Subjective Outcomes after Knee Arthroplasty

Abstract: Outcome questionnaires are increasingly being established as a validated mode of acquiring unbiased information on the results after health interventions. Using an assortment of questionnaires, distributed by mail to 27 372 and to a subgroup of 3 600 patients on file in the Swedish Knee Arthroplasty register (SKAR), relevant questionnaires were found to represent a feasable means of acquiring information regarding these elderly patients in a cross-sectional design. In the process, one of the questionnaires, the Oxford-12-item score, was translated and validated into Swedish. On balance, using parameters like patient burden, feasability, content validity and reliability, the SF-12 and the Oxford-12 ranked as the most appropriate general and disease specific questionnaire, respectively, in the context of the SKAR . Even a global single-item questionnaire, however, can yield usable information. Over-all response rates were generally high, in the order of 90%, higher for the shorter questionnaires. Satisfaction was primarily linked to the absence of pain. All questionnaires, both general health as well as knee specific ones, were found to be highly susceptible to bias by patient co-morbidity. Hence, even the single question of ”how does your knee feel”, proved influenced by, say, heart aches. For some questionnaires, the scores were biased by more than 100%. Preoperative WOMAC scores were shown to be predictive of the postoperative outcome.