Quantitative Measurement of Inferior Patellar Mobility: Sex-based Differences and Relationship With the Restricted Knee Flexion Angle Due to Aging

Quantitative Measurement of Inferior Patellar Mobility: Sex-based Differences and Relationship With the Restricted Knee Flexion Angle Due to Aging | 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 Quantitative Measurement of Inferior Patellar Mobility: Sex-based Differences and Relationship With the Restricted Knee Flexion Angle Due to Aging Hiroshi Ohko, Susumu Ota This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1400894/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 Objective: To develop quantitative inferior patellar mobility (IPM) measurement methods and clarify the relationship between IPM and the knee flexion angle in community-dwelling elderly women. Design: The study was performed from May 2015 to December 2017. The reference value and sex difference of IPM were evaluated in 205 healthy young adults (age: 19-21 years). Additionally, 128 healthy elderly women (age: 65-79 years) were recruited from the community to evaluate the relationship between IPM and knee flexion angle. IPMs was also compared between healthy elderly women and healthy young women. IPMs were measured objectively by using our specially designed patellofemoral arthrometer (PFA); patellar mobility was calculated by normalizing to body height. IPM reliability assessment was performed prior to all measurements. Results: The intraclass correlation coefficients for intratester and intertester reliabilities varied from 0.87 to 0.99. The normal range, based on 2 standard deviations, of inferior patellar displacement/body height was 5.9%–13.5% (young men), 5.1%–14.3% (young women), and 1.2%–8.8% (elderly women). The IPM was significantly lower in elderly women than in young women ( P < 0.001). There was a significant positive correlation (r = 0.72, P < 0.01) between IPM and the knee flexion angle in healthy elderly women who were unable to fully flex the knee joint. Conclusions: Our PFA has good intratester and intertester reliability. The results suggest that IPM decreases with aging in women. IPM and the knee flexion angle are correlated among elderly women who are unable to fully flex the knee joint. inferior patellar mobility knee flexion angle patellofemoral arthrometer patellar displacement reliability Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The decrease in the range of motion (ROM) of the knee joint directly affects activities of daily living such as walking, using stairs, rising from a chair, and wearing or removing undergarments; therefore, it is important to maintain and improve ROM 1 – 3 . The decrease in the ROM of the knee flexion is associated with osteoarthritis 4 , stiffness after total knee arthroplasty (TKA) 5 , 6 , postoperative arthrofibrosis 7 , and other complications. Moreover, bed rest 8 , shortening of the rectus femoris muscle 9 , and soft tissue changes 10 such as adhesion around can occur as a result of or in tandem with underlying conditions. According to Panni et al 11 . and Dragoo et al 12 ., reduced patella mobility, especially in the inferior patella mobility, is associated with limited knee flexion 11 , 12 . Additionally, Jorosch et al. showed that the knee flexion angle could reportedly be improved in patients who undergo TKA by removing tissue adhesions around the patella (suprapatellar pouch, intra-articular fibrous bands, etc.) 13 . Although some reports claim that inferior patellar mobility is related to limited knee joint flexion 14 – 16 , such mobility has only been measured subjectively to date owing to the absence of a quantitative measurement method. The patellar gliding test, conducted by manually moving the patella in the medial and lateral, and inferior direction to end range of movement, is commonly used to measure passive patellar mobility 17 . The Cincinnati Knee Rating System and Kolowich (quadrant) method, which measure patellar mobility using the patellar sliding test, provide a subjective assessment of patellar movement 18 – 20 . Ota et al. developed the patellofemoral arthrometer (PFA), which enabled reliable quantitative measurements of medial and lateral patellar mobility 21 , 22 . They used the PFA to investigate the knee flexion angle and medial and lateral (but not inferior) patellar mobility of patients post-TKA and found that these parameters were not horizontally related 23 . Despite the aforementioned studies, the relationship between inferior patellar mobility and knee flexion angle remains relatively unexplored; to date, no quantitative method has been established for determining the former. Establishing such a quantitative evaluation method will help determine if a relationship exists between inferior patellar mobility and knee flexion angle; if so, this would validate the notion that improving inferior patellar mobility may be a therapeutic approach to improving knee joint flexion. Thus, this study was conducted to show that the knee flexion angle of elderly women with limited knee flexion was associated with decreased inferior patellar mobility. The healthy elderly recruited in this study were women with a high prevalence of knee osteoarthritis, who were expected to have reduced knee flexion angles. The purpose of this study was as follows. (1) Reliability of inferior patellar mobility was confirmed using PFA in young healthy subjects. (2) Sex differences in inferior patellar mobility in young healthy subjects were confirmed. (3) Age-related changes in inferior patellar mobility in young healthy subjects and healthy elderly women were examined. (4) The relationship between inferior patellar mobility and knee joint flexion angle in healthy elderly women was examined. Methods Subjects A total of 205 pain-free students from the Department of Rehabilitation and Care at Seijoh University, Japan, volunteered for the study (Table 1). Similarly, healthy women aged 65 years or older (n = 128) were recruited from the local community (Table 1). For each participant, we randomly chose the right or left patella by flipping a coin and then assessed its mobility. All participants were informed of the nature of the study before providing written informed consent; the study was approved by the Ethics Committees of Seijoh University (2013C0023). Exclusion criteria were having a history of knee pathology and/or testing positive on the clinical patellar test (such as Clarke’s test or the patellar femoral grinding test). Assessment of patellar mobility Instrumentation: To assess inferior patellar mobility, a modified PFA with added superior and inferior patellar measurements (Brace Fit Co., Ltd., Aichi, Japan) was used with a digital caliper (Fig. 1 ). The PFA was designed to measure patellar displacement during the initial (fixed) frontal plane motion (medial, lateral, superior and inferior translation) in millimeters. Procedures: Data from the previous study were used to determine the evaluation posture of the subjects (i.e., 0° hip rotation, supine position) 22 , 23 . The PFA was clamped to the femoral condyles and firmly secured parallel to the bed by fastening it to the thigh with a strap. The digital caliper was positioned parallel to an imaginary line connecting the medial patella to the anterior superior iliac spine (Fig. 2 ). Before each test, the level of pushing force (∼80 N) was confirmed with a handheld MicroFET2 dynamometer (Hoggan Health Industries Inc., West Jordan, UT, USA). During the assessment, leg muscle relaxation was confirmed by palpating the quadriceps and passively moving the patella in the medial and lateral directions. A pilot study