{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T19:28:57Z","timestamp":1791487737110,"version":"4.3.4"},"reference-count":53,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2021,7,29]],"date-time":"2021-07-29T00:00:00Z","timestamp":1627516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Although the Lower-Extremity Assessment Protocol (LEAP) assesses multidimensional aspects of a patient with anterior cruciate ligament (ACL) injury, there is a need to reduce the dimensionality of LEAP items to effectively assess patients. Therefore, the present study aimed to establish the validity of LEAP and to determine associated factors and components in a relationship between LEAP and the International Knee Documentation Committee (IKDC) questionnaire. Fifteen patients who had ACL reconstruction more than 1 year and less than 5 years earlier were recruited. Patients performed LEAP, including muscular strength, fatigue index, static balance, drop landing, and functional hopping assessment. They also completed the IKDC questionnaire and the Tegner Activity Score. Factor analysis and stepwise regression analysis were performed. The 14 components of LEAP were categorized into four factors (functional task, muscle strength, neuromuscular control, and fatigue), which accounted for 83.8% of the cumulative variance by factor analysis. In the stepwise regression analysis, the functional task (R2 = 0.43, p = 0.008) in factors and single-leg hop (R2 = 0.49, p = 0.004) in components were associated with patient-oriented outcomes, respectively. In conclusion, the functional task and single-leg hop may be used for providing valuable information about knee joints to patients and clinicians.<\/jats:p>","DOI":"10.3390\/ijerph18158053","type":"journal-article","created":{"date-parts":[[2021,7,29]],"date-time":"2021-07-29T10:47:46Z","timestamp":1627555666000},"page":"8053","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Determination of the Strongest Factor and Component in a Relationship between Lower-Extremity Assessment Protocol and Patient-Oriented Outcomes in Individuals with Anterior Cruciate Ligament Reconstruction: A Pilot Study"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8782-5341","authenticated-orcid":false,"given":"Hyung Gyu","family":"Jeon","sequence":"first","affiliation":[{"name":"Department of Physical Education, Yonsei University, Seoul 03722, Korea"},{"name":"International Olympic Committee Research Centre Korea, Seoul 03722, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6220-6774","authenticated-orcid":false,"given":"Byong Hun","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Yonsei University, Seoul 03722, Korea"},{"name":"International Olympic Committee Research Centre Korea, Seoul 03722, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tae Kyu","family":"Kang","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Yonsei University, Seoul 03722, Korea"},{"name":"International Olympic Committee Research Centre Korea, Seoul 03722, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8318-7322","authenticated-orcid":false,"given":"Hee Seong","family":"Jeong","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Yonsei University, Seoul 03722, Korea"},{"name":"International Olympic Committee Research Centre Korea, Seoul 03722, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sae Yong","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Yonsei University, Seoul 03722, Korea"},{"name":"International Olympic Committee Research Centre Korea, Seoul 03722, Korea"},{"name":"Institute of Convergence Science, Yonsei University, Seoul 03722, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1080\/15438627.2012.680633","article-title":"Systematic review: Annual incidence of acl injury and surgery in various populations","volume":"20","author":"Moses","year":"2012","journal-title":"Res. Sports Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1097\/JSM.0000000000000425","article-title":"Injuries among recreational football players: Results of a prospective cohort study","volume":"28","author":"Korkusuz","year":"2018","journal-title":"Clin. J. Sport Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"141","DOI":"10.5435\/00124635-200005000-00001","article-title":"Noncontact anterior cruciate ligament injuries: Risk factors and prevention strategies","volume":"8","author":"Griffin","year":"2000","journal-title":"J. Am. Acad. Orthop. Surg."},{"key":"ref_4","first-page":"311","article-title":"Epidemiology of collegiate injuries for 15 sports: Summary and recommendations for injury prevention initiatives","volume":"42","author":"Hootman","year":"2007","journal-title":"J. Athl. Train."