title: A wearable mobility assessment device for total knee replacement: A longitudinal feasibility study.
abstract: BACKGROUND
  Total knee replacement currently lacks robust indications and objective follow-up metrics. Patients and healthcare staff are under-equipped to optimise outcomes. This study aims to investigate the feasibility of using an ear-worn motion sensor (e-AR, Imperial College London) to conduct objective, home-based mobility assessments in the peri-operative setting.
  
  
  METHODS
  Fourteen patients on the waiting list for knee replacement, and 15 healthy subjects, were recruited. Pre-operatively, and at 1, 3, 6, 12 and 24 weeks post-operatively, patients underwent functional mobility testing (Timed Up and Go), knee examination (including range of motion), and an activity protocol whilst wearing the e-AR sensor. Features extracted from sensor motion data were used to assess patient performance and predict patients' recovery phase.
  
  
  RESULTS
  Sensor-derived peri-operative mobility trends correlated with clinical measures in several activities, allowing functional recovery of individual subjects to be profiled and compared, including the detection of a complication. Sensor data features enabled classification of subjects into normal, pre-operative and 24-week post-operative groups with 89% (median) accuracy. Classification accuracy was reduced to 69% when including all time intervals.
  
  
  CONCLUSIONS
  This study demonstrates a novel, objective method of assessing peri-operative mobility, which could be used to supplement surgical decision-making and facilitate community-based follow-up.
authors: Hamlyn Centre, Institute of Global Health Innovation, Imperial College London, United Kingdom. Electronic address: RMK107@imperial.ac.uk.
authors: Richard M
authors: RM
authors: Kwasnicki
authors: Hamlyn Centre, Institute of Global Health Innovation, Imperial College London, United Kingdom.
authors: Raza
authors: R
authors: Ali
authors: Department of Surgery and Cancer, Imperial College London, United Kingdom.
authors: Stevan J
authors: SJ
authors: Jordan
authors: Hamlyn Centre, Institute of Global Health Innovation, Imperial College London, United Kingdom.
authors: Louis
authors: L
authors: Atallah
authors: Department of Surgery and Cancer, Imperial College London, United Kingdom.
authors: Julian J H
authors: JJ
authors: Leong
authors: Department of Surgery and Cancer, Imperial College London, United Kingdom.
authors: Gareth G
authors: GG
authors: Jones
authors: Imperial College Healthcare NHS Trust, United Kingdom; Department of Surgery and Cancer, Imperial College London, United Kingdom.
authors: Justin
authors: J
authors: Cobb
authors: Hamlyn Centre, Institute of Global Health Innovation, Imperial College London, United Kingdom.
authors: Guang Zhong
authors: GZ
authors: Yang
authors: Hamlyn Centre, Institute of Global Health Innovation, Imperial College London, United Kingdom.
authors: Ara
authors: A
authors: Darzi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005081:Exercise Therapy / Q000295:instrumentation*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D016059:Range of Motion, Articular; D020127:Recovery of Function
keywords: Mobility; Post-operative; Sensor; Total knee replacement