Y	Y	Y	Y	Y	Y	Y	Y	9
Huang P 2023 [21]	Y	Y	Y	Y	Y	Y	Y	Y	Y	9

Keys:

Q1–Q9 represents questions used to assess the quality of included studies, which are listed below

Q1. Was the sample frame appropriate to address the target populations?

Q2. Were the study participants sampled appropriately?

Q3. Was the sample size adequate?

Q4. Were the study subjects and setting described in detail?

Q5. Was the data analysis conducted with suffcient coverage of the identifed sample?

Q6. Was a valid method used in the identification of conditions?

Q7. Was the condition measured in a standard, reliable way for all participants?

Q8. Was there an appropriate statistical analysis?

Q9. Was the response rate adequate, and if not, was the low response rate managed appropriately?

Y yes, N no, U unclear, NA not applicable

The prevalence of atypical pediatric bilateral trigger thumb (meta-analysis)

The pooled prevalence estimate of atypical pediatric bilateral trigger thumb was determined to be 5.9% (95% CI 2.7– 12.3). However, significant heterogeneity was observed across the studies included in this analysis (I² = 85%; p < 0.001) (Fig. 2). Subgroup analyses showed that the pooled prevalence of metachronisim and inconsistent degree was 3.4% (95% CI 2.5– 4.8, p < 0.001) and 10.7% (95% CI 3.1– 30.7, p = 0.002), respectively (Table 3).

Fig. 2.

The prevalence of atypical pediatric bilateral trigger thumb: a random-effect meta-analysis (I² = 85%; p < 0.001;based on random effect model)

Table 3.

Sensitivity analysis of included studies

Subgroups	Studies, n	Prevalence (%)	95% CI	Heterogeneity across the studies		Heterogeneity between groups (P-value)
				I2	P-value
Metachronism of bilateral lesions	3	3.4%	2.5–4.8	0	0.45	p < 0.001
Inconsistent degree of bilateral lesions	2	10.7%	3.1–30.7	88	0.004	0.002

Sensitivity analysis

To identify potential sources of heterogeneity across the studies and to examine the differences between groups estimating atypical pediatric bilateral trigger thumb, we conducted a stratified analysis by categorizing participants based on two key variables: metachronism of bilateral lesions and inconsistent degree of bilateral lesions. Subgroup analyses showed that the prevalence of metachronisim and inconsistent degree was 3.4% (95% CI 2.5– 4.8, p < 0.001) and 10.7% (95% CI 3.1– 30.7, p = 0.002), respectively (Table 3).

To further investigate the potential sources of heterogeneity among the studies included in our analysis, we conducted a leave-one-out sensitivity analysis. Upon excluding each study one at a time, the pooled estimated prevalence of atypical pediatric bilateral trigger thumb ranged from 4.0% (95% CI 2.8– 5.7) to 7.2% (95% CI 3.0– 16.5), thus affirming the stability of our results.

Publication bias

In our comprehensive systematic review and meta-analysis, we uncovered no indications of potential publication bias concerning the prevalence of atypical pediatric bilateral trigger thumb. This conclusion is substantiated by the symmetrical appearance of the funnel plot and corroborated by the results of regression tests associated with the funnel plot analysis (Egger’s test) ( B = 1.79, SE = 3.27, P = 0.621) (Fig. 3).

Fig. 3.

Funnel plot of the risk of publication bias for the prevalence of atypical pediatric bilateral trigger thumb

Discussion

Key findings

To the best of our knowledge, this study represents the first comprehensive systematic review and meta-analysis aimed at estimating the prevalence of atypical pediatric bilateral trigger thumb. Our review encompassed five studies that investigated this phenomenon. Both our qualitative and quantitative analyses revealed that the existing scientific evidence on the prevalence of atypical pediatric bilateral trigger thumb exhibits substantial variability depending on metachronism of bilateral lesions and inconsistent degree of bilateral lesions.

Our comprehensive meta-analysis determined that the pooled prevalence estimate of atypical pediatric bilateral trigger thumb is 5.9%. Subgroup analyses indicated that the pooled prevalence of metachronism and inconsistent degree were 3.4% and 10.7%, respectively. Age at the first visit and metachronisim, ranging from 20.1 to 31 months, 12 to 18 months, respectively. This study shows that for unilateral trigger thumb, it is necessary to fully communicate with the family and observe for 12 to 18 months to reduce the risk of second operation and anesthesia for contralateral trigger thumb.

