DEMOGRAPHIC BIASES OF SCORING INSTRUMENTS FOR THE RESULTS OF TOTAL KNEE ARTHROPLASTY

Four knee-scoring systems were used to evaluate 200 adult subjects who had no history of injury, abnormality, or treatment of the knees, hip s, lower extremities, or spine, All subjects were in the age-range (fi fty to 100 years; average, 65.5 years) typical of candidates for total knee replacement, In addition to a physical examination, complete dem ographic data were collected for each subject, The knee scores were no rmalized by dividing the observed score by the maximum possible score, The average normalized total knee score was 91 per cent (range, 22 to 100 per cent) according to the knee score of The Hospital for Special Surgery, 95 per cent (range, 10 to 100 per cent) according to the sys tem of Hungerford and Kenna, 89 per cent (range, -7.75 to 100 per cent ) according to a modification of the scoring system of The Knee Societ y, and 95 per cent (range, 26.5 to 100 per cent) according to the syst em of Hofmann et al, Demographic variables that had a significant nega tive correlation with the knee scores included advanced age (particula rly of eighty-five years or more), a family income below the poverty l evel, and two major medical conditions or more, Observed differences i n knee scores between different study groups that have not been matche d for various clinically relevant factors are at least as likely to re present differences in the patient populations as they are to represen t differences in the operative technique or the design of the implant.