Correlation of Anthropometric Measurements of Proximal Tibia in Iranian Knees with Size of Current Tibial Implants.

Background: The results of clinical studies have reported that Asian knee anatomical aspects are smaller than those of the Caucasian population. The purpose of this study was to investigate the morphometry of the proximal tibia in the standard resected surface of total knee arthroplasty (TKA).

Methods: In this descriptive study, the anthropometric data of the proximal tibia were measured in 132 knees (80 males and 52 females) using magnetic resonance imaging in 2015. The collected data included anteroposterior (AP) length, mediolateral (ML) width, medial AP, lateral AP, and aspect ratio (ML/AP). The medial and lateral AP distance to bone center was calculated for symmetry analysis. The morphometric data were also compared with the same dimensions of four current tibial implants.

Results: The mean age of the subjects was 38.26±11.45 year (age range: 20-60 years). The mean AP length and mean ML width in the resected surface of the bone, as well as the mean aspect ratio (ML/AP) of tibial bone in all the subjects, were 46.53±4.05 mm, 73.36±6.86 mm, and 1.58±0.11, respectively. The mean values of medial and lateral AP distance up to bone center were 13.40±6.17 and 17.09±6.83 mm, respectively, indicating asymmetric proximal tibia in the study population.

Conclusion: The measurements of anatomic shapes and dimensions of the proximal tibia revealed that women have smaller dimensions than their male counterparts. Prostheses with smaller AP size tended to be undersized and larger AP size had a tendency towards overhang in the mediolateral dimension. The data and obtained results of this study can be used as guidance on designing tibial implant components suitable for TKA in the Iranian population.