Experimental Studies of the Non-inflammatory Vascular Pannus 



65 



Series III: Fig. 3 illustrates the case of an animal (11) sacrificed 56 days after low 

 cervical osteotomy. The fracture had healed spontaneously with external tilting of 

 the head. In the metaphyseal marrow, which was poorly vascularized, a few enlarged 

 veins were visible. Hemopoietic 

 tissue was absent, and the internal 

 part of the cortex had become 

 spongy. The articular space was 

 greatly enlarged. The territory of 

 the artery of the ligamentum teres 

 formed a triangle of densified 

 bone, and the ligament and its 

 insertion in the socket were en- 

 larged. From it, as well as from 

 the articular capsule, fibrovascular 

 growths (vascular pannus) emer- 

 ged. This pannus war irregularly 

 developed and hyalinized over 2/3 

 of its course. The action of the 

 internal pannus upon the modifi- 

 cation of the external table of the 

 socket is especially visible at this 

 magnification. 



The internal extremity of the 

 coxo-femoral articulation was ob- 

 literated by a congested external 

 capsular pannus (Fig. 2 b) in front 

 of which the cartilage underwent 

 a lysis and was split longitudinally 

 into two sheets of equal thickness. 

 The marrow was markedly con- 

 gested and showed fibro-vascular sprouts eroding the terminal plate and reaching the 

 cartilage (internal pannus). 



Fig. 4 (rabbit 5) shows the effect of the operation after 28 days. A well limited 

 medullary territory showed congestion, plasmostasis, and reticular hyperplasia as 

 well as absence of hematopoiesis. An avascular layer of cuboidal cells covered the 

 cartilage of the femoral head; the latter showed zones of chondrocytic activation and 

 chondrolysis which, in 2 foci, had formed cysts. Serial sections showed these cysts to 

 have no topographical relation to the articular surface or to the blood vessels. 



The results of Series I, II, and III show that a local reduction of circulation 

 modifies the different tissues of an articulation. The consequent stasis is accompanied 

 by a fibro-vascular expansion originating in the synovial membrane and in the 

 vascularized ligaments of the knee (Series I: Fig. 1 a, 1 b) and of the hip (Series III: 

 Fig. 2 b); also a medullary pannus arises in the marrow. These external and internal 

 pannuses constitute the elements responsible for the modification of the osteo- 

 cartilaginous plate of the articulation. Certain modifications of the cartilage cannot 

 be accounted for by direct contact with the pannus; this suggests that the action of 

 the latter is perhaps mediated by the dift'usion of some humoral factor. 



3'''' Europ. Symp. on Cal. Tissues 



