Knee scores change with length of follow-up after total knee arthroplasty.

Patients undergoing primary total knee arthroplasty (TKA) between 1989 and 1994 were evaluated preoperatively and postoperatively with the Knee Society scoring system at 3 time intervals: 1 to 2 years, 3 to 6 years, and more than 7 years. Knee prosthesis and functional scores improved statistically after TKA. At last follow-up evaluation, a statistically significant decline was found in functional knee scores that was related to an increase in numbers of patients in category C. Progression of arthritis at other sites, especially lumbar spine and hips, and cardiopulmonary problems were the most common cause of limited functional capacity. Women were found to have lower preoperative and postoperative functional scores. Patient weight, body mass index (BMI), and age at surgery showed no correlation with postoperative functional scores. The inclusion of functional categories would appear to be warranted when reporting long-term results of TKA.