title: Assessing function in patients undergoing joint replacement: a study protocol for a cohort study.
abstract: BACKGROUND
  Joint replacement is an effective intervention for people with advanced arthritis, although there is an important minority of patients who do not improve post-operatively. There is a need for robust evidence on outcomes after surgery, but there are a number of measures that assess function after joint replacement, many of which lack any clear theoretical basis. The World Health Organisation has introduced the International Classification of Functioning, Disability and Health (ICF), which divides function into three separate domains: Impairment, activity limitations and participation restrictions. The aim of this study is to compare the properties and responsiveness of a selection of commonly used outcome tools that assess function, examine how well they relate to the ICF concepts, and to explore the changes in the measures over time.
  
  
  METHODS
  Two hundred and sixty three patients listed for lower limb joint replacement at an elective orthopaedic centre have been recruited into this study. Participants attend the hospital for a research appointment prior to surgery and then at 3-months and 1-year after surgery. At each assessment time, function is assessed using a range of measures. Self-report function is assessed using the WOMAC, Aberdeen Impairment, Activity Limitation and Participation Restriction Measure, SF-12 and Measure Yourself Medical Outcome Profile 2. Clinician-administered measures of function include the American Knee Society Score for knee patients and the Harris Hip Score for hip patients. Performance tests include the timed 20-metre walk, timed get up and go, sit-to-stand-to-sit, step tests and single stance balance test. During the performance tests, participants wear an inertial sensor and data from motion analysis are collected. Statistical analysis will include exploring the relationship between measures describing the same ICF concepts, assessing responsiveness, and studying changes in measures over time.
  
  
  CONCLUSIONS
  There are a range of tools that can be used to assess function before and after joint replacement, with little information about how these various measures compare in their properties and responsiveness. This study aims to provide this data on a selection of commonly used assessments of function, and explore how they relate to the ICF domains.
authors.affiliation: Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Bristol BS10 5NB, UK. V.Wylde@bristol.ac.uk
authors.forename: Vikki
authors.initials: V
authors.lastname: Wylde
authors.forename: Ashley W
authors.initials: AW
authors.lastname: Blom
authors.forename: Stijn
authors.initials: S
authors.lastname: Bolink
authors.forename: Luke
authors.initials: L
authors.lastname: Brunton
authors.forename: Paul
authors.initials: P
authors.lastname: Dieppe
authors.forename: Rachael
authors.initials: R
authors.lastname: Gooberman-Hill
authors.forename: Bernd
authors.initials: B
authors.lastname: Grimm
authors.forename: Cindy
authors.initials: C
authors.lastname: Mann
authors.forename: Erik
authors.initials: E
authors.lastname: Lenguerrand
mesh_terms: D019643:Arthroplasty, Replacement / Q000379:methods* / Q000592:standards / Q000639:trends*; D019644:Arthroplasty, Replacement, Hip / Q000379:methods / Q000592:standards / Q000639:trends; D019645:Arthroplasty, Replacement, Knee / Q000379:methods / Q000592:standards / Q000639:trends; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D020127:Recovery of Function / Q000502:physiology*; D057566:Self Report / Q000592:standards; D016896:Treatment Outcome