Sudden-falling: a sensitive diagnostic sign of longitudinal tear of the meniscus inferior surface under arthroscopy

Sudden-falling: a sensitive diagnostic sign of longitudinal tear of the meniscus inferior surface under arthroscopy | 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 Sudden-falling: a sensitive diagnostic sign of longitudinal tear of the meniscus inferior surface under arthroscopy Haile Pan, Aofei Gao, Mozumder Somrat Akbor, Zilong Shen, Qi Chen, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6931337/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background When the superior surface of the meniscus is intact, the longitudinal tear on the inferior surface of the meniscus is easily ignored. Therefore, it is very important to find this tear through accurate inspection. Unfortunately, there is no specific method for detecting longitudinal tears on the inferior surface of the meniscus. Methods This study retrospectively analyzed the videos of 314 patients who underwent arthroscopic meniscus surgery from September 2018 to September 2021. The number of cases with longitudinal tears and 'sudden-falling' signs on the inferior surface of the meniscus was recorded to evaluate the sensitivity and specificity of this sign. Results Of all 314 patients, 43 were finally confirmed to have the presence of longitudinal tears on the inferior surface of the meniscus after arthroscopic exploration. Meniscus tears were observed in 6 patients through direct arthroscopic exploration, and tears could not be observed in 37 patients. After a meticulous examination of the 37 cases that could not be directly diagnosed, 36 cases exhibited positive 'sudden-falling' signs, and the remaining case was negative. The sensitivity of the sign was 97.3%, and the positive predictive value was 90% (p < 0.006). Conclusions The 'sudden-falling' sign can accurately detect longitudinal tears of the meniscus' inferior surface, demonstrating high sensitivity and specificity. Therefore, it can improve the clinical diagnosis level of the longitudinal tear on the inferior surface of the meniscus. Sports Medicine and Kinesiology Sudden-falling sign longitudinal tear inferior surface meniscus arthroscopy Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The meniscus plays a key role in the stability, shock absorption, and lubrication of the knee joint. 1–5 In clinical practice, meniscus tears are a common knee injury, where the incidence of medial meniscus tears is higher. 6, 7 Meniscus tears can be divided into parrot beak tears, horizontal tears, longitudinal tears, radial tears, and complex tears. Then, the judgment of the type, location, and size of a meniscus tear is very important for the choice of treatment and the degree of postoperative healing 2, 8 Detailed history-taking and physical examination can diagnose 75% of meniscus tears. However, the examination of acute injury is affected by pain and swelling, so it is difficult to diagnose by clinical examination. It needs to be diagnosed by auxiliary examination after excluding other trauma. Currently, MRI is the primary non-invasive auxiliary diagnostic tool for meniscus injuries, with high sensitivity (93% for the medial meniscus, 79% for the lateral meniscus, and 72% for longitudinal tears). 9–11 With the development of arthroscopy technology, it is not only used for treatment but also the gold standard for the diagnosis of meniscus injury. 1 The longitudinal tear on the inferior surface of the meniscus is often not easy to find and is easily ignored in the clinic. Currently, the longitudinal tear on the inferior surface of the meniscus can be diagnosed using MRI; however, there is a specific false-negative rate in preoperative MRI diagnosis. The method is not accurate, and there is no other standard or unified inspection method. As a result, we have adopted a more reliable exploration method named 'Sudden-falling' sign in the operation: We slide the probe hook on the superior surface of the meniscus from the lateral joint capsule to the medial free edge. When there is no tear on the inferior surface of the meniscus, the probe hook moves smoothly on the superior surface; When a longitudinal tear occurs on the inferior surface of the meniscus, the probe hook suddenly falls. The position where this phenomenon occurs is the position of the tear. (Fig. 1 . Video) When we carefully probe the superior surface of the meniscus from the joint capsule to the free edge with the probe hook and slide the probe hook from the outside to the inside, the probe hook suddenly falls, and the patient may have a longitudinal tear on the inferior surface of the meniscus. The purpose of this study is to investigate the relationship between the sign and the longitudinal tear on the inferior surface of the meniscus, in order to test our hypothesis. Methods The study data represent a retrospective review of prospectively collected arthroscopic surgical videos of patients undergoing arthroscopic meniscus repair between September 2018 and September 2021. All available arthroscopic videos of patients who had arthroscopic medial meniscus repair by the same senior surgeon. This study was carried out after the approval of the ethics committee of The 2nd Affiliated Hospital of Harbin Medical University, and the informed consent of all participating patients