was performed in which the patellar displacement was measured in 20 subjects (10 men and 10 women). There were significant differences in inferior patellar mobility on the third and subsequent measurements, and stable values were obtained (first vs. second: P = 0.01, second vs. third: P = 0.04, and third vs. fourth: P = 1.0). Thus, the measurement was performed after mobility training had been conducted at least three times. To measure inferior patellar mobility, the patellar apex was palpated and located with a laser by using the adjustable laser module arm, at which point the digital caliper was set to zero (i.e., the initial position) (Fig. 3 A). The inferior displacement of the patella was then determined by manually pushing the patella inferiorly (at 80 N), at which point that patellar apex was again located by sliding the laser module arm on the caliper and reading the measurement (Fig. 3 B). Inferior patellar mobility was performed three times, and the average value was used for statistical analysis. Because displacement is thought to be affected by body size, the degree of displacement was normalized to body size as represented by height (HT) 24 . Patellar mobility was adjusted for HT (patellar mobility/HT × 100). The absolute values of inferior patellar displacement (IPD) and IPD/HT were used to compare patellar mobility between young men, young women, and elderly women. Reliability study Twenty-nine young pain-free individuals (15 men and 14 women) participated in the reliability study of IPD. The average age, HT, and body mass index of the participants (± standard deviation [SD]) were 21.5 ± 0.6 years (men, 21.7 ± 0.6 years; women, 21.4 ± 0.5 years), 166.5 ± 5.2 cm (men, 173.5 ± 5.3 cm; women, 159.5 ± 5.2 cm), and 21.5 ± 0.6 kg/m 2 (men, 22.1 ± 1.7 kg/m 2 ; women, 19.9 ± 1.7 kg/m 2 ), respectively. Intra- and intertester reliability when quantifying inferior patellar mobility were determined based on measurements made by two different testers on different days. Before data collection, testers 1 and 2 practiced measurements on 10 participants for 100 min. They then randomly measured patellar mobility in the same session in each subject. Tester 1 performed the measurements in both testing sessions, which were at least three days apart for intratester reliability. Tester 2 assessed the patellar mobility on day 1 only to determine intertester reliability. The testers were blinded to all measurements. The intra- and intertester reliability of IPD readings obtained with the PFA were assessed by using intraclass correlation (ICC). The standard error of the mean (SEM) was calculated by using the following equation: SEM = SD × (√1 – ICC). After the reliability study, the patellar mobility study commenced using the same procedures as in the practice session and reliability study. To further investigate the real patellar displacement beyond measurement errors, the smallest real difference (SRD) was used to indicate the magnitude of change that would exceed the expected trial-to-trial variability. The SRD was calculated by using the following equation: 1.96 ×√2 × SEM 25 . The ICC, SEM, and SRD values are presented in Table 2. Data analysis The Shapiro-Wilk test was used to test for normality. Unpaired t -tests were used to compare patellar mobility between young men and women as well as between young and elderly women. For comparisons between the three groups, a one-way analysis of variance was performed with the Tukey Kramer post-hoc method also used. Significance was set at P < 0.05. Healthy elderly women were classified into two groups based on whether or not they were able to sit in seiza (a Japanese style of kneeling with the buttocks resting on the turned-out heels); 92 women were able to fully flex the knee joint (the seiza-possible group), and 36 were unable to do so (< 150°) (the seiza-impossible group). In each group, the correlation between patellar mobility and knee flexion angle was assessed by using Pearson’s correlation coefficient. All statistical analyses were performed using SPSS, version 25.0 (IBM Corp., Tokyo, Japan). Results The intratester reliability in terms of IPD measurements was 0.99 (95% confidence interval [CI]: 0.98–0.99) with an SEM of 0.29 mm, while the SRD was 0.80 mm. Intertester reliability in terms of IPD measurements was 0.87 (95% CI: 0.73–0.94); the SEM and SRD were 1.12 mm and 3.14 mm, respectively (Table 2). Table 3 shows the absolute values of the IPD measurements in young men (IPD: 16.5 ± 3.3 mm, IPD/HT: 9.7 ± 1.9%) and women (IPD: 15.4 ± 3.7 mm, IPD/HT: 9.7 ± 2.3%) as well as in elderly women (IPD: 7.5 ± 2.8 mm, IPD/HT: 5.0 ± 1.9%); IPD/HT values normalized for body height are also shown. A significant difference was found in IPD between young men and women ( P = 0.02, 95% CI: 0.17–2.11). However, the normalized IPD (IPD/HT) did not differ significantly between the sexes ( P = 0.85, 95% CI: -0.64–0.53). Thus, only the absolute displacement showed sex-based differences in IPD. We defined the normal patellar mobility range as 2 SD within a specific group. In our sample, the normal IPDs in young men and women were 9.9–23.1 mm and 8.0–22.8 mm, respectively. Using the same definition, the normal IPD/HT ranges were 5.9–13.5% in young men and 5.1–14.3% in young women. Similarly, the IPD range among elderly women was 1.9–13.1 mm, while the IPD/HT range was 1.2–8.8%. Absolute and corrected values for IPD were significantly lower in the seiza-possible group (7.8 ± 2.6 mm, 5.2 ± 1.7%) and seiza-impossible group (6.7 ± 3.3 mm, 4.5 ± 2.2%) than in young women (15.4 ± 3.7 mm, 9.7 ± 2.3%) ( P < 0.001) (Table 4). Furthermore, the inferior patellar mobility in the seiza-impossible was significantly lower than that in both young women and the seiza-possible group in both adjusted and unadjusted models ( P = 0.044). Additionally, there was a significant positive correlation (r = 0.72, P < 0.001) in both adjusted and unadjusted models between inferior patellar mobility and the knee flexion angle in the seiza-impossible group (Fig. 4 ). Discussion The newly developed modified PFA with inferior patellar measurement can measure the inferior patellar mobility with good intra- and inter-examiner reliability (ICC, 0.87–0.99) and is suitable for clinical application. The main findings in this study are as follows. There was a significant difference in the absolute value of IPD between young men and women, but when adjusted for body height, the significant difference disappeared. Absolute and normalized values for IPD were significantly lower in elderly women than in young women. In addition, the seiza-impossible group of the elderly had significantly lower IPD than the seiza-possible group and young women. Additionally, in the seiza-impossible group of the elderly, there were significant positive correlations between the absolute and normalized values for IPD and the knee flexion angle. Methods for evaluating the patella include tracking 26 , magnetic resonance imaging (MRI), computed tomography, conventional radiography in the static position 27 – 30 , and medial and lateral mobility assessment 21 – 24 . However, our method is a non-invasive method for dynamic evaluation of inferior patella mobility. It has been shown that the decrease in inferior patellar mobility is related to limited knee joint flexion 31 . To date, however, the inferior patellar mobility has been measured using subjective measurements of patellar flexibility [The Cincinnati Knee Rating System and Kolowich (quadrant) method] 17 , 19 . Hence, we are the also demonstrate its relationship with knee flexion angle using objective measurements. Additionally, using the