Ultrasonographic Assessment of Common Extensor Tendon Thickness and Its Correlation with Pain and Disability in Patients with Lateral Epicondylitis

Ultrasonographic Assessment of Common Extensor Tendon Thickness and Its Correlation with Pain and Disability in Patients with Lateral Epicondylitis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Ultrasonographic Assessment of Common Extensor Tendon Thickness and Its Correlation with Pain and Disability in Patients with Lateral Epicondylitis Seyyed Mohammadreza Hoseini, Mohammad Taghipour, Rahmatollah Jokar, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7970593/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background Lateral epicondylitis is a prevalent tendinopathy associated with pain and impaired upper-limb function. Ultrasonography is increasingly used to evaluate tendon pathology, yet its relationship with clinical outcomes remains unclear. Objective To investigate differences in common extensor tendon thickness between symptomatic and contralateral asymptomatic arms in patients with lateral epicondylitis, and to assess the correlation between common extensor tendon thickness, pain intensity, and functional disability. Methods 42 patients with clinically confirmed lateral epicondylitis were enrolled. common extensor tendon thickness was measured bilaterally using high-resolution ultrasonography. Pain intensity was assessed by the Visual Analogue Scale, and functional disability by the Disabilities of the Arm, Shoulder and Hand questionnaire at baseline, 2 weeks, and 4 weeks. Paired-samples t-tests were used to compare common extensor tendon thickness between arms, and Pearson correlation tested associations between common extensor tendon thickness, pain, and disability scores. Results Common extensor tendon thickness was significantly greater in symptomatic arms compared with contralateral asymptomatic arms (mean difference = 0.545 mm, 95% CI [0.70, 1.46]). However, no significant correlations were found between common extensor tendon thickness and pain or disability scores at any time point. Conclusion Ultrasonography confirms tendon thickening in symptomatic arms, highlighting its diagnostic role in lateral epicondylitis. Nevertheless, tendon thickness does not predict pain severity or functional disability, suggesting that clinical management should prioritize patient-reported outcomes over ultrasonographic findings. Lateral epicondylitis Tennis elbow Tendon injuries Ultrasonography Figures Figure 1 Introduction Lateral epicondylitis (LE) is one of the most common causes of elbow pain. It is mainly due to overloading and repetitive microtrauma at the attachment site of the Common Extensor Tendon(CET) (particularly the extensor carpi radialis brevis) to the lateral epicondyle (1). Despite its name, this condition is primarily a chronic tendinopathic and degenerative process rather than a true inflammatory one. Histopathological studies have demonstrated microscopic tendon tears and fibroblast proliferation with angiofibroblastic tendinosis (2). Clinically, patients usually present with localized pain over the lateral epicondyle and reduced grip strength, which are exacerbated by palpation of the tendon origin or resisted wrist extension (3). Ultrasound is a valuable non-invasive imaging modality for evaluating LE. Sonographic assessment of the common extensor tendon can confirm the presence of LE and indicate the severity of tendon pathology (4). Several studies have confirmed that the thickness of CET is significantly greater in patients with LE than in healthy individuals (5–7). However, there is a paucity of ultrasound-based evidence directly comparing the thickness of the CET between the affected and unaffected arms within the same patient. In clinical studies on lateral epicondylitis, pain intensity and functional disability are commonly assessed. Pain is typically measured using the Visual Analogue Scale(VAS) (8), Functional disability of the upper limb is evaluated with the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire (9). Nevertheless, the relationship between ultrasound findings and clinical outcomes remains unclear. Previous researchs indicate that imaging abnormalities do not always correlate with pain intensity or functional limitation. Kizilkurt et al. reported that vascular changes detected by ultrasound using Superb Microvascular Imaging (SMI) did not show a significant correlation with functional recovery (10). Other studies also emphasized that hypoechoic regions, focal tendinopathy, and other ultrasonographic abnormalities may not directly correspond to clinical symptoms (11, 12). Given this gap in the literature and the lack of sufficient evidence, the present study aims to: [1] compare the thickness of the CET at the lateral epicondyle between the affected and unaffected arms in patients with LE, and [2] to examine the correlation between tendon thickness in the affected arm and clinical outcomes, namely pain intensity and functional disability. Methods Study design and participants This study was designed as an observational study with a cross-sectional analytical approach, evaluating tendon thickness and its correlation with clinical outcomes in patients with lateral epicondylitis. Sample-size estimation was based on previously published ultrasonographic studies of CET thickness in LE. Lee et al. reported mean CET thickness values of approximately 4.7 ± 0.7 mm in affected elbows and 4.2 ± 0.5 mm in controls, corresponding to a between-arm difference of 0.5 mm (13). Similarly, Krogh et al. found an average increase of 0.53 mm in symptomatic elbows compared with contralateral sides (14). Assuming a mean paired difference of 0.5 mm and a standard deviation of paired differences of 0.7–0.8 mm, a minimum of 16–21 patients would be required to achieve 80% power at a two-sided α = 0.05 using a paired-samples t-test. We therefore enrolled 42 patients, which provided sufficient power to detect clinically meaningful differences in CET thickness while allowing for potential variability. Diagnosis was based on clinical examination and positive findings on Cozen’s, Mill’s, or Maudsley’s tests (15, 16). Exclusion criteria included previous elbow surgery, cervical radiculopathy, rheumatological