Although defendant's conduct in failing to maintain plaintiff's medical records was not necessarily contumacious, it was clearly negligent. Defendant breached his ethical and statutory duty to retain plaintiff's medical records for at least six years (Education Law § 6530; 8 NYCRR 29.2 [a] [3]). Since this failure deprived plaintiff of any means of establishing a prima facie case, the striking of defendant's answer is the appropriate remedy ( Herrera v. Matlin, 303 AD2d 198; see also Cabasso v. Goldberg, 288 AD2d 116).