mean ± 2 SDs (94.2% of normal distribution among men and 94.6% of that among women), it was necessary to establish the mean inferior patellar mobility in young men and women and adjust for normalized by body height, as described in the previous reports 21 . The inferior patellar mobility values among both the seiza-possible and seiza-impossible groups of elderly women were significantly lower than that among young women, with both elderly groups showing half the mobility of their young counterparts. Diminished muscle flexibility and increased soft tissue stiffness due to aging have been demonstrated in humans 32 . In particular, decreased soft tissue and muscle flexibility near the base of patella and distal thigh may affect the inferior patella mobility 11 – 13 . The inferior patellar mobility was significantly lower in the seiza-impossible group than in the seiza-possible group. Furthermore, there was a significant correlation between inferior patellar mobility and knee flexion angle in the seiza-impossible group, suggesting that inferior patellar mobility influenced knee flexion angle. Suprapatellar pouch lesion is considered to be one of the causes of the inferior patellar mobility. As the patella and suprapatellar pouch are connected, and adhesion of these two components may cause pain, flexion contractures, and stiffness 13 , 33 , which may reduce patellar mobility. Kapandji also reported that, when knee flexion increases from 90 degrees to more than 135 degrees, the suprapatellar pouch becomes completely ‘unpleated’ (i.e., straight without creases) 34 . The function of the suprapatellar pouch during knee flexion has been reported to be anatomically important; hence, it is possible that the inferior patellar mobility may be caused by diminished flexibility of soft tissues around the knee, including the suprapatellar pouch 11 . The relationship between the flexibility of soft tissues around the knee and inferior patellar mobility was described as playing a role in some diseases that cause limited knee joint flexion. In the case of knee osteoarthritis, it has recently been suggested that joint inflammation is not only confined in the articular cartilage of the knee but also affects the surrounding soft tissues, leading to peripatellar lesions and knee stiffness 35 . In patients with knee joint fibrosis, the signs and symptoms of arthrofibrosis include reduced patellar mobility, diminished knee ROM, tenderness around the knee, pain, and atrophy of the quadriceps. Inferior patellar mobility has been shown to be a factor affecting diminished knee flexion ROM 36 – 40 . Furthermore, in patients with knee joint fibrosis, lesions around the patella such as in the infrapatellar fat pad, pretibial recess, anterior interval, and suprapatellar pouch may arise 41 , affecting inferior patellar mobility. However, the causative factors of inferior patellar mobility have not been clearly determined because of the lack of methods that objectively evaluate it. Moving forward, it is necessary to clarify the relationship between inferior patellar mobility and soft tissue flexibility around the knee in patients with limited knee flexion. If the limit of inferior patellar mobility are identified, improvements in such mobility using therapeutic interventions can lead to an increased knee flexion angle. Our study has some limitations. First, the subject was a healthy group, and patellar mobility was not compared in the patient population. In future studies, it would be necessary to examine patellar mobility in patients with knee osteoarthritis. Second, we did not compare our results with those obtained using gold-standard procedures (i.e., MRI or X-ray fluoroscopy) for validation. Ota et al. evaluated the mobility of the medial and lateral patella with MRI using conventional PFA and obtained good results 22 . Moreover, the position of the patella at rest needs to be specifically examined, as it may be related to the inferior mobility of the patella. Specifically, it is necessary to evaluate the Insall-Salvati ratio using radiography 27 . Third, we did not quantify the force that pushes down the patella; rather, we used a dynamometer that we practiced pushing at 80 N prior to measurement. However, it was unclear whether the optimal force was applied to push the patella downward in actual measurements. To solve this problem, it is necessary to consider obtaining measurements while pressing back the patella in real-time using a sheet sensor, for example. Conclusion The PFA that we developed can measure inferior patellar mobility with good intra- and inter-examiner reliability. Our results suggested that inferior patellar mobility decreases with aging in women. The mobility of the inferior patella in unable Seiza was significantly lower in elderly women who were unable to sit in seiza. And the knee flexion angle and inferior patellar mobility were correlated among elderly women who were unable to sit in seiza. Abbreviations CI: Confidence interval; HT: Height; ICC: Intraclass correlation; IPD: Inferior patellar displacement; MRI: Magnetic resonance imaging; PFA: Patellofemoral arthrometer; ROM: Range of motion; SD: Standard deviation; SEM: Standard error of the mean; SRD: Smallest real difference; TKA: Total knee arthroplasty. Declarations Ethical Approval and Consent to participate All participants were informed of the nature of the study before providing written informed consent; the study was approved by the Ethics Committees of Seijoh University (2013C0023). Consent for publication 'Not applicable' Funding There was no funding supporting this study. Authors' contributions All authors have made substantial contributions to all three of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content; and (3) final approval of the version to be submitted. All authors critically appraised the manuscript and agreed to the final submission. Acknowledgements 'Not applicable' References Laubenthal KN, Smidt GL, Kettlekamp DB. A quantitative analysis of knee motion during activities of daily living. Phys Ther 1972;52:34–43. https://doi.org/10.1093/ptj/52.1.34 Bergström G, Aniansson A, Bjelle A, Grimby G, Lundgren-Lindquist B, Svanborg A. Functional consequences of joint impairment at age 79. Scand J Rehabil Med 1985;17:183–90. Odding E, Valkenburg HA, Algra D, Vandenouweland FA, Grobbee DE, Hofman A. 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Treatment of limited motion after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 1999;7:85–92. https://doi.org/10.1007/s001670050127 Shelbourne KD, Patel DV, Martini DJ. Classification and management of arthrofibrosis of the knee after anterior cruciate ligament reconstruction. Am J Sports Med 1996;24:857–62. https://doi.org/10.1177/036354659602400625 Enad JG. Arthroscopic lysis of adhesions for the stiff total knee arthroplasty. Arthrosc Tech 2014;3:e611–4. https://doi.org/10.1016/j.eats.2014.07.001 Tables Tables 1 to 4 xlsx are available in the Supplemental Files section. Additional Declarations No competing interests reported. Supplementary Files Table1.xlsx Table2.xlsx Table3.xlsx Table4.xlsx 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-1400894","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":87045346,"identity":"8cd3d8a3-5efb-4094-9f72-42006cc6b076","order_by":0,"name":"Hiroshi Ohko","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5UlEQVRIie2RsarCMBSG/xDQJZK1peB9hUhHxb5KQyGuwn0BQYijawUfwtGxEKhL0VVwUfocilFu4S62dRPMN4SfQz5yzgngcHwiXgcgsxFAEdOqKFoo6n3FPDOtvVnBAy3PZHuIeBeXcgoDvsjwO61R/HVuBClOcjVHEqZW8YoYNrxGHCc6uOpTLAxU0LvZDo9AyBoUj+h9FD0UZl/5aVZUbpWMbOifIpoUP1WJIDqRqbGzMEzYoJCz2lm4pwZnoscRXxayZBj2+zuTh3Ub+weLn6f9Jh22M9DNqkTLlorD4XB8B3e7fkHkVyEAcQAAAABJRU5ErkJggg==","orcid":"","institution":"Seijoh University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Hiroshi","middleName":"","lastName":"Ohko","suffix":""},{"id":87045347,"identity":"603450f6-362e-4c90-9119-977f1f199988","order_by":1,"name":"Susumu Ota","email":"","orcid":"","institution":"Seijoh University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Susumu","middleName":"","lastName":"Ota","suffix":""}],"badges":[],"createdAt":"2022-02-27 12:44:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1400894/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1400894/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":18797856,"identity":"0af95602-869e-4769-9ddc-869a89b7ac0e","added_by":"auto","created_at":"2022-03-02 21:28:50","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1202774,"visible":true,"origin":"","legend":"\u003cp\u003eComponents of the patellofemoral arthrometer. (1) base, (2) digital caliper, (3) adjustable laser module arm, (4) plane adjuster, (5) clamping mechanism, (6) thigh strap, and (7) fixed arm.