P underwent a total knee replacement at Catholic Medical Center (D), and a prosthetic knee was surgically implanted. D provided the prosthetic. P complained of pain after the operation and it was discovered that the prosthetic was defective. P underwent a second operation and then sued under strict liability as D had sold him a prosthesis with a design defect that was in an unreasonably dangerous condition. D moved to dismiss the suit; it was not a seller of goods under strict products liability. D was granted its motion and P appealed.