title: The association between radiographic severity and pre-operative function in patients undergoing primary knee replacement for osteoarthritis.
abstract: OBJECTIVE
  To determine the association between radiographic osteoarthritis (OA) and pre-operative function in patients undergoing primary knee replacement.
  
  
  METHODS
  Single centre study examining pre-operative outcomes in a consecutive series of 525 patients who underwent primary knee replacement for OA between January 2006 and December 2007. Pre-operative data included: demographics, American Society of Anaesthesiologists (ASA) status and OA in the contralateral knee. The International Knee Society (IKS) rating and Short Form-12 (SF-12) were recorded for each patient. Pre-operative radiographs were read by a single observer for Kellgren and Lawrence (K&L) grading and Osteoarthritis Research Society International (OARSI) atlas features. Multiple linear regression was used to assess the strength of associations between radiographic OA severity and function, adjusting for clinically relevant variables.
  
  
  RESULTS
  Lateral tibiofemoral osteophyte grade was an independent predictor of pre-operative function as determined by the functional sub-scale of the IKS in patients undergoing primary knee replacement (coefficient=2.58, p=0.033). No associations were evident between pre-operative function and modified K&L, joint space narrowing, Ahlbäck attrition and coronal plane deformity. Other statistically significant predictors of poorer pre-operative function included: advancing age, female gender, knee pain and poorer SF-12 mental component summary scores which including osteophyte grade accounted for 24.6% of the variation in functional scores, (r=0.496).
  
  
  CONCLUSIONS
  Osteophytes in the lateral compartment of the knee were associated with pre-operative function in patients with advanced knee OA. Further studies are required which examine individual radiographic features specifically in patients with advanced knee OA to determine their relationship to pre-operative pain and function.
authors.affiliation: Department of Orthopaedics and The University of Melbourne Department of Surgery, St. Vincent's Hospital Melbourne, Australia.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Dowsey
authors.forename: Paul
authors.initials: P
authors.lastname: Dieppe
authors.forename: Stefan
authors.initials: S
authors.lastname: Lohmander
authors.forename: David
authors.initials: D
authors.lastname: Castle
authors.forename: Danny
authors.initials: D
authors.lastname: Liew
authors.forename: Peter F M
authors.initials: PF
authors.lastname: Choong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D011237:Predictive Value of Tests; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012307:Risk Factors; D012720:Severity of Illness Index; D016896:Treatment Outcome