468 THE INFERIOR EXTREMITY 



Avulsion of the Tibial Tuberosity occurs in youth before 

 the completion of ossification (p. 452), and is usually due to 

 excessive muscular strain. Minor degrees of this accident cause 

 loosening and partial separation of the tuberosity. If untreated, 

 the condition may become chronic owing to repeated strains 

 and want of rest, and it then gives rise to lameness and to pain 

 and swelling locally (Schlatter's disease). 



Dislocation of the Knee-Joint is a somewhat rare injury. In the least 

 uncommon variety the tibia is displaced forwards and proximally in front 

 of the femoral condyles. The condition results from violent hyperextension 

 and the cruciate ligaments are torn, while the posterior ligament is either 

 ruptured or stripped up with the periosteum on the posterior aspect of the 

 tibia. 



Reduction of this variety is obtained by downward traction on the leg 

 and direct backward pressure on the proximal extremity of the tibia. If 

 this method is unsuccessful, hyperextension may be added to the previous 

 manipulations, but it may result in injuries to the large nerves in the popliteal 



In posterior dislocations, which result from direct violence applied either 

 to the front of the leg or to the back of the thigh, the proximal extremity 

 of the tibia occupies the popliteal fossa, and may injure or compress the 

 popliteal vessels. 



Ossification of the Head of the Fibula begins about the 

 third year and forms an epiphysis, which unites with the shaft 

 between the ages of twenty and twenty-four. Separation of 

 the proximal epiphysis and fractures of the head or neck of the 

 fibula are very rare injuries, but when they do occur they are 

 apt to involve the common peroneal (ext. popliteal) nerve 

 (p. 446). 



When tuberculous disease originates in the fibular diaphysis 

 near the epiphyseal cartilage, it does not commonly spread to 

 the proximal tibio-fibular joint, as the epiphyseal cartilage is 

 entirely extra-capsular (Fig. 132). On the other hand, if the 

 disease begins in the proximo-lateral part of the tibial diaphysis, 

 the joint may be infected, as its capsule receives partial attach- 

 ment to the tibial diaphysis. 



THE LEG. 



Surface Landmarks. The medial surface of the tibia is 

 for the most part covered only by the skin and superficial 

 fascia, and it can therefore be examined without difficulty. 

 On the other hand, the shaft of the fibula is clothed with muscles 



