[1] St Georges Univ, Sch Physiotherapy, Fac Hlth & Social Care Sci, London SW17 0RE, England
[2] Kingston Univ, Sch Physiotherapy, Fac Hlth & Social Care Sci, London SW17 0RE, England
[3] St Georges Healthcare NHS Trust, Med Phys & Clin Engn Dept, London SW17 0QT, England
[4] Kings Coll Hosp NHS Fdn Trust, Therapies Dept, London SE5 9RS, England