Identification of stiff-knee gait in stroke survivors

Identification of stiff-knee gait in stroke survivors | 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 Identification of stiff-knee gait in stroke survivors Odair Bacca, Melissa Leandro Celestino, José Angelo Barela, Ana Maria Forti Barela This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4797428/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Sep, 2025 Read the published version in BMC Biomedical Engineering → Version 1 posted 12 You are reading this latest preprint version Abstract Background: Though stiff-knee gait is a common movement disorder in individuals with stroke, the criteria for identifying it in this population are not yet well established. This study investigated suitable criteria to identify stroke survivors with stiff-knee gait. Twenty-four stroke survivors (45.2±13.7 years old) and 24 individuals matched by age and sex (45.5±13.5 years old) with no known gait impairment participated in this study. They walked along a 10-m extension walkway at a self-selected comfortable speed. A computerized analysis system registered the trajectories of retroreflective markers placed on specific body landmarks, and different measurements were calculated regarding knee flexion during gait cycle, such as its peak during the swing period, total range of motion (RoM), equivalent to the difference between maximum and minimum knee excursion during gait cycle (“RoM cycle”), and RoM from toe-off to peak knee flexion (“RoM swing”). Results: Overall, peak knee flexion during the swing period and knee RoM swing were the most remarkable measurements to identify stiff-knee gait in stroke survivors. Conclusions: Based upon the found results, we suggest using at least two criteria to identify stiff-knee gait in individuals with stroke. The most suitable ones are peak knee flexion during the swing period <50° and the knee RoM from toe-off to peak knee flexion <12°. Finally, our results suggest that it is inappropriate to consider the non-paretic limb and total knee flexion RoM to classify stiff-knee gait in individuals with stroke. kinematics walking range of motion peak knee flexion Figures Figure 1 Figure 2 Figure 3 Background Limited knee flexion during the swing period of the gait is a common movement disorder in stroke survivors [ 1 , 2 , 3 ], often referred to as a stiff-knee gait [ 4 ]. Consequences of a stiff knee gait include reduced foot clearance leading to tripping, increased risk of falling, compensatory movements, and increased energy expenditure [ 5 ]. Although several studies have explored the causes of stiff knee gait in stroke survivors [ 6 , 7 ] and appropriate treatments to diminish its consequences [ 8 , 9 , 10 ], the standardized criteria for identifying individuals with stiff knee gait who have also experienced stroke are not well established. A recent attempt to classify the severity of stiff knee gait in stroke survivors using retrospective unsupervised cluster analysis [ 11 ] has highlighted the need for standardization to characterize this movement disorder in patients with a stroke. Different criteria have been employed to identify stiff knee gait in stroke survivors. The most commonly used applied quantitative criteria are peak knee flexion of less than 45° during the swing period [ 6 , 12 ], range of motion from toe-off to maximum knee flexion of less than 10° in the swing period [ 2 ], range of motion of at least 16° [ 13 ] or 20° [ 7 ] less on the paretic limb compared to the non-paretic limb. In addition, the same criteria have been applied as in children with cerebral palsy [ 8 ]. A subjective criterion “observable reduced maximum knee flexion during the swing period” [ 10 , 14 , 15 ] has been employed to identify the stiff-knee gait in these individuals. Stiff-knee gait is common among stroke survivors, prompting many investigations into mitigating its impact on daily life activities. Standardizing the characterization of stiff-knee gait specifically for these individuals seems appropriate. In children with cerebral palsy, whose stiff knee gait is also a common gait disturbance [ 16 ], other criteria have been used to identify those with a stiff knee gait, such as maximum knee flexion in the swing period, range of knee motion, and timing of maximum knee flexion during the swing period [ 16 , 17 , 18 , 19 , 20 ]. Goldberg et al. [ 18 ] selected four gait parameters to identify stiff knee gait in children with cerebral palsy: (1) maximum knee flexion in the swing period, (2) knee range of motion from toe-off to maximum knee flexion in the swing period, (3) total knee range of motion during the gait cycle, and (4) timing of maximum knee flexion during the swing period of gait. The general characteristics of patients with cerebral palsy differ from those of stroke survivors in many aspects. For example, individuals with cerebral palsy commonly present with secondary deficits, such as muscle contractures and bone deformities [ 21 ]. Furthermore, gait deviation in these individuals may vary depending on the topography of the impairment [ 22 ], such as spastic hemiplegia (drop foot, equinus gait with different knee positions), spastic diplegia (jump knee gait, crouch gait) [ 23 ], and other motor disturbances [ 24 ]. In contrast, stroke survivors and individuals with cerebral palsy commonly experience adverse effects, such as spasticity, muscle weakness, and loss of selective motor control [ 25 , 26 ]. Nevertheless, considering the four gait parameters identified by Goldberg et al. [ 18 ] as a basis for standardizing the characterization of stiff knee gait in stroke survivors is plausible. The study aimed to examine suitable criteria for identifying stroke survivors with a stiff knee gait by assessing the strengths and limitations of the criteria adopted by Goldberg et al. [ 18 ] for stroke survivors who present with stiff knee gait. Methods Participants Twenty-four stroke survivors and 24 individuals matched by age and sex (control group), were conveniently sampled and included in this cross-sectional study. The inclusion criteria for stroke survivors having experienced stroke (either ischemic or hemorrhagic) more than 6 months prior, ability to walk at least 10 m with no assistance, ability to follow verbal instruction, absence of any orthopedic or neurological impairment other than stroke, and no surgical intervention, including botulinum toxin injection, within the previous 6 months. For the control group, the inclusion criterion was the absence of any known neurological or orthopedic impairment or musculoskeletal injury that could compromise gait. The Institutional Review Board of Cruzeiro do Sul University approved all procedures. All participants provided written informed consent prior to the experimental session. Procedures Following the recommendations of the International Society of Biomechanics (ISB) [ 27 ], retroreflective markers and rigid clusters were placed on specific body anatomical landmarks and lower limb segments, as described in previous studies [ 28 , 29 ]. A calibrated anatomical system technique (CAST) was employed to record the three-dimensional kinematics of the lower extremities [ 30 ]. A t-pose kinematic calibration trial was performed with all retroreflective markers placed on anatomical landmarks. Subsequently, markers from the anterior and posterior superior iliac spine, medial and lateral epicondyles of the femur, tibialis tuberosity, medial and lateral malleoli, and intermalleolus were removed. Each participant walked in their own shoes at a self-selected comfortable speed on a 10-m extension walkway equipped with two embedded force plates (Kistler, model 9286BA) covered with a thin rubber carpet. Prior to data acquisition, the participants practiced a few trials until they felt comfortable