REGION OF THE ANKLE. 



557 



3. The foot may be rotated out on its own anteroposterior horizontal axis (paral- 

 lel with the sole). 



4. It may be rotated in on its anteroposterior horizontal axis. Both these may 

 be accompanied by fractures. 



5. The foot may be rotated inward on a vertical axis longitudinally through 

 the leg. 



6. It may be rotated outward on a vertical axis. 



7. The foot may be luxated backward, the tibia coming forward on the 

 astragalus (Fig. 572). 



8. It may be luxated forward. 



9. The astragalus may be pushed up between the bones of the leg. 



In Numbers i and 2 inward and outward displacement the foot is not immedi- 

 ately beneath the leg, but is to one side of the leg. The outward luxation when 

 accompanied with laceration of the inferior tibiofibular ligaments or tearing off of a 

 small portion of the tibia and fracture of the 

 internal malleolus and fibula constitutes Dupuy- 

 tren's or Pott's fracture. In Numbers 3 and 4 

 the foot remains beneath the leg bones and is 

 not displaced much laterally. Numbers i and 3 

 are usually grouped together as outward luxa- 

 tions, and 2 and 4 as inward luxations. Num- 

 bers 5 and 6 are very rare. The foot is rotated 

 so that one side looks forward and the other 

 backward. 



Number 7 backward luxation is the most 

 common, with the exception of Number i. 

 When associated with Pott's fracture, backward 

 luxation is produced by hyperextension followed 

 by a thrust and is often compound. The leg is 

 bent backward until the anterior and lateral lig- 

 aments rupture, and then the thrust sends the 

 tibia forward on the instep. The articular sur- 

 face of the astragalus being wider in front op- 

 poses the luxation, and fracture of one or both 

 malleoli may result. 



Numbers 8 and 9 forward and upward lux- 

 ations are extremely rare, the former on account 

 of the difficulty in the application of the dislo- 

 cating force, the flexion and thrust, and the 

 latter on account of the extreme strength of the 

 inferior tibiofibular ligaments. 



Treatment. In attempting reduction of 

 these luxations the principal thing is to relax the tendo calcaneus (Achillis) by flexing 

 the knee. If this is not sufficient, tenotomy should be practiced. Simple extension 

 with slight rotation and manipulation will then accomplish reposition. 



FRACTURES OF THE ANKLE. 



Fractures of the ankle are usually the result of a force applied laterally, though 

 sometimes a turning of the foot on the vertical axis of the leg may assist. The force 

 applied causes fracture by inversion or eversion of the foot. 



Pott's Fracture or Fracture by Eversion. This is named after Sir Perci- 

 val Pott, Surgeon to St. Bartholomew's Hospital, London, who described the injury, 

 and was himself a victim of it. The French call it Dupuytren's fracture. It is pro- 

 duced by forcing the foot outward, or by having the foot firmly fixed and then 

 bending the limb outward, thus breaking it at the ankle. The fibula is broken 4 to 

 7.5 cm. (i/4 to 3 in. ) above its lower end and the ligamentum deltoideum (internal 

 lateral) is either ruptured or the internal malleolus is torn off. Rarely the outer 

 portion of the articular surface of the tibia may be torn off and displaced outward 



FIG. 572. Backward luxation of the foot at 

 the ankle-joint. 