disease, diabetic neuropathy, pregnancy, corticosteroid injections in the past 6 months, and Bilateral involvement (17, 18). This study was approved by the Ethics Committee of Babol University of Medical Sciences (approval code: IR.MUBABOL.HRI.REC.1401.097) and was conducted in accordance with the principles of the Declaration of Helsinki. All participants provided written informed consent prior to enrollment in the study. Interventions and follow-up Interventions and follow-up An experienced orthopedic surgeon with 20 years of clinical practice evaluated all participants for eligibility based on predefined inclusion and exclusion criteria. All patients received standard clinical management for lateral epicondylitis, according to established protocols (15, 19). Outcome measures, including VAS, functional disability, and CET thickness, were assessed at three time points: baseline (prior to intervention), 2 weeks post-treatment, and 4 weeks post-treatment. Ultrasonographic assessment Ultrasonography was performed using a Voluson E6 system (GE Healthcare, USA) with a 7–12 MHz linear probe. Patients were seated with the elbow flexed at 90°, forearm pronated, and arm resting on the examination table (20). The thickness of the common extensor tendon (CET) at the lateral epicondyle was measured bilaterally, which included tendon thickness measured 1 cm distal to the lateral epicondyle (the '1-cm measure') (Fig. 1 ) (21). All imaging scans were performed by an experienced musculoskeletal radiologist who was blinded to the patients’ clinical information. Statistical analysis All analyses were performed using SPSS version 27 (IBM, Armonk, NY). Continuous variables were expressed as mean ± standard deviation (SD). To assess the distribution of the data, the Shapiro–Wilk test was primarily applied, while the Kolmogorov–Smirnov test was used as supportive evidence. The associations between tendon thickness in the symptomatic arm and clinical outcomes, at baseline, two weeks, and four weeks after treatment, were analyzed using Pearson correlation coefficient (r). A complete-case approach was used for correlation analyses, and no imputation was performed for missing data. Effect sizes for correlation coefficients (r) were interpreted according to established guidelines. Following Cohen’s conventions and updated empirical recommendations, correlations of r ≈ 0.10–0.20 were considered small, r ≈ 0.30 medium, and r ≥ 0.50 large (22, 23). Results A total of 42 patients with LE were included in the analysis. All patients had unilateral involvement, making them eligible for paired comparison between the symptomatic and contralateral asymptomatic arms. The mean age of participants was 44 ± 7 years, with 29 (69%) females and 13 (31%) males. Normality testing using the Shapiro-Wilk test indicated that the baseline tendon thickness values for the symptomatic and asymptomatic arms were normally distributed (P symptomatic = 0.437 and P asymptomatic = 0.085) (Table 1 ). Consequently, a paired-samples t-test was applied for comparison. The analysis revealed a statistically significant mean increase in tendon thickness of 0.545 mm at the lateral epicondyle in the symptomatic arms compared to the asymptomatic contralateral arms (t = 7.05, p < 0.001, Cohen’s d = 1.09, 95% CI [0.70, 1.46]) (Table 2 ). Table 1 Tests of Normality (Shapiro–Wilk) Variable Shapiro-Wilk Sig. Kolmogorov-Smirnov Sig. VAS1 0.026 0.170 VAS2 0.095 0.200 VAS3 0.009 0.118 S1E* 0.437 0.200 S2E* 0.221 0.200 S3E* 0.346 0.107 DASH1 0.446 0.200 DASH2 0.076 0.200 DASH3 0.087 0.200 SHEALTHE** 0.085 0.071 * S1E, S2E, S3E = Tendon thickness in the symptomatic arm at baseline (S1E), 2 weeks (S2E), and 4 weeks ** SHEALTHE = Tendon thickness in the contralateral (healthy) arm Table 2 Paired t-test (S1E vs SHEALTHE) Comparison Mean Difference t 95% CI for mean Sig. (2-tailed) Cohen’s d 95% CI for Cohen’s d S1E vs SHEALTHE 0.545 7.049 0.39 0.70 < 0.001 1.09 0.70 1.46 For the correlation analyses, although some clinical outcome scores (VAS1 and VAS3) slightly deviated from normality, the sample size was sufficient to invoke the Central Limit Theorem; therefore, Pearson’s correlation coefficient was considered appropriate. No significant correlations were observed between tendon thickness in the symptomatic arm and either VAS or disability scores at baseline, 2 weeks, or 4 weeks (Table 3 ). In contrast, pain and disability scores (VAS and DASH) demonstrated strong, positive, and statistically significant correlations with each other at baseline and 2 weeks (p < 0.001) (Table 3 ). Table 3 Pearson correlations between tendon thickness, pain (VAS), and functional disability (DASH) at baseline, 2 weeks, and 4 weeks Time point Correlation pair r (Pearson) p-value Baseline VAS1 vs. S1E –0.107 0.500 DASH1 vs. S1E –0.042 0.793 VAS1 vs. DASH1 0.524 < 0.001 2 weeks VAS2 vs. S2E –0.028 0.867 DASH2 vs. S2E –0.135 0.643 VAS2 vs. DASH2 0.671 < 0.001 4 weeks VAS3 vs. S3E 0.107 0.516 DASH3 vs. S3E 0.097 0.555 VAS3 vs. DASH3 0.703 0.964 Discussion In this study of 42 patients with lateral epicondylitis, the common extensor tendon was notably thicker in the symptomatic arm compared to the contralateral arm. This finding reflects a substantial morphological alteration associated with the condition, suggesting pronounced tendon remodeling in the affected limb. These observations are consistent with the current pathophysiological understanding of lateral tendinopathy, in which tendon thickening arises from collagen disorganization, fibroblast proliferation, and angiofibroblastic hyperplasia.