with the experimental setup. Each participant underwent a minimum of five trials. A computerized gait analysis system (VICON, Inc.) with eight infrared cameras was used to synchronously acquire all the marker positions and force plate data at a frequency of 100 Hz. Stroke survivors were clinically examined using the Fugl-Meyer test [ 31 ] and functional independent measurements (motor domain) [ 32 ]. These data were solely used for characterizing these individuals. Data processing and analysis We analyzed two consecutive steady-state strides (paretic and non-paretic for stroke survivors, and right and left for the control group) per trial, for a total of five trials for each participant. Foot contact and toe-off events were identified for each stride using force plate signals and foot vertical velocity [ 33 ]. These events were used to define each stride and calculate the stance and swing periods [ 4 ]. The knee joint angle was calculated using a commercial algorithm (Visual3D; C-Motion, Inc.) and further analyzed using custom algorithms (MATLAB; MathWorks, Inc.). Kinematic data were digitally filtered using a low-pass 4th order, and zero-lag Butterworth filter with a 6 Hz cut-off. The gait cycle durations were time-normalized and averaged to obtain the mean cycle for each participant. We quantified four parameters: (1) peak knee flexion during the swing period of gait, identifying the maximum value of knee flexion, (2) knee range of motion (RoM) from toe-off to peak flexion, calculated as the difference between maximum knee angle and knee angle at toe-off (RoM-swing), (3) total knee RoM across the entire gait cycle, calculated as the difference between maximum and minimum knee angles, and (4) timing to peak knee flexion during the swing period of gait, expressed as a percentage of the stance period duration, as in previous investigation [ 18 ]. Figure 1 illustrates each of these four parameters. Subsequently, we replicated the procedures adopted by Goldberg et al. [ 18 ] to calculate the average value of each parameter for the control group (“normal values”) and used the values to identify the “stiff-knee,” as the stroke survivors presented the values greater than two standard deviations either below (for parameters 1–3) or above (for the parameter 4) the observed average normal value. A limb was classified as “stiff-knee” if at least three of these four parameters met the established criteria [ 18 ]. [Figure 1 near here] The following variables were selected for analysis: mean walking speed; instant of occurrence of toe-off and peak knee flexion during swing period; peak knee flexion during the swing period; RoM of knee flexion from toe-off to peak knee flexion (“RoM swing”); total RoM of knee flexion (“RoM cycle”); and timing to maximum knee flexion during the swing period. Notably, no limb effects were observed in the control group; we combined data from the right and left limbs and considered them as the “control limb”[ 28 ]. Statistical analyses One-way univariate analyses of variance (ANOVA) were employed to compare age and mean walking speed between both groups (stroke and control), as well as to compare swing duration and timing to peak knee flexion among limbs (control, paretic, and non-paretic). One-way multivariate analysis of variance (MANOVA) was used to compare body mass and height between the groups, with the limb (control, paretic, and non-paretic) as a factor for the following dependent variables: an instant of toe-off, instant of peak knee flexion, peak knee flexion, and knee RoM during swing. Univariate analysis and post-hoc pairwise comparisons with Bonferroni adjustments were performed as necessary. An alpha of 0.05 was set for all statistical tests, which were performed using SPSS software. Results Following the four stiff knee criteria [ 18 ] for the paretic limb, three stroke survivors did not meet at least three of these criteria and were excluded from the matched controls. Among the remaining stroke survivors (n = 21), some did not meet the criteria in the paretic limb for peak knee flexion during the swing period (n = 1), knee RoM swing (n = 2), knee RoM cycle (n = 1), or the timing of peak knee flexion (n = 20). For the nonparetic limb, some did not meet the criteria for peak knee flexion during the swing period (n = 4), knee RoM swing (n = 10), knee RoM cycle (n = 11), or timing of peak knee flexion (n = 20). Table 1 presents the general characteristics of the 21 participants in each group (stroke and control) that were considered for further analysis. ANOVA revealed no group effect for age (F 1,41 =0.004, p = 0.951), and MANOVA revealed no group effect for mass or height (Wilks’ Lambda = 0.87, F 2,39 =2.83, p = 0.071). Stroke survivors were in the chronic stage, and most exhibited high levels of motor function (Table 1 ). Table 1 General characteristics of participants analyzed Characteristics Stroke Control Sex (female/male) 14/7 14/7 Age (years)* 46.4±13.8 46.5±13.8 Mass (kg)* 77.0±20.4 67.6±10.3 Height (m)* 1.67±0.09 1.65±0.10 Time poststroke (months)* 84.6±40.5 - Type of lesion (ischemic/hemorrhagic) 12/9 - Hemiparesis side (right/left) 12/9 - Fugl-Meyer score (maximum, 84)* 63.9±5.9 - Functional independence (maximum, 91)* 81.7±4.1 - * Mean±standard deviation Regarding walking speed, ANOVA revealed that stroke survivors walked slower (0.64±0.28 m/s) than their peers (1.26±0.13 m/s) (F 1,41 =90.36, p < 0.001). In addition, ANOVA results indicated a limb effect on swing period duration (F 2,62 =379.88, p < 0.001). Post hoc tests showed shorter swing durations for the paretic and non-paretic limbs than for the control limb and longer swing durations for the paretic limb than for the non-paretic limb (Table 2 ). Table 2 Mean (±SD) values of instants of toe-off and peak knee flexion during the swing period, swing duration, and timing of peak knee flexion for the control limb in the control group and for the paretic and non-paretic limbs in individuals with stroke. Measures Control Paretic Non-paretic Swing duration (%) 39.8±1.4 35.4±6.6 27.7±6.7 Instant of toe-off (%) 60.2±1.43 64.6±6.6 72.3±6.7 Instant of peak knee flexion (%) 70.5±1.3 70.8±6.8 79.0±4.8 Timing of peak knee flexion (% swing period) 25.7±2.2 18.2±7.4 23.8±4.1 Regarding the timing of toe-off and peak knee flexion, MANOVA revealed a limb effect (Wilks’ Lambda = 0.34, F 4,118 =21.29, p < 0.001). Univariate analysis revealed differences in toe-off (F 2,62 =26.17, p < 0.001) and peak knee flexion (F 2,62 =20.87, p < 0.001) between groups. Post hoc tests revealed that toe-off occurred later in the gait cycle for the non-paretic limb compared to the paretic and control limbs, and later in the paretic limb than in the control limb. Peak knee flexion occurred later in the non-paretic limb than in the paretic and control limbs (Table 2 ). ANOVA for the timing of peak knee flexion also revealed a limb effect (F 2,62 =12.64, p < 0.001). Post-hoc tests showed that peak knee flexion occurred earlier for the paretic limb than for the non-paretic and control limbs (Table 2 ). Figure 2 shows the mean (±SD) time series of the knee angles for the control, paretic, and non-paretic limbs during the gait cycle. Overall, the kinematic patterns were similar for the three limbs but still depicted some adaptations. For instance, knee flexion of the paretic limb was reduced compared to that of the control and non-paretic limbs, and peak knee flexion occurred later in the non-paretic limb compared to the control and paretic limbs. [Figure 2 near here] Figure 3 depicts the mean (±SD) values of peak knee flexion during the swing period, knee RoM swing, and knee RoM cycle in the control, paretic, and non-paretic limbs. MANOVA revealed a limb effect (Wilks’ Lambda = 0.21, F 6,116 =22.84, p < 0.001). Univariate analyses revealed differences