328 



DISEASES OF THE ORGANS OF LOCOMOTION 



it is well to have a skiagraph (X-ray) made of the affected part (Fig. 103). 

 Where there is an external wound which becomes rapidly closed 

 by the blood and the purulent agents cannot penetrate between the 

 fractured ends of the bone, we have a form of fracture that is not so 

 difficult to treat; but if any septic materials should have penetrated 

 into the wound and found their way between the ends of the bones, 

 the condition is generally indicated in the following manner: There is a 

 marked inflammatory sweUing in the neighborhood of the wound. At 

 first the discharge from the wound is blood-colored, then rapidly becomes 

 pus-like, and finally purulent in character. If the discharge becomes 

 ol)structed in any way, we quickly notice a purulent, oedematous swelling 

 all around the part, which is always a very grave symptom. If the 



course is favorable, the injured part becomes 

 rapidly filled with red, granulating tissue, 

 which finally dries, becomes hard, and forms 

 a scab. By means of strict antiseptic treat- 

 ment this is possible, and we can reduce 

 the danger and time of an open fracture by 

 strictly following the usual antiseptic forms 

 of treatment. In the dog, however, this is 

 always rather difficult to accomplish, as the 

 animals are hard to confine, moving about 

 constantly and pullirtg or tearing the band- 

 ages. 



The Phenomena of Union in Fractures. 

 — The healing and union of the fractured 

 ends of a bone are very similar to those of 

 wounds, either by first intention (primum 

 intentionem) or by second intention (secun- 

 dum intentionem) . In simple fractures we 

 generally get union by first intention, and in compound fractures, unless 

 the union be extremely small, we get union by second intention (Fig. 

 104). In both cases the union is accomplished by means of a callus 

 growing around the ends of the bone — that is to say, a soft cellular 

 tissue which forms an envelope surrounding the bone and gradually 

 becoming hard through the ossific action of the periosteum and the 

 marrow of the bones. The ring-shaped or external callus surrounds the 

 fractured parts. This cellular tissue is formed of osteoblasts. The 

 inner callus is formed by the marrow, forming a peculiar plug-shaped 

 body and filling up the open ends. The periosteum is the true factor 

 in making union between l)roken ends of bones. This is especially noticed 

 in fractures where the periosteum is exposed, and where that envelope 

 is torn or injured, union is almost twice as long as where the peri- 



FiG. 104. — Diagram of union of frac- 

 ture in the tibia of the dog: a, outer 

 callus; b, periosteum; c, inner callus: d, 

 inflammatory deposit. 