(24). Furthermore, it supports the use of ultrasonography as a reliable diagnostic tool, corroborating previous studies that have identified increased tendon thickness as a key diagnostic criterion. For instance, Lee et al. established a diagnostic threshold of ≥ 4.2 mm with high specificity (95%) (13), Likewise, Krogh et al. found an average CET thickness increase of about 0.53 mm in the affected elbow compared to the opposite arm (14). The use of the patient's own asymptomatic arm as an internal control strengthens this finding by eliminating inter-individual anatomical variability, a methodological advantage over studies that compare against external healthy controls. Despite this structural difference, we did not observe any significant correlation between CET thickness and patient-reported outcomes. At baseline and at 2- and 4-week follow-up, CET thickness was unrelated to pain intensity or functional disability. This lack of correlation suggests that the degree of tendon thickening is not a primary determinant of the severity of a patient's pain or functional limitations. A recent randomized trial by Kizilkurt et al. found that, although Platelet-Rich Plasma (PRP) injections improved pain and function, corresponding ultrasonographic measures showed no parallel change. The authors concluded that ultrasonography had limited utility for early follow-up monitoring of LE (10). Similarly, Bal and Cetin examined a range of grayscale and Doppler ultrasound parameters in LE and likewise found no simple link between those sonographic features and patient pain or function (11). Our data support the growing view that ultrasound features of tendon pathology, such as thickening, often lag behind symptomatic improvement in LE. Indeed, empirical studies have demonstrated that patient-reported pain and function can improve markedly within weeks or months, even when sonographic structural abnormalities persist (25). The tendon continuum model provides a useful framework to explain this temporal dissociation, in which early reactive changes progress into slower matrix remodeling, and normalization of collagen organization along with a reduction in tendon thickness may take several months or longer to appear (26). Basic science and tendon healing research further suggest that tissue remodeling, alignment of collagen fibers, neovascular regression, and restoration of extracellular matrix integrity are protracted processes that often outlast clinical recovery by a considerable margin (27, 28). By contrast, in our study pain scores and disability scores were strongly interrelated: patients with higher pain reported greater disability at all time points. This result is not surprising given the nature of LE as a painful tendinopathy, and it aligns with earlier observations. For instance, Alizadehkhaiyat et al. found that patients with tennis elbow exhibited markedly elevated pain and functional disability compared to controls (29). In other words, pain intensity and arm/hand disability tend to rise together. Our findings reinforce that notion, demonstrating that in LE the subjective experience of pain and the impact on daily activities are closely coupled. This study has several limitations that should be acknowledged. The short follow-up period (4 weeks) restricted our ability to capture long-term changes in tendon structure and symptoms. The relatively modest sample size (n = 42) may have limited statistical power to detect subtle associations and precluded more comprehensive multivariate analyses. Furthermore, objective measures such as electromyography were not included, and ultrasonographic assessments remain operator-dependent, which may have introduced variability. To address these limitations, future research should employ larger and longitudinal cohorts to better clarify how tendon morphology evolves alongside symptoms over time. Incorporating advanced imaging modalities such as MRI, Doppler ultrasound, or shear wave elastography may provide more sensitive indicators of tendon pathology and recovery. Additionally, integrating functional performance tests and potential biochemical markers could further improve prognostic accuracy and clinical applicability. Although these limitations exist, the present findings provide valuable insights. Specifically, we observed a significant increase in common extensor tendon thickness in the symptomatic arms, reflecting a distinct structural alteration associated with lateral epicondylitis and reinforcing the diagnostic value of ultrasound. However, tendon thickness did not correlate with pain or disability, highlighting that treatment decisions should continue to rely primarily on patient-reported outcomes. In conclusion, ultrasonography confirms tendon thickening in symptomatic arms, highlighting its diagnostic role in lateral epicondylitis, but its clinical significance remains limited. A multidimensional approach that combines imaging, functional measures, and patient-reported outcomes holds the greatest promise for guiding management and improving patient care. Declarations Ethics Approval and Consent to Participate All participants provided written informed consent prior to data collection. The study protocol was approved by the Ethics Committee of Babol University of Medical Sciences (IR.MUBABOL.HRI.REC.1401.097) and conducted in accordance with the Declaration of Helsinki. Consent for Publication Not applicable. Competing Interests The authors declare that they have no competing interests. Funding No funding was received for this study. Author Contribution S.M.H. and M.T. wrote the main manuscript text.S.M.H., R.J., and M.M. performed data curation.S.M.H. and H.S. conducted formal analysis.S.M.H. and R.J. carried out the investigation.S.M.H., M.T., R.J., M.M., and H.S. developed the methodology.S.M.H. and M.T. managed the project administration.S.M.H. provided resources.S.M.H. and M.T. supervised the study.S.M.H. and K.J. performed validation.S.M.H., M.T., and K.J. handled visualization.S.M.H. and M.T. reviewed and edited the manuscript.All authors reviewed and approved the final manuscript. 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Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 09 Dec, 2025 Reviewers agreed at journal 30 Nov, 2025 Reviewers invited by journal 28 Nov, 2025 Editor invited by journal 03 Nov, 2025 Editor assigned by journal 31 Oct, 2025 Submission checks completed at journal 31 Oct, 2025 First submitted to journal 28 Oct, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7970593","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":552962618,"identity":"3b61fb93-aade-4273-9c97-7671adf907b4","order_by":0,"name":"Seyyed Mohammadreza Hoseini","email":"","orcid":"","institution":"Iran University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Seyyed","middleName":"Mohammadreza","lastName":"Hoseini","suffix":""},{"id":552962619,"identity":"5da34651-5948-466d-afff-8617a58f42a3","order_by":1,"name":"Mohammad 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15:26:50","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":53472,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7970593/v1/1d6c9c2ff5fe950ee25a46ba.html"},{"id":97461367,"identity":"bfbf7a2f-7891-4d99-b43e-5969eab845c7","added_by":"auto","created_at":"2025-12-04 15:26:50","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":47654,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of tendon thickness.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7970593/v1/2ea87cf6ec23398f2d7fa105.jpg"},{"id":97677603,"identity":"42d44fe2-c472-456c-800f-6ea7d7bc0b28","added_by":"auto","created_at":"2025-12-08 09:53:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":648223,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7970593/v1/221ee3d7-de76-463a-9f65-b84103218936.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Ultrasonographic Assessment of Common Extensor Tendon Thickness and Its Correlation with Pain and Disability in Patients with Lateral Epicondylitis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLateral epicondylitis (LE) is one of the most common causes of elbow pain. It is mainly due to overloading and repetitive microtrauma at the attachment site of the Common Extensor Tendon(CET) (particularly the extensor carpi radialis brevis) to the lateral epicondyle (1). Despite its name, this condition is primarily a chronic tendinopathic and degenerative process rather than a true inflammatory one. Histopathological studies have demonstrated microscopic tendon tears and fibroblast proliferation with angiofibroblastic tendinosis (2). Clinically, patients usually present with localized pain over the lateral epicondyle and reduced grip strength, which are exacerbated by palpation of the tendon origin or resisted wrist extension (3).\u003c/p\u003e\u003cp\u003eUltrasound is a valuable non-invasive imaging modality for evaluating LE. Sonographic assessment of the common extensor tendon can confirm the presence of LE and indicate the severity of tendon pathology (4). Several studies have confirmed that the thickness of CET is significantly greater in patients with LE than in healthy individuals (5\u0026ndash;7). However, there is a paucity of ultrasound-based evidence directly comparing the thickness of the CET between the affected and unaffected arms within the same patient.\u003c/p\u003e\u003cp\u003eIn clinical studies on lateral epicondylitis, pain intensity and functional disability are commonly assessed. Pain is typically measured using the Visual Analogue Scale(VAS) (8), Functional disability of the upper limb is evaluated with the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire (9). Nevertheless, the relationship between ultrasound findings and clinical outcomes remains unclear. Previous researchs indicate that imaging abnormalities do not always correlate with pain intensity or functional limitation. Kizilkurt et al. reported that vascular changes detected by ultrasound using Superb Microvascular Imaging (SMI) did not show a significant correlation with functional recovery (10). Other studies also emphasized that hypoechoic regions, focal tendinopathy, and other ultrasonographic abnormalities may not directly correspond to clinical symptoms (11, 12).\u003c/p\u003e\u003cp\u003eGiven this gap in the literature and the lack of sufficient evidence, the present study aims to: [1] compare the thickness of the CET at the lateral epicondyle between the affected and unaffected arms in patients with LE, and [2] to examine the correlation between tendon thickness in the affected arm and clinical outcomes, namely pain intensity and functional disability.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy design and participants\u003c/h2\u003e\u003cp\u003eThis study was designed as an observational study with a cross-sectional analytical approach, evaluating tendon thickness and its correlation with clinical outcomes in patients with lateral epicondylitis. Sample-size estimation was based on previously published ultrasonographic studies of CET thickness in LE. Lee et al. reported mean CET thickness values of approximately 4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 mm in affected elbows and 4.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 mm in controls, corresponding to a between-arm difference of 0.5 mm (13). Similarly, Krogh et al. found an average increase of 0.53 mm in symptomatic elbows compared with contralateral sides (14). Assuming a mean paired difference of 0.5 mm and a standard deviation of paired differences of 0.7\u0026ndash;0.8 mm, a minimum of 16\u0026ndash;21 patients would be required to achieve 80% power at a two-sided α\u0026thinsp;=\u0026thinsp;0.05 using a paired-samples t-test. We therefore enrolled 42 patients, which provided sufficient power to detect clinically meaningful differences in CET thickness while allowing for potential variability. Diagnosis was based on clinical examination and positive findings on Cozen\u0026rsquo;s, Mill\u0026rsquo;s, or Maudsley\u0026rsquo;s tests (15, 16). Exclusion criteria included previous elbow surgery, cervical radiculopathy, rheumatological disease, diabetic neuropathy, pregnancy, corticosteroid injections in the past 6 months, and Bilateral involvement (17, 18). This study was approved by the Ethics Committee of Babol University of Medical Sciences (approval code: IR.MUBABOL.HRI.REC.1401.097) and was conducted in accordance with the principles of the Declaration of Helsinki. All participants provided written informed consent prior to enrollment in the study.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eInterventions and follow-up\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eInterventions and follow-up\u003c/div\u003e\u003cp\u003eAn experienced orthopedic surgeon with 20 years of clinical practice evaluated all participants for eligibility based on predefined inclusion and exclusion criteria. All patients received standard clinical management for lateral epicondylitis, according to established protocols (15, 19). Outcome measures, including VAS, functional disability, and CET thickness, were assessed at three time points: baseline (prior to intervention), 2 weeks post-treatment, and 4 weeks post-treatment.