{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T06:05:41Z","timestamp":1775196341500,"version":"3.50.1"},"reference-count":42,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Planning for Humanities and Social Sciences Research Projects\/Youth Fund Program of the Ministry of Education","award":["21XJC760003"],"award-info":[{"award-number":["21XJC760003"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To investigate how knee joint protector design affects the biomechanical characteristics of knee motion under various activities, this pilot study (n = 5) examined how knee joint protector design modulates knee biomechanics across walking, jogging, squatting, and sit-to-stand tasks using optical motion capture and AnyBody musculoskeletal modeling (FullBody_GRFPrediction). We quantified knee flexion kinematics, model-estimated joint reaction forces and moments, and model-estimated muscle activity of eight lower-limb muscles under four conditions with different levels of structural constraint: no protector (Pro.off), a conventional sleeve-type protector (Pro.a), a segmented support protector (Pro.b), and a wrapping fixation protector (Pro.c). The biomechanical protective performance of the knee joint protector was task- and phase-dependent. The results showed that Pro.a optimized muscle activation. Pro.b increased sagittal-plane design but increased joint loading and muscle activity. Pro.c induced noticeable distal compensation along the kinetic chain. The findings revealed that protector effects were task-dependent. Dynamic tasks mainly affected coronal-plane stability parameters, whereas quasi-static tasks more clearly altered sagittal load distribution. In this study, biomechanical protective performance is defined as reduced knee joint loading without disproportionate increases in model-estimated muscle activity or excessive loss of functional knee flexion range. Under this definition, greater structural constraint did not consistently produce a more favorable biomechanical profile. These results provide a feasibility baseline for task-specific protector evaluation and motivate confirmatory studies with larger cohorts and experimental validation. This study provides theoretical and methodological insights to guide future design and optimization of knee joint protectors.<\/jats:p>","DOI":"10.3390\/s26072168","type":"journal-article","created":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T16:34:08Z","timestamp":1774974848000},"page":"2168","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Study on the Influence of Protector Design on the Biomechanical Characteristics of Knee Joint Movement"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1705-1923","authenticated-orcid":false,"given":"Jiaxin","family":"Zhao","sequence":"first","affiliation":[{"name":"School of Mechanical Engineering, Xi\u2019an University of Technology, Xi\u2019an 710048, China"},{"name":"School of Art and Design, Xi\u2019an University of Technology, Xi\u2019an 710054, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7380-7399","authenticated-orcid":false,"given":"Xupeng","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Xi\u2019an University of Technology, Xi\u2019an 710048, China"},{"name":"School of Art and Design, Xi\u2019an University of Technology, Xi\u2019an 710054, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-5150-7809","authenticated-orcid":false,"given":"Lingxiao","family":"Xi","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Xi\u2019an University of Technology, Xi\u2019an 710048, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-5320-1484","authenticated-orcid":false,"given":"Xinran","family":"Cheng","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Xi\u2019an University of Technology, Xi\u2019an 710048, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2143-6308","authenticated-orcid":false,"given":"Jihyun","family":"Bae","sequence":"additional","affiliation":[{"name":"Human-Tech Convergence Program, Department of Clothing & Textiles, Hanyang University, Seoul 04763, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1466-0291","authenticated-orcid":false,"given":"Yongwei","family":"Li","sequence":"additional","affiliation":[{"name":"Human-Tech Convergence Program, Department of Clothing & Textiles, Hanyang University, Seoul 04763, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"103394","DOI":"10.1016\/j.robot.2019.103394","article-title":"Assistive Devices of Human Knee Joint: A review","volume":"125","author":"Zhang","year":"2020","journal-title":"Robot. Auton. Syst."