The "hanging drop" sign on radiographs is indicative of an orbital floor fracture, where the inferior rectus muscle and orbital contents herniate into the maxillary sinus. This results in a characteristic drooping or "hanging" appearance of soft tissue within the sinus on imaging. Recognition of this sign is critical as it guides the surgeon to evaluate for muscle entrapment and orbital volume changes, which can lead to diplopia and enophthalmos. Prompt surgical repair is essential to restore orbital anatomy and prevent long-term functional and cosmetic deficits.

Reference: Oral and Maxillofacial Trauma, James R. Hupp, 5th Edition.