title: Degeneration in ACL Injured Knees with and without Reconstruction in Relation to Muscle Size and Fat Content-Data from the Osteoarthritis Initiative.
abstract: BACKGROUND
  Anterior cruciate ligaments (ACL) injuries represent a major risk factor for early osteoarthritis (OA).
  
  
  OBJECTIVE
  To evaluate the prevalence and 4-year progression of knee OA measured with 3T MR-imaging in individuals with ruptured, reconstructed or normal ACL and to assess the impact of thigh muscle characteristics.
  
  
  METHODS
  A total of 54 knees (23/54 male, 31/54 female) were recruited from the Osteoarthritis Initiative (OAI). At baseline, 15/54 subjects had prevalent ACL ruptures and 15/54 subjects had prevalent ACL reconstruction (24/54 normal ACL). Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores, Physical Activity Scores of the Elderly (PASE) and thigh muscle characteristics including strength, fat infiltration (Goutallier score) and thigh muscle cross-sectional area (CSA) MR measurements were obtained at baseline. Whole-organ MR-imaging Scores (WORMS) were obtained at baseline and at a 4-year follow-up time-point. Multivariate regression models, adjusting for covariates (age, gender, body mass index), were used for statistical analysis.
  
  
  RESULTS
  At baseline, subjects with prevalent ACL ruptures had worse WORMS total scores (mean±SEM, 44.1±3.5) than subjects with ACL reconstruction (30.8±4.0; P = 0.015) and worse than subjects with normal ACL (21.3±3.0; P<0.001). Cartilage scores were worse in both femorotibial compartments in ACL injured knees than in knees with normal ACL (P<0.05). Knees with ACL reconstruction showed an increased degeneration of the medial meniscus (P = 0.036), cartilage degeneration at the medial femoral condyle (P = 0.011). In a multivariate regression model, including both ACL groups and total muscle characteristics as influence parameters, high thigh muscle CSA, high muscle/ fat ratio and low Goutallier scores were associated with less degenerative changes at the knee, independent of ACL status. Knees with ACL reconstruction showed an increased progression of cartilage degeneration at the medial tibia compared to the normal ACL group (P = 0.027).
  
  
  CONCLUSIONS
  High thigh muscle CSA is associated with less degenerative changes at the knee, independent of the ACL status and may potentially be advantageous in the prevention of early OA.
authors.affiliation: Department of Radiology, Technische Universitaet Muenchen, Munich, Germany.
authors.forename: Pia M
authors.identifier: http://orcid.org/0000-0003-2198-3678
authors.initials: PM
authors.lastname: Jungmann
authors.affiliation: Department of Radiology, Technische Universitaet Muenchen, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baum
authors.affiliation: Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Nevitt
authors.affiliation: Musculoskeletal and Quantitative Imaging Research, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Nardo
authors.affiliation: Department of Radiology, Technische Universitaet Muenchen, Munich, Germany.
authors.forename: Alexandra S
authors.initials: AS
authors.lastname: Gersing
authors.affiliation: Department of Internal Medicine, UC Davis Medical Center, Sacramento, California, United States of America.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Lane
authors.affiliation: Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCulloch
authors.affiliation: Department of Radiology, Technische Universitaet Muenchen, Munich, Germany.
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Rummeny
authors.affiliation: Musculoskeletal and Quantitative Imaging Research, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
mesh_terms: D016118:Anterior Cruciate Ligament / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods; D002358:Cartilage, Articular / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D018450:Disease Progression; D015444:Exercise / Q000502:physiology; D005223:Fats / Q000378:metabolism*; D005260:Female; D005269:Femur / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007717:Knee / Q000503:physiopathology* / Q000601:surgery; D007719:Knee Joint / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008592:Menisci, Tibial / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D052097:Quadriceps Muscle / Q000378:metabolism / Q000503:physiopathology; D013977:Tibia / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery
chemical_list: D005223:Fats