Human patellar articular proportions: recent and Pleistocene patterns.

The degrees of mediolateral asymmetry of the patellar articular facet, as well as the median and lateral articular angles of the facet, were compared across samples of recent humans and of Pleistocene archaic and modern fossil humans. All samples exhibit considerable variability in these patellar proportions. The articular angles are similar across the different samples, but there is a trend towards decreasing lateral angles with decreasing robusticity. The archaic humans exhibit significantly more symmetry of the medial and lateral facets than do any of the recent human samples. However, given the variability in medial versus lateral patellofemoral contact forces documented for extant humans and the roles of the distal oblique portions of vastus medialis and vastus lateralis in patellar stabilisation, it is unclear to what extent this variation in patellar articular proportions may affect knee kinesiology. The contrasts may be related to different levels of patellar stability and/or musculoskeletal hypertrophy, but they appear unlikely to have affected primary knee function.