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 to become completely fractured. They are, however, subject to what is known as green stick fracture.
Impacted fractures are usually occasioned by falls. When the weight of the body is suddenly caught by a member in such manner as to forcefully drive the epiphyseal portions of bone into and against the diaphysis, multiple longitudinal fractures occur at the point of least resistance. Parts so affected undergo a fibrillary separation, increasing the transverse diameter of the bone; or if the impact has been sufficiently violent, the portion becomes an amorphous mass.
In a treatise on the subject of lameness, the bones chiefly concerned and most often affected must be especially considered. The shape and size of a bone when injured, determines in a measure, the course and probable outcome in most cases, but of first and greater importance is the function of the bone. A fracture of the fibula in the horse need not incapacitate the subject, but a tibial fracture is serious and generally proves cause for fatal termination. The body of the scapula may be completely fractured and recovery will probably result in most cases without much attention being given to the subject, yet a fracture of the neck of this same bone constitutes an injury of serious consequence. The difference in the function of different parts of this same bone, as well as its shape and mode of attachment, determine the gravity of the case; so it is in fractures of other bones with respect to the course and prognosis of the case—function is the important factor to be considered.