498 Pott's Fracture 



It is not always easy to recognise fracture in the upper two-thirds 

 of the fibula, for the bone is deeply shrouded by muscular attachments : 

 the soleus and flexor longus pollicus behind, the peroneus longus 

 and brevis on the outer side, and the extensors longus digitorum and 

 proprius hallucis in front. The unbroken tibia steadies the fragments 

 of the fibula, and prevents the surgeon obtaining crepitus. 



The lower third of the fibula is subcutaneous in the interval 

 between the peroneus longus and brevis, behind, and the tertius and 

 extensor longus digitorum in front ; a break in this part of the bone 

 is, as a rule, easily detected. 



THE ANKLE-JOINT 



The ankle-joint is formed by the lower end of the tibia, the two- 

 malleoli, and the astragalus. The fibular malleolus descends to a 

 lower level than the tibial, therefore the outer articular surface of the 

 astragalus is larger than the inner. 



The anterior and posterior ligaments are unimportant ; they 

 descend from the front and back of the lower end of the tibia to the 

 adjacent parts of the astragalus. 



The internal lateral ligament is deltoid, spreading from the end 

 of the malleolus to the scaphoid, the sustentaculum tali, and, behind, 

 to the astragalus (see operation for club-foot, p. 503). There is a deep 

 part of this ligament between the tip of the malleolus and the adjacent 

 part of the astragalus. This deltoid ligament is crossed by the tendons 

 of the tibialis posticus and the flexor longus digitorum. The external 

 lateral ligament sends an anterior and a posterior band to the 

 astragalus, and a vertical one to the os calcis ; this last is crossed by 

 the tendons of the peroneus longus and brevis. 



The synovial membrane of the ankle-joint lines the anterior, 

 posterior, and the lateral ligaments, and often sends up a slip into the 

 lower tibio-fibular joint. 



Supply. The vessels come from the anterior and posterior tibials, 

 the malleolar and the peroneals. The nerves are branches of the 

 internal saphenous and of the anterior and posterior tibials. 



Structures around ankle. Beginning in front and passing from 

 within outwards : the tibialis anticus, extensor proprius hallucis, 

 the anterior tibial artery between its companion veins ; the anterior 

 tibial nerve ; the extensor longus digitorum and the peroneus tertius. 

 The peroneus brevis and longus ; the flexor longus hallucis, the pos- 

 terior tibial nerve, and the artery with its companion veins ; the 

 flexor longus digitorum and the tibialis posticus. Behind all is the 

 tendo Achillis. 



When articular effusion occurs, the capsule bulges under the ten- 

 dons at the front of the ankle, obscuring their outline and obliterating 

 the furrows between them. There is also a fulness around the malleoli, 



