title: Ipsilateral lower extremity joint involvement increases the risk of poor pain and function outcomes after hip or knee arthroplasty.
abstract: BACKGROUND
  Poor pain and function outcomes are undesirable after an elective surgery such as total hip or knee arthroplasty (THA/TKA). Recent studies have indicated that the presence of contralateral joint influences outcomes of THA/TKA, however the impact of ipsilateral knee/hip involvement on THA/TKA outcomes has not been explored. The objective of this study was to assess the association of ipsilateral knee/hip joint involvement on short-term and medium-term pain and function outcomes after THA/TKA.
  
  
  METHODS
  In this retrospective study of prospectively collected data, we used the data from the Mayo Clinic Total Joint Registry to assess the association of ipsilateral knee or hip joint involvement with moderate to severe pain and moderate to severe activity limitation at 2-year and 5-year follow-up after primary and revision THA and TKA using multivariable-adjusted logistic regression analyses.
  
  
  RESULTS
  At 2 years, 3,823 primary THA, 4,701 primary TKA, 1,218 revision THA and 725 revision TKA procedures were studied. After adjusting for multiple covariates, ipsilateral knee pain was significantly associated with outcomes after primary THA (all P values <0.01): (1) moderate to severe pain: at 2 years, odds ratio (OR), 2.3 (95% confidence interval (CI) 1.5 to 3.6); at 5 years, OR 1.8 (95% CI 1.1 to 2.7); (2) moderate to severe activity limitation: at 2 years, OR 3.1 (95% CI 2.3 to 4.3); at 5 years, OR 3.6 (95% CI 2.6 to 5.0). Ipsilateral hip pain was significantly associated with outcomes after primary TKA (all P values <0.01): (1) moderate to severe pain: at 2 years, OR 3.3 (95% CI 2.3 to 4.7); at 5 years, OR 1.8 (95% CI 1.1 to 2.7); (2) moderate to severe activity limitation: at 2 years, OR 3.6 (95% CI 2.6 to 4.9); at 5 years, OR 2.2 (95% CI 1.6 to 3.2). Similar associations were noted for revision THA and TKA patients.
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the first study showing that the presence of ipsilateral joint involvement after THA or TKA is strongly associated with poor pain and function outcomes. A potential way to improve outcomes is to address ipsilateral lower extremity joint involvement.
authors.affiliation: Medicine Service and Center for Surgical Medical Acute care Research and Transitions (C-SMART), Birmingham VA Medical Center, Birmingham, AL, USA. Jasvinder.md@gmail.com
authors.forename: Jasvinder A
authors.initials: JA
authors.lastname: Singh
authors.forename: David G
authors.initials: DG
authors.lastname: Lewallen
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome