War Surgery and Medicine
The General Problem of the Function of the Foot
The General Problem of the Function of the Foot
It is very difficult to get a proper perspective to evaluate the foot as to its functions in locomotion. It is unfortunate that the physiological outlook has for so long been neglected and that the anatomical shape of the foot has come, in the minds of perhaps the majority of medical men, to be considered of supreme importance. This has led to a classification of foot disabilities under anatomical groups and a false idea of a normal foot has evolved. The position of the foot, in what we may call the mid-position between rest and activity, is treated as the ideal foot, and a relatively high longitudinal arch is considered ideal. If the arch is still more prominent, as it is in pes cavus, the appearance of the foot seems preferable to the pronated flat-looking foot, which is the normal position of rest. If the foot is very mobile, then during rest it will appear very flat, and under the anatomical classification will be a flat foot and disability will be expected. The foot is looked upon as a mechanical means of support and the bones and ligaments are looked upon as the structures that take the strain, and it is natural to expect them to function better if the shape of the foot appears to be mechanically better able to sustain the body weight. This outlook has vitiated the whole management of foot conditions.page 399
It would be of great value if, for a while, the anatomy of the foot were forgotten and the medical student had instead to study the foot in action in athletics, in walking, in standing, and at rest. Perhaps the foot of the ballet dancer is as efficient as any other, yet at rest it is very flat and pronated. The bare foot of the native races also appears to be a flattish foot. If one is observant one will have noticed many of our fellows with just such flat feet who are able to do the most strenuous work. Even rigid flat feet are no bar to strenuous and prolonged work. What it is essential to realise is that the foot is normally a very mobile and pliable structure with constant changes in position. There is a position of activity with the foot adducted, the longitudinal arch raised, the foot extended, the toes flexed, and the muscles of the leg and foot acting strongly. Then there is the position of rest with no muscular action the foot pronated or abducted, and the longitudinal arch flattened. Then there is the mid-position adopted during standing, when the muscles are acting less strongly and the bony ligamentous structures have to take part of the strain.
On muscular activity depends the functional efficiency of the foot. Pliability of the foot is essential to full function, and the real disabilities of the foot are associated with rigidity of the foot structures, especially when this is associated with any inflammatory condition. This is seen in the partially rigid foot due to inflammatory adhesions, which is often relieved by manipulation. The foot with bony rigidity, though awkward, generally gives rise to little trouble. Pes cavus in a marked degree is often a serious disability as regards marching.
When there is marked muscular weakness, often associated with general debility, and so often seen in adolescents, there will be undue strain put on the ligaments of the foot during activity, including standing, and this strain tends to exaggerate and sometimes fix the position of rest and later to bring about some generally slight anatomical changes such as hallux valgus. The causative factor has been the muscular weakness; the anatomical changes are secondary. On the other hand, with strongly developed muscles even a foot weak structurally will be able to act efficiently, always remembering that a freely mobile foot is not a weak foot.
A valuable demonstration of the essential difference between anatomical structure and physiological efficiency was given by an investigation carried out in the British Army to ascertain what number of men in a typical infantry brigade had anatomical deformities of the feet which were symptomless. A thorough examination of the feet of all the men was carried out and the following abnormalities observed: (i) abducted feet, (ii) pes cavus, (iii) deformity of the toes. Rigorous tests were then carried page 400 out, including 3-mile runs and 14- and 21-mile route marches. Some 24 per cent of the men had foot deformities, but the feet were supple and they were not foot conscious. There was relatively no more disability recorded in the men with deformities. These conclusions were reached: firstly, in an infantry brigade there were men with anatomical deformities of the feet who were performing normal duties; therefore anatomical deformity of the foot alone was not a sufficient indication for down-grading. Secondly, approximately the same proportion of men with normal and abnormal feet reported sick with foot complaints. This investigation suggested that the deformed foot was no more liable to give rise to disablement than the normal foot.
This was valuable support to the idea that anatomical abnormalities, when unassociated with rigidity, are of no importance as regards the efficiency of the soldier.
The two factors of prime importance in the fitness of the soldier are graduated training and psychological normality.