Anterior to this position the most serious mischief that can ordinarily result is stabbing of the os pedis.

Posterior to the position we have named, the only structure to be injured is the plantar cushion.

Anatomically, then, the inferior surface of the foot may be divided into three zones, as follows: 

A.  Anterior, extending from the toe to the point of the frog.

B.  Middle, extending from the point of the frog to the commencement of its median lacuna.

C.  Posterior, including everything posterior to the middle zone.

This division of the inferior surface of the foot into zones will be somewhat of a guide also when describing the complications next to follow: 

(a) Suppuration.—­This is the common complication of most wounds of the foot.  When detected, it calls for immediate surgical interference in the shape of removal of the horn of the sole or the frog, as the case may be.  This we shall consider further under the treatment.

(b) Separation of the Horny Frog.—­This is a sequel to pus formation in the sensitive structures immediately beneath it, and the condition makes itself apparent by a line of separation between the horn and the skin of the heel of the injured side.

(c) Wounding of the Plantar Aponeurosis.—­This occurs when a moderately-deep penetration of the horn of the middle zone has taken place.  It is always most painful, especially when complicated by necrosis.  The heel is then persistently elevated, and lameness is extreme, in some cases so severe as to cause the leg to be carried altogether.

In favourable cases the necrosed piece of tendon is sloughed off by the process of suppuration, and escapes with the discharges from the wound.  There is then an abatement in the symptoms, and recovery is rapid.

Commonly, however, on account of the non-vascularity of the structure of the tendon, the necrotic spot in it tends to spread.  The wound is thus led to become fistulous in character, and the pus forming within it prevented from escaping from the original opening.  As a result, lameness and fever persist.  There is a gradual increase in the severity of the symptoms, and later fistulous openings appear in the hollow of the heel.

(d) Puncture of the Navicular Bursa.—­This results from a prick in exactly the same position as that last described, and means that the penetrating object has gone deeper, It may be distinguished from puncture of the plantar aponeurosis alone by the fact that there is an excessive discharge of synovia from the wound.  This, as it escapes, is at first clear and straw-coloured.  Later it becomes cloudy and flaked with pus, and shows a tendency to coagulate in yellowish clots.

Pain and accompanying fever is most marked, much more so than when the plantar aponeurosis alone is injured.

Should the original wound be insufficiently enlarged, or should its opening become occluded by the solid matters of the discharge, then this condition, like the last, ends in the formation of fistulous openings in the heel.  These make their appearance as hot, painful, and fluctuating swellings in that position.  Later they break, discharge their contents, and leave a fistulous track behind.