Abstract
Background:
The flexor digitorum superficialis of the little finger (FDS-small) exhibits anatomical variation, with absence reported in 2% to 30% of individuals. As FDS is the only flexor of the proximal interphalangeal joint (PIPJ), its absence may affect finger dexterity, particularly in professional musicians who depend on precise finger control. This study evaluates the impact of FDS-small presence or absence on the technical abilities of pianists and string musicians using novel dynamic assessment tools.
Methods:
Thirty-one Bachelor of Music students (21 string players, 10 pianists) were assessed for FDS-small function and classified as “independent,” “common,” or “absent.” Tests included grip strength, static gap, and stretch tests, and a novel assessment method comprising custom-composed double-stop trill etudes for piano and strings. Technical performance was evaluated by 2 professional musicians using predefined criteria. Statistical analyses were conducted using Fisher’s exact tests, t tests, analysis of variance, and nonparametric equivalents.
Results:
Ten participants had absent FDS-small function in at least 1 hand. Pianists with bilateral absent FDS-small demonstrated superior coordination and regularity compared with those with FDS-small presence, while FDS-small absence did not significantly affect string players. Female pianists excelled in dynamic tests despite male musicians’ higher grip strength and trill speed.
Conclusion:
Absence of FDS-small does not impair, and may even enhance, fine motor performance in pianists. For string musicians, FDS-small status does not influence technique. These findings may contribute to evaluating the risk versus benefits of FDS-small surgical repair and have implications for instrument selection and pedagogy.
Introduction
The anatomical variations of the flexor digitorum superficialis of the little finger (FDS-small), especially its absence, ranges from 2% to 30%.1,2 Since FDS is the only flexor of the proximal interphalangeal joint (PIPJ), independent flexion of the little finger at the PIPJ may thus be functionally different between individuals with differing anatomy.3,4 Consequently, individuals in whom the FDS-small is absent depend solely on the flexor digitorum profundus for concurrent flexion at both interphalangeal joints of the little finger.5,6 As a result, if there is an absence of FDS-small, there may be a difference in dexterity and fine motor function of the little finger, which may impact individuals who rely heavily on precise finger movement. Professional musicians require a large repertoire of highly skilled finger movements, including but not limited to accurate, precise, and dexterous maneuvers. 7 They thus represent a relevant population for studying the FDS-small, which will provide valuable insights into the functional implications of FDS-small absence in real-world contexts.
The authors believe that evaluating the impact of absent or present FDS-small function on the technical abilities of professional musicians requires a combination of both static and dynamic testing methods. To the authors’ knowledge, this is the first study in the literature which has developed novel dynamic testing and standardized criteria to evaluate the impact of FDS-small on the technical abilities of string players and pianists.
This also has wider implications for the general public. For example, if tendon lacerations are sustained to the FDS-small, especially in zone II of the hand, which is a challenging site to operate, 8 a surgeon would need to weigh the advantages and disadvantages of such an operation, and thus the exact importance of FDS-small needs to be carefully ascertained.
The aim of our study is to use a novel dynamic testing methodology to assess the impact of FDS-small presence or absence on the fine motor abilities of professional musicians, which will aid in evaluating the benefits and risks associated with its surgical repair.
Methods
We conducted an anatomic study in a music conservatory of a tertiary institution, and Bachelor of Music students who are professionally trained were recruited from February 2024 to October 2024.
Flexor digitorum superficialis of the little finger function was assessed using the standard (Supplemental Figure 1) and modified tests (Supplemental Figure 2), it is classified as either “independent,” “common,” or “absent” (Table 1). Independent function requires more than 80° flexion of the little finger at the PIPJ.9,10
Description of the Standard and Modified FDS-Small Function Tests, Which Are Used to Classify the FDS-Small Function as “Independent,” “Common,” or “Absent.”
Note. FDS-small = flexor digitorum superficialis of the little finger; FDS-ring = flexor digitorum superficialis of the ring finger; IPJ = interphalangeal joints; PIPJ = proximal interphalangeal joint; DIPJ = distal interphalangeal joints.
All participants were asked to perform a grip strength test, static tests and a dynamic test—this comprises the Liau Dexterity Hand Assessment which is a self-developed assessment by the authors that incorporates existing literature (Table 2).11,12 Bilateral hand grip strength was measured for all participants using a handheld dynamometer. Static tests include a gap (Supplemental Figure 3) and stretch test (Supplemental Figure 4), while the dynamic test required the participants to play a double-stop trill etude, which consist of a strings musical excerpt by Yang-Liau and a piano musical excerpt by Liau-Yang (Supplemental Figure 5). 13 Both musical excerpts are original compositions by our authors, which are designed to technically challenge the presence or absence of FDS-small. Two professional musicians then assessed the performances independently, using a predevised set of criteria that can holistically judge the technical ability of participants (Table 3).
