We now pass to the theory of Bordenave, Bichat, and Richerand, who make the union of fractures analogous to that of the soft parts by the second intention, or by means ofIgranu lation. Like other pathologists, they have supported their opinions by observation and experiment; and without entering into the minuter circumstances connected with this hy pothesis, it will be necessary to mention some very familiar facts that bear upon the case. In necrosis, the surface of the new or grow ing bone is eten seen covered with granu lations. In cases of amputation, when the bone protrudes after eight or ten days, the cut extremity is observed to be fungoid and granu lated. And in some cases of compound frac ture we can observe the process of granulation going forward, and actually see that it is thus the union is completed. It nevertheless ap pears very doubtful whether granulation has any part in the process of uniting a fracture, unless where a communication exists between the broken ends of the fragments and the ex ternal air. In a compound fracture, or in the case of a bone protruding from a stump, there will be granulations, often to a degree of excessive exuberance ; and in them there will be a deposit of osseous substance, because new structures always assume to a certain extent the nature of the parts from which they are produced ; but in a case of simple fracture; where there is no wound, no communication with the atmosphere, and not a single drop of purulent matter is formed, it is very doubt ful whether granulations could exist; at least their existence has never been demonstrated.
Amongst modern pathologists, Meckers* opi nion is entitled to very great respect, although we may not be disposed to accede implicitly to his views. He ranks among those who consider the process of consolidation in frac ture to be similar to that of original ossi fication, and states, that at first there is an effusion of a gelatinous substance which gra dually becomes firmer and more solid in con sistence, and is converted into cartilage, in the interior of which osseous nuclei appear that join to each other and to the broken ends of the bone, and also envelope any fragments that may have been detached. At the same time the spiculae or scales become rounded off in order that the surrounding parts may not suffer injury or irritation. It is not necessary to the perfection of this union that the ends of the fragments should be accurately in contact: it is sufficient if they lie against each other, and then the union occurs by the same means, and exactly on the principle of anchylosis takino- place between different bones. It must be unt'derstood that this ossific deposit is laid down both external to and within the bone ; that when union is complete, the bone is di vided into two cavities' internally ; and that, for a length of time afterwards or for ever, it may be known, by making a longitudinal section, whether a bone had ever been broken or not. Ile further states that the part sur
rounded and joined by ossified callus is stronger and firmer than any other, and to all appearance this observation is correct, but it is contrary to one of Mr. Ilowship's experiments, who saw the callus break down and crumble away in an attempt to calcine it, and therefore concluded that it was softer and more highly animalizect.
Hitherto we have noticed a number of the ories all of which, with the exception of that of 15uhamel, bear a strong similarity to each other, the principal points of difference being, 1. as to whether the soft gelatinous substance, which all agree in having seen, was the fibrine of the blood deprived of its colouring matter, or genuine coagulating lymph effused by in flamed vessels : 2. whether this in process of time was changed into real cartilage, or the osseous deposition took place into this lymph ,very much inspissated : and, 3. whether any thing like adhesion happened, or the conso lidation was perfected after the manner of union by- the second intention, namely, by granulation. We now proceed to take a view of a new theory bearing some resemblance to that of Duhamel, and supported by the autho rity of Dupuytren. He supposes that there are two distinct and different processes in the union of bone. First, that there is a callus formed like a brace or ferule round the frag ments externally, with a plug of the same material vvithin, the object of this provision being, to hold the ends of the fracture in ap position whilst the union that is to be per manent is going forward : thus we are to imagine a kind of natural splint placed around and within the fractured pieces in order to preserve them in situ. This preliminary pro cess commences almost immediately after the accident, and is completed in the space of from four to six weeks. Matters remain thus, while the ends of the bones are becoming per manently united, which they are in about eight months, during the latter period of which time the mass of new material is declining in size, and is eventually removed so as to leave the bone of its natural extent and figure. The formation of this first callus, which he calls 44 cal provisoire," is attributed to the perios teum and occasionally to all the surrounding structures, and in the centre of it he sup poses the fracture to remain for a considerable time un-united, the limb being, of course, weaker here, so that, in the event of the occur rence of a new fracture, this will be the spot in which it will give way. The second or per manent callus, which he calls " cal definitif," is the actual medium of union between the fragments, and remains like the cicatrix of a wound in the soft parts.