has been obtained. There were no age restrictions for patients to be included in this study. All patients diagnosed with longitudinal tears of the inferior surface of the meniscus, confirmed by arthroscopy, were included in the study. The entire patient underwent an MRI and a related physical examination before the operation. This study included all patients who underwent arthroscopic meniscus surgery. With the patients in a supine position under general anesthesia or spinal anesthesia, standard anterolateral and anteromedial portals were used. Under arthroscopy, first examine the upper surface, and then pay special attention to whether the tear is hidden on the inferior surface of the meniscus. If there is a longitudinal tear on the inferior surface of the meniscus, carefully probe the superior surface of the meniscus from the joint capsule to the free edge with the probe hook, slide the probe hook from the outside to the inside, and observe whether the probe hook suddenly falls. If the tear cannot be found directly, we will combine the MRI results with the presence of a 'sudden-falling' sign and re-examine for any missing tears. All data were analyzed using the Chi-squared test with statistical software SPSS version 19.0 (IBM Corp., Armonk, New York, USA). Spearman's correlation was used to assess the relationship between wave sign and longitudinal tear on the lower surface. Statistical significance was set at p < 0.05. Results We retrospectively analyzed the videos of 314 patients who underwent arthroscopic meniscus surgery from September 2018 to September 2021. Of all patients, 43 cases were finally confirmed to have longitudinal tears on the inferior surface of the meniscus after arthroscopic exploration (comprising 25 males and 18 females, with an average age of 46.17 years). Meniscus tears were observed in 6 patients through direct arthroscopic examination, while no tears were found in 37 patients. Because the preoperative MRI showed a positive sign, the longitudinal tear on the inferior surface of the meniscus was found after meticulous examination. Of the 37 cases of longitudinal tear on the inferior surface of the meniscus that could not be diagnosed by direct arthroscopic exploration, 36 cases had positive 'sudden-falling' signs, and the other one was negative. (Fig. 2 and Table 1 ) Table 1 The outcome of the ‘Sudden-falling’ sign in the diagnosis of longitudinal tear on the inferior surface of the meniscus n (%) Group Which could not be diagnosed with direct examination (n = 314) Which could be diagnosed with direct examination (n = 314) Total P ‘Sudden-falling’ sign (+) 36 (TP) 4 (FP) 40 (12.73) 0.006 ‘Sudden-falling’ sign (-) 1 (FN) 2 (TN) 3 (0.95) Total 37 6 43 (13.69) Results show that the ‘sudden-falling’ sign (+) has an AUC of 0.65, indicating moderate discriminatory power. It is highly sensitive (97.3%), but poorly specific (33.2%) for detecting occult meniscal tears. While statistically significant positive predictive value was 90% (p < 0.006), use the ‘Sudden-falling’ (+) to confirm tears (highly sensitive). The ‘Sudden-falling’ (-) has an AUC of 0.35, indicating poor performance. Avoid relying on the ‘Sudden-falling’ (-) to exclude tears due to its low sensitivity. The characteristic of the 'sudden-falling' sign is of diagnostic significance for the longitudinal tear on the inferior surface of the meniscus. (Fig. 4 .) Discussion A longitudinal tear on the inferior surface of the meniscus is a special occult meniscus tear. Currently, there is no standard examination method for tears. Suppose this tear cannot be identified and treated early. In such cases, the symptoms will not be completely relieved, and it is likely to progress to a full-thickness tear, rendering the meniscus irreparable, especially in cases of compound meniscus injuries. Especially, the longitudinal tear on the inferior surface of the meniscus, associated with articular cartilage injury, will affect stress distribution and increase pressure on the cartilage. 12 Consequently, it is particularly important to judge this hidden tear in the early stages. 13 MRI is the most crucial imaging examination of a meniscus longitudinal tear, which shows a high signal line in the vertical direction; nevertheless, some tears are difficult to identify, especially the longitudinal tear on the posterior horn of the lateral meniscus with complex posterior attachment. 14 And arthroscopic meniscus repair and suture is the prime method. 1, 4, 8 Arthroscopic explorations before repair are necessary, which can not only help us confirm the diagnosis but also avoid unnecessary repeated surgery caused by the neglect of longitudinal tear of the meniscus inferior surface. 9 A characteristic arthroscopic 'eyelid-turnup' sign, which is indicative of a partial-thickness longitudinal medial meniscus tear, has been reported in the literature. 