Evaluation of 2 Cement Techniques for Augmentation of Stripped 1.5 mm Screw Sites in the Distal Metaphysis of Feline Radii
To evaluate the effect of 2 cement augmentation techniques on pullout strength of 1.5 mm screws placed in stripped 1.5 mm screw sites in the distal metaphysis of feline radii. Study Design
Experimental study. Sample Population
Feline radii (21 pairs). Methods
Treatment groups (n=4) were allocated according to a Latin square design to 4 sites in each pair of radii. Positive and negative controls were a 1.5 mm screw and a screw of the same diameter in a previously stripped screw hole, respectively. Treatment groups were a 1.5 mm screw implanted in a previously stripped screw hole after injection of polymethylmethacrylate (PMMA) or a bioresorbable calcium phosphate cement (CPC, Norian® skeletal repair system (SRS)). The ultimate pullout strength was compared between groups. Results
The mean (±SEM) pullout strength of screws augmented with either bone cement was less than that of the positive control group and greater than that of the negative control. Injection of CPC or PMMA before screw implantation increased the pullout strength of the negative control by 86.8±22.9% and 104.1±32.1%, respectively. Holding power of the positive control screws differed from these 2 groups, and was 274.8±39.17% higher than that of the negative control. Conclusion
Injection of CPC or PMMA increases but does not restore the holding power of stripped 1.5 mm diameter screws. Clinical Relevance
The use of CPC (Norian® SRS) augmentation of stripped 1.5 mm diameter screws warrants clinical investigation as it combines biomechanical results similar to PMMA with osteoconduction and resorbability.