title: Predictors of outcomes of total knee replacement surgery.
abstract: OBJECTIVE
  To identify pre-operative predictors of patient-reported outcomes of primary total knee replacement (TKR) surgery.
  
  
  METHODS
  The Elective Orthopaedic Centre database is a large prospective cohort of 1991 patients receiving primary TKR in south-west London from 2005 to 2008. The primary outcome is the 6-month post-operative Oxford Knee Score (OKS). To classify whether patients had a clinically important outcome, we calculated a patient acceptable symptom state (PASS) for the 6-month OKS related to satisfaction with surgery. Potential predictor variables were pre-operative OKS, age, sex, BMI, deprivation, surgical side, diagnosis, operation type, American Society of Anesthesiologists grade and EQ5D anxiety/depression. Regression modelling was used to identify predictors of outcome.
  
  
  RESULTS
  The strongest determinants of outcome include pre-operative pain/function-those with less severe pre-operative disease obtain the best outcomes; diagnosis in relation to pain outcome-patients with RA did better than those with OA; deprivation-those living in poorer areas had worse outcomes; and anxiety/depression-worse pre-operative anxiety/depression led to worse pain. Differences were observed between predictors of pain and functional outcomes. Diagnosis of RA and anxiety/depression were associated with pain, whereas age and gender were specifically associated with function. BMI was not a clinically important predictor of outcome.
  
  
  CONCLUSIONS
  This study identified clinically important predictors of attained pain/function post-TKR. Predictors of pain were not necessarily the same as functional outcomes, which may be important in the context of a patient's expectations of surgery. Other predictive factors need to be identified to improve our ability to recognize patients at risk of poor TKR outcomes.
authors.affiliation: Oxford NIHR Musculoskeletal Biomedical Research Unit, University of Oxford, Headington, Oxford, UK. andrew.judge@ndorms.ox.ac.uk
authors.forename: Andy
authors.initials: A
authors.lastname: Judge
authors.forename: Nigel K
authors.initials: NK
authors.lastname: Arden
authors.forename: Cyrus
authors.initials: C
authors.lastname: Cooper
authors.forename: M
authors.initials: M
authors.lastname: Kassim Javaid
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Carr
authors.forename: Richard E
authors.initials: RE
authors.lastname: Field
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dieppe
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000534:rehabilitation / Q000601:surgery*; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000534:rehabilitation / Q000601:surgery*; D010146:Pain / Q000534:rehabilitation / Q000601:surgery; D017060:Patient Satisfaction; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011788:Quality of Life; D016896:Treatment Outcome