Description of the Tests Assessed and Measurements Taken From All Participants.
Note. DIPJ = distal interphalangeal joints; MRDL = Musicians Reported Difficulty Level.
Criteria Assessed by Two Independent Professional Musicians.
This study and research protocol was approved by the National Healthcare Group Ethics and Compliance Online System (Institutional Review Board approval number: 2023/0043). Informed consent was obtained from all participants before their enrolment into the study.
Fisher’s exact tests were used to test differences between categorical data. The Shapiro-Wilk test was used to assess the normality of the continuous data recorded. All continuous data had a normal distribution except for the regularity and intonation scores. Mean values were compared using parametric tests including Student’s t test or one-way analysis of variance (ANOVA), while medians were compared using nonparametric tests including the Mann-Whitney U test or Kruskal-Wallis H test. Values are reported with a 95% confidence interval (95% CI). A P value of <.05 was considered statistically significant.
Results
Our participants consisted of 21 string musicians and 10 pianists. String musicians were further comprised of 16 violinists and 5 cellists. Table 4 shows the demographics of the musicians and illustrates the prevalence of the different FDS-small functions in the participants. Overall, 10 out of 31 participants had absent FDS-small function in at least 1 hand. Five of them had unilateral absence while 5 had bilateral absence. Results obtained from the tests conducted are given in Table 5, and further subgroup analysis by bilateral FDS-small function and by gender are given in Table 6.
Demographics of Participants.
Note. FDS-small = flexor digitorum superficialis of the little finger; 95% CI = 95% confidence interval.
Recorded Measurements of the Tests Performed on Participants.
Note. 95% CI = 95% confidence interval; DIPJ = distal interphalangeal joints.
Subgroup Analysis by Bilateral FDS-Small Function and by Gender.
Note. Bold indicates statistical significance. FDS-small = flexor digitorum superficialis of the little finger; 95% CI = 95% confidence interval.
Pianists with bilateral absent FDS-small function performed better than pianists with nonbilateral absent function in terms of regularity ([median 7.94, 95% CI 5.82-10.1] vs [median 4.86, 95% CI 3.56-6.16]) and coordination ([mean 7.69, 95% CI 5.57-9.81] vs [mean 4.14, 95% CI 2.71-5.57]). Pianists reported significantly greater difficulty when playing the trill with their right hand (mean 6.00, 95% CI 4.42-7.58) compared with their left hand (mean 3.80, 95% CI 2.50-5.10) (P = .026).
The absence or presence of FDS-small did not significantly affect the technique of string musicians. Both groups performed similarly for regularity, coordination, intonation and the number of trills in 10 seconds.
Female pianists performed significantly better in the dynamic tests than male pianists. They performed more trills in 10 seconds ([mean 37.8, 95% CI 33.1-42.4] vs [mean 32.3, 95% CI 28.8-35.7]), had a higher regularity score ([median 7.34, 95% CI 6.48-8.21] vs [median 4.23, 95% CI 3.40-5.06]), and higher coordination score ([mean 6.94, 95% CI 5.93-7.95] vs [mean 3.46, 95% CI 2.59-4.33]).
For string musicians, male musicians had stronger right hand grip strength ([mean 31.7, 95% CI 26.4-37.0] vs [mean 21.5, 95% CI 18.5-24.5]), stronger left hand grip strength ([mean 28.7, 95% CI 22.6-34.8] vs [mean 20.9, 95% CI 16.6-25.2]), and performed more trills in 10 seconds ([mean 32.9, 95% CI 27.4-38.5] vs [mean 23.9, 95% CI 19.1-28.8]).
Discussion
A previous study by Godwin et al only conducted the static gap and stretch tests on musicians, however we agree with Godwin et al 13 that their chosen static tests were arbitrary and not classical musical exercises, which have little relevance to musicians in actual performance settings. We believe that the dynamic tests that comprises double-stop trill etudes developed by Yang-Liau for strings, and Liau-Yang for piano, are more representative of the specific skills and movements musicians are required to perform, and is thus a more appropriate tool to accurately evaluate their abilities.
Interestingly, our study did not show that absent FDS-small function causes poorer performance amongst pianists. Instead, pianists with bilateral absent FDS-small function performed significantly better than those with nonbilateral absent FDS-small function, in terms of regularity and coordination. This suggests that the presence of common or independent FDS-small in either hand may hamper piano technique. Our study did not show any significant relationship between grip strength and FDS-small function, which aligns with a previous study done. 2
Our study found that the presence or absence of FDS-small function in string musicians had no significant impact on string technique. This contrasts with the findings of Godwin et al who recommended assessing FDS-small function in children before offering them the violin or viola. Their conclusion was based solely on the lower prevalence of FDS-small absence amongst professional string musicians compared with nonmusicians, without evaluating the technical abilities of musicians with or without FDS-small function. Thus, we disagree with Godwin et al’s recommendation and believe that discriminatory access to string instruments amongst young musicians who aspire to become professionals should not be based on the absence of FDS-small function.
