Reinforced bone cement containing a small amount of short, high-modulus carbon fibers dispersed randomly in surgical polymethylmethacrylate bone cement has been developed and successfully used in a few cases for neoplastic bone replacement. The mechanical properties of this material were evaluated with respect to the bone cement used presently in prosthetic and restorative orthopaedic surgery. Superior mechanical properties were observed in reinforced acrylic compared with unreinforced material; specifically, monotonic tensile strength increased from 28 to 38 MPa (4060 to 5510 psi) and monotonic tensile, cyclic tensile, and compressive modulii were significantly higher in reinforced acrylic. An increase of about 50 percent in fatigue strength was achieved at long lives (10⁵ cycles), that is 15 MPa (2175 psi) as compared to 10 MPa (1450 psi) for unreinforced acrylic.

Both reinforced and unreinforced surgical acrylic are porous materials by virtue of their mode of preparation, that is, operating room conditions. Additional comparative studies were performed only on carbon-reinforced full-density acrylic. The relatively small improvement in mechanical properties for these full-density systems is accounted for by poor fiber distribution.

Strain-rate dependence of tensile properties studied over the 5 × 10^-6 to 2 × 10^-2s^-1 range was found to be low for both reinforced and unreinforced porous acrylics.

The fracture surfaces of the static and cyclically loaded specimens studied by scanning electron microscopy (SEM) revealed the role of intrinsic voids and the carbon fibers in the process of crack initiation and propagation.