Patella tracking calculation from patellofemoral positions at finite angles of knee flexion.

Patellofemoral (PF) pain is a common knee disease. Patella tracking has a significant correlation with PF pain, therefore it could be used as an index for diagnosis and treatment evaluation. Previous research has proposed a method for measuring in vivo patella tracking by means of an interpolation algorithm. The present study aimed to quantify the effect of the interpolation parameters on the accuracy of the patella tracking with a motion capture experiment. The precise patella tracking of 5 knee specimens was collected and compared with the interpolated tracking. The results showed that the total interpolation error decreased to 2 mm with the number of interpolation angles increasing to 6. The number of interpolation reference points had a slight influence on the accuracy. The findings consolidated the feasibility of using interpolation to measure the in vivo patella tracking, and can help to optimize the accuracy and efficiency of the methodology.