\u003c/p\u003e\n\u003ch3\u003eUltrasonographic assessment\u003c/h3\u003e\n\u003cp\u003eUltrasonography was performed using a Voluson E6 system (GE Healthcare, USA) with a 7\u0026ndash;12 MHz linear probe. Patients were seated with the elbow flexed at 90\u0026deg;, forearm pronated, and arm resting on the examination table (20). The thickness of the common extensor tendon (CET) at the lateral epicondyle was measured bilaterally, which included tendon thickness measured 1 cm distal to the lateral epicondyle (the '1-cm measure') (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) (21). All imaging scans were performed by an experienced musculoskeletal radiologist who was blinded to the patients\u0026rsquo; clinical information.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eAll analyses were performed using SPSS version 27 (IBM, Armonk, NY). Continuous variables were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). To assess the distribution of the data, the Shapiro\u0026ndash;Wilk test was primarily applied, while the Kolmogorov\u0026ndash;Smirnov test was used as supportive evidence.\u003c/p\u003e\u003cp\u003eThe associations between tendon thickness in the symptomatic arm and clinical outcomes, at baseline, two weeks, and four weeks after treatment, were analyzed using Pearson correlation coefficient (r). A complete-case approach was used for correlation analyses, and no imputation was performed for missing data.\u003c/p\u003e\u003cp\u003e Effect sizes for correlation coefficients (r) were interpreted according to established guidelines. Following Cohen\u0026rsquo;s conventions and updated empirical recommendations, correlations of r\u0026thinsp;\u0026asymp;\u0026thinsp;0.10\u0026ndash;0.20 were considered small, r\u0026thinsp;\u0026asymp;\u0026thinsp;0.30 medium, and r\u0026thinsp;\u0026ge;\u0026thinsp;0.50 large (22, 23).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 42 patients with LE were included in the analysis. All patients had unilateral involvement, making them eligible for paired comparison between the symptomatic and contralateral asymptomatic arms. The mean age of participants was 44\u0026thinsp;\u0026plusmn;\u0026thinsp;7 years, with 29 (69%) females and 13 (31%) males.\u003c/p\u003e\u003cp\u003eNormality testing using the Shapiro-Wilk test indicated that the baseline tendon thickness values for the symptomatic and asymptomatic arms were normally distributed (P symptomatic\u0026thinsp;=\u0026thinsp;0.437 and P asymptomatic\u0026thinsp;=\u0026thinsp;0.085) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Consequently, a paired-samples t-test was applied for comparison. The analysis revealed a statistically significant mean increase in tendon thickness of 0.545 mm at the lateral epicondyle in the symptomatic arms compared to the asymptomatic contralateral arms (t\u0026thinsp;=\u0026thinsp;7.05, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, Cohen\u0026rsquo;s d\u0026thinsp;=\u0026thinsp;1.09, 95% CI [0.70, 1.46]) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTests of Normality (Shapiro\u0026ndash;Wilk)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eShapiro-Wilk Sig.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eKolmogorov-Smirnov Sig.\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVAS1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.026\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.170\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVAS2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.095\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.200\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVAS3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.009\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.118\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS1E*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.437\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.200\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS2E*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.221\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.200\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS3E*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.346\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.107\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDASH1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.446\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.200\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDASH2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.076\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.200\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDASH3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.087\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.200\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSHEALTHE**\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.085\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.071\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"3\"\u003e\u003cb\u003e*\u003c/b\u003eS1E, S2E, S3E\u0026thinsp;\u003cb\u003e=\u003c/b\u003e\u0026thinsp;Tendon thickness in the symptomatic arm at baseline (S1E), 2 weeks (S2E), and 4 weeks\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"3\"\u003e** SHEALTHE\u0026thinsp;=\u0026thinsp;Tendon thickness in the contralateral (healthy) arm\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePaired t-test (S1E vs SHEALTHE)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComparison\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMean Difference\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003et\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e95% CI for mean\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSig. (2-tailed)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eCohen\u0026rsquo;s d\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e95% CI for Cohen\u0026rsquo;s d\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS1E vs SHEALTHE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.545\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.049\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eFor the correlation analyses, although some clinical outcome scores (VAS1 and VAS3) slightly deviated from normality, the