13 However, it does not apply to all longitudinal tears of the inferior surface of the meniscus. We can divide the manifestations of the free edge of the longitudinal tear of the inferior surface of the meniscus into different parts into the following three types: (1) When the middle part of the meniscus is torn, there will be a wave-like edge, (2) When the meniscus is torn in the red or red-white zone that is closer to the free inner edge, an upturned edge corresponding to the above literature can appear, (3) There is also a normal free edge without any performance. Undoubtedly, all longitudinal tears of the medial or lateral meniscus inferior surface show the 'sudden-falling' sign we described. (Fig. 3 ) In clinical practice, although the superior surface appears intact, it is necessary to explore the concealed longitudinal tear on the inferior surface of the meniscus more accurately. We discovered a new exploration marker, the 'sudden-falling' sign, which enables more precise and effective detection of the longitudinal tear on the inferior surface of the meniscus. The results of this study demonstrate that, compared to other conventional methods, the newly proposed exploration method can accurately detect the longitudinal tear of the inferior meniscus surface and exhibits high sensitivity and specificity. This method of microscopic exploration, known as the 'sudden-falling' sign, is proposed for the first time in the literature, addressing the lack of diagnosis for special types of occult meniscus tears. Our method has the following advantages: firstly, this exploration method is simple and easy under arthroscopy, allowing for quick judgment of whether the inferior surface of the meniscus is torn and the location of the tears. Additionally, the method applies to all longitudinal tears on the inferior surface of the meniscus, particularly those small tears near the joint capsule that are difficult to detect. Finally, arthroscopy is the gold standard and more reliable than any other modality, including MRI and ultrasound. However, this research has some limitations: First, the small sample size limits generalizability, so further studies with larger cohorts are needed. Simultaneously, the study is retrospective. Additionally, arthroscopy has a subjective component, relying on the surgeon’s skill level, which is also a factor to consider. 8 Conclusions The 'sudden-falling' sign under arthroscopy is a characteristic indicator for occult longitudinal tears on the inferior surface of the meniscus. It can improve the clinical diagnosis of longitudinal tear of the meniscus' inferior surface and avoid omission. Declarations Ethics approval and consent to participate The study has gotten approval from the Medical Ethics Committee of the Second Affiliated Hospital of Harbin Medical University. All participants read and signed a written informed consent before the start of this study. All methods were performed in accordance with the principles outlined in the Declaration of Helsinki. Consent for publication This section is not applicable to our study. Availability of data and materials The datasets generated and/or analyzed during the current study are not publicly available due to ethical restrictions, but are available from the corresponding author upon reasonable request. Conflicts of interest The authors don’t have any conflicts of interest relevant to this article. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit organizations. Authors' contributions HLP, AFG, and ZLS contributed to the conception and design of the study. HLP and ZLS were the leading surgeons in the current study. AFG, QC, XWW, and CW contributed to the acquisition of the data. QC, XWW, HMR, and CW contributed to the analysis and interpretation of the data. AFG and MSA were major contributors to drafting the manuscript. ZLS and MSA contributed to the critical revision of important intellectual content. All authors approved the final version to be submitted. HLP contributed responsibility for the overall content as guarantors. All authors read and approved the final manuscript. Acknowledgements This section is not applicable to our study. References Beaufils P, Becker R, Kopf S, Matthieu O, Pujol N. The knee meniscus: management of traumatic tears and degenerative lesions. EFORT Open Rev. May 2017;2(5):195-203. doi:10.1302/2058-5241.2.160056 Kurnaz R, Asci M, Ergun S, Akgun U, Gunes T. Repair of Longitudinal Meniscal Tears by Single or Double Vertical Loop Sutures: In vitro Biomechanical Study under Cyclic Loading. J Knee Surg. Mar 2020;33(3):314-318. doi:10.1055/s-0039-1700571 Ozeki N, Seil R, Krych AJ, Koga H. Surgical treatment of complex meniscus tear and disease: state of the art. J ISAKOS. Jan 2021;6(1):35-45. doi:10.1136/jisakos-2019-000380 Uzun E, Misir A, Kizkapan TB, Ozcamdalli M, Akkurt S, Guney A. Evaluation of Midterm Clinical and Radiographic Outcomes of Arthroscopically Repaired Vertical Longitudinal and Bucket-Handle Lateral Meniscal Tears. Orthop J Sports Med. May 2019;7(5):2325967119843203. doi:10.1177/2325967119843203 Jarraya M, Roemer FW, Englund M, et al. Meniscus morphology: Does tear type matter? A narrative review with focus on relevance for osteoarthritis research. Semin Arthritis Rheum. Apr 2017;46(5):552-561. doi:10.1016/j.semarthrit.2016.11.005 Chen Z, Zhang H, Luo H, et al. Contact mechanics after mattress suture repair of medial meniscus vertical longitudinal tear: an in vitro study. Arch Orthop Trauma Surg. Sep 2020;140(9):1221-1230. doi:10.1007/s00402-020-03428-0 Gee SM, Tennent DJ, Cameron KL, Posner MA. The Burden of Meniscus Injury in Young and Physically Active Populations. Clin Sports Med. Jan 2020;39(1):13-27. doi:10.1016/j.csm.2019.08.008 Kopf S, Beaufils P, Hirschmann MT, et al. Management of traumatic meniscus tears: the 2019 ESSKA meniscus consensus. Knee Surg Sports Traumatol Arthrosc. Apr 2020;28(4):1177-1194. doi:10.1007/s00167-020-05847-3 Nguyen JC, De Smet AA, Graf BK, Rosas HG. MR imaging-based diagnosis and classification of meniscal tears. Radiographics. 