My 3 grandkids who live with me have staph sores. ii had bilateral knee replacement 10 weeks ago. could this be dangerous for me? should i notify my orthopedic surgeon?

Yes: If your incisions are well-healed, then direct contact with a staph infection of the skin on another person would typically cause an infection of your skin or possibly the fatty tissues just below the skin. It is not likely that you would get a direct infection of the joint unless you first contaminated your own skin and fatty tissue and then it penetrated deeper; nonetheless, keep your distance.

Good Habits : It's unlikely, but make sure the whole family is using regular hand washing, avoid direct contact with the sores, don't share towels, etc etc . It's unlikely the staph could get into your bloodstream and then into your new knees, but good hygiene practices will help ensure that. If by some chance your knees be become more painfully, red, or swollen let your surgeon know immediately.