The contact owns a 2011 Lincoln MKS. The contact stated that while attempting to secure items into the trunk of the vehicle, the rear trunk door suddenly came down and struck the contact on the head. During the incident, the contact sustained a head contusion which did not require medical treatment. The contact indicated that the failure had occurred on multiple occasions. The cause of the failure was not determined. The local dealer and manufacturer were not contacted. The VIN was not available. The failure mileage was 100,000.