\u003c/p\u003e","description":"","filename":"Fig.1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/fbd37e47d5f71a2a97932852.jpg"},{"id":18798319,"identity":"cfd87d1b-c5dc-4d62-aa15-6acd846737b2","added_by":"auto","created_at":"2022-03-02 21:31:49","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1539637,"visible":true,"origin":"","legend":"\u003cp\u003eThe patellofemoral arthrometer can be clamped to the femoral condyles. The plane adjuster allows the digital caliper to lie parallel to the imaginary line between the center of the patella and the anterior superior iliac spine (ASIS).\u003c/p\u003e","description":"","filename":"Fig.2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/0f064e0401ee17354b7d778c.jpg"},{"id":18797858,"identity":"4a054e0d-5d73-40c8-9320-3c10a8eba1c3","added_by":"auto","created_at":"2022-03-02 21:28:50","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":152706,"visible":true,"origin":"","legend":"\u003cp\u003e(3A) The patellar apex was located by palpation and aligned to the laser of the adjustable laser module arm. This was considered the initial position for patellar mobility measurements, with the digital caliper set to 0 mm. (3B) Inferior patellar mobility was measured as the difference between the initial position (patellar apex) and the position following the application of an 80 N inferior force.\u003c/p\u003e","description":"","filename":"Fig.3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/a37d24371d30d236ad164892.jpg"},{"id":18797852,"identity":"e9d4cc96-e0ab-4de3-8664-b6493f7f7888","added_by":"auto","created_at":"2022-03-02 21:28:49","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":143690,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between inferior patellar mobility and knee flexion angle among elderly women who could not sit in the ‘seiza’ position.\u003c/p\u003e\u003cp\u003eThe correlations between patellar mobility and the knee flexion angle in the seiza possible and seiza impossible groups were assessed by using Pearson’s correlation coefficient. Abbreviations: IPD, inferior patellar displacement; HT, height.\u003c/p\u003e","description":"","filename":"Fig.4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/5243a47f20aeeb3b8e2d5814.jpg"},{"id":18798458,"identity":"8e9a13e7-60a9-414d-b115-5cb05292a809","added_by":"auto","created_at":"2022-03-02 21:34:52","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":533553,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/a6cf3cd4-bc31-4702-b5df-7065230281ee.pdf"},{"id":18798320,"identity":"e6d93346-a74a-49f1-88c5-5844962d075a","added_by":"auto","created_at":"2022-03-02 21:31:49","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":10960,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/5ec69d401175674cbad87e21.xlsx"},{"id":18798322,"identity":"921f8401-925b-49ef-bae8-f1676125106d","added_by":"auto","created_at":"2022-03-02 21:31:50","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":10692,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/46607c2d1efa8049e2628dec.xlsx"},{"id":18797854,"identity":"4e8d52d2-3886-4d10-93ee-b29eede18ab8","added_by":"auto","created_at":"2022-03-02 21:28:49","extension":"xlsx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":10825,"visible":true,"origin":"","legend":"","description":"","filename":"Table3.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/3808f1e24361769005c5f2b8.xlsx"},{"id":18798457,"identity":"8131d102-f305-4efc-875d-add62093d7fa","added_by":"auto","created_at":"2022-03-02 21:34:50","extension":"xlsx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":11194,"visible":true,"origin":"","legend":"","description":"","filename":"Table4.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-1400894/v1/0513e129e0b8591fe78dfcb1.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eQuantitative Measurement of Inferior Patellar Mobility: Sex-based Differences and Relationship With the Restricted Knee Flexion Angle Due to Aging\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe decrease in the range of motion (ROM) of the knee joint directly affects activities of daily living such as walking, using stairs, rising from a chair, and wearing or removing undergarments; therefore, it is important to maintain and improve ROM\u003csup\u003e\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. The decrease in the ROM of the knee flexion is associated with osteoarthritis\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e, stiffness after total knee arthroplasty (TKA)\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, postoperative arthrofibrosis\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e, and other complications. Moreover, bed rest\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e, shortening of the rectus femoris muscle\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, and soft tissue changes\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e such as adhesion around can occur as a result of or in tandem with underlying conditions.\u003c/p\u003e \u003cp\u003eAccording to Panni et al\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. and Dragoo et al\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e., reduced patella mobility, especially in the inferior patella mobility, is associated with limited knee flexion\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. Additionally, Jorosch et al. showed that the knee flexion angle could reportedly be improved in patients who undergo TKA by removing tissue adhesions around the patella (suprapatellar pouch, intra-articular fibrous bands, etc.)