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1177\/03635465010290021301","article-title":"Intrinsic and extrinsic risk factors for anterior cruciate ligament injury in Australian footballers","volume":"29","author":"Orchard","year":"2001","journal-title":"Am. J. Sports Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"i47","DOI":"10.1136\/bjsm.2007.037192","article-title":"Mechanisms of non-contact acl injuries","volume":"41","author":"Yu","year":"2007","journal-title":"Br. J. Sports Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1007\/s001670050190","article-title":"A decision-making scheme for returning patients to high-level activity with nonoperative treatment after anterior cruciate ligament rupture","volume":"8","author":"Fitzgerald","year":"2000","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1417","DOI":"10.1007\/s00402-014-1992-x","article-title":"Return to play following acl reconstruction: A systematic review about strength deficits","volume":"134","author":"Petersen","year":"2014","journal-title":"Arch. Orthop. Trauma Surg."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"353","DOI":"10.1007\/s00402-008-0681-z","article-title":"Rotational instability of the knee: Internal tibial rotation under a simulated pivot shift test","volume":"129","author":"Diermann","year":"2009","journal-title":"Arch. Orthop. Trauma Surg."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1007\/s12178-017-9431-6","article-title":"Non-operative care of the patient with an acl-deficient knee","volume":"10","author":"Paterno","year":"2017","journal-title":"Curr. Rev. Musculoskelet. Med."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1543","DOI":"10.1136\/bjsports-2013-093398","article-title":"Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: An updated systematic review and meta-analysis including aspects of physical functioning and contextual factors","volume":"48","author":"Ardern","year":"2014","journal-title":"Br. J. Sports Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1136\/bjsm.2010.076364","article-title":"Return to sport following anterior cruciate ligament reconstruction surgery: A systematic review and meta-analysis of the state of play","volume":"45","author":"Ardern","year":"2011","journal-title":"Br. J. Sports Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"632","DOI":"10.1177\/036354659402200511","article-title":"Fate of the acl-injured patient. A prospective outcome study","volume":"22","author":"Daniel","year":"1994","journal-title":"Am. J. Sports Med."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"273","DOI":"10.47102\/annals-acadmedsg.V37N4p273","article-title":"Return to sports after anterior cruciate ligament reconstruction\u2014A review of patients with minimum 5-year follow-up","volume":"37","author":"Lee","year":"2008","journal-title":"Ann. Acad. Med. Singap."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"762","DOI":"10.1016\/S0749-8063(03)00398-0","article-title":"Beliefs and attitudes of members of the American Academy of Orthopaedic Surgeons regarding the treatment of anterior cruciate ligament injury","volume":"19","author":"Marx","year":"2003","journal-title":"Arthroscopy"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"172","DOI":"10.1272\/jnms.67.172","article-title":"Knee functions and a return to sports activity in competitive athletes following anterior cruciate ligament reconstruction","volume":"67","author":"Nakayama","year":"2000","journal-title":"J. Nippon Med. Sch."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"827","DOI":"10.1007\/s00402-013-1741-6","article-title":"Technique of anatomical footprint reconstruction of the acl with oval tunnels and medial portal aimers","volume":"133","author":"Petersen","year":"2013","journal-title":"Arch. Orthop. Trauma Surg."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"729","DOI":"10.2519\/jospt.2015.0109","article-title":"Anterior cruciate ligament injury prevention and rehabilitation: Let\u2019s get it right","volume":"45","author":"Wilk","year":"2015","journal-title":"J. Orthop. Sports Phys. Ther."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"605","DOI":"10.1016\/S0030-5898(02)00010-X","article-title":"Anatomy and biomechanics of the anterior cruciate ligament","volume":"33","author":"Dienst","year":"2002","journal-title":"Orthop. Clin. N. Am."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1177\/036354658401200304","article-title":"Quadriceps atrophy in the anterior cruciate insufficient knee","volume":"12","author":"Baugher","year":"1984","journal-title":"Am. J. Sports Med."