Orthopaedic procedures rely on strict sterilization techniques to prevent surgical site infections. Surgical instrument trays are wrapped for sterilization, and these wraps routinely are inspected by operating room personnel to evaluate for breaches before using the contained instruments. The sensitivity of this practice for detecting wrap defects has not been established. We divided 90 sterilization wraps into groups with no defect and with six sizes of defects ranging from 1.1 to 10.0 mm in diameter. Puncture-type defects were created using nails of known diameter. All wraps were evaluated by medical personnel for evidence of a breach. Detection rates ranged from 6.7% to 96.7% from the smallest to largest defects, respectively. The potential for bacterial transmission through wrap defects also was evaluated, and contaminated nails of the smallest size transmitted bacterial contaminants through the wrap during the creation of puncture defects. Thus, substantial perforations in sterilization wraps frequently are missed when evaluated with commonly used techniques. Defects with a diameter approximately that of a pencil (6.7 mm) were missed 18% of the time, although contamination can be transmitted by a nail with the diameter of a pin (1.1 mm). These results raise questions about a common screening method.