It must appear curious to the reader that no positive conclusion should have been obtained on a point which has occasioned so much inquiry, and which apparently was so easy of determination. It is open to experiment ; obvious to the senses; and there are few sources of fallacy except such as might arise from previously adopted views of the expe rimentalist, and perhaps from different periods puring the progress of ossification being chosen for making the observations, and the same thing, of course, being seen under different circumstances. We think it might have been reasonably suspected from analogy, (and the experiments of Breschet and Villerme have confirmed the idea,) that nature, in the sim plicity of her operations, produced every where similar effects Irom similar causes, and that, in whatever manner the re-union of divided soft parts was accomplished, the same would hold good as to bone, only allowing a longer time in order to admit of the consolidation of the lymph by osseous deposition. And such is probably the fact. In an incredibly short space of time after the receipt of a fracture, the process of repair seems to be actively com menced : coagulating lymph is effiised in con siderable quantity, probably mixed with blood, as the coagulum is found to possess a more than ordinary firmness and consistence. At the end of the second day the tom edges of the periosteum are evidently thickened, pulpy, and vascular, easily receiving coloured in jections. At the end of the fourth day, we have seen the sharp edge of the fracture be ginninff to be rounded off. Where the surfaces of thefragments are broad and thick, it is easy to observe them coated with a deep layer of lymph,which adheres to them tenaciously from a very early period. If the fragments are in apposition, the torn extremities of the peri osteum are united by the intervention of this lymph, the membrane appears greatly thick ened also, and seems to afford a kind of pro tection to the fracture ; or, otherwise, an im mense and irregular mass of lymph is thrown out around both fragments, filling up all the space that has been occasioned by the dis placement of the bones and the laceration of the soft parts. In effecting this deposition, all the vessels of the part, those of the bone, periosteum, and adjacent structures seem to be equally engaged. In process of' time this lymph becomes organised, assumes a ligamen tous rather than a cartilaginous appearance, although, strictly speaking, the new structure possesses not the true characters of either, and finally is converted into bone by the simul taneous establishment of numerous but irre gular specks. of ossification. This process varies as to the time required for its com pletion according to a number of circum stances, such as the situation of the bone, the part of it broken, the apposition of the frag-, ments, rest, and many others that need not be enumerated here ; as well as the age and con stitution of the patient, which exert such marked influence on all cases, that it is im possible to lay down certain rules for calcu lating the time that may be required for the union of any given fracture.
The process of re-union, however, is some times very imperfectly performed ; sometimes it is suspended indefinitely, and occasionally it is not performed at all. Of the causes that occasion these deviations from the natural and usual progress of ossific union we are in ge neral ignorant, although there are many cases in which former experience may enable us to predict the occurrence of such an event. It has been already stated that the diseases which occasion a fragility of bone will be likely to interfere with its subsequent union, and in these cases little more is accomplished than the removal of the sharp spiculated edges by ab sorption : the presence of such a constitutional derangement as would occasion a bone to give way in the effort to turn in bed will be suf ficient to explain its want of re-union. But
these are not the cases generally met with. When there is an un-united fracture, or as it has been termed, a false joint, the ends of the fragments are not smooth and polished moving on each other like articulated surfaces, but are joined together by the intervention of a liga mento-cartilaginous substance, which, accord ing to its extent, is more or less flexible, and of course incapacitates the bone from the per formance of its functions of support and rno tion. This imperfect union occurs in some bones with wonderful regularity; we may, for instance, calculate on such an event in frac tures of the neck of the thigh, and in the trans verse fracture of the olecranon and patella ; but it happens at other times quite unexpect edly, in cases wherein we could suspect no possible cause, in which there may have been no neglect, no impropriety of treatment, to lead to such a result. We have lately seen two cases of fractured femur remain un-united at the end of five and six months in the per sons of fine and apparently healthy young men, although the ends of the bones were kept in apposition, and in every other respect the treatment was correct.
The chief causes* to which this imperfect union has been attributed are a removal, or rather a withdrawing of the broken surface of one fragment from the other, a want of vascu larity in one of the fragments, and the fracture not being maintained in a state of uninter rupted repose.
The frequency of this occurrence in fractures of the above-mentioned bones, in which the fragments are always withdrawn from each other, was too remarkable not to lead, to the connexion of the circumstances as cause and effect, the only objection being that the' result is not uniform and universal. Fractures have been submitted to each of the above con ditions, more especially to the maintenance of exact co-aptation for months, yet has no ossific union been produced ; and again a firm consolidation has taken place between two bones, the extremities of which had been sawed off and the parts placed under circum stances that could not permit of the approxima tion of the divided surfaces. We have a case published as having occurred in the hospital of La Charite in Paris, in which the os calcis was broken ; and although the surfaces of the fragments were never completely separated, yet the usual kind of ligamentous connexion took place ; and for proof that a solid union may occur under the circumstances above stated, we refer our readers to Mr. Crampton's second case of extirpation of the knee-joint.1' If we can subscribe to Larrey's opinion that only the vessels of the bone itself can minister to osseous union, and that those of the peri osteum and adjacent structures are incom petent to such function, (an opinion in which he is to a certain extent supported by Air. Liston,t) it is obvious that a union between fragments at a distance from each other would be difficult if not impossible. Here, however, as well as in every other part of the history of ossific union, it is only conjecture. We have nothing like substantial definite proof, and must only rest satisfied with a knowledge of the fact without being able to explain it, that the medium of union between fragments, the faces of which are withdrawn from each other, is in general not osseous.