in the peak knee flexion (F 2,62 =55.77, p < 0.001), knee RoM swing (F 2,62 =37.09, p < 0.001), and knee RoM cycle (F 2,62 =38.72, p < 0.001). Post hoc tests revealed reduced peak flexion, RoM swing, and RoM cycle for the paretic limb compared to the non-paretic and control limbs, and reduced RoM swing and RoM cycle for the non-paretic limb compared to the control limb. [Figure 3 near here] Discussion In this study, we examined the suitable criteria for identifying stiff knee gait in stroke survivors. Among the four criteria adopted by Goldberg et al. [ 18 ], peak knee flexion during the swing period was the most remarkable for these individuals, followed by the RoM of knee flexion from toe-off to peak flexion during swing. However, total knee flexion RoM and the timing of peak knee flexion were not suitable for identifying stiff knee gait in stroke survivors. Regarding the total knee flexion RoM, it is important to note that the knee displacement observed in stroke survivors in this study was different from that in individuals with cerebral palsy. Specifically, while individuals with cerebral palsy usually adopt either a crouched or a jump gait during the stance period [ 34 , 35 ], most of stroke survivors presented with knee hyperextension. These behavioral differences affect the total RoM knee flexion and could lead to a misleading criterion for identifying stiff knee gait in stroke survivors. Regarding the timing of peak knee flexion during the swing period, stroke survivors anticipated maximum knee flexion compared to individuals with cerebral palsy [ 18 ], with high variability for the paretic limb (Table 2 ). Although there is a consensus that diminished peak knee flexion during the swing period of gait that characterizes stiff-knee gait in stroke survivors [ 2 , 3 , 6 , 12 , 18 ], it remains unclear whether it occur either earlier or later in the swing period of a gait cycle. Contrary to the knee angle, which indicates the relative excursion between the thigh and shank, the timing is directly related to the locomotor coordination, which is affected in stroke survivors [ 36 , 37 ]. However, the relative timing of the stance and swing periods of the gait cycle differs between stroke survivors and non-disabled individuals [ 36 ], as well as between paretic and non-paretic limbs [ 36 , 38 ]. Notably, locomotor coordination disturbances might be due to factors other than stiff-knee gait, such as slow walking speed and balance impairment. Therefore, we suggest that the timing of peak knee flexion is not a suitable criterion for identifying stiff knee gait in stroke survivors. Altogether, the findings of this study suggest that the most suitable criteria for identifying stiff knee gait in individuals with stroke are maximum knee flexion < 50° and ROM of knee flexion from toe-off to peak flexion at swing < 12°. Nevertheless, if one decides to use the timing of peak knee flexion during the swing period as a criterion, the value to be considered should be < 21%. Finally, our results suggest that it is inappropriate to consider the non-paretic limb to identify stiff-knee gait in stroke survivors, as in previous investigations [ 7 , 13 ]. Our results revealed that some of the criteria were also observed for the non-paretic limb in some stroke survivors, and differences were noted between the non-paretic and control limbs (Table 2 , Fig. 2 ). This finding is probably due to motor compensation [ 39 ], which could lead to the appropriate identification of stiff-knee gait for these individuals. Although the present study provides valuable insights into standardizing the criteria for identifying stiff knee gait in stroke survivors, several limitations should be noted. First, the sample size was limited to 24 stroke survivors with a high level of independence, predominantly under 55 years of age (n = 16), which could be explained by the increase in stroke incidence among younger individuals [ 40 ]. Second, this study was limited to investigating suitable criteria for identifying stiff knee gait in stroke survivors. Future studies should employ these criteria adopted in this study across a wider range of stroke survivors in terms of independence level and age and investigate the causes of their stiff-knee gait, which was beyond the scope of this study. Conclusion In summary, based on our findings, the suitable criteria for identifying stiff knee in stroke survivors are preferentially peak knee flexion during the swing period < 50° and knee RoM from toe-off to peak knee flexion < 12°. Abbreviations CAST: calibrated anatomical system technique; RoM: range of motion; ANOVA: univariate analyses of variance; MANOVA: multivariate analyses of variance. Declarations Ethics approval and consent to participate The Institutional Review Board of Cruzeiro do Sul University approved all procedures. All participants provided written informed consent prior to the experimental session. Consent for publication Not applicable Availability of data and materials The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding This study was supported by the São Paulo Research Foundation (FAPESP) under the grant number 2018/04964-8. Authors’ contribution OB contributed to the acquisition, analysis, and interpretation of data, and have drafted the work; MLC and JAB contributed to the interpretation of data and substantively revised the work; AMFB contributed to the conception of the work, analysis and interpretation of data, and substantively revised it. All authors read and approved the submitted version. Acknowledgments Not applicable References Olney SJ, Richards C: Hemiparetic gait following stroke. Part I: Characteristics. Gait Posture 1996, 4(2):136-148. Kerrigan DC, Roth RS, Riley PO: The modelling of adult spastic paretic stiff-legged gait swing period based on actual kinematic data. Gait Posture 1998, 7(2):117-124. Merlo A, Campanini I: Impact of instrumental analysis of stiff knee gait on treatment appropriateness and associated costs in stroke patients. Gait Posture 2019, 72:195-201. 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Cite Share Download PDF Status: Published Journal Publication published 01 Sep, 2025 Read the published version in BMC Biomedical Engineering → Version 1 posted Editorial decision: Revision requested 04 Apr, 2025 Reviews received at journal 22 Mar, 2025 Reviewers agreed at journal 28 Feb, 2025 Reviews received at journal 07 Feb, 2025 Reviewers agreed at journal 16 Jan, 2025 Reviewers agreed at journal 01 Dec, 2024 Reviewers agreed at journal 30 Sep, 2024 Reviewers invited by journal 30 Jul, 2024 Editor invited by journal 29 Jul, 2024 Editor assigned by journal 25 Jul, 2024 Submission checks completed at journal 25 Jul, 2024 First submitted to journal 24 Jul, 2024 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-4797428","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":338754962,"identity":"56ba024a-ce70-4eaf-86ef-e588968f1cb6","order_by":0,"name":"Odair Bacca","email":"","orcid":"","institution":"Cruzeiro do Sul University","correspondingAuthor":false,"prefix":"","firstName":"Odair","middleName":"","lastName":"Bacca","suffix":""},{"id":338754963,"identity":"b8ca025c-3937-4317-b205-d2680ff81d68","order_by":1,"name":"Melissa Leandro Celestino","email":"","orcid":"","institution":"Federal University of Pernambuco","correspondingAuthor":false,"prefix":"","firstName":"Melissa","middleName":"Leandro","lastName":"Celestino","suffix":""},{"id":338754964,"identity":"23b99e7b-4611-4a62-8dde-1c69542f7a2c","order_by":2,"name":"José Angelo Barela","email":"","orcid":"","institution":"São Paulo State University","correspondingAuthor":false,"prefix":"","firstName":"José","middleName":"Angelo","lastName":"Barela","suffix":""},{"id":338754966,"identity":"4873059f-053b-4590-a7a8-359c5c183eed","order_by":3,"name":"Ana Maria Forti Barela","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIiWNgGAWjYFACHhBhwcAPohIKiNciwSDZANJiQIoWgwMgmhgt/NPOHvxcUSEhb3x+deKHBwYM8vxiB/Brkbidlyx55oyE4bYbbzdLAB1mOHN2AgFrbucYSDa2STBuu3F2A0hLgsFtAlrkb+cY/2z8J2G/ecbZzT+I0mJwO8dMsrFBInEDf+824mwxvJ2XZtlwTCJ5xg3ebRYJBhKE/SJ3O/fwzYYaG9v+/rObb/6osJHnlyagBQEkwColiFUOAvwHSFE9CkbBKBgFIwkAAFeyRSo6rbeAAAAAAElFTkSuQmCC","orcid":"","institution":"Cruzeiro do Sul University","correspondingAuthor":true,"prefix":"","firstName":"Ana","middleName":"Maria Forti","lastName":"Barela","suffix":""}],"badges":[],"createdAt":"2024-07-24 18:56:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4797428/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4797428/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s42490-025-00097-1","type":"published","date":"2025-09-01T15:57:19+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62942702,"identity":"709d7c03-d9c0-447a-9508-c225bdae40d2","added_by":"auto","created_at":"2024-08-21 09:48:50","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":202334,"visible":true,"origin":"","legend":"\u003cp\u003eTime series profile of knee angle and the four gait parameters used to identify stiff-knee gait. Note: data from the control (left) and paretic (right) limbs were used to illustrate the parameters.\u003c/p\u003e","description":"","filename":"figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4797428/v1/d5cb8b1e68299ec919508ff2.jpg"},{"id":62942700,"identity":"1c55a21c-4686-4d64-be2a-777ae34bcf3c","added_by":"auto","created_at":"2024-08-21 09:48:50","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":110070,"visible":true,"origin":"","legend":"\u003cp\u003eMean (±SD) time series profile of knee angle for control, paretic, and non-paretic limbs during the normalized gait cycle.\u003c/p\u003e","description":"","filename":"figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4797428/v1/c978d6676229df9cf5c7883c.jpg"},{"id":62942701,"identity":"acc92eff-5ee1-4cda-af58-bb91431a8908","added_by":"auto","created_at":"2024-08-21 09:48:50","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":82938,"visible":true,"origin":"","legend":"\u003cp\u003eMean (±SD) values of peak knee flexion during the swing period, range of knee flexion from toe-off to peak flexion (RoM swing), and range of knee flexion during the gait cycle (RoM cycle) for the control, paretic, and non-paretic limbs.\u003c/p\u003e","description":"","filename":"floatimage3copy.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4797428/v1/11cf8ea20e6f7aad0279d81f.jpg"},{"id":90827924,"identity":"71f09585-e33d-40a7-9f81-610c1f6b7cc4","added_by":"auto","created_at":"2025-09-08 16:03:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":959807,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4797428/v1/7d00b9e3-d860-4da0-b120-9794ca370ace.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Identification of stiff-knee gait in stroke survivors","fulltext":[{"header":"Background","content":"\u003cp\u003eLimited knee flexion during the swing period of the gait is a common movement disorder in stroke survivors [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], often referred to as a stiff-knee gait [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Consequences of a stiff knee gait include reduced foot clearance leading to tripping, increased risk of falling, compensatory movements, and increased energy expenditure [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Although several studies have explored the causes of stiff knee gait in stroke survivors [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and appropriate treatments to diminish its consequences [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], the standardized criteria for identifying individuals with stiff knee gait who have also experienced stroke are not well established. A recent attempt to classify the severity of stiff knee gait in stroke survivors using retrospective unsupervised cluster analysis [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] has highlighted the need for standardization to characterize this movement disorder in patients with a stroke.\u003c/p\u003e \u003cp\u003eDifferent criteria have been employed to identify stiff knee gait in stroke survivors. The most commonly used applied quantitative criteria are peak knee flexion of less than 45\u0026deg; during the swing period [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], range of motion from toe-off to maximum knee flexion of less than 10\u0026deg; in the swing period [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], range of motion of at least 16\u0026deg; [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] or 20\u0026deg; [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] less on the paretic limb compared to the non-paretic limb. In addition, the same criteria have been applied as in children with cerebral palsy [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. A subjective criterion \u0026ldquo;observable reduced maximum knee flexion during the swing period\u0026rdquo; [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] has been employed to identify the stiff-knee gait in these individuals.\u003c/p\u003e \u003cp\u003eStiff-knee gait is common among stroke survivors, prompting many investigations into mitigating its impact on daily life activities. Standardizing the characterization of stiff-knee gait specifically for these individuals seems appropriate. In children with cerebral palsy, whose stiff knee gait is also a common gait disturbance [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], other criteria have been used to identify those with a stiff knee gait, such as maximum knee flexion in the swing period, range of knee motion, and timing of maximum knee flexion during the swing period [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Goldberg et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] selected four gait parameters to identify stiff knee gait in children with cerebral palsy: (1) maximum knee flexion in the swing period, (2) knee range of motion from toe-off to maximum knee flexion in the swing period, (3) total knee range of motion during the gait cycle, and (4) timing of maximum knee flexion during the swing period of gait.\u003c/p\u003e \u003cp\u003eThe general characteristics of patients with cerebral palsy differ from those of stroke survivors in many aspects. For example, individuals with cerebral palsy commonly present with secondary deficits, such as muscle contractures and bone deformities [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Furthermore, gait deviation in these individuals may vary depending on the topography of the impairment [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], such as spastic hemiplegia (drop foot, equinus gait with different knee positions), spastic diplegia (jump knee gait, crouch gait) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], and other motor disturbances [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In contrast, stroke survivors and individuals with cerebral palsy commonly experience adverse effects, such as spasticity, muscle weakness, and loss of selective motor control [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Nevertheless, considering the four gait parameters identified by Goldberg et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] as a basis for standardizing the characterization of stiff knee gait in stroke survivors is plausible.\u003c/p\u003e \u003cp\u003eThe study aimed to examine suitable criteria for identifying stroke survivors with a stiff knee gait by assessing the strengths and limitations of the criteria adopted by Goldberg et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] for stroke survivors who present with stiff knee gait.