\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. Although some reports claim that inferior patellar mobility is related to limited knee joint flexion\u003csup\u003e\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, such mobility has only been measured subjectively to date owing to the absence of a quantitative measurement method. The patellar gliding test, conducted by manually moving the patella in the medial and lateral, and inferior direction to end range of movement, is commonly used to measure passive patellar mobility\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. The Cincinnati Knee Rating System and Kolowich (quadrant) method, which measure patellar mobility using the patellar sliding test, provide a subjective assessment of patellar movement\u003csup\u003e\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eOta et al. developed the patellofemoral arthrometer (PFA), which enabled reliable quantitative measurements of medial and lateral patellar mobility\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. They used the PFA to investigate the knee flexion angle and medial and lateral (but not inferior) patellar mobility of patients post-TKA and found that these parameters were not horizontally related\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eDespite the aforementioned studies, the relationship between inferior patellar mobility and knee flexion angle remains relatively unexplored; to date, no quantitative method has been established for determining the former. Establishing such a quantitative evaluation method will help determine if a relationship exists between inferior patellar mobility and knee flexion angle; if so, this would validate the notion that improving inferior patellar mobility may be a therapeutic approach to improving knee joint flexion. Thus, this study was conducted to show that the knee flexion angle of elderly women with limited knee flexion was associated with decreased inferior patellar mobility. The healthy elderly recruited in this study were women with a high prevalence of knee osteoarthritis, who were expected to have reduced knee flexion angles.\u003c/p\u003e \u003cp\u003eThe purpose of this study was as follows. (1) Reliability of inferior patellar mobility was confirmed using PFA in young healthy subjects. (2) Sex differences in inferior patellar mobility in young healthy subjects were confirmed. (3) Age-related changes in inferior patellar mobility in young healthy subjects and healthy elderly women were examined. (4) The relationship between inferior patellar mobility and knee joint flexion angle in healthy elderly women was examined.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv class=\"Section2\" id=\"Sec3\"\u003e\n \u003ch2\u003eSubjects\u003c/h2\u003e\n \u003cp\u003eA total of 205 pain-free students from the Department of Rehabilitation and Care at Seijoh University, Japan, volunteered for the study (Table\u0026nbsp;1). Similarly, healthy women aged 65 years or older (n\u0026thinsp;=\u0026thinsp;128) were recruited from the local community (Table\u0026nbsp;1). For each participant, we randomly chose the right or left patella by flipping a coin and then assessed its mobility. All participants were informed of the nature of the study before providing written informed consent; the study was approved by the Ethics Committees of Seijoh University (2013C0023). Exclusion criteria were having a history of knee pathology and/or testing positive on the clinical patellar test (such as Clarke\u0026rsquo;s test or the patellar femoral grinding test).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec4\"\u003e\n \u003ch2\u003eAssessment of patellar mobility\u003c/h2\u003e\n \u003cp\u003eInstrumentation: To assess inferior patellar mobility, a modified PFA with added superior and inferior patellar measurements (Brace Fit Co., Ltd., Aichi, Japan) was used with a digital caliper (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The PFA was designed to measure patellar displacement during the initial (fixed) frontal plane motion (medial, lateral, superior and inferior translation) in millimeters.\u003c/p\u003e\n \u003cp\u003eProcedures: Data from the previous study were used to determine the evaluation posture of the subjects (i.e., 0\u0026deg; hip rotation, supine position)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. The PFA was clamped to the femoral condyles and firmly secured parallel to the bed by fastening it to the thigh with a strap. The digital caliper was positioned parallel to an imaginary line connecting the medial patella to the anterior superior iliac spine (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). Before each test, the level of pushing force (\u0026sim;80 N) was confirmed with a handheld MicroFET2 dynamometer (Hoggan Health Industries Inc., West Jordan, UT, USA). During the assessment, leg muscle relaxation was confirmed by palpating the quadriceps and passively moving the patella in the medial and lateral directions.\u003c/p\u003e\n \u003cp\u003eA pilot study was performed in which the patellar displacement was measured in 20 subjects (10 men and 10 women). There were significant differences in inferior patellar mobility on the third and subsequent measurements, and stable values were obtained (first vs. second: \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.01, second vs. third: \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04, and third vs. fourth: \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.0). Thus, the measurement was performed after mobility training had been conducted at least three times.\u003c/p\u003e\n \u003cp\u003eTo measure inferior patellar mobility, the patellar apex was palpated and located with a laser by using the adjustable laser module arm, at which point the digital caliper was set to zero (i.e., the initial position) (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eA). The inferior displacement of the patella was then determined by manually pushing the patella inferiorly (at 80 N), at which point that patellar apex was again located by sliding the laser module arm on the caliper and reading the measurement (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eB). Inferior patellar mobility was performed three times, and the average value was used for statistical analysis. Because displacement is thought to be affected by body size, the degree of displacement was normalized to body size as represented by height (HT)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Patellar mobility was adjusted for HT (patellar mobility/HT \u0026times; 100). The absolute values of inferior patellar displacement (IPD) and IPD/HT were used to compare patellar mobility between young men, young women, and elderly women.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec5\"\u003e\n \u003ch2\u003eReliability study\u003c/h2\u003e\n \u003cp\u003eTwenty-nine young pain-free individuals (15 men and 14 women) participated in the reliability study of IPD. The average age, HT, and body mass index of the participants (\u0026plusmn;\u0026thinsp;standard deviation [SD]) were 21.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 years (men, 21.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 years; women, 21.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 years), 166.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2 cm (men, 173.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3 cm; women, 159.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2 cm), and 21.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 kg/m\u003csup\u003e2\u003c/sup\u003e (men, 22.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 kg/m\u003csup\u003e2\u003c/sup\u003e; women, 19.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 kg/m\u003csup\u003e2\u003c/sup\u003e), respectively. Intra- and intertester reliability when quantifying inferior patellar mobility were determined based on measurements made by two different testers on different days.\u003c/p\u003e\n \u003cp\u003eBefore data collection, testers 1 and 2 practiced measurements on 10 participants for 100 min. They then randomly measured patellar mobility in the same session in each subject. Tester 1 performed the measurements in both testing sessions, which were at least three days apart for intratester reliability. Tester 2 assessed the patellar mobility on day 1 only to determine intertester reliability. The testers were blinded to all measurements.