Augmentation of cancellous screw fixation with a bioactive cement (cap) in vivo

摘要

We studied the effect of bioactive cement (CAP) and polymethylmethacrylate (PMMA) cement on augmentation of cancellous screw fixation in rabbit tibia. CAP is composed of 77percent w/w hydroxyapatite granules and bis-phenol-A glycidyl methacrylate-based resin. CAP has superior mechanical strength and osteoconductive property. A cancellous screw was placed in the proximal end of tibia to the point where threads engaged cancellous bone. One side was randomly selected to be augmented with PMMA or CAP. The contralateral side had a screw without cement (control). Thirty-six rabbits were operated on and sacrificed 1 and 3 months after surgery, and then the pull-out strength was determined for each screw. At 1 month mean values of pull-out strength of screws augmented with CAP and PMMA (319+-58N* and 284+-100N**, respectively) were higher than those for controls (control for CAP; 105+-41N* and control for PMMA; 132+-71N**). Although all values of pull-out strength increased at 3 months, the CAP augmented screws maintained the greatest value (CAP vs control; 387+-109N***vs 196+-107N***, PMMA vs control; 372+-145N vs 242+-100N) (*,**,***; p<0.05). The effect of augmentation using CAP was equal with that for PMMA. In addition, CAP may promote and not impede fracture healing because of its osteoconductive property and low curing temperature. These results suggested that CAP had a good potential for clinical indication.