The findings of the Canadian Army Foot Survey lead to the conclusion that a short first metatarsal seldom, if ever, is the cause of foot disability. Soldiers undergo the strenuous activity of military training with no disability from short metatarsals, and react in no way differently from those who have long first metatarsals.
See table in the PDF file
See image in the PDF file
On the other hand, callus under the heads of the central metatarsals occurs in 0.97 per cent. of young men, and is the cause of appreciable disability. It is not specifically related to short first metatarsals, in the vast majority of which this evidence of local excess of pressure is not displayed. Also, it occurs almost as frequently in feet in which the first metatarsal is longer than the second. It probably is due to sharp concentration of pressure under a metatarsal head prominent for reasons entirely different from shortness of the first metatarsal.
Measurable shortness of the first metatarsal relative to the second does not necessarily mean that it cannot as readily reach the ground and that less weight will be transmitted through this bone. The obliquity of the metatarsals in relation to the ground means that all can share equally in weight-bearing, provided the longer metatarsals are on a higher plane than the shorter. This normally will be the case if the metatarsal arch exists. It is then possible for the second and third metatarsals to extend farther forward than the first before reaching the ground, because they are at the apex of the metatarsal arch (Figs. 7-A and 7-B).
In any case, the efficient use of the foot to support the weight of the body and to propel it in walking and running is hot entirely dependent upon perfection of structure, even though this is of importance. In feet which are not perfect in their structure, compensatory mechanisms of considerable efficiency develop, which tend to offset the ill effects that might arise as the result of deviation from standard structure. In the case of the first metatarsal segment, the flexor hallucis longus, as has already been indicated, can provide the necessary supplement to function. After all, foot function is dynamic as well as static.