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eParticipants\u003c/h2\u003e\n \u003cp\u003eTwenty-four stroke survivors and 24 individuals matched by age and sex (control group), were conveniently sampled and included in this cross-sectional study. The inclusion criteria for stroke survivors having experienced stroke (either ischemic or hemorrhagic) more than 6 months prior, ability to walk at least 10 m with no assistance, ability to follow verbal instruction, absence of any orthopedic or neurological impairment other than stroke, and no surgical intervention, including botulinum toxin injection, within the previous 6 months. For the control group, the inclusion criterion was the absence of any known neurological or orthopedic impairment or musculoskeletal injury that could compromise gait. The Institutional Review Board of Cruzeiro do Sul University approved all procedures. All participants provided written informed consent prior to the experimental session.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003eProcedures\u003c/h2\u003e\n \u003cp\u003eFollowing the recommendations of the International Society of Biomechanics (ISB) [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e], retroreflective markers and rigid clusters were placed on specific body anatomical landmarks and lower limb segments, as described in previous studies [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. A calibrated anatomical system technique (CAST) was employed to record the three-dimensional kinematics of the lower extremities [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eA t-pose kinematic calibration trial was performed with all retroreflective markers placed on anatomical landmarks. Subsequently, markers from the anterior and posterior superior iliac spine, medial and lateral epicondyles of the femur, tibialis tuberosity, medial and lateral malleoli, and intermalleolus were removed.\u003c/p\u003e\n \u003cp\u003eEach participant walked in their own shoes at a self-selected comfortable speed on a 10-m extension walkway equipped with two embedded force plates (Kistler, model 9286BA) covered with a thin rubber carpet. Prior to data acquisition, the participants practiced a few trials until they felt comfortable with the experimental setup. Each participant underwent a minimum of five trials. A computerized gait analysis system (VICON, Inc.) with eight infrared cameras was used to synchronously acquire all the marker positions and force plate data at a frequency of 100 Hz.\u003c/p\u003e\n \u003cp\u003eStroke survivors were clinically examined using the Fugl-Meyer test [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e] and functional independent measurements (motor domain) [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]. These data were solely used for characterizing these individuals.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003eData processing and analysis\u003c/h2\u003e\n \u003cp\u003eWe analyzed two consecutive steady-state strides (paretic and non-paretic for stroke survivors, and right and left for the control group) per trial, for a total of five trials for each participant. Foot contact and toe-off events were identified for each stride using force plate signals and foot vertical velocity [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. These events were used to define each stride and calculate the stance and swing periods [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe knee joint angle was calculated using a commercial algorithm (Visual3D; C-Motion, Inc.) and further analyzed using custom algorithms (MATLAB; MathWorks, Inc.). Kinematic data were digitally filtered using a low-pass 4th order, and zero-lag Butterworth filter with a 6 Hz cut-off. The gait cycle durations were time-normalized and averaged to obtain the mean cycle for each participant.\u003c/p\u003e\n \u003cp\u003eWe quantified four parameters: (1) peak knee flexion during the swing period of gait, identifying the maximum value of knee flexion, (2) knee range of motion (RoM) from toe-off to peak flexion, calculated as the difference between maximum knee angle and knee angle at toe-off (RoM-swing), (3) total knee RoM across the entire gait cycle, calculated as the difference between maximum and minimum knee angles, and (4) timing to peak knee flexion during the swing period of gait, expressed as a percentage of the stance period duration, as in previous investigation [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e illustrates each of these four parameters. Subsequently, we replicated the procedures adopted by Goldberg et al. [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e] to calculate the average value of each parameter for the control group (\u0026ldquo;normal values\u0026rdquo;) and used the values to identify the \u0026ldquo;stiff-knee,\u0026rdquo; as the stroke survivors presented the values greater than two standard deviations either below (for parameters 1\u0026ndash;3) or above (for the parameter 4) the observed average normal value. A limb was classified as \u0026ldquo;stiff-knee\u0026rdquo; if at least three of these four parameters met the established criteria [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003e[Figure 1 near here]\u003c/h3\u003e\n\u003cp\u003eThe following variables were selected for analysis: mean walking speed; instant of occurrence of toe-off and peak knee flexion during swing period; peak knee flexion during the swing period; RoM of knee flexion from toe-off to peak knee flexion (\u0026ldquo;RoM swing\u0026rdquo;); total RoM of knee flexion (\u0026ldquo;RoM cycle\u0026rdquo;); and timing to maximum knee flexion during the swing period.\u003c/p\u003e\n\u003cp\u003eNotably, no limb effects were observed in the control group; we combined data from the right and left limbs and considered them as the \u0026ldquo;control limb\u0026rdquo;[\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003eStatistical analyses\u003c/h2\u003e\n \u003cp\u003eOne-way univariate analyses of variance (ANOVA) were employed to compare age and mean walking speed between both groups (stroke and control), as well as to compare swing duration and timing to peak knee flexion among limbs (control, paretic, and non-paretic). One-way multivariate analysis of variance (MANOVA) was used to compare body mass and height between the groups, with the limb (control, paretic, and non-paretic) as a factor for the following dependent variables: an instant of toe-off, instant of peak knee flexion, peak knee flexion, and knee RoM during swing.\u003c/p\u003e\n \u003cp\u003eUnivariate analysis and post-hoc pairwise comparisons with Bonferroni adjustments were performed as necessary. An alpha of 0.05 was set for all statistical tests, which were performed using SPSS software.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eFollowing the four stiff knee criteria [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] for the paretic limb, three stroke survivors did not meet at least three of these criteria and were excluded from the matched controls. Among the remaining stroke survivors (n\u0026thinsp;=\u0026thinsp;21), some did not meet the criteria in the paretic limb for peak knee flexion during the swing period (n\u0026thinsp;=\u0026thinsp;1), knee RoM swing (n\u0026thinsp;=\u0026thinsp;2), knee RoM cycle (n\u0026thinsp;=\u0026thinsp;1), or the timing of peak knee flexion (n\u0026thinsp;=\u0026thinsp;20). For the nonparetic limb, some did not meet the criteria for peak knee flexion during the swing period (n\u0026thinsp;=\u0026thinsp;4), knee RoM swing (n\u0026thinsp;=\u0026thinsp;10), knee RoM cycle (n\u0026thinsp;=\u0026thinsp;11), or timing of peak knee flexion (n\u0026thinsp;=\u0026thinsp;20).