Lameness of the Horse | Page 5

to a lack

of mineral substance in the bony structure of the affected animals, and
is known as rachitis--commonly called rickets. Since the affected
subjects suffer involvement of several of the extremities at the same
time, the theory of rachitic origin seems well supported.
Fractures.
Fractures of bones constitute serious conditions and are always
manifested by lameness. A sub-classification is essential here for the
student of veterinary medicine who would comprehend the technic of
reduction and subsequent treatment in such cases.
Fractures are classified by many authorities as being simple, compound,
and comminuted. This method is practical because it separates
dissimilar conditions. There are also grouped fractures, the pathologic
anatomy of which is similar. Classification on an etiological basis
would attempt to associate conditions, the morbid anatomy and gravity
of which would justly preclude their being combined.
Simple Fracture is a condition where the continuity of the bone has
been broken without serious destruction of the soft structures adjacent,
and where no opening has been made to the surface of the flesh. Such
fractures do not reduce the bone to fragments. Long bones are
frequently subjected to simple fracture, while short thick bones, such as
the second phalanx, may suffer multiple or comminuted fractures.
Compound Fracture designates a break of bone with the destruction of
the soft tissues covering it, making an open wound to the surface of the
skin. This form of fracture is serious because of the attendant danger of
infection, and in treatment, necessitates special precaution being taken
in the application of splints that the wound may be cared for without
infection of the tissues. These fractures generally occur as a result of
some forceful impact through the flesh to the bone, or where the bones
are driven outward by the blow. Common examples are in fractures of
the metacarpus and metatarsus of the first phalanx. This kind of injury
in mature horses usually produces an irreparable condition, and viewed
economically, is generally considered fatal.

Comminuted Fractures, as the term implies, are those cases wherein the
bone is reduced to a number of small pieces. This kind of break may be
classified as simple-comminuted fracture when the skin is unbroken,
and when the bone is exposed as a result of the injury, it is known as a
compound-comminuted fracture. Such fractures are caused by violent
contusion or where the member is caught between two objects and
crushed.
Multiple Fractures.
Fractures are called multiple when the bone is reduced to a number of
pieces of large size. This condition differs from a comminuted fracture
in that the multiple fracture may break the bone into several pieces
without the pieces being ground or crushed, and the affected bone may
still retain its normal shape.
Further classification is of value in describing fractures of bone with
respect to the manner in which the bone is broken--the direction of the
fissure or fissures in relation to its long axis.
A fracture is transverse when the bone is broken at a right angle from
its long axis. Such breaks when simple, are the least trouble to care for
because there is little likelihood that the broken ends of bone will
become so displaced that they will not remain in apposition. Simple
transverse fracture of the metacarpus, for instance, constitutes a
favorable case for treatment if other conditions are favorable.
Oblique fractures, as may be surmised, are solutions of continuity of
bone in such manner that the fissure crosses the long axis of a bone at
an acute or obtuse angle. These fractures are prone to injure the soft
structures adjacent, and are frequently compound, as well. Moreover,
because of the fact that the apposing pieces of bone are beveled, the
broken ends of bone are likely to pass one another in such a way as to
shorten the distance between the extremities of the injured member.
Contraction of muscles also tends to exert traction upon a bone so
fractured, resulting in a lateral approximation of the diaphysis and thus
preventing union because the broken surfaces are not in proper contact.

Fractures are longitudinal when the fissure is parallel with the long axis
of the bone. This variety of break is not infrequent in the first phalanx;
and a vertical fracture of the second phalanx is also said to be
longitudinal, however, there is little difference (if any, in some subjects)
between the vertical and transverse diameters of this particular bone.
Green stick fractures are essentially those resulting from falls to young
animals. They are usually sub-periosteal and when the periosteum is
left intact or nearly so, no crepitation is discernible. If this fracture is
simple, prompt recovery may be expected. Bones of young animals,
because they do not contain proportionately as much mineral substance
as do bones of adults, are more resilient and less apt