A Treatise on Fractures, Luxations, and Other Affections of the Bones

by P.-J. Desault

12. But, when a luxation has taken place, this apophysis, still remaining on a level with the two condyls, even although the fore-arm be half-bent, is oftentimes separated from the internal one, and driven towards the other: a preternatural protuberance announces this change of position of the olecranon. The coronoid apophysis, whose posterior surface glides in the large groove of the humerus, corresponds to this groove now only with its anterior surface: sometimes the olecranon cavity[21] receives its extremity. The radius passes backward over the small head of the humerus. At the fold of the arm, a transverse protuberance, more perceptible on the internal side, announces the presence of the displaced articular extremity of the os humeri. Over this extremity are reflected the biceps and the brachialis muscles in a state of violent distension. These muscles, greatly irritated by such distension, continue in a state of habitual contraction, in consequence of which, they keep the fore-arm half-bent. Nor can the anconeus muscle, which is necessarily relaxed, act so as to prevent this semiflection. Severe pains would be the consequence of attempts to extend the fore-arm; the limb is in a state of pronation; yet I find among the cases collected by Desault, several examples where supination existed; this state is explained by the relaxed condition of the pronator muscles. At the level of or opposite to the coronoid cavity is a depression or hollow manifesting the absence of the apophysis of that name.

13. Should chance give rise to a luxation forward, an anterior projection of the two bones of the forearm, and above all, of the coronoid eminence, a depression corresponding to the olecranon cavity, the extremity of the humerus carried backward and downward, the rigid extension of the fore-arm, a protuberance behind formed by the fractured olecranon (5), and severe pains, necessarily resulting from attempts to bend the limb, &c. would constitute the principal characteristic signs of the displacement.

14. In lateral luxations, a protuberance at the internal or external side of the articulation, always shows of what kind it is. If the displacement be to the internal side, the olecranon is then situated behind the small tuberosity: the middle protuberance of the os humeri bears on the radius, which is sometimes placed even behind the internal articular eminence of that bone, which then rests on the external depression of the great sigmoid cavity. Hence, as Petit judiciously observes, arises the direction of the fore-arm outward, the above eminence presenting a manifest obliquity in that direction. In this luxation, the ulna has been known to lose entirely its connexion with the humerus, and the radius to be brought into contact with the internal condyl of that bone. This is what some authors call a complete luxation. Others reserve that name for cases where, the two articular ranges have lost their correspondence or apposition entirely.

15. In a luxation outwards, the olecranon corresponds to the external condyl; the middle projection of the humerus, to the internal depression of the great sigmoid cavity; the small head of this bone, to the external depression; the radius projects outwards; and the humerus makes a protuberance inwardly.

16. After all, these changes of situation vary remarkably, and it belongs to theory rather than practice, to trace their history, with precision. In general, luxations outwardly happen more frequently than those inwardly, a circumstance which is fully explained by the structure of the joint. In both, the lateral ligaments are almost always lacerated.

A swelling more or less considerable accompanies all the different kinds of luxation, and is sometimes carried so far as to involve the diagnosis in great uncertainty, particularly when the displacement is not very great. This phenomenon (the swelling), seems, in general, to correspond, in a direct ratio, to the force with which the articulation resists. Indeed the violence, and consequently the irritation, are always in proportion to the resistance of the parts.

§ IV.

OF THE REDUCTION.

17. The means of reduction vary according to the different kinds of displacement. They are all, however, founded on nearly the same principles, and it will be easy to form proper ideas of them, when we shall have given an account of the means necessary to be employed in luxations backward, of which the others are only modifications.