\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the general characteristics of the 21 participants in each group (stroke and control) that were considered for further analysis. ANOVA revealed no group effect for age (F\u003csub\u003e1,41\u003c/sub\u003e=0.004, p\u0026thinsp;=\u0026thinsp;0.951), and MANOVA revealed no group effect for mass or height (Wilks\u0026rsquo; Lambda\u0026thinsp;=\u0026thinsp;0.87, F\u003csub\u003e2,39\u003c/sub\u003e=2.83, p\u0026thinsp;=\u0026thinsp;0.071). Stroke survivors were in the chronic stage, and most exhibited high levels of motor function (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGeneral characteristics of participants analyzed\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStroke\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (female/male)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14/7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14/7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46.4\u0026plusmn;13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.5\u0026plusmn;13.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMass (kg)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e77.0\u0026plusmn;20.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67.6\u0026plusmn;10.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (m)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.67\u0026plusmn;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.65\u0026plusmn;0.10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime poststroke (months)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.6\u0026plusmn;40.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType of lesion (ischemic/hemorrhagic)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12/9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemiparesis side (right/left)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12/9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFugl-Meyer score (maximum, 84)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63.9\u0026plusmn;5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFunctional independence (maximum, 91)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81.7\u0026plusmn;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003e* Mean\u0026plusmn;standard deviation\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eRegarding walking speed, ANOVA revealed that stroke survivors walked slower (0.64\u0026plusmn;0.28 m/s) than their peers (1.26\u0026plusmn;0.13 m/s) (F\u003csub\u003e1,41\u003c/sub\u003e=90.36, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In addition, ANOVA results indicated a limb effect on swing period duration (F\u003csub\u003e2,62\u003c/sub\u003e=379.88, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Post hoc tests showed shorter swing durations for the paretic and non-paretic limbs than for the control limb and longer swing durations for the paretic limb than for the non-paretic limb (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMean (\u0026plusmn;SD) values of instants of toe-off and peak knee flexion during the swing period, swing duration, and timing of peak knee flexion for the control limb in the control group and for the paretic and non-paretic limbs in individuals with stroke.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMeasures\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParetic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNon-paretic\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSwing duration (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e39.8\u0026plusmn;1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e35.4\u0026plusmn;6.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e27.7\u0026plusmn;6.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInstant of toe-off (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e60.2\u0026plusmn;1.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e64.6\u0026plusmn;6.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e72.3\u0026plusmn;6.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInstant of peak knee flexion (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e70.5\u0026plusmn;1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e70.8\u0026plusmn;6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e79.0\u0026plusmn;4.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTiming of peak knee flexion (% swing period)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e25.7\u0026plusmn;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e18.2\u0026plusmn;7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e23.8\u0026plusmn;4.1\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\u003eRegarding the timing of toe-off and peak knee flexion, MANOVA revealed a limb effect (Wilks\u0026rsquo; Lambda\u0026thinsp;=\u0026thinsp;0.34, F\u003csub\u003e4,118\u003c/sub\u003e=21.29, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Univariate analysis revealed differences in toe-off (F\u003csub\u003e2,62\u003c/sub\u003e=26.17, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and peak knee flexion (F\u003csub\u003e2,62\u003c/sub\u003e=20.87, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) between groups. Post hoc tests revealed that toe-off occurred later in the gait cycle for the non-paretic limb compared to the paretic and control limbs, and later in the paretic limb than in the control limb. Peak knee flexion occurred later in the non-paretic limb than in the paretic and control limbs (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). ANOVA for the timing of peak knee flexion also revealed a limb effect (F\u003csub\u003e2,62\u003c/sub\u003e=12.64, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Post-hoc tests showed that peak knee flexion occurred earlier for the paretic limb than for the non-paretic and control limbs (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the mean (\u0026plusmn;SD) time series of the knee angles for the control, paretic, and non-paretic limbs during the gait cycle. Overall, the kinematic patterns were similar for the three limbs but still depicted some adaptations. For instance, knee flexion of the paretic limb was reduced compared to that of the control and non-paretic limbs, and peak knee flexion occurred later in the non-paretic limb compared to the control and paretic limbs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003e[Figure 2 near here] \u003c/h3\u003e\n\u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e depicts the mean (\u0026plusmn;SD) values of peak knee flexion during the swing period, knee RoM swing, and knee RoM cycle in the control, paretic, and non-paretic limbs. MANOVA revealed a limb effect (Wilks\u0026rsquo; Lambda\u0026thinsp;=\u0026thinsp;0.21, F\u003csub\u003e6,116\u003c/sub\u003e=22.84, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Univariate analyses revealed differences in the peak knee flexion (F\u003csub\u003e2,62\u003c/sub\u003e=55.77, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), knee RoM swing (F\u003csub\u003e2,62\u003c/sub\u003e=37.09, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and knee RoM cycle (F\u003csub\u003e2,62\u003c/sub\u003e=38.72, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Post hoc tests revealed reduced peak flexion, RoM swing, and RoM cycle for the paretic limb compared to the non-paretic and control limbs, and reduced RoM swing and RoM cycle for the non-paretic limb compared to the control limb.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003e[Figure 3 near here]\u003c/h3\u003e\n"},{"header":"Discussion","content":"\u003cp\u003eIn this study, we examined the suitable criteria for identifying stiff knee gait in stroke survivors. Among the four criteria adopted by Goldberg et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], peak knee flexion during the swing period was the most remarkable for these individuals, followed by the RoM of knee flexion from toe-off to peak flexion during swing. However, total knee flexion RoM and the timing of peak knee flexion were not suitable for identifying stiff knee gait in stroke survivors.