1Department of Anthropology, Pennsylvania State University, 2Center for Quantitative X-Ray Imaging, EMS Energy Institute, Pennsylvania State University
March 27, 2015 , Archview Ballroom
The knee joint is characterized by functional asymmetry of the medial and lateral compartments. In humans, the medial compartment of the knee transmits higher loads than the lateral compartment, and functions as a static axis upon which the knee rotates through lateral condylar movement. This study quantifies density variation in the subchondral cortical bone together with the structure of underlying trabecular bone in the distal femur and proximal tibia in a diverse sample of modern humans. MicroCT scans were collected for paired femora and tibiae. Subchondral bone density patterns were visualized using false-color maps and three-dimensional trabecular bone structure was quantified. Subchondral density mapping revealed a consistent pattern of larger regions of high density in the medial compartment compared to the lateral compartment. Trabecular bone showed no significant difference in bone volume fraction between the medial and lateral compartments. However, the medial condyle had significantly more anisotropic trabeculae than the lateral in both femur and tibia. In addition, trabecular bone in the medial tibial condyle was significantly more anisotropic than the corresponding medial femoral condyle. These results indicate that subchondral cortical bone and the underlying trabecular bone reveal complementary locomotor signals for habitual bipedal loading. The subchondral bone provides a clear signal of the differential loading and suggests a habitual loading posture of a slightly flexed knee. The 3D arrangement of trabecular bone reveals the contrasting patterns of mobility in the lateral compartment and immobility of the medial compartment.
Grant Support: NSF IIA 1158603 (TMR)