Design of Human and Implanted Knee Model using Anthropometric Data for Total Knee Replacement

Abstract

The objective of this study is to estimate the mismatch error between the human knee and implanted knee for total knee replacement with the help of data analysis considering the anthropometric and implant data for the Indian population. Anthropometric data collected for 150 cases from the hospital was contrasted with the typical implant data from the Johnson & Johnson Company and Zimmer. In the data collected for 150 cases, 91 were female patients and 59 were male patients. The maximum cases were for osteoarthritis and rheumatoid arthritis. For each patient—male and female—the mismatch error was computed separately. Major focus of the study was laid on the femoral condyle. Zimmer implant mismatch errors were computed as follows: -1.18 for A/P and 4.95 for M/L in patients who were male; -5.6 for A/P and -3.3 for M/L in patients who were female and male. -3.4 for A/P and -0.4 for M/L in female patients; 1.85 for A/P and 8.18 for M/L in male patients was the mismatch error computed for Johnson & Johnson implants. The total discrepancy in implant results was 1.83 for men and -4.4 for women for Zimmer, and 5.01 for men and -1.89 for women for Johnson & Johnson. A mismatch of -19 (for females), -15 (for men) was identified for Zimmer, and -11 (for females), -7 (for males) was found for Johnson & Johnson. The femoral condyle was the cause of several inaccuracies. On the basis of results from data analysis it was found that female patients were more into pray of high mismatch errors. Also, femoral condyle mismatch was majorly responsible for the improper fitting of implants error. So, a 3-D model was developed using Slicr3r to justify that the gap between the implant and implanted knee must not exceed 2mm for femoral condyle in order to get the best fit. A patent on Asymmetric Prosthetic Tibial Component is available to explain a similar concept.