\u003c/p\u003e\n \u003cp\u003eThe intra- and intertester reliability of IPD readings obtained with the PFA were assessed by using intraclass correlation (ICC). The standard error of the mean (SEM) was calculated by using the following equation: SEM\u0026thinsp;=\u0026thinsp;SD \u0026times; (\u0026radic;1 \u0026ndash; ICC). After the reliability study, the patellar mobility study commenced using the same procedures as in the practice session and reliability study. To further investigate the real patellar displacement beyond measurement errors, the smallest real difference (SRD) was used to indicate the magnitude of change that would exceed the expected trial-to-trial variability. The SRD was calculated by using the following equation: 1.96 \u0026times;\u0026radic;2 \u0026times; SEM\u003csup\u003e25\u003c/sup\u003e. The ICC, SEM, and SRD values are presented in Table\u0026nbsp;2.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec6\"\u003e\n \u003ch2\u003eData analysis\u003c/h2\u003e\n \u003cp\u003eThe Shapiro-Wilk test was used to test for normality. Unpaired \u003cem\u003et\u003c/em\u003e-tests were used to compare patellar mobility between young men and women as well as between young and elderly women. For comparisons between the three groups, a one-way analysis of variance was performed with the Tukey Kramer post-hoc method also used. Significance was set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\n \u003cp\u003eHealthy elderly women were classified into two groups based on whether or not they were able to sit in seiza (a Japanese style of kneeling with the buttocks resting on the turned-out heels); 92 women were able to fully flex the knee joint (the seiza-possible group), and 36 were unable to do so (\u0026lt;\u0026thinsp;150\u0026deg;) (the seiza-impossible group). In each group, the correlation between patellar mobility and knee flexion angle was assessed by using Pearson\u0026rsquo;s correlation coefficient. All statistical analyses were performed using SPSS, version 25.0 (IBM Corp., Tokyo, Japan).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe intratester reliability in terms of IPD measurements was 0.99 (95% confidence interval [CI]: 0.98\u0026ndash;0.99) with an SEM of 0.29 mm, while the SRD was 0.80 mm. Intertester reliability in terms of IPD measurements was 0.87 (95% CI: 0.73\u0026ndash;0.94); the SEM and SRD were 1.12 mm and 3.14 mm, respectively (Table\u0026nbsp;2). Table\u0026nbsp;3 shows the absolute values of the IPD measurements in young men (IPD: 16.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3 mm, IPD/HT: 9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9%) and women (IPD: 15.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7 mm, IPD/HT: 9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3%) as well as in elderly women (IPD: 7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8 mm, IPD/HT: 5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9%); IPD/HT values normalized for body height are also shown. A significant difference was found in IPD between young men and women (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.02, 95% CI: 0.17\u0026ndash;2.11). However, the normalized IPD (IPD/HT) did not differ significantly between the sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.85, 95% CI: -0.64\u0026ndash;0.53). Thus, only the absolute displacement showed sex-based differences in IPD.\u003c/p\u003e\n\u003cp\u003eWe defined the normal patellar mobility range as 2 SD within a specific group. In our sample, the normal IPDs in young men and women were 9.9\u0026ndash;23.1 mm and 8.0\u0026ndash;22.8 mm, respectively. Using the same definition, the normal IPD/HT ranges were 5.9\u0026ndash;13.5% in young men and 5.1\u0026ndash;14.3% in young women. Similarly, the IPD range among elderly women was 1.9\u0026ndash;13.1 mm, while the IPD/HT range was 1.2\u0026ndash;8.8%.\u003c/p\u003e\n\u003cp\u003eAbsolute and corrected values for IPD were significantly lower in the seiza-possible group (7.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6 mm, 5.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7%) and seiza-impossible group (6.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3 mm, 4.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2%) than in young women (15.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7 mm, 9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3%) (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Table\u0026nbsp;4).\u003c/p\u003e\n\u003cp\u003eFurthermore, the inferior patellar mobility in the seiza-impossible was significantly lower than that in both young women and the seiza-possible group in both adjusted and unadjusted models (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.044). Additionally, there was a significant positive correlation (r\u0026thinsp;=\u0026thinsp;0.72, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in both adjusted and unadjusted models between inferior patellar mobility and the knee flexion angle in the seiza-impossible group (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe newly developed modified PFA with inferior patellar measurement can measure the inferior patellar mobility with good intra- and inter-examiner reliability (ICC, 0.87\u0026ndash;0.99) and is suitable for clinical application. The main findings in this study are as follows. There was a significant difference in the absolute value of IPD between young men and women, but when adjusted for body height, the significant difference disappeared. Absolute and normalized values for IPD were significantly lower in elderly women than in young women. In addition, the seiza-impossible group of the elderly had significantly lower IPD than the seiza-possible group and young women. Additionally, in the seiza-impossible group of the elderly, there were significant positive correlations between the absolute and normalized values for IPD and the knee flexion angle.\u003c/p\u003e \u003cp\u003eMethods for evaluating the patella include tracking\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, magnetic resonance imaging (MRI), computed tomography, conventional radiography in the static position\u003csup\u003e\u003cspan additionalcitationids=\"CR28 CR29\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e, and medial and lateral mobility assessment\u003csup\u003e\u003cspan additionalcitationids=\"CR22 CR23\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. However, our method is a non-invasive method for dynamic evaluation of inferior patella mobility. It has been shown that the decrease in inferior patellar mobility is related to limited knee joint flexion\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. To date, however, the inferior patellar mobility has been measured using subjective measurements of patellar flexibility [The Cincinnati Knee Rating System and Kolowich (quadrant) method]\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Hence, we are the also demonstrate its relationship with knee flexion angle using objective measurements. Additionally, using the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;2 SDs (94.2% of normal distribution among men and 94.6% of that among women), it was necessary to establish the mean inferior patellar mobility in young men and women and adjust for normalized by body height, as described in the previous reports\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe inferior patellar mobility values among both the seiza-possible and seiza-impossible groups of elderly women were significantly lower than that among young women, with both elderly groups showing half the mobility of their young counterparts. Diminished muscle flexibility and increased soft tissue stiffness due to aging have been demonstrated in humans\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. In particular, decreased soft tissue and muscle flexibility near the base of patella and distal thigh may affect the inferior patella mobility\u003csup\u003e\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. The inferior patellar mobility was significantly lower in the seiza-impossible group than in the seiza-possible group. Furthermore, there was a significant correlation between inferior patellar mobility and knee flexion angle in the seiza-impossible group, suggesting that inferior patellar mobility influenced knee flexion angle.