The accuracy of assessing total hip arthroplasty outcomes - A prospective correlation study of walking ability and 2 validated measurement devices

The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) an d the SF-36 are used to assess subjective outcome after total hip arthropla sty (THA). Although these indices have been validated, neither the WOMAC no r the SF-36 has been tested for accuracy against objective data in this cli nical setting. Thirty osteoarthritic patients undergoing elective primary T HA were subjectively evaluated preoperatively and 1 year postoperatively wi th the WOMAC and the SF-36 and objective evaluated at the same interval wit h basic stride analysis and the 6-minute walk test. Correlation analysis of the subjective and objective data (both perioperative improvement and post operative absolute scores) yielded Pearson coefficients of r = 0.50-0.81. T his work demonstrates a sound statistical relationship between walking abil ity and the functional aspects of the WOMAC and the SF-36, supporting the u se of these instruments in assessing the functional outcome after THA.