title: Unilateral total hip replacement patients with symptomatic leg length inequality have abnormal hip biomechanics during walking.
abstract: BACKGROUND
  Symptomatic leg length inequality accounts for 8.7% of total hip replacement related claims made against the UK National Health Service Litigation authority. It has not been established whether symptomatic leg length inequality patients following total hip replacement have abnormal hip kinetics during gait.
  
  
  METHODS
  Hip kinetics in 15 unilateral total hip replacement patients with symptomatic leg length inequality during gait was determined through multibody dynamics and compared to 15 native hip healthy controls and 15 'successful' asymptomatic unilateral total hip replacement patients.
  
  
  RESULTS
  More significant differences from normal were found in symptomatic leg length inequality patients than in asymptomatic total hip replacement patients. The leg length inequality patients had altered functions defined by lower gait velocity, reduced stride length, reduced ground reaction force, decreased hip range of motion, reduced hip moment and less dynamic hip force with a 24% lower heel-strike peak, 66% higher mid-stance trough and 37% lower toe-off peak. Greater asymmetry in hip contact force was also observed in leg length inequality patients.
  
  
  CONCLUSIONS
  These gait adaptions may affect the function of the implant and other healthy joints in symptomatic leg length inequality patients. This study provides important information for the musculoskeletal function and rehabilitation of symptomatic leg length inequality patients.
authors.affiliation: Department of Design Engineering, School of Science and Technology, Middlesex University, UK.
authors.forename: Junyan
authors.initials: J
authors.lastname: Li
authors.affiliation: Leeds Institute for Rheumatic and Musculoskeletal Medicine, School of Medicine, University of Leeds, UK; NIHR Leeds Biomedical Research Unit, Leeds Teaching Hospitals Trust, Leeds, UK.
authors.forename: Anthony B
authors.initials: AB
authors.lastname: McWilliams
authors.affiliation: NIHR Leeds Biomedical Research Unit, Leeds Teaching Hospitals Trust, Leeds, UK; Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK; School of Mechanical Engineering, Xi'an Jiaotong University, PR China.
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Jin
authors.affiliation: NIHR Leeds Biomedical Research Unit, Leeds Teaching Hospitals Trust, Leeds, UK; Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK.
authors.forename: John
authors.initials: J
authors.lastname: Fisher
authors.affiliation: NIHR Leeds Biomedical Research Unit, Leeds Teaching Hospitals Trust, Leeds, UK; Leeds Teaching Hospitals Trust, Chapel Allerton Hospital, Leeds, UK.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Stone
authors.affiliation: Leeds Institute for Rheumatic and Musculoskeletal Medicine, School of Medicine, University of Leeds, UK; NIHR Leeds Biomedical Research Unit, Leeds Teaching Hospitals Trust, Leeds, UK.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Redmond
authors.affiliation: NIHR Leeds Biomedical Research Unit, Leeds Teaching Hospitals Trust, Leeds, UK; Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK. Electronic address: T.D.Stewart@leeds.ac.uk.
authors.forename: Todd D
authors.initials: TD
authors.lastname: Stewart
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D007870:Leg Length Inequality / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016138:Walking / Q000502:physiology*
keywords: Arthroplasty; Contact force; Gait analysis; Hip; Leg length inequality