Assessment of the efficiency of different chemical treatments and ultrasonic cleaning for defatting of cancellous bone samples

Our study aimed to asses the defatting efficiency of different methods, which are commonly used and easily available in the laboratory in order to find a method that is effective, convenient, safe, and economical. Cylindrical cancellous bone specimens were obtained from fresh-frozen human cadaver femoral condyles, cut into multiple small specimens (Ø8 × 2 mm), and assigned to two groups that were treated with either chemical solvent soaking (Solvent group) or ultrasonic cleaning (Ultrasound group). Each group was divided into several subgroups based on different treatments. Digital photographs were taken of each specimen. The difference of material density (Δρ(b)), apparent density (Δρ(app)), and porosity (ΔP) before and after treatment were used as evaluation indicators. For the solvent group, in Δρ(b), only the combination of 99% ethanol and detergent solution showed a significant difference before and after treatment (P = 0.00). There was no significant difference in ΔP among acetone, the mixture of 99% ethanol and acetone, and the combination of 99% ethanol and detergent solution (P = 0.93). For the ultrasound group, the median of all subgroups in Δρ(app) and ΔP were all lower than the solvent group. The combination of 99% ethanol and detergent solution (v/v = 1:20), as well as the mixture of 99% ethanol and acetone (v/v = 1:1), seem to be the optimal defatting methods for 2 mm thick cancellous bone slices due to their effectiveness, availability, low-cost and safety. Chemical soaking for 24 h is more effective than ultrasonic cleaning with 99% ethanol or acetone for 20 or 40 min.