Allen's fossa—An attempt to dissolve the confusion of different nonmetric variants on the anterior femoral neck

Abstract

A comparison of different studies is only possible if the same guidelines are used. However, due to the rather imprecise description of the different nonmetric traits on the anterior femoral neck (i.e., Allen's fossa, femoral plaque, Poirier's facet), it is impossible to compare the results of different authors. This is especially the case for the variant called Allen's fossa or cervical fossa of Allen, which has severely been mistaken in a lot of previous studies. As a consequence, a clarified and more detailed definition of this variant is required what enables the comparison of the results of different investigators. This study gives a detailed overview on the variety of different terms, which are often used simultaneously. The aim of the study is to develop a clarified definition of the term Allen's fossa, including the description of any sex‐ or age‐related differences, based on morphological examinations of archaeological skeletal remains from Karacamirli (Azerbaijan), Unterigling (Germany), and Ur (Iraq). Allen's fossa is shown to be usually bilaterally present in individuals of all age classes, including infants and rather old individuals, without any signs of modifications with increasing age. In addition, the variant is present in both sexes with the same manifestation. These findings are in contrast to other studies, what is very likely the result of previously mistaken variants. The study provides a detailed definition of Allen's fossa and a clear distinction from other variants at the femoral neck. The presented guidelines will allow a better comparability between different investigators in further studies. Individual differences, including vascular deficits and pathological conditions, can cause a considerable amount of variations in the manifestation of Allen's fossa, which is most likely caused by grinding of the zona orbicularis on the femoral neck.