Hello, A very thorough medical history is absolutely necessary before any dental treatment. A blood thinner such as Coumadin affects the body s ability to clot. This is the initial stage of healing required after an extraction. If the clot is disturbed, delayed healing may occur. A dry socket or infection after the extraction is a risk. I routinely take my patient s off blood thinners including aspirin. If there are high risk conditions, I refer to the oral surgeon specialist. All doctors and specialists should consult, discuss risks and agree to treatment. Premedication for dental treatment, especially extractions, is necessary after knee replacement surgery. An antibiotic such as Amoxicillin should be prescribed. I suggest a consultation with an oral surgeon. Factors such as the amount of tooth in bone and risks need to be considered. Surgical complication risks will also need to be considered when choosing a location. I hope this is helpful and thank you for your inquiry.