Subperiosteal

Subperiosteal refers to the location beneath the periosteum, the dense membrane that covers bone surfaces except at joint ends. The periosteum consists of an outer fibrous layer and an inner cambium layer rich in osteogenic cells, and it plays a key role in bone growth, nutrition, and repair. The space between the periosteum and the underlying bone is known as the subperiosteal space, a potential space that can become real after injury or in certain disease states.

Clinically, the term appears in several contexts. Subperiosteal hematoma is the accumulation of blood beneath the periosteum, often after blunt trauma. In newborns, a skull subperiosteal hematoma is called a cephalhematoma and typically resolves over weeks to months without surgical intervention. In adults, subperiosteal hematomas can occur with fractures and may cause localized swelling and tenderness; imaging helps delineate the collection and the bone surface.

In dentistry, subperiosteal implants are an older form of dental implant placed on top of the jawbone beneath the periosteum. They were designed for patients with insufficient bone height and have largely been superseded by endosseous implants, but they are documented in historical and clinical literature regarding implant techniques.

In radiology and pathology, subperiosteal reactions describe new bone formation along the outer bone surface beneath the periosteum in response to infection, trauma, or tumor processes. Overall, subperiosteal is an orientation term used across anatomy, medicine, and dental practice to denote a location relative to the periosteum.