title: Knee Extensor Strength and Risk of Structural, Symptomatic, and Functional Decline in Knee Osteoarthritis: A Systematic Review and Meta-Analysis.
abstract: To perform a systematic review and meta-analysis on the association between knee extensor strength and the risk of structural, symptomatic, or functional deterioration in individuals with or at risk of knee osteoarthritis (KOA).
  
  
  
  We systematically identified and methodologically appraised all longitudinal studies (≥1-year followup) reporting an association between knee extensor strength and structural (tibiofemoral, patellofemoral), symptomatic (self-reported, knee replacement), or functional (subjective, objective) decline in individuals with or at risk of radiographic or symptomatic KOA. Results were pooled for each of the above associations using meta-analysis, or if necessary, summarized according to a best-evidence synthesis.
  
  
  
  Fifteen studies were included, evaluating >8,000 participants (51% female), with a followup time between 1.5 and 8 years. Meta-analysis revealed that lower knee extensor strength was associated with an increased risk of symptomatic (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] pain: odds ratio [OR] 1.35, 95% confidence interval [95% CI] 1.10-1.67) and functional decline (WOMAC function: OR 1.38, 95% CI 1.00-1.89, and chair-stand task: OR 1.03, 95% CI 1.03-1.04), but not increased risk of radiographic tibiofemoral joint space narrowing (JSN) (OR 1.15, 95% CI 0.84-1.56). No trend in risk was observed for KOA status (present versus absent). Best-evidence synthesis showed inconclusive evidence for lower knee extensor strength being associated with increased risk of patellofemoral deterioration.
  
  
  
  Meta-analysis showed that lower knee extensor strength is associated with an increased risk of symptomatic and functional deterioration, but not tibiofemoral JSN. The risk of patellofemoral deterioration in the presence of knee extensor strength deficits is inconclusive.
authors: Institute of Anatomy, Paracelsus Medical University Salzburg & Nuremberg, Salzburg, Austria, and School of Allied Health, La Trobe University, Bundoora, Melbourne, Victoria, Australia.
authors: Adam G
authors: AG
authors: Culvenor
authors: Institute of Anatomy, Paracelsus Medical University Salzburg and Nuremberg, Salzburg, Austria.
authors: Anja
authors: A
authors: Ruhdorfer
authors: University of Southern Denmark, Odense, Denmark, and University Hospital of Copenhagen, Herlev and Gentofte, Denmark.
authors: Carsten
authors: C
authors: Juhl
authors: Institute of Anatomy, Paracelsus Medical University Salzburg and Nuremberg, Salzburg, Austria.
authors: Felix
authors: F
authors: Eckstein
authors: Oslo and Akershus University College of Applied Sciences, Oslo, Norway.
authors: Britt Elin
authors: BE
authors: Øiestad
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D011859:Radiography; D012307:Risk Factors