title: Walking patterns and hip contact forces in patients with hip dysplasia.
abstract: BACKGROUND
  Several studies have investigated walking characteristics in hip dysplasia patients, but so far none have described all hip rotational degrees of freedom during the whole gait cycle. This descriptive study reports 3D joint angles and torques, and furthermore extends previous studies with muscle and joint contact forces in 32 hip dysplasia patients and 32 matching controls.
  
  
  METHODS
  3D motion capture data from walking and standing trials were analysed. Hip, knee, ankle and pelvis angles were calculated with inverse kinematics for both standing and walking trials. Hip, knee and ankle torques were calculated with inverse dynamics, while hip muscle and joint contact forces were calculated with static optimisation for the walking trials.
  
  
  RESULTS
  No differences were found between the two groups while standing. While walking, patients showed decreased hip extension, increased ankle pronation and increased hip abduction and external rotation torques. Furthermore, hip muscle forces were generally lower and shifted to more posteriorly situated muscles, while the hip joint contact force was lower and directed more superiorly.
  
  
  CONCLUSIONS
  During walking, patients showed lower and more superiorly directed hip joint contact force, which might alleviate pain from an antero-superiorly degenerated joint.
authors.affiliation: Section of Sport Science, Department of Public Health, Faculty of Health Sciences, Aarhus University, Dalgas Avenue 4, DK-8000 Aarhus C, Denmark. Electronic address: skalshoi@gmail.com.
authors.forename: Ole
authors.initials: O
authors.lastname: Skalshøi
authors.affiliation: Section of Sport Science, Department of Public Health, Faculty of Health Sciences, Aarhus University, Dalgas Avenue 4, DK-8000 Aarhus C, Denmark. Electronic address: christianhauskov@outlook.com.
authors.forename: Christian Hauskov
authors.initials: CH
authors.lastname: Iversen
authors.affiliation: Section of Sport Science, Department of Public Health, Faculty of Health Sciences, Aarhus University, Dalgas Avenue 4, DK-8000 Aarhus C, Denmark. Electronic address: zirdennis@hotmail.com.
authors.forename: Dennis Brandborg
authors.initials: DB
authors.lastname: Nielsen
authors.affiliation: Department of Physiotherapy and Occupational Therapy, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: julie_svj@hotmail.com.
authors.forename: Julie
authors.initials: J
authors.lastname: Jacobsen
authors.affiliation: Department of Physiotherapy and Occupational Therapy, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: inger.mechlenburg@au.dk.
authors.forename: Inger
authors.initials: I
authors.lastname: Mechlenburg
authors.affiliation: Department of Orthopedic Surgery, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: kjeld@soballe.com.
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
authors.affiliation: Section of Sport Science, Department of Public Health, Faculty of Health Sciences, Aarhus University, Dalgas Avenue 4, DK-8000 Aarhus C, Denmark. Electronic address: hs@ph.au.dk.
authors.forename: Henrik
authors.initials: H
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000843:Ankle Joint / Q000502:physiology; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D005684:Gait / Q000502:physiology; D006617:Hip Dislocation / Q000503:physiopathology*; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D016059:Range of Motion, Articular; D012399:Rotation; D019415:Torque; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Gait analysis; Hip dysplasia; Joint contact force; Muscle force; OpenSim