},{"key":"ref_2","first-page":"234","article-title":"Research on the Design Method of Wearable Products for Aging-Friendly Orthopedic Rehabilitation","volume":"40","author":"Wang","year":"2024","journal-title":"J. Xi \u2018Univ. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Kleist, E., Henke, P., Ruehrmund, L., Kebbach, M., Bader, R., and Woernle, C. (2024). Impact of Structural Compliance of a Six Degree of Freedom Joint Simulator on Virtual Ligament Force Calculation in Total Knee Endoprosthesis Testing. Life, 14.","DOI":"10.3390\/life14040531"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"McGibbon, C.A., Brandon, S., Bishop, E.L., Cowper-Smith, C., and Biden, E.N. (2021). Biomechanical Study of a Tricompartmental Unloader Protector for Patellofemoral or Multicompartment Knee Osteoarthritis. Front. Bioeng. Biotechnol., 8.","DOI":"10.3389\/fbioe.2020.604860"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Hall, M., Starkey, S., Hinman, R.S., Diamond, L.E., Lenton, G.K., Knox, G., Pizzolato, C., and Saxby, D.J. (2022). Effect of a Valgus Protector on Medial Tibiofemoral Joint Contact Force in Knee Osteoarthritis with Varus Malalignment: A Within-Participant Cross-Over Randomised Study with an Uncontrolled Observational Longitudinal Follow-Up. PLoS ONE, 17.","DOI":"10.1371\/journal.pone.0257171"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.1097\/PHM.0000000000002521","article-title":"Neuromuscular Adaptations Related to Medial Knee Osteoarthritis and Influence of Unloader Protectors on Neuromuscular Activity in Knee Osteoarthritis Subjects-A Systematic Review","volume":"103","author":"Rogoschin","year":"2024","journal-title":"Am. J. Phys. Med. Rehabil."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1371","DOI":"10.1016\/j.joca.2024.08.010","article-title":"Knee Protectors for Knee Osteoarthritis: A Scoping Review and Narrative Synthesis of Interventions in Randomised Controlled Trials","volume":"32","author":"Holden","year":"2024","journal-title":"Osteoarthr. Cartil."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e2500412","DOI":"10.1002\/adma.202500412","article-title":"Transforming Healthcare: Intelligent Wearable Sensors Empowered by Smart Materials and Artificial Intelligence","volume":"37","author":"Chen","year":"2025","journal-title":"Adv. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2068","DOI":"10.1109\/TBME.2016.2586891","article-title":"Full-Body Musculoskeletal Model for Muscle-Driven Simulation of Human Gait","volume":"63","author":"Rajagopal","year":"2016","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Latreche, A., D\u00e6hlin, T.E., Ross, S.A., Konow, N., Biewener, A.A., Nigam, N., and Wakeling, J. (2025). Influence of Scaling Mass and Height on a Musculoskeletal Model of Joint Moments During Walking: A Simulation Study. 2025 11th International Conference on Mechatronics and Robotics Engineering, IEEE.","DOI":"10.1109\/ICMRE64970.2025.10976321"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Seth, A., Hicks, J.L., Uchida, T.K., Habib, A., Dembia, C.L., Dunne, J.J., Ong, C.F., DeMers, M.S., Rajagopal, A., and Millard, M. (2018). OpenSim: Simulating Musculoskeletal Dynamics and Neuromuscular Control to Study Human and Animal Movement. PLoS Comput. Biol., 14.","DOI":"10.1371\/journal.pcbi.1006223"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1016\/j.knee.2019.04.006","article-title":"Contributions of Muscles and External Forces to Medial Knee Load Reduction Due to Osteoarthritis Protectors","volume":"26","author":"Brandon","year":"2019","journal-title":"Knee"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"011010","DOI":"10.1115\/1.4064031","article-title":"Evaluation of an Unloading Concept for Knee Osteoarthritis: A Pilot Study in a Small Patient Group","volume":"146","author":"Stoltze","year":"2024","journal-title":"J. Biomech. Eng."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1528","DOI":"10.1177\/09544119221122067","article-title":"A Developed Multibody Knee Model for Unloading Knee with Cartilage Penetration Depth Control","volume":"236","author":"Javanfar","year":"2022","journal-title":"Proc. Inst. Mech. Eng. Part H"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1007\/s11044-016-9537-4","article-title":"Prediction of Ground Reaction Forces and Moments During Sports-Related Movements","volume":"39","author":"Skals","year":"2017","journal-title":"Multibody Syst. Dyn."