sample size was sufficient to invoke the Central Limit Theorem; therefore, Pearson\u0026rsquo;s correlation coefficient was considered appropriate. No significant correlations were observed between tendon thickness in the symptomatic arm and either VAS or disability scores at baseline, 2 weeks, or 4 weeks (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). In contrast, pain and disability scores (VAS and DASH) demonstrated strong, positive, and statistically significant correlations with each other at baseline and 2 weeks (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePearson correlations between tendon thickness, pain (VAS), and functional disability (DASH) at baseline, 2 weeks, and 4 weeks\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTime point\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCorrelation pair\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003er (Pearson)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eBaseline\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS1 vs. S1E\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;0.107\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDASH1 vs. S1E\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;0.042\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.793\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS1 vs. DASH1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.524\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e2 weeks\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS2 vs. S2E\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;0.028\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.867\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDASH2 vs. S2E\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;0.135\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.643\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS2 vs. DASH2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.671\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e4 weeks\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS3 vs. S3E\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.107\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.516\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDASH3 vs. S3E\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.097\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.555\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS3 vs. DASH3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.703\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.964\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study of 42 patients with lateral epicondylitis, the common extensor tendon was notably thicker in the symptomatic arm compared to the contralateral arm. This finding reflects a substantial morphological alteration associated with the condition, suggesting pronounced tendon remodeling in the affected limb. These observations are consistent with the current pathophysiological understanding of lateral tendinopathy, in which tendon thickening arises from collagen disorganization, fibroblast proliferation, and angiofibroblastic hyperplasia.(24). Furthermore, it supports the use of ultrasonography as a reliable diagnostic tool, corroborating previous studies that have identified increased tendon thickness as a key diagnostic criterion. For instance, Lee et al. established a diagnostic threshold of \u0026ge;\u0026thinsp;4.2 mm with high specificity (95%) (13), Likewise, Krogh et al. found an average CET thickness increase of about 0.53 mm in the affected elbow compared to the opposite arm (14). The use of the patient's own asymptomatic arm as an internal control strengthens this finding by eliminating inter-individual anatomical variability, a methodological advantage over studies that compare against external healthy controls.\u003c/p\u003e\u003cp\u003eDespite this structural difference, we did not observe any significant correlation between CET thickness and patient-reported outcomes. At baseline and at 2- and 4-week follow-up, CET thickness was unrelated to pain intensity or functional disability. This lack of correlation suggests that the degree of tendon thickening is not a primary determinant of the severity of a patient's pain or functional limitations. A recent randomized trial by Kizilkurt et al. found that, although Platelet-Rich Plasma (PRP) injections improved pain and function, corresponding ultrasonographic measures showed no parallel change. The authors concluded that ultrasonography had limited utility for early follow-up monitoring of LE (10). Similarly, Bal and Cetin examined a range of grayscale and Doppler ultrasound parameters in LE and likewise found no simple link between those sonographic features and patient pain or function (11).\u003c/p\u003e\u003cp\u003eOur data support the growing view that ultrasound features of tendon pathology, such as thickening, often lag behind symptomatic improvement in LE. Indeed, empirical studies have demonstrated that patient-reported pain and function can improve markedly within weeks or months, even when sonographic structural abnormalities persist (25).\u003c/p\u003e\u003cp\u003eThe tendon continuum model provides a useful framework to explain this temporal dissociation, in which early reactive changes progress into slower matrix remodeling, and normalization of collagen organization along with a reduction in tendon thickness may take several months or longer to appear (26). Basic science and tendon healing research further suggest that tissue remodeling, alignment of collagen fibers, neovascular regression, and restoration of extracellular matrix integrity are protracted processes that often outlast clinical recovery by a considerable margin (27, 28).\u003c/p\u003e\u003cp\u003eBy contrast, in our study pain scores and disability scores were strongly interrelated: patients with higher pain reported greater disability at all time points. This result is not surprising given the nature of LE as a painful tendinopathy, and it aligns with earlier observations. For instance, Alizadehkhaiyat et al. found that patients with tennis elbow exhibited markedly elevated pain and functional disability compared to controls (29). In other words, pain intensity and arm/hand disability tend to rise together. Our findings reinforce that notion, demonstrating that in LE the subjective experience of pain and the impact on daily activities are closely coupled.