Pure flat-foot without eversion in the ankle joint (pes planus) arises as an anatomical variation, as a family or race peculiarity, but seldom gives rise to weight pains. And by investigations in armies we have found of late years that recruits with flatter feet, i.e., lower arches, can on the whole march longer and more seldom get weight pains than those who have high arches.

Without going more into detail here concerning the symptoms of these pains and their diagnosis, we may give only those which are common to all, however various they may be. They always arise when the foot is weighted and disappear during rest. The aching and tenderness felt on palpation are always met with on the medial and plantar aspects of the foot. And the frequency of these cases is such that, without exaggeration, one may say 80 per cent. of all patients who seek advice on account of foot trouble suffer from weight pains. Finally, it may be said that these cases ought by no means to be scorned or neglected by the doctor, as often happens; the trouble must, on the contrary, be looked upon as serious, and in those cases in which suitable treatment does not have the desired effect may compel the patient to change his occupation, which is no trifling matter.

As regards medical gymnastics and massage in the treatment of these patients, it has often been said that this form of treatment forms the sovereign remedy for such cases of flat-foot. This, however, is only true in a modified sense. They both, without doubt, play a great part, but a little thought will at once show to any one who understands the nature of the disease that such treatment must nevertheless in a large number of cases be quite insufficient.

The mechano-therapeutic treatment of this disease consists partly of gymnastic exercise of certain muscles, partly of massage applied locally to the tender parts of the foot. This last is especially beneficial when, as often happens, by continual strain of the capsular ligaments on the internal and plantar side they become irritated and cause oedema, infiltrations, and effusion.

From the standpoint of treatment of the cause massage is less important than gymnastics. The most prominent deformity lies in an exaggerated valgus position of the foot, i.e., a position of eversion, and this faulty and unfavourable condition of the bones of the foot causes weakness, and so the trouble arises. We must try by gymnastics to exercise the muscles of inversion to the greatest possible extent. And it is evident that the increased power of the muscles of inversion will be able, at least for a time, to counteract the deformity and to prevent the increase of the symptoms. Yet this is often done without the help of gymnastics; for in many cases it may be found that Tibialis Anticus, the chief muscle of inversion, is considerably hypertrophied. A muscle cannot be exercised beyond a certain point; sooner or later it reaches the limit of its functional power. When the unfavourable mechanical conditions increase and put more and more strain on the muscles of inversion, at last there comes a time when the muscles are forced to give way and the deformity increases. Contrasting with the strength of the muscles of inversion in the early stages, in the later stages when the deformity has reached the severe form of pes valgo-planus these muscles arc seen to be somewhat atrophied. The deformity has thus reached that stage when other mechanical conditions, especially the fact that the inner border of the foot touches the ground, prevent further development of the deformity and the muscles are of no further service.

In the vast majority of cases of weight deformity, which are only temporarily relieved by massage and gymnastic treatment, and return as soon as treatment is left off, the orthopaedist must, as in other similar conditions, avail himself of external mechanical means to increase the power of the weakened muscles by inversion.

It is important to keep the foot in the normal position, or slightly inverted, while it is in use, i.e., while the weight of the body is resting on it. Without further discussing the means which are resorted to in order to correct the position of the foot, it may here be mentioned that these all simply aim at placing the foot on an inclined plane, with its inner border raised. The foot is thus brought when weighted into an inverted position. We often find, moreover, that the patient has resorted to this method by instinct; also that in walking, the patient with one-sided flat-foot, or with one foot worse than the other, tries to avail himself of any slope of the ground, e.g., the edge of the pavement which suits him best, in order that the painful foot may have its inner border higher than the outer. Frequently we find by examining the patient's shoes that the outer side of the heel is well worn away, showing that the patient in walking has tried to prevent, by means of inversion, the ligaments and capsule on the inner side from being stretched and thereby causing pain. In orthopaedics this inversion is produced by means of specially-built shoes with slanting heels (the inner side of course higher), or by means of a movable flat-foot arch of various materials and shapes. It is also clear that the physician must direct his attention to the various conditions which may have caused this deformity, such as rickets, anaemia, etc. Treatment of the cause, which is the most effective, is to give up standing and walking as much as possible, and in most cases is equivalent to changing the occupation, which the patient will not do unless it is absolutely necessary.

There is not much that can be said here of the gymnastic technique in this case. The only exercise that can be beneficial is inversion; and this can be done mechanically by apparatus with resistance or manually with resistance. There are two excellent machines suitable for this purpose constructed by Krukenberg and Zander (notice especially Zander's excellent machine B : 13). The patient is also able to do a very effective inversion alone. Heel-raising, toe marching, and running with parallel or inward rotated feet, are all excellent exercises for the muscles of inversion, especially Tibialis Posticus and the muscles of the calf, which are of great importance in inversion when the foot is plantar flexed. The medical gymnast must of necessity himself find out exercises in this as in other cases which attain the desired end, and therefore he must be thoroughly acquainted with his work. Should the gymnast fail to do this, the result of his treatment will be of little value. We frequently find flat-foot treated exclusively by energetic local massage on the tender spots, the least important and least effective part of the treatment.