Objective: Approximately 20% of patients experience chronic pain after total knee replacement (TKR), yet there is no consensus about how best to assess such pain. This systematic review aimed to identify measures used to characterise chronic pain after TKR.
Methods: MEDLINE, Embase, PsycINFO, Cochrane Library and CINAHL databases were searched for research articles published in all languages from January 2002- November 2011. Articles were eligible for inclusion if they assessed knee pain at a minimum of 3-months after TKR, yielding a total of 1,164 articles. Data extracted included study design, country, timings of assessments, and outcome measures containing pain items. Outcome measures were compared with domains recommended by IMMPACT for inclusion in assessment of chronic pain related outcomes within clinical trials. Temporal trends were also explored.
Results: The review found use of a wide variety of composite and single-item measures, with the American Knee Society Score most common. Many measures used in published studies do not capture the multi-dimensional nature of pain recommended by IMMPACT; of those commonly used, the WOMAC and Oxford Knee Score are most comprehensive. Geographical trends were evident, with nation-specific preferences for particular measures. A recent reduction in use of some clinically-administered tools was accompanied by increased use of patient-reported outcome measures.
Conclusion: There was wide variation in methods of pain assessment alongside nation-specific preferences and changing temporal trends in pain assessment after TKR. Standardisation and improvements in assessment is needed to enhance the quality of research and facilitate the establishment of a core outcome set