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Han, X.J., Jiang, Y., Wang, W.M., Fang, G.X., Gill, S., Zang, Z.Q., Wang, S.F., Saito, J., Kumar, D., and Luo, Z.X. (2024). Motion-Driven Neural Optimizer for Prophylactic Protectors Made by Distributed Microstructures. SIGGRAPH Asia 2024 Conference Papers, Association for Computing Machinery.","DOI":"10.1145\/3680528.3687661"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1080\/00222895.1989.10735488","article-title":"Biomechanics of Normal and Pathological Gait","volume":"21","author":"Winter","year":"2013","journal-title":"J. Mot. Behav."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1","DOI":"10.34256\/ijpefs2131","article-title":"Biomechanics of Running: An Overview on Gait cycle","volume":"10","author":"Kapri","year":"2021","journal-title":"Int. J. Phys. Educ. Fit. Sports"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"490","DOI":"10.26603\/001c.94600","article-title":"A Biomechanical Review of the Squat Exercise: Implications for Clinical Practice","volume":"19","author":"Straub","year":"2024","journal-title":"Int. J. Sports Phys. Ther."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1007\/s41315-021-00188-x","article-title":"Experimental Study on Sit-to-Stand (STS) Movement: A Systematic Review","volume":"6","author":"Xue","year":"2021","journal-title":"Int. J. Intell. Robot. Appl."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1080\/23335432.2014.993706","article-title":"Scaling of Musculoskeletal Models from Static and Dynamic Trials","volume":"2","author":"Lund","year":"2015","journal-title":"Int. Biomech."},{"key":"ref_22","first-page":"102","article-title":"A Two-Step Muscle\/Tendon-Length Calibration in Musculoskeletal Models\/\/XXIV Congress of the International Society of Biomechanics","volume":"2013","author":"Heinen","year":"2013","journal-title":"Natal Int. Soc. Biomech."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"965","DOI":"10.1109\/TNSRE.2021.3082459","article-title":"Knee Swing Phase Flexion Resistance Affects Several Key Features of Leg Swing Important to Safe Transfemoral Prosthetic Gait","volume":"29","author":"Kent","year":"2021","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1186\/s13018-024-05447-8","article-title":"Effect of Knee Extension Constraint Training on Walking Biomechanics 6 Months After Anterior Cruciate Ligament Reconstruction: A Double-Blind Randomized Controlled Clinical Trial","volume":"20","author":"Gao","year":"2025","journal-title":"J. Orthop. Surg. Res."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"234","DOI":"10.2519\/jospt.2024.12070","article-title":"Knee Confidence, Fear of Movement, and Psychological Readiness for Sport in Individuals with Knee Conditions: A Systematic Review and Meta-analysis","volume":"54","author":"Hart","year":"2024","journal-title":"J. Orthop. Sports Phys. Ther."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.medengphy.2020.10.009","article-title":"Kinematics and Kinetics of Lower-Extremity Joints in Parachuting Landing with Backpack and Knee Protector","volume":"86","author":"Jiang","year":"2020","journal-title":"Med. Eng. Phys."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Jiang, X.Y., B\u00edr\u00f3, I., S\u00e1rosi, J., Fang, Y., and Gu, Y. (2024). Comparison of Ground Reaction Forces as Running Speed Increases Between Male and Female Runners. Front. Bioeng. Biotechnol., 12.","DOI":"10.3389\/fbioe.2024.1378284"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1494","DOI":"10.1519\/JSC.0000000000004838","article-title":"The Use of Free Weight Squats in Sports: A Narrative Review\u2014Squatting Movements, Adaptation, and Sports Performance: Physiological","volume":"38","author":"Stone","year":"2024","journal-title":"J. Strength Cond. