In moving for summary judgment dismissing the complaint, defendant was required to come forward with competent medical evidence negating plaintiff's claim that the subject accident caused her serious injury within the meaning of Insurance Law § 5102 (d). Defendant met this initial burden by submitting, inter alia, the sworn report of a radiologist who, based on his review of MRI films of plaintiff's left and right knees, opined that both knees were affected by degenerative processes long predating the subject accident, and that there was no evidence of any traumatic injury the accident might have caused. The sworn medical report plaintiff submitted in opposition failed to refute, or even to address, the opinion of defendant's expert that the limitations of plaintiff's knees resulted from a preexisting degenerative condition. Since plaintiff thus failed to rebut defendant's prima facie showing that plaintiff did not sustain a serious injury as the result of the subject accident, defendant is entitled to summary judgment ( see Pommells v. Perez, 4 NY3d 566, 574-575, 579-580; Montgomery v. Pena, 19 AD3d 288, 290).