title: Is long-term physical activity safe for older adults with knee pain?: a systematic review.
abstract: OBJECTIVE
  To determine whether long-term physical activity is safe for older adults with knee pain.
  
  
  METHODS
  A comprehensive systematic review and narrative synthesis of existing literature was conducted using multiple electronic databases from inception until May 2013. Two reviewers independently screened, checked data extraction and carried out quality assessment. Inclusion criteria for study designs were randomised controlled trials (RCTs), prospective cohort studies or case control studies, which included adults of mean age over 45 years old with knee pain or osteoarthritis (OA), undertaking physical activity over at least 3 months and which measured a safety related outcome (adverse events, pain, physical functioning, structural OA imaging progression or progression to total knee replacement (TKR)).
  
  
  RESULTS
  Of the 8614 unique references identified, 49 studies were included in the review, comprising 48 RCTs and one case control study. RCTs varied in quality and included an array of low impact therapeutic exercise interventions of varying cardiovascular intensity. There was no evidence of serious adverse events, increases in pain, decreases in physical function, progression of structural OA on imaging or increased TKR at group level. The case control study concluded that increasing levels of regular physical activity was associated with lower risk of progression to TKR.
  
  
  CONCLUSIONS
  Long-term therapeutic exercise lasting 3 to 30 months is safe for most older adults with knee pain. This evidence supports current clinical guideline recommendations. However, most studies investigated selected, consenting older adults carrying out low impact therapeutic exercise which may affect result generalizability.
  
  
  BACKGROUND
  PROSPERO 2014:CRD42014006913.
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute for Primary Care and Health Sciences, Keele University, Keele, Staffordshire, ST5 5BG, United Kingdom. Electronic address: j.g.quicke@keele.ac.uk.
authors.forename: J G
authors.initials: JG
authors.lastname: Quicke
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute for Primary Care and Health Sciences, Keele University, Keele, Staffordshire, ST5 5BG, United Kingdom. Electronic address: n.foster@keele.ac.uk.
authors.forename: N E
authors.initials: NE
authors.lastname: Foster
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute for Primary Care and Health Sciences, Keele University, Keele, Staffordshire, ST5 5BG, United Kingdom. Electronic address: m.thomas@keele.ac.uk.
authors.forename: M J
authors.initials: MJ
authors.lastname: Thomas
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute for Primary Care and Health Sciences, Keele University, Keele, Staffordshire, ST5 5BG, United Kingdom. Electronic address: m.holden@keele.ac.uk.
authors.forename: M A
authors.initials: MA
authors.lastname: Holden
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D005081:Exercise Therapy / Q000009:adverse effects; D006801:Humans; D007719:Knee Joint; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D010146:Pain / Q000503:physiopathology; D011859:Radiography
keywords: Exercise; Knee pain; Osteoarthritis; Physical activity; Safety; Systematic review