Ischemic Marrow Disease in Mandibular Condyles Removed for Severe Osteoarthritis

Introduction

Chronic Ischemic medullary disease (CIMD) is now known to occur in 50-80% of femoral heads with osteoarthritis. It occurs, moreover, so frequently before cartilage damage that some have suggested that poor medullary blood flow may be a major cause of desiccation of overlying hard tissues.

Methods & Materials

A convenience sample of 7 condylar heads surgically removed because of severe, painful osteoarthritis, were histopathologically assessed for features of ischemic disease in the marrow immediately beneath the damaged hard tissues. Changes looked for were the same as those found in affected hips and bone marrow edema: 1) ischemic myelofibrosis; 2) dilated medullary capillaries; 3) oil cysts (large bubbles of liquefied fat) or fatty microvesicles, as evidence of past fat necrosis; 4) osteocavitations; 5) ischemic marrow atrophy (denuded trabeculae); 6) intramedullary fibrous scar tissue; 7) stagnant immature bone; 8) osteosclerosis; 9) reticular fatty degeneration; 10) focal osteoporosis; 11) plasmostasis (serous ooze); 12) mast cell presence.

Results

Of 7 temporomandibular joints examined, 6 showed evidence of CIMD: one severe, 4 moderately severe and 1 mildly damaged. Three joints showed CIMD consistent with a diagnosis of bone marrow edema, while 5 showed marrow voids or cavitations; 3 showed areas of focal osteoporosis; all showed either oil cysts or fatty microvesicles. Five affected condyles showed focal fibrosis, and none demonstrated osteosclerosis. Very few lymphocytes were seen, but small numbers of mast cells were found in areas of wispy fibrosis. Four of the specimens showed multiple, usually small areas of ischemic damage, separated by normal marrow. Surface cartilage was fissured, broken or missing in all condyles, while underlying bone was only focally nonviable (focal areas of empty lacunae).

Conclusion

As with femoral heads, condylar heads affected by osteoarthritis show ischemic medullary damage beneath the damaged cartilage/bone (6 of 7 condylar heads).