Background: Until now, the activity of the lower limb could only be exactly measured with expensive electronic pedometers. The aim of this study was to develop a feasible questionnaire to measure the activity of patients after arthroplasty.
Methods: The "Daily Activity Questionnaire" (DAQ) was developed in several steps and the evaluation was carried out in three groups of patients with osteoarthritis of the hip (160 patients and 855 investigated days). The psychometric characteristics were verified.
Results: The retest reliability (ICC) of the DAQ is in a range comparable to the electronic pedometer StepWatch. The testing of the criterion validity showed high correlations between the StepWatch and the DAQ (r=0.743).
Conclusion: Because of its high correlations to the load changes actually performed, the DAQ is especially suited to answer arthroplasty-related questions. In all patient groups, projected load changes between 1.8 and 2.4 million per year were found, which by far exceed the generally accepted test standards for endoprostheses.