Although male musicians have a mechanical advantage in terms of stronger right hand grip strength, stronger left hand grip strength, and can perform trills faster as corroborated by another study, they scored lower than female musicians for dynamic tests, suggesting a trade-off between strength and dexterity. 14 These findings highlight the potential value of tailoring pedagogical approaches to address gender specific tendencies in hand strength and dexterity.
In our study, our population had a higher prevalence of absent FDS-small function of 10 out of 31, which is higher than the 8.4% reported in a meta-analysis of 13 studies and is in contrast to another study which concluded that professional musicians usually have independent FDS-small function.5,13 This could be due to our application of a more stringent criteria requiring a PIPJ flexion angle greater than 80° to define independent function, while other papers did not have a defined objective criteria for independent function.
While our findings suggest that the absence of FDS-small does not significantly impair fine motor function in professional musicians, caution should be exercised when extrapolating these results to all FDS-small injuries. Patients with acquired FDS-small function loss may experience different functional outcomes compared with those with congenital absence. Therefore, the decision to repair FDS-small in zone II injuries should be individualized, considering the potential risks of adhesions or rupture against the patient’s preinjury functional demands and expectations.
We recognize the limitations of the study. First, factors other than FDS-small function could have influenced the independent movement of the little finger, such as overall hand coordination and training . Second, definite evaluation of FDS-small presence or absence could have been evaluated with ultrasound. However, to standardize with existing literature, we instead determined the absence and presence based on the standard and modified physical examinations as described above. Third, our sample size was relatively small. However, this already represents 85% of the string musicians in the orchestra. Finally, in our study, we did not include any viola or double bass musicians. This is due to the very small numbers that preclude meaningful statistical analyses.
Supplemental Material
sj-docx-1-han-10.1177_15589447251369032 – Supplemental material for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance
Supplemental material, sj-docx-1-han-10.1177_15589447251369032 for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance by Haoyang Chen, Hao-Xing Lai, Siddarth Venkateswaran, Shuxiang Yang, Brett Stemple, Mandy Zhang and Zi Qiang Glen Liau in HAND
Supplemental Material
sj-docx-2-han-10.1177_15589447251369032 – Supplemental material for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance
Supplemental material, sj-docx-2-han-10.1177_15589447251369032 for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance by Haoyang Chen, Hao-Xing Lai, Siddarth Venkateswaran, Shuxiang Yang, Brett Stemple, Mandy Zhang and Zi Qiang Glen Liau in HAND
Supplemental Material
sj-docx-3-han-10.1177_15589447251369032 – Supplemental material for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance
Supplemental material, sj-docx-3-han-10.1177_15589447251369032 for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance by Haoyang Chen, Hao-Xing Lai, Siddarth Venkateswaran, Shuxiang Yang, Brett Stemple, Mandy Zhang and Zi Qiang Glen Liau in HAND
Supplemental Material
sj-docx-4-han-10.1177_15589447251369032 – Supplemental material for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance
Supplemental material, sj-docx-4-han-10.1177_15589447251369032 for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance by Haoyang Chen, Hao-Xing Lai, Siddarth Venkateswaran, Shuxiang Yang, Brett Stemple, Mandy Zhang and Zi Qiang Glen Liau in HAND
Supplemental Material
sj-docx-5-han-10.1177_15589447251369032 – Supplemental material for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance
Supplemental material, sj-docx-5-han-10.1177_15589447251369032 for Evaluation of Flexor Digitorum Superficialis-Small Function: A Novel Dynamic Assessment Technique in Professional Music Performance by Haoyang Chen, Hao-Xing Lai, Siddarth Venkateswaran, Shuxiang Yang, Brett Stemple, Mandy Zhang and Zi Qiang Glen Liau in HAND
Footnotes
Acknowledgements
The authors thank the students and staff from the Yong Siew Toh Conservatory of Music, National University of Singapore.
Author Contributions
HYC, HXL, and SV were involved with data curation, formal analysis, and writing of the manuscript. SY, BS, MZ, and ZQJL were involved with the conceptualization, supervision, review, and editing of the manuscript. All authors reviewed and edited the manuscript and approved the final version of the manuscript.
Ethical Approval
This study was approved by our institutional review board. Ethical approval for this study was obtained from the National Healthcare Group Ethics and Compliance Online System (Institutional Review Board approval number: 2023/0043).
Statement of Human and Animal Rights
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5). Informed consent was obtained from all patients for being included in the study.
Statement of Informed Consent
Informed consent was obtained from all patients for being included in the study.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Supplemental material is available in the online version of the article.
References
Supplementary Material
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