144 WILSON— OSTEITIS DEFORMANS. [April 5, 



dorsal and lumbar spine. In consequence of this change in the 

 spinal column the head is carried forward and lower than normal, 

 and the height of the patient is reduced — a reduction much in- 

 creased by the curvature of the bones of the lower extremities and 

 amounting in some of the cases to six or seven inches. 



The clavicles are prominent and thickened, the chest short and 

 narrow, the abdomen short and broad and the pelvis wide and low. 



Associated with these changes are marked deformities of the long 

 bones of the extremities. The humerus is thickened and enlarged ; 

 its surface is irregular, and the shaft is markedly curved, the con- 

 cavity presenting toward the flexor surface. The ulna and radius 

 show similar deformities and are strongly bent and twisted. The 

 bones of the lower extremities are deformed and bent in a like 

 manner. The femur, tibia and fibula are bent outward and forward. 



In fully developed cases the patients bear a curious resemblance 

 to each other. The diminution in stature causes the arms to appear 

 disproportionately long — like those of the anthropoid apes. 



The disease usually makes its appearance in middle life and is 

 mostly unattended by subjective symptoms, although in some cases 

 rheumatoid pains have been present at the outset. It has no con- 

 stant relation to any particular visceral or nervous pathological 

 process, nor to malignant disease as was at one time thought. I 

 have called attention to the high grade of muscular atrophy present 

 in well developed cases. 



Paget, whose name has been given to the disease and whose 

 original description remains the best that has thus far appeared, 

 regarded the changes in the bones as inflammatory, and Butlin's 

 account of the histological changes lends support to this opinion. 



The process consists of a progressive absorption of bone tissue 

 which becomes porous and rarified ; the coincident formation of 

 new bone, which remains for a time uncalcified so that abnormal 

 curvatures develop, and finally dense calcification of the subperiosteal 

 layers of the overgrown and deformed bones. The marrow under- 

 goes fibrous changes. The pathological changes have been espe- 

 cially studied by Butlin, von Recklinghausen, Stilling and Packard 

 Steele and Kirkbride. 



The etiology of the disease is involved in complete obscurity. 

 To state that it is due to trophic derangements is a mere general 

 restatement of the facts. 



Tiie hypertrophic changes in the bones of an extremity, which 