\u003c/p\u003e \u003cp\u003eSuprapatellar pouch lesion is considered to be one of the causes of the inferior patellar mobility. As the patella and suprapatellar pouch are connected, and adhesion of these two components may cause pain, flexion contractures, and stiffness\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e, which may reduce patellar mobility. Kapandji also reported that, when knee flexion increases from 90 degrees to more than 135 degrees, the suprapatellar pouch becomes completely \u0026lsquo;unpleated\u0026rsquo; (i.e., straight without creases)\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. The function of the suprapatellar pouch during knee flexion has been reported to be anatomically important; hence, it is possible that the inferior patellar mobility may be caused by diminished flexibility of soft tissues around the knee, including the suprapatellar pouch\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe relationship between the flexibility of soft tissues around the knee and inferior patellar mobility was described as playing a role in some diseases that cause limited knee joint flexion. In the case of knee osteoarthritis, it has recently been suggested that joint inflammation is not only confined in the articular cartilage of the knee but also affects the surrounding soft tissues, leading to peripatellar lesions and knee stiffness\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. In patients with knee joint fibrosis, the signs and symptoms of arthrofibrosis include reduced patellar mobility, diminished knee ROM, tenderness around the knee, pain, and atrophy of the quadriceps. Inferior patellar mobility has been shown to be a factor affecting diminished knee flexion ROM\u003csup\u003e\u003cspan additionalcitationids=\"CR37 CR38 CR39\" citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Furthermore, in patients with knee joint fibrosis, lesions around the patella such as in the infrapatellar fat pad, pretibial recess, anterior interval, and suprapatellar pouch may arise\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e, affecting inferior patellar mobility.\u003c/p\u003e \u003cp\u003eHowever, the causative factors of inferior patellar mobility have not been clearly determined because of the lack of methods that objectively evaluate it. Moving forward, it is necessary to clarify the relationship between inferior patellar mobility and soft tissue flexibility around the knee in patients with limited knee flexion. If the limit of inferior patellar mobility are identified, improvements in such mobility using therapeutic interventions can lead to an increased knee flexion angle.\u003c/p\u003e \u003cp\u003eOur study has some limitations. First, the subject was a healthy group, and patellar mobility was not compared in the patient population. In future studies, it would be necessary to examine patellar mobility in patients with knee osteoarthritis. Second, we did not compare our results with those obtained using gold-standard procedures (i.e., MRI or X-ray fluoroscopy) for validation. Ota et al. evaluated the mobility of the medial and lateral patella with MRI using conventional PFA and obtained good results\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Moreover, the position of the patella at rest needs to be specifically examined, as it may be related to the inferior mobility of the patella. Specifically, it is necessary to evaluate the Insall-Salvati ratio using radiography\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. Third, we did not quantify the force that pushes down the patella; rather, we used a dynamometer that we practiced pushing at 80 N prior to measurement. However, it was unclear whether the optimal force was applied to push the patella downward in actual measurements. To solve this problem, it is necessary to consider obtaining measurements while pressing back the patella in real-time using a sheet sensor, for example.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe PFA that we developed can measure inferior patellar mobility with good intra- and inter-examiner reliability. Our results suggested that inferior patellar mobility decreases with aging in women. The mobility of the inferior patella in unable Seiza was significantly lower in elderly women who were unable to sit in seiza. And the knee flexion angle and inferior patellar mobility were correlated among elderly women who were unable to sit in seiza.\u003c/p\u003e "},{"header":"Abbreviations","content":"\u003cp\u003eCI: Confidence interval; HT: Height; ICC: Intraclass correlation; IPD: Inferior patellar displacement; MRI: Magnetic resonance imaging; PFA: Patellofemoral arthrometer; ROM: Range of motion; SD: Standard deviation; SEM: Standard error of the mean; SRD: Smallest real difference; TKA: Total knee arthroplasty.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval and Consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll participants were informed of the nature of the study before providing written informed consent; the study was approved by the Ethics Committees of Seijoh University (2013C0023).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026apos;Not applicable\u0026apos;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere was no funding supporting this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors have made substantial contributions to all three of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content; and (3) final approval of the version to be submitted. All authors critically appraised the manuscript and agreed to the final submission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026apos;Not applicable\u0026apos;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eLaubenthal KN, Smidt GL, Kettlekamp DB. A quantitative analysis of knee motion during activities of daily living. Phys Ther 1972;52:34\u0026ndash;43. https://doi.org/10.1093/ptj/52.1.34\u003c/li\u003e\n \u003cli\u003eBergstr\u0026ouml;m G, Aniansson A, Bjelle A, Grimby G, Lundgren-Lindquist B, Svanborg A. Functional consequences of joint impairment at age 79. Scand J Rehabil Med 1985;17:183\u0026ndash;90.\u003c/li\u003e\n \u003cli\u003eOdding E, Valkenburg HA, Algra D, Vandenouweland FA, Grobbee DE, Hofman A. The association of abnormalities on physical examination of the hip and knee with locomotor disability in the Rotterdam Study. 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Am J Phys Med Rehabil 2006;85:234\u0026ndash;43. https://doi.org/10.1097/01.phm.0000200390.67408.f0\u003c/li\u003e\n \u003cli\u003eWilk KE, Davies GJ, Mangine RE, Malone TR. Patellofemoral disorders: a classification system and clinical guidelines for nonoperative rehabilitation. J Orthop Sports Phys Ther 1998;28:307\u0026ndash;22.\u003c/li\u003e\n \u003cli\u003eNissen CW, Cullen MC, Hewett TE, Noyes FR. Physical and arthroscopic examination techniques of the patellofemoral joint. J Orthop Sports Phys Ther 1998;28:277\u0026ndash;85.\u003c/li\u003e\n \u003cli\u003eKolowich PA, Paulos LE, Rosenberg TD, Farnsworth S. Lateral release of the patella: indications and contraindications. Am J Sports Med 1990;18:359\u0026ndash;65.