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1055\/s-2008-1034576","article-title":"Isokinetic thigh muscle strength after ligament reconstruction in the knee joint: Results from a 5\u201310 year follow-up after reconstructions of the anterior cruciate ligament in the knee joint","volume":"2","author":"Arvidsson","year":"1981","journal-title":"Int. J. Sports Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1039","DOI":"10.1016\/j.knee.2014.07.021","article-title":"Asymmetries in explosive strength following anterior cruciate ligament reconstruction","volume":"21","author":"Knezevic","year":"2014","journal-title":"Knee"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1016\/j.gaitpost.2020.09.032","article-title":"Athletes with an acl reconstruction show a different neuromuscular response to environmental challenges compared to uninjured athletes","volume":"83","author":"Smeets","year":"2021","journal-title":"Gait Posture"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e15124","DOI":"10.1097\/MD.0000000000015124","article-title":"Impaired neuromuscular control up to postoperative 1 year in operated and nonoperated knees after anterior cruciate ligament reconstruction","volume":"98","author":"Lee","year":"2019","journal-title":"Medicine"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1567","DOI":"10.1177\/0363546514530088","article-title":"Incidence of second acl injuries 2 years after primary acl reconstruction and return to sport","volume":"42","author":"Paterno","year":"2014","journal-title":"Am. J. Sports Med."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1123\/jsr.2016-0126","article-title":"Relationships of functional tests following acl reconstruction: Exploratory factor analyses of the lower extremity assessment protocol","volume":"27","author":"DiFabio","year":"2018","journal-title":"J. Sport Rehabil."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"750","DOI":"10.2519\/jospt.2012.4194","article-title":"The impact of quadriceps femoris strength asymmetry on functional performance at return to sport following anterior cruciate ligament reconstruction","volume":"42","author":"Schmitt","year":"2012","journal-title":"J. Orthop. Sports Phys. Ther."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1177\/1941738115578112","article-title":"Deficits in quadriceps strength and patient-oriented outcomes at return to activity after acl reconstruction: A review of the current literature","volume":"7","author":"Lepley","year":"2015","journal-title":"Sports Health"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"34","DOI":"10.5763\/kjsm.2021.39.1.34","article-title":"Objective and subjective analysis of the knee joint function using lower extremity assessment protocol after anterior cruciate ligament reconstruction","volume":"39","author":"Kim","year":"2021","journal-title":"Korean Soc. Sports Med."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1007\/s00167-019-05461-y","article-title":"Post-traumatic osteoarthritis diagnosed within 5 years following acl reconstruction","volume":"28","author":"Bodkin","year":"2020","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"337","DOI":"10.2522\/ptj.20060143","article-title":"Hop testing provides a reliable and valid outcome measure during rehabilitation after anterior cruciate ligament reconstruction","volume":"87","author":"Reid","year":"2007","journal-title":"Phys. Ther."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1996","DOI":"10.1177\/0363546509343200","article-title":"The landing error scoring system (LESS) is a valid and reliable clinical assessment tool of jump-landing biomechanics: The jump-acl study","volume":"37","author":"Padua","year":"2009","journal-title":"Am. J. Sports Med."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2348","DOI":"10.1177\/0363546512457551","article-title":"Single-legged hop tests as predictors of self-reported knee function after anterior cruciate ligament reconstruction: The Delaware-oslo acl cohort study","volume":"40","author":"Logerstedt","year":"2012","journal-title":"Am. J. Sports Med."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1177\/1941738114529532","article-title":"Association of the single-limb hop test with isokinetic, kinematic, and kinetic asymmetries in patients after anterior cruciate ligament reconstruction","volume":"7","author":"Xergia","year":"2015","journal-title":"Sports Health"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Sueyoshi, T., Nakahata, A., Emoto, G., and Yuasa, T. (2017). Single-leg hop test performance and isokinetic knee strength after anterior cruciate ligament reconstruction in athletes. Orthop. J. Sports Med., 5.","DOI":"10.1177\/2325967117739811"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.ptsp.2004.02.003","article-title":"A systematic review of evidence for anterior cruciate ligament rehabilitation: How much and what type?","volume":"5","author":"Lewek","year":"2004","journal-title":"Phys. Ther. Sport"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1136\/bjsports-2012-091786","article-title":"Variables associated with return to sport following anterior cruciate ligament reconstruction: A systematic review","volume":"48","author":"Czuppon","year":"2014","journal-title":"Br. J. Sports Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1560","DOI":"10.2106\/00004623-200209000-00008","article-title":"Determinants of patient satisfaction with outcome after anterior cruciate ligament reconstruction","volume":"84","author":"Kocher","year":"2002","journal-title":"Bone Jt. Surg. Am."