\u003c/p\u003e\u003cp\u003eThis study has several limitations that should be acknowledged. The short follow-up period (4 weeks) restricted our ability to capture long-term changes in tendon structure and symptoms. The relatively modest sample size (n\u0026thinsp;=\u0026thinsp;42) may have limited statistical power to detect subtle associations and precluded more comprehensive multivariate analyses. Furthermore, objective measures such as electromyography were not included, and ultrasonographic assessments remain operator-dependent, which may have introduced variability. To address these limitations, future research should employ larger and longitudinal cohorts to better clarify how tendon morphology evolves alongside symptoms over time. Incorporating advanced imaging modalities such as MRI, Doppler ultrasound, or shear wave elastography may provide more sensitive indicators of tendon pathology and recovery. Additionally, integrating functional performance tests and potential biochemical markers could further improve prognostic accuracy and clinical applicability. Although these limitations exist, the present findings provide valuable insights. Specifically, we observed a significant increase in common extensor tendon thickness in the symptomatic arms, reflecting a distinct structural alteration associated with lateral epicondylitis and reinforcing the diagnostic value of ultrasound. However, tendon thickness did not correlate with pain or disability, highlighting that treatment decisions should continue to rely primarily on patient-reported outcomes.\u003c/p\u003e\u003cp\u003eIn conclusion, ultrasonography confirms tendon thickening in symptomatic arms, highlighting its diagnostic role in lateral epicondylitis, but its clinical significance remains limited. A multidimensional approach that combines imaging, functional measures, and patient-reported outcomes holds the greatest promise for guiding management and improving patient care.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics Approval and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll participants provided written informed consent prior to data collection. The study protocol was approved by the Ethics Committee of Babol University of Medical Sciences (IR.MUBABOL.HRI.REC.1401.097) and conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eS.M.H. and M.T. wrote the main manuscript text.S.M.H., R.J., and M.M. performed data curation.S.M.H. and H.S. conducted formal analysis.S.M.H. and R.J. carried out the investigation.S.M.H., M.T., R.J., M.M., and H.S. developed the methodology.S.M.H. and M.T. managed the project administration.S.M.H. provided resources.S.M.H. and M.T. supervised the study.S.M.H. and K.J. performed validation.S.M.H., M.T., and K.J. handled visualization.S.M.H. and M.T. reviewed and edited the manuscript.All authors reviewed and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eS\u0026aacute;nchez-Mil\u0026aacute; Z, Abu\u0026iacute;n-Porras V, Fidalgo-G\u0026oacute;mez H, M\u0026iacute;nguez-Esteban I, Almaz\u0026aacute;n-Polo J, Vel\u0026aacute;zquez-Saornil J. 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JAAOS Global Research \u0026amp; Reviews. 2018;2(3):e088.\u003c/li\u003e\n\u003cli\u003eFranchignoni F, Vercelli S, Giordano A, Sartorio F, Bravini E, Ferriero G. Minimal clinically important difference of the disabilities of the arm, shoulder and hand outcome measure (DASH) and its shortened version (QuickDASH). Journal of orthopaedic \u0026amp; sports physical therapy. 2014;44(1):30-9.\u003c/li\u003e\n\u003cli\u003eKizilkurt T, Aydin AS, Yagci TF, Ersen A, Ercan CC, Salmaslioglu A. Platelet-Rich Plasma Provides Superior Clinical Outcomes Without Radiologic Differences in Lateral Epicondylitis: Randomized Controlled Trial. Medicina. 2025;61(5):894.\u003c/li\u003e\n\u003cli\u003eBal E, Cetin O. Demonstrating the relationship of ultrasonographic parameters with disease activity and pain in lateral epicondylitis. Medicine. 2023;102(40):e35499.\u003c/li\u003e\n\u003cli\u003eSharif F, Ahmad A, Shabbir A. Does the ultrasound imaging predict lower limb tendinopathy in athletes: a systematic review. BMC Medical Imaging. 2023;23(1):217.\u003c/li\u003e\n\u003cli\u003eLee MH, Cha JG, Jin W, Kim BS, Park JS, Lee HK, et al. Utility of sonographic measurement of the common tensor tendon in patients with lateral epicondylitis. American Journal of Roentgenology. 2011;196(6):1363-7.\u003c/li\u003e\n\u003cli\u003eKrogh TP, Fredberg U, Ammitzb\u0026oslash;ll C, Ellingsen T. Clinical value of ultrasonographic assessment in lateral epicondylitis versus asymptomatic healthy controls. The American journal of sports medicine. 2020;48(8):1873-83.\u003c/li\u003e\n\u003cli\u003eKo\u0026ccedil;ak FA, Kurt EE, Şaş S, Tuncay F, Erdem HR. Short-term effects of steroid injection, kinesio taping, or both on pain, grip strength, and functionality of patients with lateral epicondylitis: A single-blinded randomized controlled trial. American journal of physical medicine \u0026amp; rehabilitation. 2019;98(9):751-8.\u003c/li\u003e\n\u003cli\u003eYi R, Bratchenko WW, Tan V. Deep friction massage versus steroid injection in the treatment of lateral epicondylitis. Hand. 2018;13(1):56-9.\u003c/li\u003e\n\u003cli\u003eAu IP, Fan PCP, Lee WY, Leong MW, Tang OY, An WW, et al. Effects of Kinesio tape in individuals with lateral epicondylitis: A deceptive crossover trial. Physiotherapy theory and practice. 2017;33(12):914-9.\u003c/li\u003e\n\u003cli\u003eCho Y-T, Hsu W-Y, Lin L-F, Lin Y-N. Kinesio taping reduces elbow pain during resisted wrist extension in patients with chronic lateral epicondylitis: a randomized, double-blinded, cross-over study. BMC musculoskeletal disorders. 2018;19(1):193.\u003c/li\u003e\n\u003cli\u003eStruijs PA, Smidt N, Arola H, Van Dijk C, Buchbinder R, Assendelft WJ, et al. Orthotic devices for the treatment of tennis elbow. Cochrane Database of Systematic Reviews. 1996;2010(1).