Morphometric measurement of the patella on 3D model reconstructed from CT scan images for the southern Chinese population

Background Due to racial differences in the morphology of the knee joint and due to most prostheses available in the market being designed using measurements from Caucasians, the objective of this study was to provide the morphometric data of the patella for the southern Chinese population for total knee arthroplasty (TKA), patellar resurfacing, and prostheses design. Methods The CT slices of the knee joint were obtained from both knees of 40 Chinese volunteers (20 females, 20 males, and age from 20-25 years) by performing a computer tomographic scan. A 3D model was reconstructed by Mimics software based on the computed tomography images. Six metrical characteristics were measured by digital ruler. Statistical analysis was performed with the SPSS statistical program. Results The mean, standard deviation and P values of measurements and ratios were calculated using SPSS. All dimensions showed a significant gender difference with P<0.05, but the six variables of the left and right knees had no statistical significance with P>0.05. In addition, we studied the relationship between six couples (H-W, H-T, H-HAF, W-T, W-HAF, T-HAF) of the four variables (H: height, W: width, T: thickness and HAF: height of articulating facet) that were measured, which showed a significant correlation. Conclusions Examination of the southern Chinese population revealed that males have larger patellae than women. In both genders, comparing data between left and right knees shows no statistically significant difference. Compared with Westerners in previous studies, the patella in our study was thin and small. There was a good linear regression correlation between measurements of the patella. The indirect measurement method on 3D models makes it easy to obtain anatomical data, and the results can provide a region and gender specific database for morphometric measurements of the patella, and can be helpful for designing implants suited for southern Chinese patients.