\u003c/li\u003e\n \u003cli\u003eNomura E, Inoue M, Kobayashi S. Generalized joint laxity and contralateral patellar hypermobility in unilateral recurrent patellar dislocators. 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Sex differences in passive lateral and medial patellar mobility in healthy young adults. J Back Musculoskelet Rehabil 2017;31:127\u0026ndash;32. https://doi.org/10.3233/BMR-169704\u003c/li\u003e\n \u003cli\u003eBeckerman H, Roebroeck ME, Lankhorst GJ, Becher JG, Bezemer PD, Verbeek AL. Smallest real difference, a link between reproducibility and responsiveness. Qual Life Res 2001;10:571\u0026ndash;8. https://doi.org/10.1023/a:1013138911638\u003c/li\u003e\n \u003cli\u003eTanaka MJ, Elias JJ, Williams AA, Demehri S, Cosgarea AJ. Characterization of patellar maltracking using dynamic kinematic CT imaging in patients with patellar instability. Knee Surg Sports Traumatol Arthrosc 2016;24:3634\u0026ndash;41. https://doi.org/10.1007/s00167-016-4216-9\u003c/li\u003e\n \u003cli\u003eInsall J, Falvo KA, Wise DW. Chondromalacia patellae. A prospective study. J Bone Joint Surg Am. 1976;58:1\u0026ndash;8.\u003c/li\u003e\n \u003cli\u003eGrelsamer RP, Newton PM, Staron RB. The medial-lateral position of the patella on routine magnetic resonance imaging: when is normal not normal? Arthroscopy 1998;14:23\u0026ndash;8. https://doi.org/10.1016/s0749-8063(98)70116-1\u003c/li\u003e\n \u003cli\u003eHerrington L. The effect of corrective taping of the patella on patella position as defined by MRI. Res Sports Med 2006;14:215\u0026ndash;23.\u003c/li\u003e\n \u003cli\u003eMirza Tolouei F, Afshar A, Salarilak S, Sina A. CT patellar cortex tilt angle: a radiological method to measure patellar tilt. Iran J Radiol 2005;3:17\u0026ndash;21.\u003c/li\u003e\n \u003cli\u003eSweitzer BA, Cook C, Steadman JR, Hawkins RJ, Wyland DJ. The inter-rater reliability and diagnostic accuracy of patellar mobility tests in patients with anterior knee pain. Phys Sportsmed 2010;38:90\u0026ndash;6. https://doi.org/10.3810/psm.2010.10.1813\u003c/li\u003e\n \u003cli\u003e32. Buckwalter JA. Maintaining and Restoring Mobility in Middle and Old Age: The Importance of the Soft Tissues. Instr Course Lect. 1997; 46: 459-69.\u003c/li\u003e\n \u003cli\u003eFitzsimmons SE, Vazquez EA, Bronson MJ. How to treat the stiff total knee arthroplasty?: a systematic review. Clin Orthop Relat Res 2010;468:1096\u0026ndash;106. https://doi.org/10.1007/s11999-010-1230-y\u003c/li\u003e\n \u003cli\u003eKapandji IA. The physiology of the joints. Vol 2. Lower limb. Honore LH (translator). Churchill and Livingstone, Edinburgh 1970: 92\u0026ndash;103.\u003c/li\u003e\n \u003cli\u003eFelson DT, Lawrence RC, Dieppe PA, Hirsch R, Helmick CG, Jordan JM, et al. Osteoarthritis: new insights. Part 1: the disease and its risk factors. Ann Intern Med 2000;133:635\u0026ndash;46. \u003ca href=\"https://doi.org/10.7326/0003-4819-133-8-200010170-00016\"\u003ehttps://doi.org/10.7326/0003-4819-133-8-200010170-00016\u003c/a\u003e\u003c/li\u003e\n \u003cli\u003ede Miguel malesdieta E, Cobo Ib\u0026aacute;\u0026ntilde;ez T, Us\u0026oacute;n Jaeger J, Bonilla Hern\u0026aacute;n G, Mart\u0026iacute;n Mola E. Clinical and ultrasonographic findings related to knee pain in osteoarthritis. Osteoarthritis Cartilage 2006;14:540\u0026ndash;4. https://doi.org/10.1016/j.joca.2005.12.012\u003c/li\u003e\n \u003cli\u003eEakin CL. Knee arthrofibrosis: prevention and management of a potentially devastating condition. Phys Sportsmed 2001;29:31\u0026ndash;42. https://doi.org/10.3810/psm.2001.03.668\u003c/li\u003e\n \u003cli\u003eMillett PJ, Wickiewicz TL, Warren RF. Motion loss after ligament injuries to the knee. Part I: causes. Am J Sports Med 2001;29:664\u0026ndash;75. https://doi.org/10.1177/03635465010290052401\u003c/li\u003e\n \u003cli\u003eShelbourne KD, Patel DV. Treatment of limited motion after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 1999;7:85\u0026ndash;92. https://doi.org/10.1007/s001670050127\u003c/li\u003e\n \u003cli\u003eShelbourne KD, Patel DV, Martini DJ. Classification and management of arthrofibrosis of the knee after anterior cruciate ligament reconstruction. Am J Sports Med 1996;24:857\u0026ndash;62. https://doi.org/10.1177/036354659602400625\u003c/li\u003e\n \u003cli\u003eEnad JG. Arthroscopic lysis of adhesions for the stiff total knee arthroplasty. Arthrosc Tech 2014;3:e611\u0026ndash;4. \u003ca href=\"https://doi.org/10.1016/j.eats.2014.07.001\"\u003ehttps://doi.org/10.1016/j.eats.2014.07.001\u003c/a\u003e\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 4 xlsx are available in the Supplemental Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"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":"inferior patellar mobility, knee flexion angle, patellofemoral arthrometer, patellar displacement, reliability","lastPublishedDoi":"10.21203/rs.3.rs-1400894/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1400894/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eObjective: To develop quantitative inferior patellar mobility (IPM) measurement methods and clarify the relationship between IPM and the knee flexion angle in community-dwelling elderly women.\u003c/p\u003e\u003cp\u003eDesign: The study was performed from May 2015 to December 2017. The reference value and sex difference of IPM were evaluated in 205 healthy young adults (age: 19-21 years). Additionally, 128 healthy elderly women (age: 65-79 years) were recruited from the community to evaluate the relationship between IPM and knee flexion angle. IPMs was also compared between healthy elderly women and healthy young women. IPMs were measured objectively by using our specially designed patellofemoral arthrometer (PFA); patellar mobility was calculated by normalizing to body height. IPM reliability assessment was performed prior to all measurements. \u003c/p\u003e\u003cp\u003eResults: The intraclass correlation coefficients for intratester and intertester reliabilities varied from 0.87 to 0.99. The normal range, based on 2 standard deviations, of inferior patellar displacement/body height was 5.9%–13.5% (young men), 5.1%–14.3% (young women), and 1.2%–8.8% (elderly women). The IPM was significantly lower in elderly women than in young women (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.001). There was a significant positive correlation (r = 0.72, \u003cem\u003eP \u003c/em\u003e\u0026lt; 0.01) between IPM and the knee flexion angle in healthy elderly women who were unable to fully flex the knee joint.\u003c/p\u003e\u003cp\u003eConclusions: Our PFA has good intratester and intertester reliability. The results suggest that IPM decreases with aging in women. IPM and the knee flexion angle are correlated among elderly women who are unable to fully flex the knee joint.\u003c/p\u003e","manuscriptTitle":"Quantitative Measurement of Inferior Patellar Mobility: Sex-based Differences and Relationship With the Restricted Knee Flexion Angle Due to Aging","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-03-02 21:28:48","doi":"10.21203/rs.3.rs-1400894/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":"105c49d8-7745-4672-a468-824bb3053cdd","owner":[],"postedDate":"March 2nd, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-03-02T21:28:49+00:00","versionOfRecord":[],"versionCreatedAt":"2022-03-02 21:28:48","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1400894","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1400894","identity":"rs-1400894","version":["v1"]},"buildId":"uwybb5PU2iWlRI8EIam5Y","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}