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1249\/MSS.0000000000000946","article-title":"Quadriceps Strength Predicts Self-reported Function Post-ACL Reconstruction","volume":"48","author":"Pietrosimone","year":"2016","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1007\/s00167-008-0645-4","article-title":"Knee extension and flexion muscle power after anterior cruciate ligament reconstruction with patellar tendon graft or hamstring tendons graft: A cross-sectional comparison 3 years post surgery","volume":"17","author":"Ageberg","year":"2009","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1967","DOI":"10.1177\/0363546509335000","article-title":"Identification of athletes at future risk of anterior cruciate ligament ruptures by neuromuscular screening","volume":"37","author":"Zebis","year":"2009","journal-title":"Am. J. Sports Med."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"179","DOI":"10.11138\/jts\/2015.3.4.179","article-title":"Anterior cruciate ligament reconstruction and rehabilitation: Predictors of functional outcome","volume":"3","author":"Ricci","year":"2015","journal-title":"Joints"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1968","DOI":"10.1177\/0363546510376053","article-title":"Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport","volume":"38","author":"Paterno","year":"2010","journal-title":"Am. J. Sports Med."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"492","DOI":"10.1177\/0363546504269591","article-title":"Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: A prospective study","volume":"33","author":"Hewett","year":"2005","journal-title":"Am. J. Sports Med."},{"key":"ref_45","first-page":"106","article-title":"Effects of muscular fatigue on knee joint laxity and neuromuscular characteristics of male and female athletes","volume":"34","author":"Rozzi","year":"1999","journal-title":"J. Athl. Train."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"598","DOI":"10.2519\/jospt.2001.31.10.598","article-title":"Effect of fatigue on knee proprioception: Implications for dynamic stabilization","volume":"31","author":"Hiemstra","year":"2001","journal-title":"J. Orthop. Sports Phys. Ther."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1055\/s-2007-1024562","article-title":"The effect of exercise on anterior knee laxity in female basketball players","volume":"13","author":"Sakai","year":"1992","journal-title":"Int. J. Sports Med."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1002\/jor.1100040115","article-title":"Effect of fatigue on joint position sense of the knee","volume":"4","author":"Skinner","year":"1986","journal-title":"J. Orthop. Res."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1307","DOI":"10.2106\/00004623-199072090-00005","article-title":"Measurement of anterior\u2013posterior displacement of the knee. A comparison of the results with instrumented devices and with clinical examination","volume":"72","author":"Steiner","year":"1990","journal-title":"J. Bone Jt. Surg. Am."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Csapo, R., Pointner, H., Hoser, C., Gf\u00f6ller, P., Raschner, C., and Fink, C. (2020). Physical fitness after anterior cruciate ligament reconstruction: Influence of graft, age, and sex. Sports, 8.","DOI":"10.3390\/sports8030030"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1186\/s40814-018-0326-0","article-title":"Pilot and feasibility studies in exercise, physical activity, or rehabilitation research","volume":"4","author":"Giangregorio","year":"2018","journal-title":"Pilot Feasibility Stud."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"837","DOI":"10.4085\/1062-6050-459-17","article-title":"Sex differences on the landing error scoring system among individuals with anterior cruciate ligament reconstruction","volume":"53","author":"Kuenze","year":"2018","journal-title":"J. Athl. Train."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/j.ptsp.2020.04.035","article-title":"Clinical implications of Landing Error Scoring System calculation methods","volume":"44","author":"Athens","year":"2020","journal-title":"Phys. Ther. Sport"}],"container-title":["International Journal of Environmental Research and Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-4601\/18\/15\/8053\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:36:56Z","timestamp":1760164616000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-4601\/18\/15\/8053"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,7,29]]},"references-count":53,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2021,8]]}},"alternative-id":["ijerph18158053"],"URL":"https:\/\/doi.org\/10.3390\/ijerph18158053","relation":{},"ISSN":["1660-4601"],"issn-type":[{"value":"1660-4601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,7,29]]}}}