title: Tibiofemoral Contact Forces in the Anterior Cruciate Ligament-Reconstructed Knee.
abstract: To investigate differences in anterior cruciate ligament-reconstructed (ACLR) and healthy individuals in terms of the magnitude of the tibiofemoral contact forces, as well as the relative muscle and external load contributions to those contact forces, during walking, running, and sidestepping gait tasks.
  
  
  
  A computational EMG-driven neuromusculoskeletal model was used to estimate the muscle and tibiofemoral contact forces in those with single-bundle combined semitendinosus and gracilis tendon autograft ACLR (n = 104, 29.7 ± 6.5 yr, 78.1 ± 14.4 kg) and healthy controls (n = 60, 27.5 ± 5.4 yr, 67.8 ± 14.0 kg) during walking (1.4 ± 0.2 m·s), running (4.5 ± 0.5 m·s) and sidestepping (3.7 ± 0.6 m·s). Within the computational model, the semitendinosus of ACLR participants was adjusted to account for literature reported strength deficits and morphological changes subsequent to autograft harvesting.
  
  
  
  ACLR had smaller maximum total and medial tibiofemoral contact forces (~80% of control values, scaled to bodyweight) during the different gait tasks. Compared with controls, ACLR were found to have a smaller maximum knee flexion moment, which explained the smaller tibiofemoral contact forces. Similarly, compared with controls, ACLR had both a smaller maximum knee flexion angle and knee flexion excursion during running and sidestepping, which may have concentrated the articular contact forces to smaller areas within the tibiofemoral joint. Mean relative muscle and external load contributions to the tibiofemoral contact forces were not significantly different between ACLR and controls.
  
  
  
  ACLR had lower bodyweight-scaled tibiofemoral contact forces during walking, running, and sidestepping, likely due to lower knee flexion moments and straighter knee during the different gait tasks. The relative contributions of muscles and external loads to the contact forces were equivalent between groups.
authors.affiliation: 1Innovations in Health Technology, Menzies Health Institute Queensland, Griffith University, Gold Coast, AUSTRALIA; 2Centre for Health, Exercise and Sports Medicine, University of Melbourne, AUSTRALIA; 3Department of Mechanical Engineering, University of Sheffield, UNITED KINGDOM; 4INSIGNEO Institute for In Silico Medicine, University of Sheffield, UNITED KINGDOM; 5Laboratory of Human Motion, Education and Health, University of Nice Sophia-Antipolis, Nice, FRANCE; 6Department of Epidemiology and Preventive Medicine, Monash University, AUSTRALIA; 7Knee Research Australia, AUSTRALIA; 8OrthoSport Victoria, Epworth Richmond, Melbourne, AUSTRALIA; 9College of Science, Health and Engineering, La Trobe University, Melbourne, AUSTRALIA; and 10Coast Orthopaedics, Gold Coast, AUSTRALIA.
authors.forename: David John
authors.initials: DJ
authors.lastname: Saxby
authors.forename: Adam L
authors.initials: AL
authors.lastname: Bryant
authors.forename: Luca
authors.initials: L
authors.lastname: Modenese
authors.forename: Pauline
authors.initials: P
authors.lastname: Gerus
authors.forename: Bryce A
authors.initials: BA
authors.lastname: Killen
authors.forename: Jason
authors.initials: J
authors.lastname: Konrath
authors.forename: Karine
authors.initials: K
authors.lastname: Fortin
authors.forename: Tim V
authors.initials: TV
authors.lastname: Wrigley
authors.forename: Kim L
authors.initials: KL
authors.lastname: Bennell
authors.forename: Flavia M
authors.initials: FM
authors.lastname: Cicuttini
authors.forename: Christopher
authors.initials: C
authors.lastname: Vertullo
authors.forename: Julian A
authors.initials: JA
authors.lastname: Feller
authors.forename: Tim
authors.initials: T
authors.lastname: Whitehead
authors.forename: Price
authors.initials: P
authors.lastname: Gallie
authors.forename: David G
authors.initials: DG
authors.lastname: Lloyd
mesh_terms: D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013996:Time and Motion Studies; D014182:Transplantation, Autologous; D016138:Walking / Q000502:physiology*