Anthropometric measurements of the Japanese knee joint using magnetic resonance imaging. Correlation to the sizing of total knee prostheses

Anthropometric measurement in the title was performed to compare the obtained data with components in total knee anthroplasty (TKA) systems routinely used in authors' hospital. Occipitofrontal and transverse diameters of femur (FL and FW, respectively) and tibia (TL and TW) at the knee joint were measured in MR images of 503 joints which had been obtained for diagnoses of meniscus and ligament injuries in 15-87 years old patients (M 200/F 303). MRI machines were Toshiba 0.5 T Mrt. 50A and Flex Art to get T2-weighted images. The components in TKA systems were in software's of KU4 (Japan Med. Mat. Corp.), Scorpio (Stryker), PFCΣ (Depuy) and Nexgen (Zimmer). Positive correlations were found between FL and FW and between TL and TW with rather great fluctuations. FL/FW ratio vs FW and TL/TW vs TW were negatively correlated, and the lager the FW was, the flatter the predicted surface for osteotomy, which was also true in tibia in a smaller extent. FL/FW was found to be often unfitted to the commercially available TKA component size and the system to select the most suitable component for both femur and tibia was awaited for development. (R.T.)