182 CLINICAL FORMS OF SURGICAL TUBERCULOSIS. 



bones. Before the age of puberty it is safe to state that the primary 

 lesion in tubercular affections of joints is located in one or both of 

 the epiphyses of the bones which enter into the formation of the 

 joint, while in the adult primary tuberculosis of the syuovial mem- 

 brane is more frequently met with. As age advances and the pro- 

 cess of ossification is completed, the predisposing localizing causes 

 in bone seem to disappear, while the syuovial membrane becomes 

 more susceptible to primary localization. 



Of 204 specimens of tuberculous joints examined by Miiller and 

 quoted by Konig (Die Tubereulose der Knochen und G-elenke, Ber- 

 lin, 1884, p. 66), 158 were primary osteal and 46 primary synovial 

 tuberculosis. 



As soon as embolic infection in bone has taken place, a process 

 of decalcification occurs around the tubercular em bolus or thrombus, 

 and the preexisting connective tissue is transformed into embryonal 

 or granulation tissue which imparts to the product of the specific 

 inflammation its characteristic fungous appearance. It is not often 

 that only a single focus of tubercular infection in bone is present ; 

 more frequently, two or three foci appear at the same time or in 

 slow or rapid succession, and it is not unusual to find that two 

 neighboring epiphyses are infected at the same time, or during the 

 course of the disease. The granulation tissue in bone undergoes 

 the same secondary degenerative tissue-changes as in the lymphatic 

 glands, hence, in advanced cases we expect to meet with caseation, 

 liquefaction of the caseous material, and suppuration in cases of 

 secondary infection with pyogenic microbes. The obstruction of a 

 small artery by an embolus or thrombus which contains the bacilli 

 of tuberculosis usually leads to sequestration of a triangular piece of 

 bone which maps out the area of tissue which received its blood- 

 supply from the obstructed vessel; thus the triangular sequestra are 

 formed that are so frequently met with in osteal tuberculosis of the 

 epiphyseal extremities. It is seldom that tuberculosis of bone de- 

 velops in the course of pulmonary tuberculosis, but pulmonary and 

 miliary tuberculosis can often be traced to a tuberculous focus in a 

 bone. The intimate relations which exist between the tubercular 

 nodule in bone and the bloodvessels furnish a satisfactory explana- 

 tion of the frequency with which systemic infection takes place. As 

 soon as the granulation process reaches an adjacent vein, the tissues 

 of the vein-wall undergo the same process, and the bacilli reach the 

 lumen of the vessel and reenter the systemic circulation, and give 

 rise to miliary tuberculosis in organs which are anatomically pre- 

 disposed to localization. As long as the decalcification of the sur- 

 rounding bone goes on, the infection is progressive ; but as soon as 

 sclerosis takes place the process becomes limited, as the microorgan- 

 isms are shut in, as it were, by an impermeable wall of sclerosed 



