title: MRI volume and signal intensity of ACL graft predict clinical, functional, and patient-oriented outcome measures after ACL reconstruction.
abstract: BACKGROUND
  Clinical, functional, and patient-oriented outcomes are commonly used to evaluate the efficacy of treatments after anterior cruciate ligament (ACL) injury; however, these evaluation techniques do not directly measure the biomechanical changes that occur with healing.
  
  
  OBJECTIVE
  To determine if the magnetic resonance (MR) image-derived parameters of graft volume and signal intensity (SI), which have been used to predict the biomechanical (ie, structural) properties of the graft in animal models, correlate with commonly used clinical (anteroposterior [AP] knee laxity), functional (1-legged hop), and patient-oriented outcome measures (Knee Injury and Osteoarthritis Outcome Score [KOOS]) in patients 3 and 5 years after ACL reconstruction.
  
  
  METHODS
  Cohort study (diagnosis); Level of evidence, 3.
  
  
  METHODS
  Based on a subset of participants enrolled in an ongoing ACL reconstruction clinical trial, AP knee laxity, 1-legged hop test, and KOOS were assessed at 3- and 5-year follow-up. Three-dimensional, T1-weighted MR images were collected at each visit. Both the volume and median SI of the healing graft were determined and used as predictors in a multiple regression linear model to predict the traditional outcome measures.
  
  
  RESULTS
  Graft volume combined with median SI in a multiple linear regression model predicted 1-legged hop test at both the 3- and 5-year follow-up visits (R(2) = 0.40, P = .008 and R(2) = 0.62, P = .003, respectively). Similar results were found at the 5-year follow-up for the KOOS quality of life (R(2) = 0.49, P = .012), sport/function (R(2) = 0.37, P = .048), pain (R(2) = 0.46, P = .017), and symptoms (R(2) = 0.45, P = .021) subscores, although these variables were not significant at 3 years. The multiple linear regression model for AP knee laxity at 5-year follow-up approached significance (R(2) = 0.36, P = .088).
  
  
  CONCLUSIONS
  The MR parameters (volume and median SI) used to predict ex vivo biomechanical properties of the graft in an animal model have the ability to predict clinical or in vivo outcome measures in patients at 3- and 5-year follow-up.
  
  
  CONCLUSIONS
  Results from this study may enhance clinical evaluation of graft health by relating the MR parameters of volume and median SI to traditional outcome measures and could potentially aid researchers in determining the appropriate timing for athletes to return to sport.
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Biercevicz
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Akelman
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fadale
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hulstyn
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Shalvoy
authors.affiliation: Department of Medical Biostatistics, University of Vermont, Burlington, Vermont, USA.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Badger
authors.affiliation: Department of Diagnostic Imaging, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Tung
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Heidi L
authors.initials: HL
authors.lastname: Oksendahl
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA Braden_Fleming@brown.edu.
authors.forename: Braden C
authors.initials: BC
authors.lastname: Fleming
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods; D018771:Arthralgia / Q000209:etiology; D064592:Autografts / Q000033:anatomy & histology / Q000502:physiology / Q000637:transplantation; D001696:Biomechanical Phenomena; D064594:Bone-Patellar Tendon-Bone Grafts / Q000033:anatomy & histology* / Q000502:physiology; D015331:Cohort Studies; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D007593:Joint Instability / Q000209:etiology; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D011237:Predictive Value of Tests; D011788:Quality of Life; D013710:Tendons / Q000033:anatomy & histology* / Q000502:physiology / Q000637:transplantation; D016896:Treatment Outcome; D055815:Young Adult
keywords: ACL; MRI; biomechanics; clinical assessment; patient outcome