TRABECULAR MICROSTRUCTURE IN THE MEDIAL CONDYLE OF THE PROXIMAL TIBIAOF PATIENTS WITH KNEE OSTEOARTHRITIS

The microstructural characteristics of osteoarthritic subchondral bone in the medial tibial condyle are clearly different from normal age-ma tched bone. Subchondral sclerosis in osteoarthritis indicates not only an increase in bone volume fraction but also alteration in other micr ostructural characteristics. Eleven medial tibial condyles were collec ted from ten subjects during arthroplastic surgery for knee osteoarthr itis. They were compared to four medial tibial condyles from four age- matched controls with no history of any bone or joint disorder. Six se ctions from anterior to posterior and three levels from proximal to di stal were evaluated in each medial condyle. Five histomorphometric par ameters were measured: bone volume fraction (BVf), trabecular thicknes s (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.S), and trabecular connectivity (Tb.C). In general, the osteoarthritic subcho ndral bone had a higher bone volume fraction than control bone but the microstructure was characterized by fewer, widely spaced, thicker tha n normal trabeculae. There were also highly localized regional differe nces by depth from the articular surface and from anterior to posterio r across the medial condyle. These variations in OA subchondral bone m icrostructure may significantly affect biomechanical competence of bon e in a way not predictable by bone volume fraction measurements alone.