496 



Pott 'j Fracture 



be jealously protected in excision of the knee. The tibial epiphyses 

 rarely become detached either by disease or injury. 



The fibula also has three centres, the shaft beginning 

 to ossify soon after the tibia. The lower epiphysis begins 

 to ossify in the second year, as in the tibia. The upper 

 epiphysis begins to ossify in the fourth year, and joins at 

 manhood, as in the tibia. But the lower epiphysis, which 

 was the first to ossify, joins a little earlier. This is the 

 exception to the rule, that the epiphysis which ossifies 

 first joins last. The head of the fibula lies far back beneath 

 the outer tuberosity of the tibia, and is on a level with the 

 tubercle of that bone. Tailors often develop a bursa over 

 the external malleolus. 



Fracture From direct violence, as when a wheel 

 passes over them, the two bones may be broken at the 

 same level ; but when the fracture is the result of indirect 

 violence, as in a fall, they are likely to break in their 

 weakest parts, the tibia in its lower third, the fibula 



near its neck. 



Pott's fracture re- 

 sults from a sudden twist 

 of the foot, the internal 

 malleolus or the lateral 

 ligament giving way, and 

 the fibula breaking a few 

 inches above the ankle- 

 joint. The condition was 

 first described by Pott, 

 from whose * Chirurgical 

 Works ' the adjoining 

 wood-cuts are adapted. 



With a violent twist of 

 the foot the lower end of 

 the fibula becomes a lever 

 of the first order : the ful- 

 crum being at the lower 

 tibio-fibular joint, the 

 power the outward thrust 

 against the external 

 malleolus, and the resist- 

 ance telling just where 

 the bone yields. This 

 spot is not the weakest 

 part of the entire bone, 



for that is in the upper third, and can hardly be influenced by a twibt 

 at the ankle. 