2014 Jul-Aug;34(4):981-99. doi: 10.1148/rg.344125202. PMID: 25019436. Oei EH, Nikken JJ, Verstijnen AC, Ginai AZ, Myriam Hunink MG. MR imaging of the menisci and cruciate ligaments: a systematic review. Radiology. 2003 Mar;226(3):837-48. doi: 10.1148/radiol.2263011892. Epub 2003 Jan 15. PMID: 12601211. Jung JY, Jee WH, Park MY, Lee SY, Kim JM. Meniscal tear configurations: categorization with 3D isotropic turbo spin-echo MRI compared with conventional MRI at 3 T. AJR Am J Roentgenol. Feb 2012;198(2):W173-80. doi:10.2214/AJR.11.6979 Tachibana Y, Mae T, Shino K, et al. A longitudinal tear in the medial meniscal body decreased the in situ meniscus force under an axial load. Knee Surg Sports Traumatol Arthrosc. Nov 2020;28(11):3457-3465. doi:10.1007/s00167-019-05735-5 Liang Z, Ren S, He F, Jiang X, Zhang W, Zhang X. The characteristic arthroscopic 'eyelid- turnup' sign indicated for partial-thickness longitudinal medial meniscus tear. Technol Health Care. 2019;27(6):661-668. doi:10.3233/THC-191640 De Smet AA, Nathan DH, Graf BK, Haaland BA, Fine JP. Clinical and MRI findings associated with false-positive knee MR diagnoses of medial meniscal tears. AJR Am J Roentgenol. Jul 2008;191(1):93-9. doi:10.2214/AJR.07.3034 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-6931337","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":473628970,"identity":"5d763ced-9fe8-42c2-8c0e-d876ce2d2d1b","order_by":0,"name":"Haile Pan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCElEQVRIie3Qv2qDQBzA8d8h6GKb9SeG+Ao/ES4JBNpHOSnU5VKaLVsThHPxAczSxygdDYKTpWugiw/gAwjN0FsKWbQZO9x3uoPfh/sDYDL9z2wAWsDEYvuW7RYz28nKawiCl6UVsR1Gt24jriCAQE39iJrEr3hPo/Nz56Nu+2ecwUmSv3nHRCEI6Ldvg2SZPyVhThixQlJ0aHCt/H3J8uZrkFApObqEcYqSHm6UJtNSWEyNkM+Oe2fCF6VJpUlio6BxcpLc16cI163jVBPxJ1kWHfenhGHhpJV1UBgq/cnHsbfMJ5J73XkV3FUs+96oVRBk2bHttyMXu9xYv4tycH6QmEwmk+myHybrUpXiNBz5AAAAAElFTkSuQmCC","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":true,"prefix":"","firstName":"Haile","middleName":"","lastName":"Pan","suffix":""},{"id":473628971,"identity":"37d65148-766e-4a70-81bb-a8a515d56cc2","order_by":1,"name":"Aofei Gao","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Aofei","middleName":"","lastName":"Gao","suffix":""},{"id":473628972,"identity":"a259c8b6-462c-44dc-ae78-356d1e937757","order_by":2,"name":"Mozumder Somrat Akbor","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Mozumder","middleName":"Somrat","lastName":"Akbor","suffix":""},{"id":473628973,"identity":"e5e29cb4-ad21-4332-a7eb-fc1bef94e81c","order_by":3,"name":"Zilong Shen","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Zilong","middleName":"","lastName":"Shen","suffix":""},{"id":473628974,"identity":"e3e74649-32e5-4504-8e56-dd7241a9c846","order_by":4,"name":"Qi Chen","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Qi","middleName":"","lastName":"Chen","suffix":""},{"id":473628975,"identity":"6504895f-5b28-4178-8dbf-9ebd0bed7bd9","order_by":5,"name":"Hasan Md Rasadul","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Hasan","middleName":"Md","lastName":"Rasa","suffix":"Md"},{"id":473628976,"identity":"d03f741b-1eb8-449f-ba01-db387a0624a5","order_by":6,"name":"Xiangwei Wen","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Xiangwei","middleName":"","lastName":"Wen","suffix":""},{"id":473628977,"identity":"633743e4-ec9c-4f4b-bc30-6a5ec0830256","order_by":7,"name":"Chen Wang","email":"","orcid":"","institution":"The Second Affiliated Hospital of Harbin Medical University, Heilongjiang, China","correspondingAuthor":false,"prefix":"","firstName":"Chen","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2025-06-19 12:45:53","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":true,"humanSubjectCaseReport":true,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6931337/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6931337/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85186380,"identity":"abaaa847-9b3e-4984-9544-32671e24831b","added_by":"auto","created_at":"2025-06-23 08:12:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":231669,"visible":true,"origin":"","legend":"\u003cp\u003e(A and B) Position of probe hook before and after falling under arthroscopy. (C) The corresponding position of the longitudinal tear of the meniscus' inferior surface under arthroscopy.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6931337/v1/e7dfa8e41789c8222f6773d6.png"},{"id":85186379,"identity":"24df26b2-cefe-4706-b313-62cc6e13a1bf","added_by":"auto","created_at":"2025-06-23 08:12:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":125646,"visible":true,"origin":"","legend":"\u003cp\u003eThe occurrence of a 'sudden-falling' sign in longitudinal tear on the inferior surface of the meniscus.