Volume 1

The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd.

Date:
1836-59
Catalogue details

Licence: Public Domain Mark

Credit: The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd. Source: Wellcome Collection.

    173/832 (page 159)
    malleolus iiiternus is Iraciured, and in general, \ve suppose, with the obliquity fVoin above downwards, and within outwards, above de- scribed. The deltoid ligament remains un- broken, the capsular membrane is torn in front, the fibula has been found obliquely fractured, as well as the tibia, or the three ligaments which connect it to the tarsus have given way; none of the tendons suffer, and luEmorrhage to any extent in these cases seldom or never occurs, as the large arteries generally escape injury. Lvxuliun of the tibia and fibula J'oi'ivards, and also luxation of these bones backwards from the articular pulley of the astragalus, without fracture.—In the simple and complete luxa- tion of the bones of the leg forwards at the ankle-joint, (without fracture,) the articular pulley of the astragalus is placed behind the inferior extremity of the tibia, which last rests partly on the superior surface of the neck of the astragalus, and partly on the os naviculare. In the simple and complete luxation of the tibia backwards, (without fracture,) the inferior extremity of the tibia is placed behind the arti- cular pulley of the astragalus, and corresponds to the posterior part of the superior surface of the os calcis. In both these luxations, the na- tural connexion with each other of the bones of the leg remains undisturbed, and the two mal- leoli advance or recede together, according to the direction in which the displacement has occurred. In both, the capsular membrane and the posterior and lateral ligaments must be ex- tensively lacerated, and most of the flexor and extensor tendons, in some degree, put upon the stretch. The luxation of the bones of the leg forwards cannot take place, but in a forced and sudden extension of the leg on the foot, when the latter being retained by some obstacle, and solidly supported, we fall backwards. The luxation of the tibia backwards, on the contrary, cannot happen unless when the foot is strongly flexed, the toes being elevated and retained in this position, we fall forwards. Authors have seldom failed to notice these simple luxations forward^ and backwards of the bones of the leg, yet for our part, no mat- ter to what source we apply for information, we cannot satisfy our minds that we can adduce a single well-marked example of luxation of the bones of the leg at the ankle-joint, unac- companied bij a fracture of one or both (f the malleoli; we would not, however, be under- stood to deny the possibility of such an occur- rence, but merely to state our conviction that such an accident must be exceedingly rare. V\ e have now to consider luxations of the tibia from the astragalus, forwards and back- wards, when complicated with a simple frac- ture of the fibula or tibia close to the articula- tion : these may be complete or partial. Complete luxation of the tibia forwai'ds from the articular part of the astragalus compli- cated with a simple fracture of the fibula.— This accident may arise from the same causes nearly as those which may be supposed to influence the more simple luxalion in the same direction; and as we know that when the fibula is fractured near its malleolus, the pe- ronsei muscles may under certain circumstances effect a lu.xation of the tibia inwards, so that displacement which we are now considering may be the result of the action of the gastro- cnemius and solaeus. These acting on the foot, which in consequence of the fracture is no longer fixed by the malleolus exteriuis, cause the astragalus to slip from before backwards, and the lower end of the tibia forwards, and move the lower fragment of the fibula in such a manner that its malleolar extremity is carried backwards, and the upper part forwards. This action of these muscles, however, only pro- duces a very incomplete dislocation whenever the internal malleolus is uninjured, or the foot in this case being carried outwards and back- wards at the same time; but when, as often happens, either the internal malleolus or del- toid ligament is broken, this displacement may be as complete and direct as the simple dis- location forwards of the tibia. We then find the foot lengthened behind and shortened in front; a semicircular excavation occurs in the former direction, and an osseous tumour raises the tendons and ligaments on the front of the ankle, but it is to be particularly remarked that, whilst in the simplest form of luxation of the tibia, i. e. where there is no fracture, the external malleolus follows the tibia and fibula, and forms a projection corresponding to that of the internal, it is in this case dragged backwards with the foot to which it is attached by the lateral ligaments, and no longer has the same direction as the bones of the leg. In the dislocation forwards of the tibia (whether simple or complicated with a frac- ture of the fibula) from the astragalus, the articular pulley of this bone is placed behind the inferior articular cavity formed for it in tlie tibia; but this latter bone at the same time, it will be recollected, must now rest on the dor- sum of the tarsus, where it is formed by the upper part of the neck of the astragalus and os navi- culare. When the tibia has thus once advanced before the articular pulley of the astragalus, the luxation forwards is as complete as it well can be; in our opinion, to imagine any more com- plete luxation of the tibia forwards, we should be obliged to presume that this bone in its advance on the dorsum of the foot had com- pletely cleared the astragalus, and then rested “ on the os naviculare and os cuneforme in- ternumf* which last form part of the anterior • The weight that so justly attaches to any ob- servations from Sir A. Cooper, induced us to con- sider well the account he gives of the dissection of this complete luxation of the tibia forwards, in his work on Dislocations and Fractures; and we find that we cannot reconcile it with our ideas of the anatomy of the injury. We are sorry in this in- stance to be obliged to differ from an authority, to which we feel indebted for many observations copied into tliesc pages ; but we think there must be error in the following passage taken from the valuable work to which wo allude, page 178, 8th edition. “ On dissection, the tibia is found to rest upon the upper surface of the os naviculare and oscunci-