The significance of the supratrochlear aperture (STA) in elbow range of motion: an anatomical study

Assessment of the range of motion at a joint is among the methods employed by orthopedic surgeons and physiotherapists to determine courses of therapy and joint recovery. Females tend to have a greater range of motion at the elbow joint than males. In the present case–control study, the elbow extension angle was compared between males and females with and without the supratrochlear aperture. A total of 453 dry humeri and their corresponding ulnae were included in the study, and elbow extension angle was measured using a goniometer. The average extension angle in this sample was 173°, and it was significantly greater when the STA was present (\(\bar{X}\) = 175.4°) than when it was absent (\(\bar{X}\) = 171°). It was greater in females (\(\bar{X}\) = 174.5°) than in males (\(\bar{X}\) = 171.3°) irrespective of STA status, and was greater on the left in both sexes. Hyperextension characterized 13 % of the sample, whereas the majority (76 %) showed hypoextension and only a few (11 %) exhibited normal extension. Trochlear notch depth and olecranon–coronoid distance would found to be useful for predicting the presence of the supratrochlear aperture, while the transverse and vertical diameters of the supratrochlear aperture were found to be the most useful parameters when predicting the degree of extension. The functional benefits of hyperextension at the elbow joint are not fully understood. However, these results are important to orthopedic surgeons and physiotherapists as they permit a greater understanding of normal elbow range of motion in the South African population.