Preoperative psychological distress and functional outcome after knee replacement

Background: Fifteen to thirty percent of patients report no or little functional improvement 12 months after total knee replacement (TKR). Self-reported psychological distress prior to knee replacement is common and there is some evidence that it may be an important determinant of poor functional outcome in the short to medium term. The aim of this study was to review systematically the literature on the relationship between preoperative psychological distress and post-operative functional outcome after TKR. Methods: A literature search through the University of Melbourne Library Catalogue, Web of Science, SCOPUS - V.4, Medline, CINAHL PLUS, PsycINFO, Pubmed and the Cochrane Library was performed with the following key words and terms: joint replacement, arthroplasty, mental health, pre-operative distress, preoperative distress, psychological distress and knee. Additional screening of the reference lists was performed. All eligible publications were quality assessed by two independent reviewers according to the Newcastle-Ottawa Scale. Results: The search found 10 cohort studies. The results of the studies were conflicting as six studies found a correlation between preoperative distress and functional outcome, whereas four did not. Conclusion: The results from this review are conflicting. The use of different questionnaires to assess psychological distress and functional outcome makes it difficult to draw any conclusions. Future research should focus on using appropriate scales to measure exposure and outcome. We suggest using disease-specific questionnaires to assess preoperative psychological distress and a sensitive knee-specific outcome score to assess post-operative function.