title: The relationship between external knee moments and muscle co-activation in subjects with medial knee osteoarthritis.
abstract: OBJECTIVE
  External knee moments are reliable to measure knee load but it does not take into account muscle activity. Considering that muscle co-activation increases compressive forces at the knee joint, identifying relationships between muscle co-activations and knee joint load would complement the investigation of the knee loading in subjects with knee osteoarthritis. The purpose of this study was to identify relationships between muscle co-activation and external knee moments during walking in subjects with medial knee osteoarthritis.
  
  
  METHODS
  19 controls (11 males, aged 56.6±5, and BMI 25.2±3.3) and 25 subjects with medial knee osteoarthritis (12 males, aged 57.3±5.3, and BMI 28.2±4) were included in this study. Knee adduction and flexion moments, and co-activation (ratios and sums of quadriceps, hamstring, and gastrocnemius) were assessed during walking and compared between groups. The relationship between knee moments and co-activation was investigated in both groups.
  
  
  RESULTS
  Subjects with knee osteoarthritis presented a moderate and strong correlation between co-activation (ratios and sums) and knee moments.
  
  
  CONCLUSIONS
  Muscle co-activation should be used to measure the contribution of quadriceps, hamstring, and gastrocnemius on knee loading. This information would cooperate to develop a more comprehensive approach of knee loading in this population.
authors.affiliation: Universidade Federal de São Carlos, Departamento de Fisioterapia, Laboratório de Análise da Função Articular, São Carlos, São Paulo 13565-905, Brazil; University of Salford, School of Health Sciences, Brian Blatchford Building, Salford M6 6PU, United Kingdom. Electronic address: lfaselistre@gmail.com.
authors.forename: Luiz Fernando Approbato
authors.initials: LF
authors.lastname: Selistre
authors.affiliation: Universidade Federal de São Carlos, Departamento de Fisioterapia, Laboratório de Análise da Função Articular, São Carlos, São Paulo 13565-905, Brazil.
authors.forename: Stela Márcia
authors.initials: SM
authors.lastname: Mattiello
authors.affiliation: Universidade Federal de São Carlos, Departamento de Fisioterapia, Laboratório de Avaliação e Intervenção em Ortopedia e Traumatologia, São Carlos, São Paulo 13565-905, Brazil.
authors.forename: Theresa Helissa
authors.initials: TH
authors.lastname: Nakagawa
authors.affiliation: Universidade Federal de São Carlos, Departamento de Fisioterapia, Laboratório de Análise da Função Articular, São Carlos, São Paulo 13565-905, Brazil.
authors.forename: Glaucia Helena
authors.initials: GH
authors.lastname: Gonçalves
authors.affiliation: Universidade Federal de São Carlos, Departamento de Fisioterapia, Laboratório de Análise da Função Articular, São Carlos, São Paulo 13565-905, Brazil.
authors.forename: Marina
authors.initials: M
authors.lastname: Petrella
authors.affiliation: University of Salford, School of Health Sciences, Brian Blatchford Building, Salford M6 6PU, United Kingdom.
authors.forename: Richard Keith
authors.initials: RK
authors.lastname: Jones
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D016059:Range of Motion, Articular; D016138:Walking