Meeting Abstract
Subchondral and trabecular bone comprise the ends of long bones and underlie articular surfaces. These tissues provide for a combination of transmission of joint force to stronger cortical bone and some compliant absorption of loads. Both tissues are known to respond to different patterns of loading by increasing apparent density or aligning to trabecular orientation to the direction of applied loads, respectively. Our research program tests how experimentally induced differences in exercise and joint postures affect local stiffness and strength of subchondral and trabecular tissues and alter load transmission through the whole epiphysis. Fifteen lambs (x ̅=60d) were assigned to one of three groups: (i) incline treadmill exercise (15% grade), (ii) flat treadmill exercise, and (iii) non-exercise controls. The first step toward this goal involves characterizing the magnitude of postural and loading differences within and between treatment groups. Groups (i) and (ii) were exercised twice daily at 2.5m/s for 20 min/bout. Kinematic data were obtained using a Qualisys motion capture system and ground reaction forces were obtained for incline and flat locomotion for all individuals. All sheep were housed together in an indoor enclosure at the University of Illinois Sheep and Beef Cattle facility. Ground reaction forces did not differ significantly between incline and flat walking, and preliminary analysis of knee joint angles shows that the incline group used more flexed knee postures at midstance than exercise or control groups. These results will be used to explain local differences in structural characteristics of subchondral and trabecular structures and to test hypotheses about the functional characteristics of epiphyseal structure. Funded by NSF BCS-1638756; University of Illinois Research Board.