\u003c/p\u003e \u003cp\u003eRegarding the total knee flexion RoM, it is important to note that the knee displacement observed in stroke survivors in this study was different from that in individuals with cerebral palsy. Specifically, while individuals with cerebral palsy usually adopt either a crouched or a jump gait during the stance period [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], most of stroke survivors presented with knee hyperextension. These behavioral differences affect the total RoM knee flexion and could lead to a misleading criterion for identifying stiff knee gait in stroke survivors.\u003c/p\u003e \u003cp\u003eRegarding the timing of peak knee flexion during the swing period, stroke survivors anticipated maximum knee flexion compared to individuals with cerebral palsy [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], with high variability for the paretic limb (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Although there is a consensus that diminished peak knee flexion during the swing period of gait that characterizes stiff-knee gait in stroke survivors [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], it remains unclear whether it occur either earlier or later in the swing period of a gait cycle. Contrary to the knee angle, which indicates the relative excursion between the thigh and shank, the timing is directly related to the locomotor coordination, which is affected in stroke survivors [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. However, the relative timing of the stance and swing periods of the gait cycle differs between stroke survivors and non-disabled individuals [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], as well as between paretic and non-paretic limbs [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Notably, locomotor coordination disturbances might be due to factors other than stiff-knee gait, such as slow walking speed and balance impairment. Therefore, we suggest that the timing of peak knee flexion is not a suitable criterion for identifying stiff knee gait in stroke survivors.\u003c/p\u003e \u003cp\u003eAltogether, the findings of this study suggest that the most suitable criteria for identifying stiff knee gait in individuals with stroke are maximum knee flexion\u0026thinsp;\u0026lt;\u0026thinsp;50\u0026deg; and ROM of knee flexion from toe-off to peak flexion at swing\u0026thinsp;\u0026lt;\u0026thinsp;12\u0026deg;. Nevertheless, if one decides to use the timing of peak knee flexion during the swing period as a criterion, the value to be considered should be \u0026lt;\u0026thinsp;21%. Finally, our results suggest that it is inappropriate to consider the non-paretic limb to identify stiff-knee gait in stroke survivors, as in previous investigations [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Our results revealed that some of the criteria were also observed for the non-paretic limb in some stroke survivors, and differences were noted between the non-paretic and control limbs (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This finding is probably due to motor compensation [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e], which could lead to the appropriate identification of stiff-knee gait for these individuals.\u003c/p\u003e \u003cp\u003eAlthough the present study provides valuable insights into standardizing the criteria for identifying stiff knee gait in stroke survivors, several limitations should be noted. First, the sample size was limited to 24 stroke survivors with a high level of independence, predominantly under 55 years of age (n\u0026thinsp;=\u0026thinsp;16), which could be explained by the increase in stroke incidence among younger individuals [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Second, this study was limited to investigating suitable criteria for identifying stiff knee gait in stroke survivors. Future studies should employ these criteria adopted in this study across a wider range of stroke survivors in terms of independence level and age and investigate the causes of their stiff-knee gait, which was beyond the scope of this study.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn summary, based on our findings, the suitable criteria for identifying stiff knee in stroke survivors are preferentially peak knee flexion during the swing period\u0026thinsp;\u0026lt;\u0026thinsp;50\u0026deg; and knee RoM from toe-off to peak knee flexion\u0026thinsp;\u0026lt;\u0026thinsp;12\u0026deg;.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCAST: calibrated anatomical system technique; RoM: range of motion; ANOVA: univariate analyses of variance; MANOVA: multivariate analyses of variance.\u003c/p\u003e\n"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Institutional Review Board of Cruzeiro do Sul University approved all procedures. All participants provided written informed consent prior to the experimental session.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the S\u0026atilde;o Paulo Research Foundation (FAPESP) under the grant number 2018/04964-8.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOB contributed to the acquisition, analysis, and interpretation of data, and have drafted the work; MLC and JAB contributed to the interpretation of data and substantively revised the work; AMFB contributed to the conception of the work, analysis and interpretation of data, and substantively revised it. All authors read and approved the submitted version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eOlney SJ, Richards C: Hemiparetic gait following stroke. Part I: Characteristics. Gait Posture\u003cem\u003e \u003c/em\u003e1996, 4(2):136-148.\u003c/li\u003e\n\u003cli\u003eKerrigan DC, Roth RS, Riley PO: The modelling of adult spastic paretic stiff-legged gait swing period based on actual kinematic data. Gait Posture\u003cem\u003e \u003c/em\u003e1998, 7(2):117-124.\u003c/li\u003e\n\u003cli\u003eMerlo A, Campanini I: Impact of instrumental analysis of stiff knee gait on treatment appropriateness and associated costs in stroke patients. Gait Posture\u003cem\u003e \u003c/em\u003e2019, 72:195-201.\u003c/li\u003e\n\u003cli\u003ePerry J: Gait analysis - normal and pathological function. 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J Biomech\u003cem\u003e \u003c/em\u003e2006, 39(4):689-698.\u003c/li\u003e\n\u003cli\u003eGage JR, Perry J, Hicks RR, Koop S, Werntz JR: Rectus femoris transfer to improve knee function of children with cerebral palsy. Dev Med Child Neurol\u003cem\u003e \u003c/em\u003e1987, 29(2):159-166.\u003c/li\u003e\n\u003cli\u003eOunpuu S, Muik E, Davis RB, 3rd, Gage JR, DeLuca PA: Rectus femoris surgery in children with cerebral palsy. Part I: The effect of rectus femoris transfer location on knee motion. J Pediatr Orthop\u003cem\u003e \u003c/em\u003e1993, 13(3):325-330.\u003c/li\u003e\n\u003cli\u003eBerker AN, Yalcin MS: Cerebral palsy: orthopedic aspects and rehabilitation. Pediatr Clin North Am\u003cem\u003e \u003c/em\u003e2008, 55(5):1209-1225.\u003c/li\u003e\n\u003cli\u003eArmand S, Decoulon G, Bonnefoy-Mazure A: Gait analysis in children with cerebral palsy. EFORT Open Rev\u003cem\u003e \u003c/em\u003e2016, 1(12):448-460.\u003c/li\u003e\n\u003cli\u003eRodda J, Graham HK: Classification of gait patterns in spastic hemiplegia and spastic diplegia: a basis for a management algorithm. Eur J Neurol\u003cem\u003e \u003c/em\u003e2001, 8 Suppl 5:98-108.\u003c/li\u003e\n\u003cli\u003eGanjwala D, Shah H: Management of the knee problems in spastic cerebral palsy. Indian J Orthop\u003cem\u003e \u003c/em\u003e2019, 53(1):53-62.\u003c/li\u003e\n\u003cli\u003eLamontagne A, Malouin F, Richards CL, Dumas F: Mechanisms of disturbed motor control in ankle weakness during gait after stroke. Gait Posture\u003cem\u003e \u003c/em\u003e2002, 15(3):244-255.\u003c/li\u003e\n\u003cli\u003eDamiano DL, Laws E, Carmines DV, Abel MF: Relationship of spasticity to knee angular velocity and motion during gait in cerebral palsy. Gait Posture\u003cem\u003e \u003c/em\u003e2006, 23(1):1-8.\u003c/li\u003e\n\u003cli\u003eWu G, Siegler S, Allard P, Kirtley C, Leardini A, Rosenbaum D, Whittle M, D\u0026apos;Lima DD, Cristofolini L, Witte H, et al: ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion - part I: ankle, hip, and spine. International Society of Biomechanics. J Biomech\u003cem\u003e \u003c/em\u003e2002, 35(4):543-548.\u003c/li\u003e\n\u003cli\u003eCelestino ML, van Emmerik R, Barela JA, Bacca O, Barela AMF: Effects of limited knee flexion movement in intra-limb gait coordination. J Biomech\u003cem\u003e \u003c/em\u003e2021, 128:110712.\u003c/li\u003e\n\u003cli\u003eBacca O, Celestino ML, Barela JA, Yakovenko S, de Lima AJS, Barela AMF: Compensatory strategies due to knee flexion constraint during gait of non-disabled adults. J Mot Behav\u003cem\u003e \u003c/em\u003e2022, 54(3):281-290.\u003c/li\u003e\n\u003cli\u003eCappozzo A, Catani F, Croce UD, Leardini A: Position and orientation in space of bones during movement: anatomical frame definition and determination. Clin Biomech\u003cem\u003e \u003c/em\u003e1995, 10(4):171-178.\u003c/li\u003e\n\u003cli\u003eMaki T, Quagliato EMAB, Cacho EWA, Paz LPS, Nascimento NH, Inoue MMEA, Viana MA: Estudo de confiabilidade da aplica\u0026ccedil;\u0026atilde;o da escala de Fugl-Meyer no Brasil. Rev Bras Fisioter\u003cem\u003e \u003c/em\u003e2006, 10(2):177-183.\u003c/li\u003e\n\u003cli\u003eRiberto M, Miyazaki MH, Juc\u0026aacute; SSH, Sakamoto H, Pinto PPN, Battistella LR: Valida\u0026ccedil;\u0026atilde;o da vers\u0026atilde;o brasileira da medida de independ\u0026ecirc;ncia funcional. 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Hum Mov Sci\u003cem\u003e \u003c/em\u003e2019, 68:102522.\u003c/li\u003e\n\u003cli\u003eBarela JA, Whitall J, Black P, Clark JE: An examination of constraints affecting the intralimb coordination of hemiparetic gait. Hum Mov Sci\u003cem\u003e \u003c/em\u003e2000, 19:251-273.\u003c/li\u003e\n\u003cli\u003eSousa CO, Barela JA, Prado-Medeiros CL, Salvini TF, Barela AMF: The use of body weight support on ground level: an alternative strategy for gait training of individuals with stroke. J Neuroeng Rehabil\u003cem\u003e \u003c/em\u003e2009, 6(1):43.\u003c/li\u003e\n\u003cli\u003eLevin MF, Kleim JA, Wolf SL: What do motor \u0026quot;recovery\u0026quot; and \u0026quot;compensation\u0026quot; mean in patients following stroke? Neurorehabil Neural Repair\u003cem\u003e \u003c/em\u003e2009, 23(4):313-319.\u003c/li\u003e\n\u003cli\u003eMartin SS, Aday AW, Almarzooq ZI, Anderson CAM, Arora P, Avery CL, Baker-Smith CM, Barone Gibbs B, Beaton AZ, Boehme AK, et al: 2024 Heart disease and stroke statistics: a report of US and global data from the american heart association. Circulation\u003cem\u003e \u003c/em\u003e2024.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-biomedical-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bbme","sideBox":"Learn more about [BMC Biomedical Engineering](http://bmcbiomedeng.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bbme/default.aspx","title":"BMC Biomedical Engineering","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"kinematics, walking, range of motion, peak knee flexion","lastPublishedDoi":"10.21203/rs.3.rs-4797428/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4797428/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Though stiff-knee gait is a common movement disorder in individuals with stroke, the criteria for identifying it in this population are not yet well established. This study investigated suitable criteria to identify stroke survivors with stiff-knee gait. Twenty-four stroke survivors (45.2±13.7 years old) and 24 individuals matched by age and sex (45.5±13.5 years old) with no known gait impairment participated in this study. They walked along a 10-m extension walkway at a self-selected comfortable speed. A computerized analysis system registered the trajectories of retroreflective markers placed on specific body landmarks, and different measurements were calculated regarding knee flexion during gait cycle, such as its peak during the swing period, total range of motion (RoM), equivalent to the difference between maximum and minimum knee excursion during gait cycle (“RoM cycle”), and RoM from toe-off to peak knee flexion (“RoM swing”).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Overall, peak knee flexion during the swing period and knee RoM swing were the most remarkable measurements to identify stiff-knee gait in stroke survivors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003eBased upon the found results, we suggest using at least two criteria to identify stiff-knee gait in individuals with stroke. The most suitable ones are peak knee flexion during the swing period \u0026lt;50° and the knee RoM from toe-off to peak knee flexion \u0026lt;12°. Finally, our results suggest that it is inappropriate to consider the non-paretic limb and total knee flexion RoM to classify stiff-knee gait in individuals with stroke.\u003c/p\u003e","manuscriptTitle":"Identification of stiff-knee gait in stroke survivors","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-21 09:40:46","doi":"10.21203/rs.3.rs-4797428/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-04T21:50:25+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-22T13:26:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"153137376350260962795586345991296549050","date":"2025-02-28T13:27:33+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-07T10:18:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"204494328541472276234256022391215421985","date":"2025-01-16T13:30:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"140442024127079134442390314254446933835","date":"2024-12-01T09:24:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"66488733006051964870942244602884375591","date":"2024-09-30T18:58:21+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-30T16:31:45+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-07-29T09:58:31+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-25T09:00:22+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-25T08:59:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Biomedical Engineering","date":"2024-07-24T18:55:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-biomedical-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bbme","sideBox":"Learn more about [BMC Biomedical Engineering](http://bmcbiomedeng.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bbme/default.aspx","title":"BMC Biomedical Engineering","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8fad9cc6-1da9-4ef5-a7c4-88d9a1945452","owner":[],"postedDate":"August 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-08T15:59:38+00:00","versionOfRecord":{"articleIdentity":"rs-4797428","link":"https://doi.org/10.1186/s42490-025-00097-1","journal":{"identity":"bmc-biomedical-engineering","isVorOnly":false,"title":"BMC Biomedical Engineering"},"publishedOn":"2025-09-01 15:57:19","publishedOnDateReadable":"September 1st, 2025"},"versionCreatedAt":"2024-08-21 09:40:46","video":"","vorDoi":"10.1186/s42490-025-00097-1","vorDoiUrl":"https://doi.org/10.1186/s42490-025-00097-1","workflowStages":[]},"version":"v1","identity":"rs-4797428","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4797428","identity":"rs-4797428","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}