\u003c/li\u003e\n\u003cli\u003eG\u0026uuml;nd\u0026uuml;z R, Malas F\u0026Uuml;, Borman P, Kocaoğlu S, \u0026Ouml;z\u0026ccedil;akar L. Physical therapy, corticosteroid injection, and extracorporeal shock wave treatment in lateral epicondylitis: clinical and ultrasonographical comparison. Clinical rheumatology. 2012;31(5):807-12.\u003c/li\u003e\n\u003cli\u003eKrogh TP, Fredberg U, Ammitzb\u0026oslash;l C, Ellingsen T. Ultrasonographic characteristics of the common extensor tendon of the elbow in asymptomatic individuals: thickness, color Doppler activity, and bony spurs. Orthopaedic journal of sports medicine. 2017;5(5):2325967117704186.\u003c/li\u003e\n\u003cli\u003eLovakov A, Agadullina ER. Empirically derived guidelines for effect size interpretation in social psychology. European Journal of Social Psychology. 2021;51(3):485-504.\u003c/li\u003e\n\u003cli\u003eCohen J. Statistical power analysis for the behavioral sciences: routledge; 2013.\u003c/li\u003e\n\u003cli\u003eBhabra G, Wang A, Ebert JR, Edwards P, Zheng M, Zheng MH. Lateral elbow tendinopathy: development of a pathophysiology-based treatment algorithm. Orthopaedic journal of sports medicine. 2016;4(11):2325967116670635.\u003c/li\u003e\n\u003cli\u003eVan Ark M, Rio E, Cook J, Van Den Akker-Scheek I, Gaida JE, Zwerver J, et al. Clinical improvements are not explained by changes in tendon structure on ultrasound tissue characterization after an exercise program for patellar tendinopathy. American journal of physical medicine \u0026amp; rehabilitation. 2018;97(10):708-14.\u003c/li\u003e\n\u003cli\u003eCook J, Rio E, Purdam C, Docking S. Revisiting the continuum model of tendon pathology: what is its merit in clinical practice and research? British journal of sports medicine. 2016;50(19):1187-91.\u003c/li\u003e\n\u003cli\u003eLi ZJ, Yang QQ, Zhou YL. Basic research on tendon repair: strategies, evaluation, and development. Frontiers in medicine. 2021;8:664909.\u003c/li\u003e\n\u003cli\u003eDarrieutort-Laffite C, Blanchard F, Soslowsky LJ, Le Goff B. Biology and physiology of tendon healing. Joint Bone Spine. 2024;91(5):105696.\u003c/li\u003e\n\u003cli\u003eAlizadehkhaiyat O, Fisher AC, Kemp GJ, Frostick SP. Pain, functional disability, and psychologic status in tennis elbow. The Clinical journal of pain. 2007;23(6):482-9.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-medical-imaging","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmim","sideBox":"Learn more about [BMC Medical Imaging](http://bmcmedimaging.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmim/default.aspx","title":"BMC Medical Imaging","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Lateral epicondylitis, Tennis elbow, Tendon injuries, Ultrasonography","lastPublishedDoi":"10.21203/rs.3.rs-7970593/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7970593/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eLateral epicondylitis is a prevalent tendinopathy associated with pain and impaired upper-limb function. Ultrasonography is increasingly used to evaluate tendon pathology, yet its relationship with clinical outcomes remains unclear.\u003c/p\u003e\u003ch2\u003eObjective\u003c/h2\u003e\u003cp\u003eTo investigate differences in common extensor tendon thickness between symptomatic and contralateral asymptomatic arms in patients with lateral epicondylitis, and to assess the correlation between common extensor tendon thickness, pain intensity, and functional disability.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003e42 patients with clinically confirmed lateral epicondylitis were enrolled. common extensor tendon thickness was measured bilaterally using high-resolution ultrasonography. Pain intensity was assessed by the Visual Analogue Scale, and functional disability by the Disabilities of the Arm, Shoulder and Hand questionnaire at baseline, 2 weeks, and 4 weeks. Paired-samples t-tests were used to compare common extensor tendon thickness between arms, and Pearson correlation tested associations between common extensor tendon thickness, pain, and disability scores.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eCommon extensor tendon thickness was significantly greater in symptomatic arms compared with contralateral asymptomatic arms (mean difference\u0026thinsp;=\u0026thinsp;0.545 mm, 95% CI [0.70, 1.46]). However, no significant correlations were found between common extensor tendon thickness and pain or disability scores at any time point.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eUltrasonography confirms tendon thickening in symptomatic arms, highlighting its diagnostic role in lateral epicondylitis. Nevertheless, tendon thickness does not predict pain severity or functional disability, suggesting that clinical management should prioritize patient-reported outcomes over ultrasonographic findings.\u003c/p\u003e","manuscriptTitle":"Ultrasonographic Assessment of Common Extensor Tendon Thickness and Its Correlation with Pain and Disability in Patients with Lateral Epicondylitis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-04 15:26:45","doi":"10.21203/rs.3.rs-7970593/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2025-12-09T14:08:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"156666335160381794558287408156974211083","date":"2025-11-30T16:33:06+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-28T12:52:22+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-11-03T08:57:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-31T09:43:37+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-31T09:42:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Medical Imaging","date":"2025-10-28T06:41:29+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-medical-imaging","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmim","sideBox":"Learn more about [BMC Medical Imaging](http://bmcmedimaging.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmim/default.aspx","title":"BMC Medical Imaging","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"25dc150d-418b-4714-ab22-11d4935d9bda","owner":[],"postedDate":"December 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-12-04T15:26:45+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-04 15:26:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7970593","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7970593","identity":"rs-7970593","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}