8. Hence it follows, 1st, that, in a state of extension, the separation is the least possible, because it is then produced on the part of the superior fragment only; 2dly, that in a state of flexion it is greatest, because then both fragments concur alike in producing it; 3dly, that it may be increased or diminished by varying the degrees of flexion.
9. This fracture is further characterized by the following circumstances, namely, a practicability of moving the fragments transversely in opposite directions, and of producing, by that means, some degree of crepitation, provided they be first brought close together; by the pain which accompanies these motions; by the swelling common to every kind of fracture of the rotula, and which, if very great, may involve the other signs in more or less uncertainty; by a difficulty of standing; and an almost entire loss of the power of walking, in consequence of the extensors being no longer able to communicate motion to the leg, unless when the fracture exists very low down, near to the inferior ligament.
10. The touch will always discover in what part of the bone the fracture is situated, which, if it be oblique, will partake more or less of the characters of the longitudinal or the transverse, accordingly as it approaches to the one or the other.
§ IV.
OF THE PROGNOSIS.
11. Many authors have pretended that fractures of the rotula cannot be cured, and it even appears that the Academy of Surgery adopted this opinion, on receiving a memoir from a Flemish physician, which contained several facts tending to establish that principle. But what do these facts prove? That in some particular cases, reunion did not take place, but they do not show that this was owing to the nature of the fracture.
12. But, what, in such cases, could prevent a cure from taking place? The structure of the rotula differs, say they, from that of the other bones. Now, admitting this difference of structure to be real, it certainly approaches to the structure of tendons to which indeed it bears a strong affinity. But, who does not know, that, when tendons are divided, they unite as readily as bones? Besides, is not the power of reunion common to every part endowed with life? I have already shown, when treating of other fractures that communicate with joints, what credit is due to those hypotheses so often revived but never confirmed, nay even clearly proved to be unfounded, such as, an effusion of callus into the joint, a failure of reunion from a want of periosteum on the posterior part of the bone, the synovia diluting the matter of callus, and thus preventing it from being duly prepared, &c.
13. The inflammation of the articulating surfaces and of the ligaments around the joint, ought to have more influence in constituting an unfavourable prognosis, than any circumstance that authors have mentioned. But experience proves, that, when judiciously treated, these fractures are not accompanied by that accident, and even that the swelling, which for the most part attends them, always yields more or less speedily, when a bandage, uniformly applied, presses equally on all parts around the joint, and thus forms a kind of discutient, while at the same time it retains the fragments.
14. Pare, Fabricius of Hilden, and a number of other writers, have pretended, that some degree of lameness must always be the consequence of this fracture. But, from what causes must this lameness so certainly arise? Is it from a want of reunion in the part? I have already shown (11 and 12) that this apprehension is wholly unfounded. Is it from an anchylosis? This accident cannot take place, except either in consequence of inflammation occurring in the articulating surfaces, (and I have already shown how that may be avoided, 13) or of a stiffness in the ligaments, and I shall hereafter make it appear that that may be readily prevented by motion. Is it from the fragments being drawn asunder, and in that state united by an intermediate substance of too great an extent? I shall prove, that a bandage properly constructed, is always sufficient to keep these fragments in contact.
From these considerations it appears, that writers have, in general, without sufficient cause, given an unfavourable prognosis, in relation to fractures of the rotula, which have, indeed, a great affinity to other affections of the same kind.