Abstract
In this study, the effects of gamma‐ray irradiation on the mechanical properties, absorbability, and osteoconductivity of porous hydroxyapatite/collagen (HAp/Col) were investigated. Porous HAp/Col was exposed to 16, 25, 35, or 50 kGy of gamma‐ray irradiation. The compressive elastic modulus showed irradiation dose‐dependence, with a particularly pronounced decrease in the 50‐kGy treatment group. An in vitro enzymatic digestion test showed that gamma‐ray irradiation of porous HAp/Col resulted in accelerated degradation by collagenase. For in vivo studies, porous HAp/Col was transplanted into the back muscles or bone defects in the femoral condyle of rats. Specimens were obtained at 2, 4, and 8 weeks postoperatively. Absorption of the implants in the muscle was time‐ and irradiation dose‐dependent, with notable absorption for the 35‐ and 50‐kGy groups at 2 weeks. At the skeletal sites, porous HAp/Col demonstrated high osteoconductivity in all irradiation treatment groups. Interestingly, not only implant absorption but also bone formation was irradiation dose‐dependent at early time points. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2010