100 CLINICAL APPLIED ANATOMY. 



abduction of the foot by slipping off from a higher on to a 

 lower level, and thus on to the inner side of the sole of 

 the foot. 



This movement throws strain upon the internal lateral ligament 

 of the ankle joint, and through it upon the internal malleolus to 

 which the apex of the deltoid ligament is attached. As a rule, 

 as has already been seen in the case of the patella, the bone 

 snaps before the ligament tears, and thus the internal malleolus 

 is dragged off. Immediately, the weight of the body is thrown 

 through the astragalus against the external malleolus. The 

 fibula, however, is held to the tibia by the strong inferior tibio- 

 fibular (interosseous) ligament, and therefore a strain is thrown 

 upon the lower part of the fibular shaft close above the ligament. 

 It is here that the fibula then breaks, and the upper end of the 

 lower fragment is tilted towards the tibia, simultaneously with a 

 marked deflection of the foot outwards, and the foot is also 

 usually carried somewhat backwards and the heel slightly raised 

 by the action of the calf muscles. 



Most commonly a dimple in the skin may be seen in the early 

 stages opposite the site of the fibular fracture, and a marked 

 stretching of the skin over the fractured internal malleolus, at 

 which latter spot the skin is likely to give way, and render the 

 fracture-dislocation an open one. 



In reducing the fracture, difficulty may be met with, firstly in 

 overcoming the outward displacement and eversion, probably 

 owing to interlocking of the fibular fragments preventing the 

 restoration of the astragalus to within the malleolar arch ; 

 secondly, in correcting the backward and upward displacement, 

 owing to the contraction of the muscles inserted in the tendo 

 Achillis. This pull may to a great extent be overcome by flexing 

 the leg upon the thigh and the thigh upon the abdomen, or 

 altogether by division of the tendon, or by placing the patient 

 under the influence of an anaesthetic. 



Dupuytren's fracture is present when, in addition to the con- 

 ditions found in Pott's fracture, the portion of the tibia to which 

 the lower tibio-fibular ligament is attached is dragged off, or 