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6931337/v1/d38961f0fbc97d6cd4f96be5.png"},{"id":85188118,"identity":"0574fb4a-9579-4598-8372-822f6f3654a5","added_by":"auto","created_at":"2025-06-23 08:28:08","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":171794,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig 4\u003c/strong\u003e. ROC Curve ‘Sudden-falling’ sign (+) vs. (-)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6931337/v1/07350b8cd05ca4d8cfb58ee5.png"},{"id":85186385,"identity":"6ff57260-a46b-4a9c-bd11-b46362ba0184","added_by":"auto","created_at":"2025-06-23 08:12:07","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":112430,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3\u003c/strong\u003e. (A) 'sudden-falling' sign. (B) wave-like edge (the middle part of the meniscus is torn). (C) upturned edge (torn in the red or red-white zone, which is closer to the free inner edge). (D) normal edge.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6931337/v1/f43be71e51bbcf85cf497f76.png"},{"id":85189593,"identity":"459578d2-ea02-409b-8a52-7fe6e27fe20c","added_by":"auto","created_at":"2025-06-23 08:44:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1237251,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6931337/v1/ceb5db2c-f2d1-4a0a-9782-159b146700c6.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eSudden-falling: a sensitive diagnostic sign of longitudinal tear of the meniscus inferior surface under arthroscopy\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe meniscus plays a key role in the stability, shock absorption, and lubrication of the knee joint.\u003csup\u003e1\u0026ndash;5\u003c/sup\u003e In clinical practice, meniscus tears are a common knee injury, where the incidence of medial meniscus tears is higher.\u003csup\u003e6, 7\u003c/sup\u003e Meniscus tears can be divided into parrot beak tears, horizontal tears, longitudinal tears, radial tears, and complex tears. Then, the judgment of the type, location, and size of a meniscus tear is very important for the choice of treatment and the degree of postoperative healing \u003csup\u003e2, 8\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eDetailed history-taking and physical examination can diagnose 75% of meniscus tears. However, the examination of acute injury is affected by pain and swelling, so it is difficult to diagnose by clinical examination. It needs to be diagnosed by auxiliary examination after excluding other trauma. Currently, MRI is the primary non-invasive auxiliary diagnostic tool for meniscus injuries, with high sensitivity (93% for the medial meniscus, 79% for the lateral meniscus, and 72% for longitudinal tears).\u003csup\u003e9\u0026ndash;11\u003c/sup\u003e With the development of arthroscopy technology, it is not only used for treatment but also the gold standard for the diagnosis of meniscus injury.\u003csup\u003e1\u003c/sup\u003e The longitudinal tear on the inferior surface of the meniscus is often not easy to find and is easily ignored in the clinic. Currently, the longitudinal tear on the inferior surface of the meniscus can be diagnosed using MRI; however, there is a specific false-negative rate in preoperative MRI diagnosis. The method is not accurate, and there is no other standard or unified inspection method. As a result, we have adopted a more reliable exploration method named \u0026apos;Sudden-falling\u0026apos; sign in the operation: We slide the probe hook on the superior surface of the meniscus from the lateral joint capsule to the medial free edge. When there is no tear on the inferior surface of the meniscus, the probe hook moves smoothly on the superior surface; When a longitudinal tear occurs on the inferior surface of the meniscus, the probe hook suddenly falls. The position where this phenomenon occurs is the position of the tear. (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Video)\u003c/p\u003e\n\u003cp\u003eWhen we carefully probe the superior surface of the meniscus from the joint capsule to the free edge with the probe hook and slide the probe hook from the outside to the inside, the probe hook suddenly falls, and the patient may have a longitudinal tear on the inferior surface of the meniscus. The purpose of this study is to investigate the relationship between the sign and the longitudinal tear on the inferior surface of the meniscus, in order to test our hypothesis.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThe study data represent a retrospective review of prospectively collected arthroscopic surgical videos of patients undergoing arthroscopic meniscus repair between September 2018 and September 2021. All available arthroscopic videos of patients who had arthroscopic medial meniscus repair by the same senior surgeon. This study was carried out after the approval of the ethics committee of The 2nd Affiliated Hospital of Harbin Medical University, and the informed consent of all participating patients has been obtained. There were no age restrictions for patients to be included in this study. All patients diagnosed with longitudinal tears of the inferior surface of the meniscus, confirmed by arthroscopy, were included in the study. The entire patient underwent an MRI and a related physical examination before the operation. This study included all patients who underwent arthroscopic meniscus surgery. With the patients in a supine position under general anesthesia or spinal anesthesia, standard anterolateral and anteromedial portals were used. Under arthroscopy, first examine the upper surface, and then pay special attention to whether the tear is hidden on the inferior surface of the meniscus. If there is a longitudinal tear on the inferior surface of the meniscus, carefully probe the superior surface of the meniscus from the joint capsule to the free edge with the probe hook, slide the probe hook from the outside to the inside, and observe whether the probe hook suddenly falls. If the tear cannot be found directly, we will combine the MRI results with the presence of a 'sudden-falling' sign and re-examine for any missing tears.