The ceramic ball used in the modern hip replacements is NOT brittle. They’re making them with aluminium oxide, which is almost as strong as diamond. The ceramic surface is extremely smooth, which reduces wear from friction. The plastic cup will wear faster with high-impact activities, like running. But when the plastic cup wears out, that piece can be replaced without replacing the entire prosthesis. The surgery to replace the plastic cup is much less invasive than the original total hip replacement surgery. My advice to you would be to run once or twice a week, and do more low-impact cross-training (biking, swimming, aquatic jogging, elliptical, or walking).