Rheumatoid erosive arthropathy as seen in 

 macerated (dry) bone specimens 



James C.C. Leisen, Howard Duncan, and J.M. Riddle 



By definition, the process of erosion 

 means a gradual wearing away of a sub- 

 stance. Medically, this term is fre- 

 quently used to describe a focal loss of 

 tissue such as occurs in the develop- 

 ment of an ulcer. Rheumatologists use 

 the term erosion more specifically to 

 denote a focal loss of articular cartilage 

 and/or bone. The affected area there- 

 fore appears radiolucent on x-ray films. 

 Radiographic erosions can be detected 

 in a number of rheumatic diseases in- 

 volving peripheral joints, and of these, 

 rheumatoid arthritis is the paradigm. 



Rheumatoid arthritis can be defined 

 clinically by a set of criteria (Ropes et 

 al. 1958:175), but none of these fea- 

 tures alone, including radiographic ero- 

 sions, is specific for this type of arthri- 

 tis. When summated, however, the 

 various clinical and laboratory findings 

 describe a cadre of patients who have a 

 chronic, nonbacterial, noncrystalline, 

 symmetrical polyarthritis in which 40 

 to 85% show bony erosions by exam- 

 ination of anteroposterior radiographs 

 of the hand (Mitchel and Fries 1982; 

 481). Pathologically, the erosion ap- 

 pears to be related to chronic infiamma- 

 tion and proliferation of the synovial 

 membrane, that is. the formation of 

 rheumatoid pannus. Contact of the pan- 

 nus with articular cartilage and/or bone 

 promotes a focal loss of underlying 

 tissue creating the erosion that is dem- 

 onstrated by radiologic examination of 

 the joint. 



Although some radiopathologic cor- 

 relations of the rheumatoid erosion in 



peripheral joints have been made (Res- 

 nick and Niwayama 1981:907), we are 

 unaware of any published studies on the 

 appearance of the rheumatoid erosion 

 in macerated (dry) bone. Such a study 

 might be useful to paleopathologists as 

 a frame of reference for interpreting 

 skeletal material. For this reason, we 

 have described the morphologic fea- 

 tures of the rheumatoid erosion as seen 

 in macerated (dry) bone of surgically 

 removed metacarpal heads and tibial 

 plateaus. In our series of over 1000 pa- 

 tients with rheumatoid arthritis seen in 

 the Rheumatology Clinic, approxi- 

 mately 50% have clinical involvement 

 of the second and/or third metacar- 

 pophalangeal joint and knee. 



Materials and methods 



Twenty-six second and third metacarpal 

 heads were obtained from the hands of 

 13 patients with classic rheumatoid ar- 

 thritis. Ten specimens from eight pa- 

 tients were selected for study because 

 they contained residual articular car- 

 tilage and adjacent pannus. Included in 

 this series were six women and two 

 men. Their mean age was 56 years 

 (range 29-72 years) and the average 

 duration of their disease was 7.9 years 

 (range 4-20 years). 



Tibial plateaus were collected from 

 the knees of seven other rheumatoid pa- 

 tients. This group included six women 

 and one man. Their mean age was 66 

 years (range 61-72 years). All of these 

 samples were available because it was 



necessary to remove the diseased joints 

 in order to introduce an artificial joint. 



Control samples, 28 second and third 

 metacarpal heads as well as 14 tibial 

 plateaus were obtained from seven 

 cadavers. The mean age of this group of 

 three women and four men was 71 

 years (range 41-83 years). Their 

 causes of death were acute myocardial 

 infarction (4), congestive heart failure 

 (2), and a cerebrovascular accident ( 1 ). 

 Tibial tables were also collected from 

 six patients who required an above-the- 

 knee amputation because of peripheral 

 vascular occlusive disease. This series 

 contained equal numbers of men and 

 women. Their mean age was 72 years 

 (range 64-85 years). 



The articular cartilage on all of the 

 joint surfaces was examined under the 

 dissecting microscope to detect car- 

 tilage fibrillation or the presence of 

 pannus. Radiographs of each metacar- 

 pal head and tibial plateau were also 

 taken to locate erosions and cysts. 



Subsequently, the specimens were 

 macerated using 5.25% sodium hypoc- 

 hlorite (Clorox) for approximately 24 

 hours to completely remove the soft 

 tissue. This step of the process was ver- 

 ified by examination with a dissecting 

 microscope. Following maceration, 

 each specimen was defatted in acetone, 

 air dried, mounted on aluminum stubs, 

 and sputter coated with a thin layer of 

 gold-palladium. This procedure not 

 only permitted study by scanning elec- 

 tron microscopy as previously de- 

 scribed (Leisen et al. 1988: 17) but also 



Zaftreh Pateopaihology Symp. 1988 



211 