\u003c/p\u003e \u003cp\u003eAll data were analyzed using the Chi-squared test with statistical software SPSS version 19.0 (IBM Corp., Armonk, New York, USA). Spearman's correlation was used to assess the relationship between wave sign and longitudinal tear on the lower surface. Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eWe retrospectively analyzed the videos of 314 patients who underwent arthroscopic meniscus surgery from September 2018 to September 2021. Of all patients, 43 cases were finally confirmed to have longitudinal tears on the inferior surface of the meniscus after arthroscopic exploration (comprising 25 males and 18 females, with an average age of 46.17 years). Meniscus tears were observed in 6 patients through direct arthroscopic examination, while no tears were found in 37 patients. Because the preoperative MRI showed a positive sign, the longitudinal tear on the inferior surface of the meniscus was found after meticulous examination. Of the 37 cases of longitudinal tear on the inferior surface of the meniscus that could not be diagnosed by direct arthroscopic exploration, 36 cases had positive 'sudden-falling' signs, and the other one was negative. (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\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\u003eThe outcome of the \u0026lsquo;Sudden-falling\u0026rsquo; sign in the diagnosis of longitudinal tear on the inferior surface of the meniscus n (%)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWhich could not be diagnosed with direct examination (n\u0026thinsp;=\u0026thinsp;314)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWhich could be diagnosed with direct examination (n\u0026thinsp;=\u0026thinsp;314)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lsquo;Sudden-falling\u0026rsquo; sign (+)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36 (TP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (FP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e40 (12.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lsquo;Sudden-falling\u0026rsquo; sign (-)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (FN)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (TN)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3 (0.95)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e43 (13.69)\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\u003eResults show that the \u0026lsquo;sudden-falling\u0026rsquo; sign (+) has an AUC of 0.65, indicating moderate discriminatory power. It is highly sensitive (97.3%), but poorly specific (33.2%) for detecting occult meniscal tears. While statistically significant positive predictive value was 90% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.006), use the \u0026lsquo;Sudden-falling\u0026rsquo; (+) to confirm tears (highly sensitive). The \u0026lsquo;Sudden-falling\u0026rsquo; (-) has an AUC of 0.35, indicating poor performance. Avoid relying on the \u0026lsquo;Sudden-falling\u0026rsquo; (-) to exclude tears due to its low sensitivity. The characteristic of the 'sudden-falling' sign is of diagnostic significance for the longitudinal tear on the inferior surface of the meniscus. (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e.)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eA longitudinal tear on the inferior surface of the meniscus is a special occult meniscus tear. Currently, there is no standard examination method for tears. Suppose this tear cannot be identified and treated early. In such cases, the symptoms will not be completely relieved, and it is likely to progress to a full-thickness tear, rendering the meniscus irreparable, especially in cases of compound meniscus injuries. Especially, the longitudinal tear on the inferior surface of the meniscus, associated with articular cartilage injury, will affect stress distribution and increase pressure on the cartilage.\u003csup\u003e12\u003c/sup\u003e Consequently, it is particularly important to judge this hidden tear in the early stages.\u003csup\u003e13\u003c/sup\u003e MRI is the most crucial imaging examination of a meniscus longitudinal tear, which shows a high signal line in the vertical direction; nevertheless, some tears are difficult to identify, especially the longitudinal tear on the posterior horn of the lateral meniscus with complex posterior attachment.\u003csup\u003e14\u003c/sup\u003e And arthroscopic meniscus repair and suture is the prime method.\u003csup\u003e1, 4, 8\u003c/sup\u003e Arthroscopic explorations before repair are necessary, which can not only help us confirm the diagnosis but also avoid unnecessary repeated surgery caused by the neglect of longitudinal tear of the meniscus inferior surface.\u003csup\u003e9\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eA characteristic arthroscopic 'eyelid-turnup' sign, which is indicative of a partial-thickness longitudinal medial meniscus tear, has been reported in the literature.