Anatomic factors
A number of the papers reviewed examined anatomic factors that potentially could influence the risk of stress fracture. Three military studies evaluated foot morphology (arch height) and stress fracture risk. Among 287 Israeli Defense Force (IDF) trainees, persons with the highest foot arches sustained 3.9 times as many stress fractures as those with the lowest arches (pes planus or flat feet) (95 percent CI: 1.02, 15.38) (
129). A 25-week prospective study of 449 trainees at the US Naval Special Warfare Training Center classified trainees into three equal-sized groups with high, normal, or low arch height but found no significant differences between groups (
130). The results of the third study of naval special warfare trainees were inconclusive (
131). Available research suggests that foot arch height may influence the risk of incurring stress fractures associated with vigorous physical training, but more research will be needed to define the nature of the association between arch type and stress fracture risk, particularly for women.