title: The value of preoperative grade of radiographic and histological changes in predicting pain relief after total knee arthroplasty for osteoarthritis.
abstract: OBJECTIVE
  Many attempts with contradictory results have been made to correlate different features of OA with pain. One reason may be that pain at rest and pain with movement are seldom considered separately although the mechanisms may be quite different. Furthermore, pain ratings are subject to individual interpretation making an inter-individual comparison questionable. By instead calculating the absolute and relative changes in pain on an intra-individual level after total knee arthroplasty (TKA), we aimed at exploring a relationship between pain and radiological and histological changes.
  
  
  METHODS
  In 69 patients undergoing TKA, preoperative radiographs and perioperative histological samples of the synovial membrane were graded for severity of osteoarthritic and inflammatory changes. The findings were related to the intensity of pain at rest and with movement both preoperatively and 18 months postoperatively according to the visual analogue scale (VAS).
  
  
  RESULTS
  The radiographic and histological findings showed no significant correlation with the mean pre- or postoperative pain scores. Instead, change in pain with movement from pre- to postoperative was significantly related to the grade of radiographic osteoarthritis. Best pain relief by TKA was achieved in patients with severe radiographic changes. This, however, only applied to pain with movement.
  
  
  CONCLUSIONS
  Pain at rest and pain with movement may have different mechanisms. We believe that assessing the intensity of pain at rest and pain with movement separately and considering changes in pain on an individual level will be helpful strategies in future follow-up studies and efforts aimed at explaining the mechanisms of pain in OA.
authors.affiliation: Department of Molecular Medicine and Surgery, Section of Orthopaedics, Karolinska Institutet at Karolinska University Hospital, Solna, 171 76 Stockholm, Sweden. henrik.lundblad@karolinska.se
authors.forename: Henrik
authors.initials: H
authors.lastname: Lundblad
authors.forename: Andris
authors.initials: A
authors.lastname: Kreicbergs
authors.forename: Veli
authors.initials: V
authors.lastname: Söderlund
authors.forename: Ann-Kristin
authors.initials: AK
authors.lastname: Ulfgren
authors.forename: Carl-Olav
authors.initials: CO
authors.lastname: Stiller
authors.forename: Karl-Åke
authors.initials: KÅ
authors.lastname: Jansson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D011300:Preoperative Care; D011859:Radiography; D013583:Synovial Membrane / Q000473:pathology*