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/j.gaitpost.2011.03.019","article-title":"A Clinical Study of the Biomechanics of Step Descent Using Different Treatment Modalities for Patellofemoral Pain","volume":"34","author":"Selfe","year":"2011","journal-title":"Gait Posture"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Schellenberg, F., Schmid, N., H\u00e4berle, R., H\u00f6rterer, N., Taylor, W.R., and Lorenzetti, S. (2017). Loading Conditions in the Spine, Hip and Knee During Different Executions of Back Extension Exercises. BMC Sports Sci. Med. Rehabil., 9.","DOI":"10.1186\/s13102-017-0074-0"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/j.gaitpost.2016.05.011","article-title":"The Effect of Proprioceptive Knee Bracing on Knee Stability During Three Different Sport Related Movement Tasks in Healthy Subjects and the Implications to the Management of Anterior Cruciate Ligament (ACL) Injuries","volume":"48","author":"Richards","year":"2016","journal-title":"Gait Posture"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2325967120981641","DOI":"10.1177\/2325967120981641","article-title":"Effect of Prophylactic Knee Bracing on Anterior Cruciate Ligament Agonist and Antagonist Muscle Forces During Perturbed Walking","volume":"9","author":"Haddara","year":"2021","journal-title":"Orthop. J. Sports Med."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Wang, Y.B., Liu, H.B., Wei, H.D., Wu, C.X., and Yuan, F.J. (2023). The Effect of a Knee Protector on Muscle Forces During Single-Leg Landings at Two Heights. Int. J. Environ. Res. Public Health, 20.","DOI":"10.3390\/ijerph20054652"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"9842","DOI":"10.1038\/s41598-022-13386-9","article-title":"Muscle Coordination Retraining Inspired by Musculoskeletal Simulations Reduces Knee Contact Force","volume":"12","author":"Uhlrich","year":"2022","journal-title":"Sci. Rep."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"4194472","DOI":"10.1155\/2022\/4194472","article-title":"Biomechanical Effect of Valgus Knee Protectors on the Treatment of Medial Gonarthrosis: A Systematic Review","volume":"2022","author":"Yan","year":"2022","journal-title":"Appl. Bionics Biomech."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"555","DOI":"10.1007\/s00167-006-0072-3","article-title":"Study on Three-Dimensional Kinematics and Electromyography of ACL Deficient Knee Participants Wearing a Functional Knee Protector During Running","volume":"14","author":"Lamontagne","year":"2006","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"575","DOI":"10.1016\/j.gaitpost.2019.01.010","article-title":"Increased Use of Stepping Strategy in Response to Medio-Lateral Perturbations in the Elderly Relates to Altered Reactive Tibialis Anterior Activity","volume":"68","author":"Afschrift","year":"2019","journal-title":"Gait Posture"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Yang, C.H., Yang, Y., Xu, Y.X., Zhang, Z.Y., Lake, M., and Fu, W.J. (2024). Whole Leg Compression Garments Influence Lower Limb Kinematics and Associated Muscle Synergies During Running. Front. Bioeng. Biotechnol., 12.","DOI":"10.3389\/fbioe.2024.1310464"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Nashrulloh, T., Biben, V., Santi, F.A., Gz, R., Moeliono, M., Wicaksono, D.H., and Hasnaoui, N. (2019, January 20\u201323). Pattern of Muscle Activation During Sit to Stand Task in Feet Forward with 80\u00b0 Knee Flexion Using Surface EMG. Proceedings of the 11th National Congress and the 18th Annual Scientific Meeting of Indonesian Physical Medicine and Rehabilitation Association, Daerah Khusus Ibukota, Indonesia.","DOI":"10.5220\/0009064000820087"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Jeon, W., Dong, X.N., Dalby, A., and Goh, C.H. (2024). The Influence of Smoothness and Speed of Stand-to-Sit Movement on Joint Kinematics, Kinetics, and Muscle Activation Patterns. Front. Hum. Neurosci., 18.","DOI":"10.3389\/fnhum.2024.1399179"},{"key":"ref_41","first-page":"4879","article-title":"Effect of Assistance Timing in Knee Extensor Muscle Activation During Sit-to-Stand Using a Bilateral Robotic Knee Exoskeleton","volume":"2021","author":"Choi","year":"2021","journal-title":"Annu. Int. Conf. IEEE Eng. Med. Biol. Soc."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Daunoraviciene, K., and Ziziene, J. (2022). Accuracy of Ground Reaction Force and Muscle Activation Prediction in a Child-Adapted Musculoskeletal Model. Sensors, 22.","DOI":"10.3390\/s22207825"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/7\/2168\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T04:11:03Z","timestamp":1775189463000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/7\/2168"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,31]]},"references-count":42,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["s26072168"],"URL":"https:\/\/doi.org\/10.3390\/s26072168","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,31]]}}}