Comparisons with the existing evidence

The current study’s prevalence estimates for atypical pediatric bilateral trigger thumb stand at 5.9%. the prevalence of metachronism was 3.4%. Age at the first visit and metachronisim, ranging from 20.1 to 31 months, 12 to 18 months, respectively. This is a similar from the conclusions previously reported by certain scholars. Lin et al. [12] reported five patients (3%) were subsequently diagnosed with contralateral trigger thumb after initial presentation of unilateral trigger thumb. Average time to contralateral trigger thumb development was 12 months after presentation in unilateral patients. Similarly, Huang et al. [21]documented 27 cases (3.4%) within the metachronisim bilateral trigger thumb. The mean age at the initial onset was 20.1 months, while the mean age at diagnosis for the contralateral thumb was 33.6 months. This finding supports the possibility of a developmental etiology of the trigger thumb, which may be due to the mismatch between the flexor pollicis longus tendon and the sheath during growth and development.

Subgroup analyses revealed that the pooled prevalence of inconsistent degree bilateral trigger thumb was 10.7%. This finding underscores the importance of thorough family discussions when addressing bilateral trigger thumbs. Baek et al. [22] reported more than half of the affected children can expect natural recovery without the need for surgical intervention, typically within an average follow-up period of approximately four years. However, sevencan et al. [23] found that surgical intervention involving A1 pulley release has demonstrated successful outcomes for children over the age of five. Based on reports regarding the time to natural recovery and the efficacy of surgery, our findings provide data that delaying surgical intervention in cases of atypical bilateral trigger thumb for a period of 12 to 18 months as a feasible approach. This strategy prioritizes patient safety, mitigates the risk of unnecessary or secondary surgical procedures, and allows for the natural recovery process to take place.

Strength and limitations

The present study has several strengths. Firstly, this systematic review and meta-analysis aims to determine the prevalence of atypical pediatric bilateral trigger thumb. By consolidating existing research, it provides a foundational understanding of this medical phenomenon. Secondly, the study estimates the prevalence rates of atypical pediatric bilateral trigger thumb by considering specific subgroups based on critical factors such as metachronism of bilateral lesions and inconsistent degree of bilateral lesions. This approach allows for assessment of the condition across different patient demographics. Thirdly, the study includes subgroup and sensitivity analyses to enhance the reliability and validity of the findings. These methodological strengths collectively support the study’s contribution to pediatric orthopedics, providing valuable insights for both clinicians and researchers.

The systematic review and meta-analysis have several inherent limitations that require careful consideration. These include non-standardized definitions of metachronism and inconsistent severity, potential overlap among subgroups, high heterogeneity (I² = 85%), and limited follow-up durations in the source studies, which may lead to an underestimation of prevalence. Furthermore, the assessment of publication bias is underpowered due to the inclusion of only five studies, and there is a risk of selection bias stemming from the requirement of at least 20 bilateral cases. It is important to note that the pooled prevalence represents only the included studies and not the true population rates. Additionally, our review exclusively focused on studies published in English.

The implication of the findings

In future research, it is essential to establish standardized definitions for metachronism and inconsistent severity, ensure uniform follow-up periods to minimize the risk of unnecessary or secondary surgical procedures, and utilize registry-based or prospective study designs to investigate the underlying reasons for the prevalence rates of atypical pediatric bilateral trigger thumb.

Conclusion

Our study demonstrates that some cases of pediatric trigger thumb exhibit bilateral metachronism and varying degrees of severity, supporting a period of 12 to 18 months of observation before surgical intervention to minimize the risk of unnecessary or secondary procedures. Given the limited evidence in this systematic review and meta-analysis, it is imperative that future research includes rigorously designed, large-sample randomized controlled trials to strengthen the evidence base.

Authors’ contributions

Miao XL conceptualized the study, performed the search conducted analyses, conducted the quality assessment, write-up and approval of the final manuscript. Tang QS was involved in data extraction, read and approved the final manuscript. Li XH and Xu Y was participated in discussion and consensus and approved the final manuscript. All authors read and approved the final manuscript.

Funding

The authors declare that there is no funding.

Data availability

All data generated or analyzed during this study are included in this article.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.