Effect of Donor Age on Bone Mineral Density in Irradiated Bone-Patellar Tendon-Bone Allografts of the Anterior Cruciate Ligament

Background: Allograft tissue remains a valuable alternative for anterior cruciate ligament reconstruction. No study to date has correlated the effect of donor age to bone mineral density (BMD) in a large series of irradiated bone-patellar tendon-bone (BPTB) allograft tissue. Hypothesis/Purpose: The authors attempted to correlate donor age with BMD in a large group of BPTB allograft specimens treated with low-dose gamma irradiation (1.0-1.3 Mrad) collected over a 4-year period. They hypothesized there would be no effect of donor age on the BMD of irradiated BPTB allografts. Study Design: Descriptive laboratory study. Methods: A total of 110 BPTB allograft specimens from 44 male and 66 female donors with a mean age of 46 years (range, 21-58 years) were analyzed. Bone mineral density data were obtained from both the patellar and tibial bone plugs of the BPTB complex. Statistical analyses were conducted using linear regression for correlations and 2-tailed Student t tests for comparisons between groups. Results: The mean BMD of the patellar bone plug (0.471 g/cm(2)) was significantly greater than the mean BMD of the tibial bone plug (0.328 g/cm(2)) (P < .001). No correlation was identified between donor age and BMD for either the patella or tibial bone plugs (R-2=.014 and .011, respectively). Both patellar and tibial BMD was significantly greater for the male grafts than the female ones. Conclusion: No correlation was found between donor age and BMD for irradiated BPTB allograft tissue. The patellar bone plugs were noted to have a greater BMD than the tibial bone plugs. Allograft tissue from male donors had higher BMD values than that harvested from female donors.