Sex estimation from knee breadth dimensions in a Finnish population

Sex estimation is an important part of osteological analysis of skeletons and forensic identification process. Traditionally cranial and pelvic traits are utilized for accurate sex estimation. However, post-cranial measurements have also been proven to accurately estimate sex especially from robust bones such as the femur. In this study, we investigated the potential of knee breadth dimensions in sex estimation in a Finnish population. To conduct this study we utilized a study sample (n = 1654) belonging to the Northern Finland Birth Cohort 1966. All individuals were 46 years of age at the time of the examination. Three knee breadth dimensions were measured from subjects' knee posteroanterior radiographs: femoral biepicondylar breadth (FBEB), mediolateral breadth of the femoral condyles (FCML), and mediolateral breadth of the tibial plateau (TPML). Sex estimation was performed using logistic regression. The study clearly demonstrated that all three measurements were different between males and females. Sectioning points for individual knee breadth measurements were 82.9 mm for FBEB, 76.6 mm for FCML and 75.4 mm for TPML. The classification rates ranged from 90.9% to 93.6%. The less commonly used measurements of FCML and TPML showed higher accuracy than FBEB in sex estimation. Our study confirmed that knee breadths can be successfully utilized to improve sex estimation in cases where the skeleton is only partially preserved and other major components of sex estimation are absent. We can also provide new standards for sex estimation from the knee joint in a Finnish population.