\u003csup\u003e13\u003c/sup\u003e However, it does not apply to all longitudinal tears of the inferior surface of the meniscus. We can divide the manifestations of the free edge of the longitudinal tear of the inferior surface of the meniscus into different parts into the following three types: (1) When the middle part of the meniscus is torn, there will be a wave-like edge, (2) When the meniscus is torn in the red or red-white zone that is closer to the free inner edge, an upturned edge corresponding to the above literature can appear, (3) There is also a normal free edge without any performance. Undoubtedly, all longitudinal tears of the medial or lateral meniscus inferior surface show the 'sudden-falling' sign we described. (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn clinical practice, although the superior surface appears intact, it is necessary to explore the concealed longitudinal tear on the inferior surface of the meniscus more accurately. We discovered a new exploration marker, the 'sudden-falling' sign, which enables more precise and effective detection of the longitudinal tear on the inferior surface of the meniscus. The results of this study demonstrate that, compared to other conventional methods, the newly proposed exploration method can accurately detect the longitudinal tear of the inferior meniscus surface and exhibits high sensitivity and specificity.\u003c/p\u003e \u003cp\u003eThis method of microscopic exploration, known as the 'sudden-falling' sign, is proposed for the first time in the literature, addressing the lack of diagnosis for special types of occult meniscus tears. Our method has the following advantages: firstly, this exploration method is simple and easy under arthroscopy, allowing for quick judgment of whether the inferior surface of the meniscus is torn and the location of the tears. Additionally, the method applies to all longitudinal tears on the inferior surface of the meniscus, particularly those small tears near the joint capsule that are difficult to detect. Finally, arthroscopy is the gold standard and more reliable than any other modality, including MRI and ultrasound.\u003c/p\u003e \u003cp\u003eHowever, this research has some limitations: First, the small sample size limits generalizability, so further studies with larger cohorts are needed. Simultaneously, the study is retrospective. Additionally, arthroscopy has a subjective component, relying on the surgeon\u0026rsquo;s skill level, which is also a factor to consider.\u003csup\u003e8\u003c/sup\u003e\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe 'sudden-falling' sign under arthroscopy is a characteristic indicator for occult longitudinal tears on the inferior surface of the meniscus. It can improve the clinical diagnosis of longitudinal tear of the meniscus' inferior surface and avoid omission.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study has gotten approval from the Medical Ethics Committee of the Second Affiliated Hospital of Harbin Medical University. All participants read and signed a written informed consent before the start of this study. All methods were performed in accordance with the principles outlined in the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis section is not applicable to our study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are not publicly available due to ethical restrictions, but are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors don\u0026rsquo;t have any conflicts of interest relevant to this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit organizations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHLP, AFG, and ZLS contributed to the conception and design of the study. HLP and ZLS were the leading surgeons in the current study. AFG, QC, XWW, and CW contributed to the acquisition of the data. QC, XWW, HMR, and CW contributed to the analysis and interpretation of the data. AFG and MSA were major contributors to drafting the manuscript. ZLS and MSA contributed to the critical revision of important intellectual content. All authors approved the final version to be submitted. HLP contributed responsibility for the overall content as guarantors. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis section is not applicable to our study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBeaufils P, Becker R, Kopf S, Matthieu O, Pujol N. The knee meniscus: management of traumatic tears and degenerative lesions. EFORT Open Rev. May 2017;2(5):195-203. doi:10.1302/2058-5241.2.160056\u003c/li\u003e\n\u003cli\u003eKurnaz R, Asci M, Ergun S, Akgun U, Gunes T. Repair of Longitudinal Meniscal Tears by Single or Double Vertical Loop Sutures: In vitro Biomechanical Study under Cyclic Loading. J Knee Surg. Mar 2020;33(3):314-318. doi:10.1055/s-0039-1700571\u003c/li\u003e\n\u003cli\u003eOzeki N, Seil R, Krych AJ, Koga H. Surgical treatment of complex meniscus tear and disease: state of the art. J ISAKOS. Jan 2021;6(1):35-45. doi:10.1136/jisakos-2019-000380\u003c/li\u003e\n\u003cli\u003eUzun E, Misir A, Kizkapan TB, Ozcamdalli M, Akkurt S, Guney A. Evaluation of Midterm Clinical and Radiographic Outcomes of Arthroscopically Repaired Vertical Longitudinal and Bucket-Handle Lateral Meniscal Tears. Orthop J Sports Med. May 2019;7(5):2325967119843203. doi:10.1177/2325967119843203\u003c/li\u003e\n\u003cli\u003eJarraya M, Roemer