Asymptomatic population reference values for three knee patient-reported outcomes measures: evaluation of an electronic data collection system and implications for future international, multi-centre cohort studies.

The aim was to assess whether the Knee Society Score, Oxford Knee Score (OKS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were comparable in asymptomatic, healthy, individuals of different age, gender and ethnicity, across two remote continents. The purpose of this study was to establish normal population values for these scores using an electronic data collection system.