154 



ABNORMAL CONDITION OF THE ANKLE-JOINT. 



the same. It is no less interesting than instruc- 

 tive to contrast these two articulations with 

 each other, for in doing so we find that the 

 modifications of structure here, as well as in 

 all other instances, are referable to the peculiar 

 function which each part is destined to perform. 

 The hand in the human subject is exclusively 

 an organ of prehension ; the foot is one merely 

 of support : now this simple fact at once fur- 

 nishes us with a clue to all difficulties. The 

 great strength and sudden expansion of the 

 tibia and fibula at the ankle, are evidently a 

 provision to sustain the weight of the body and 

 to increase the basis of its support; in the 

 radius and ulna such size and strength would 

 have been to no purpose, and hence these bones 

 at the wrist are comparatively thin and delicate. 

 At the ankle we should naturally have expected 

 frequent dislocations, owing to the great weight 

 from above, and to the great mobility which for 

 the purposes of progression must at the same 

 time necessarily exist here ; these are two most 

 formidable causes of displacement ; but, as if in 

 compensation, we find two strong buttresses (the 

 malleoli) projecting one upon either side of the 

 joint, and rendering such displacement, under 

 ordinary circumstances, almost impossible. At 

 the wrist, where there is no weight to be sup- 

 ported, such lateral splints would have been 

 superfluous : hence the imperfect and almost 

 rudimental malleoli of the radius and ulna; 

 hence the shallow and imperfect cavity ; 

 hence, in a word, the anatomical confor- 

 mation which constitutes the ankle-joint a 

 ginglymus, and the wrist an arthrodia. In 

 the motions of the ankle and wrist-joints we 

 observe likewise a striking difference: in the 

 former, lateral motion would have been super- 

 flous in reference to the function of the foot ; 

 at the wrist, on the contrary, a free lateral mo- 

 tion is indispensable to increase the sphere of 

 action of the hand. 



For the BIBLIOGRAPHY of this article, see that 

 of ARTICULATION. 



(John E. Brenan.) 



ANKLE-JOINT, ABNORMAL CONDI- 

 TION OF THE. The deviations from the na- 

 tural or normal condition of the ankle-joint may 

 be classed under those which are referable to 

 accident and to disease : any defects which 

 may be considered to result from congenital 

 malformation shall be elsewere treated of. 

 (See FOOT.) 



Accidents. The different structures which 

 immediately compose the ankle-joint, as well 

 as those which surround this articulation, and 

 are merely accessary to its functions, are, each 

 and all, liable to numerous accidents, the most 

 important of which we shall here advert to. 



These accidents may affect the tendons, the 

 ligaments, or the bones. 



Tendons. Those tendons which pass behind 

 the inner and outer malleoli are occasionally 

 displaced ; and, although the accident must be 

 considered a rare one, it ought not here be 

 overlooked. 



" The two peronaei extensor muscles," says 

 the late Mr. Wilson,* " where they pass behind 

 and below the fibula over a smooth lubricated 

 surface of that bone, are bound to it by a strong 

 ligament ; but should the ligament give way, 

 one or both of these tendons may escape from 

 the groove or pulley in which they usually play, 

 and being thrown forwards over the edge of 

 the bone, in this new situation their action on 

 the foot will be to bend it on the leg, when in 

 their natural position it was to extend it. The 

 peronsei having been habituated to act with the 

 extensor muscles, continue to contract at the 

 same time with them, but now they oppose 

 the effect which formerly in conjunction with 

 the extensor muscles they produced upon the 

 foot, and by so doing excite much pain and 

 irritation in addition to the lameness. When 

 this situation of the tendon is discovered early, 

 the tendon can be readily restored to its proper 

 place, but if this is not done, it forms a new 

 groove on the fore part of the bone, and the 

 old one is filled up, or otherwise so altered 

 that it cannot receive the tendon, and thus the 

 pain and lameness may continue for life. 

 I have seen this occurrence sometimes in the 

 living body early enough to return the tendon, 

 and have been consulted in cases where it 

 could not be returned ; in one, where the pain 

 was so violent that I recommended the divi- 

 sion and removal of part of the tendon ; the 

 muscle then contracted to its full extent, and 

 afterwards shrunk, and no inconvenience was 

 felt after the operation. I have met with two 

 or three instances of this kind of displacement 

 of tendons in bodies brought into the dissect- 

 ing-room ; but of the previous history of the 

 cases I could know nothing." Mr. Wilson 

 adds, " Those tendons which pass in grooves 

 behind the inner ankle are liable to a similar 

 displacement.'' Of the latter accident we have 

 known but one instance, but of the former 

 several. 



Ligaments. Accurate anatomical investi- 

 gations of the actual condition of the various 

 structures which compose the ankle-joint, 

 when affected by a sprain, have shown that 

 in slight cases of sprain of this joint no- 

 thing unnatural has been discovered, as the 

 bonds of union between the bones have been 

 merely stretched or strained. In others more 

 severe, the ligaments have been found broken 

 or torn from their attachment to the bones, 

 the synovial sac opened, and its fluid to have 

 escaped from the cavity of the joint ; the cel- 

 lular tissue around has been filled with extrava- 

 sated blood, and with synovial and serous fluids. 

 In these cases the nerves, bloodvessels, ten- 

 dons, even the skin itself, have been subjected 

 to a degree of stretching and extension, more 

 or less considerable. Baron Dupuytren, from nu- 

 merous observations on the living subject, from 

 post-mortem examinations, and experiments, is 

 of opinion that a slight accidental torsion of the 

 foot inwards or outwards, amounting to a 

 sprain, only produces an injury, in which 



* Wilson's Lectures on the Bones, &c. 



