A reference to the latest textbooks will give but scanty information on these points; indeed, excepting sprains of joints, little mention is made of them.

A few years ago the definition of a sprain was 'a wrench or strain resulting in stretching or laceration of the soft parts, without external wound.' Academically this definition may still be regarded as sound, but for working purposes it has been conclusively shown by the x-rays that sprains commonly so called are in quite a large proportion of cases complicated by slight fractures, a very important point in relation to treatment. In fact, under the usual nomenclature a good percentage of sprains should be classified as fractures. The fracture, however, in these cases is of subordinate importance in a pathological sense, because the sprain of the soft parts is the predominating feature. A fracture can hardly occur without a sprain at the same time, but a sprain may of course, and frequently does, occur without a fracture. For my own convenience I am in the habit of classifying sprains as follows:

1. Simple sprains involving the soft parts only.

2. Sprains with fracture, by which I mean a sprain complicated by a fracture, the symptoms of which are so slight as to make it undiagnosable under ordinary circumstances, the symptoms of sprain being altogether predominant.

3. Sprains with gross nerve injury.

For clinical purposes this classification will be found not only reasonable but useful. Speaking generally, then, a sprain may be considered as a subcutaneous laceration; at the same time, it must be allowed that certain parts may be susceptible of stretching, without actual tearing, to a degree that will cause great pain. Hence, for working purposes, sprains may be divided into those associated with swelling and those followed by pain and stiffness only, the latter condition being formerly spoken of as 'strain.'

Immediate swelling means, of course, blood extravasation or the contraction of the proximal portion of extensively ruptured muscle; deferred swelling in the immediate region of the injury being due to inflammatory exudation into the soft parts in the continuity of a limb or about the trunk, or, in the case of a joint, synovial effusion.

In relation to the question of swelling, it must be borne in mind that the possibility of defining it is in direct proportion to its nearness to the surface of the part. A swelling from extravasation on the deep surface of the erector spinae would be quite intangible, whilst in the quadratus femoris it would be easily felt; moreover, it must be remembered that deferred or remote swelling in deep sprain may show itself a long way from the seat of the original injury, in consequence of its being caused by the blood tracking along the fascial planes in the line of least resistance. I have, for example, recently seen a large haematoma below the buttock show itself a week after a severe sprain of the erector spinae whilst fencing, and I have seen a large blood tumour appear in the popliteal space many days after a sprain of the upper part of the thigh.