A new patellofemoral scoring system for total knee arthroplasty

Patellofemoral complications after total knee arthroplasty (TKA) can result in substantial dissatisfaction with the procedure for some patients. In assessing outcomes of TKA, however, there is often a discrepancy between patellofemoral symptoms and the results obtained by conventional scoring and radiographic analysis. We asked whether a new scoring system and weightbearing radiographic view would more accurately represent patellofemoral kinematics and explain related complications. Sixty-nine patients (100 knees) who underwent posterior-stabilized TKA between 1994 and 1997 were included for clinical and radiographic evaluation. A new patella score was developed to rapidly determine complications, ranged from 0 to 100 points, and included ratings for subjective and objective aspects of TKA. A new weightbearing axial radiographic view was devised by positioning the standing patient in a semisquatted position. Measurements for patella alignment (tilt and subluxation) were performed. Preoperative Knee Society knee and function scores were 43 +/- 5 points, and 39 +/- 15 points, respectively. Postoperatively, scores increased to 93 +/- 8 and 89 +/- 8 points, respectively. The patella score averaged 89 +/- 8 points and showed satisfactory interobserver variability. The new weightbearing radiographic view demonstrated sources of patellofemoral symptoms. We report a new scoring system and weightbearing view that are easy to use and more accurately represent patellofemoral kinematics than do conventional methods of analysis.