Bone Mineral Density and its Relation to Cruciate Ligament Strength in the Tibiofemoral Joint. Travis Jones, David J. Porta, Ph.D, Bellarmine University, Louisville, KY 40205. Sponsor: David Porta, Ph.D

This study was conducted so as to compare the bone mineral density with cruciate ligament strength within the knee joint. Four male and four female embalmed cadavers, ages 62 to 93,
were studied. Forearm bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) using a DTX-200 Osteometer. BMD scans showed significant differences between males and females (P<0.0001), but no significant differences between dominant and non-dominant arms (P=0.9676). Further analysis of the density scans showed expected results with the lowest BMD correlating with the lowest bone mineral content (BMC). Data also showed an expected higher BMD mean for males (0.427+/-0.055 g/cm2) versus females (0.335 +/-0.155 g/cm2 ). Both knee joints were then dissected out of each cadaver and manually torqued laterally. Force values were compared with BMD. Upon examination of the knee ligaments, we were able to predict anterior cruciate ligament (ACL) failure would occur first. Three failure modes were observed including an ACL tear with minimal PCL damage (69%), tibial avulsion fracture (25%), and failure of the test set-up (6%). Our data indicates ligament strength does not correlate with BMD (r=-0.442963) or BMC (r=-0.32055). However, it appears that specimens with low BMD and BMC levels may be more prone to tibial avulsion fractures during knee torsion.