FW, Englund M, et al. Meniscus morphology: Does tear type matter? A narrative review with focus on relevance for osteoarthritis research. Semin Arthritis Rheum. Apr 2017;46(5):552-561. doi:10.1016/j.semarthrit.2016.11.005\u003c/li\u003e\n\u003cli\u003eChen Z, Zhang H, Luo H, et al. Contact mechanics after mattress suture repair of medial meniscus vertical longitudinal tear: an in vitro study. Arch Orthop Trauma Surg. Sep 2020;140(9):1221-1230. doi:10.1007/s00402-020-03428-0\u003c/li\u003e\n\u003cli\u003eGee SM, Tennent DJ, Cameron KL, Posner MA. The Burden of Meniscus Injury in Young and Physically Active Populations. Clin Sports Med. Jan 2020;39(1):13-27. doi:10.1016/j.csm.2019.08.008\u003c/li\u003e\n\u003cli\u003eKopf S, Beaufils P, Hirschmann MT, et al. Management of traumatic meniscus tears: the 2019 ESSKA meniscus consensus. Knee Surg Sports Traumatol Arthrosc. Apr 2020;28(4):1177-1194. doi:10.1007/s00167-020-05847-3\u003c/li\u003e\n\u003cli\u003eNguyen JC, De Smet AA, Graf BK, Rosas HG. MR imaging-based diagnosis and classification of meniscal tears. Radiographics. 2014 Jul-Aug;34(4):981-99. doi: 10.1148/rg.344125202. PMID: 25019436. \u003c/li\u003e\n\u003cli\u003eOei EH, Nikken JJ, Verstijnen AC, Ginai AZ, Myriam Hunink MG. MR imaging of the menisci and cruciate ligaments: a systematic review. Radiology. 2003 Mar;226(3):837-48. doi: 10.1148/radiol.2263011892. Epub 2003 Jan 15. PMID: 12601211. \u003c/li\u003e\n\u003cli\u003eJung JY, Jee WH, Park MY, Lee SY, Kim JM. Meniscal tear configurations: categorization with 3D isotropic turbo spin-echo MRI compared with conventional MRI at 3 T. AJR Am J Roentgenol. Feb 2012;198(2):W173-80. doi:10.2214/AJR.11.6979\u003c/li\u003e\n\u003cli\u003eTachibana Y, Mae T, Shino K, et al. A longitudinal tear in the medial meniscal body decreased the in situ meniscus force under an axial load. Knee Surg Sports Traumatol Arthrosc. Nov 2020;28(11):3457-3465. doi:10.1007/s00167-019-05735-5\u003c/li\u003e\n\u003cli\u003eLiang Z, Ren S, He F, Jiang X, Zhang W, Zhang X. The characteristic arthroscopic \u0026apos;eyelid- turnup\u0026apos; sign indicated for partial-thickness longitudinal medial meniscus tear. Technol Health Care. 2019;27(6):661-668. doi:10.3233/THC-191640\u003c/li\u003e\n\u003cli\u003eDe Smet AA, Nathan DH, Graf BK, Haaland BA, Fine JP. Clinical and MRI findings associated with false-positive knee MR diagnoses of medial meniscal tears. AJR Am J Roentgenol. Jul 2008;191(1):93-9. doi:10.2214/AJR.07.3034\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Second Affiliated Hospital of Harbin Medical University","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Sudden-falling sign, longitudinal tear, inferior surface, meniscus, arthroscopy","lastPublishedDoi":"10.21203/rs.3.rs-6931337/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6931337/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eWhen the superior surface of the meniscus is intact, the longitudinal tear on the inferior surface of the meniscus is easily ignored. Therefore, it is very important to find this tear through accurate inspection. Unfortunately, there is no specific method for detecting longitudinal tears on the inferior surface of the meniscus.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis study retrospectively analyzed the videos of 314 patients who underwent arthroscopic meniscus surgery from September 2018 to September 2021. The number of cases with longitudinal tears and 'sudden-falling' signs on the inferior surface of the meniscus was recorded to evaluate the sensitivity and specificity of this sign.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOf all 314 patients, 43 were finally confirmed to have the presence of longitudinal tears on the inferior surface of the meniscus after arthroscopic exploration. Meniscus tears were observed in 6 patients through direct arthroscopic exploration, and tears could not be observed in 37 patients. After a meticulous examination of the 37 cases that could not be directly diagnosed, 36 cases exhibited positive 'sudden-falling' signs, and the remaining case was negative. The sensitivity of the sign was 97.3%, and the positive predictive value was 90% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.006).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe 'sudden-falling' sign can accurately detect longitudinal tears of the meniscus' inferior surface, demonstrating high sensitivity and specificity. Therefore, it can improve the clinical diagnosis level of the longitudinal tear on the inferior surface of the meniscus.\u003c/p\u003e","manuscriptTitle":"Sudden-falling: a sensitive diagnostic sign of longitudinal tear of the meniscus inferior surface under arthroscopy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-23 08:12:03","doi":"10.21203/rs.3.rs-6931337/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6570dc84-50ba-46fe-a9ce-967d96fe266d","owner":[],"postedDate":"June 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":50299606,"name":"Sports Medicine and Kinesiology"}],"tags":[],"updatedAt":"2025-06-23T08:12:03+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-23 08:12:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6931337","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6931337","identity":"rs-6931337","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}