Focal periphyseal edema zone

Focal periphyseal oedema zones, also known as "FOPE" zones, are regions of bone marrow oedema seen on MRI that are principally located at the physes about the knee. They are thought to represent potentially painful manifestations of physiologic physeal fusion ¹.

Epidemiology

FOPE zones are seen in both sexes. They are typically seen in females around the ages of 11-12 and in males around the ages of 13-14 (around the time of expected skeletal maturation) ¹.

Clinical presentation

Clinically, patients may present with pain, with or without a history of acute injury ¹.

Pathology

The exact cause of FOPE zones is unknown. A suggested etiologyaetiology relates these findings as part of the normal physiologic process of physeal fusion. As the physis of a long bone begins to close, osseous bridging occurs. In some bones that undergo endochondral ossification, it occurs with small bony bars before fusing completely ^2,3,5. These may act as anchors to the surrounding bone and alter the local mechanics, producing small amounts of vascular damage and bleeding in physically active adolescents ¹.

Distribution

They have been reported at the distal physis of the femur and at the proximal physis of the femur and tibia ¹.

Radiographic features

ThesePlain films are unremarkable. These are best seen on MRI. They demonstrate focal regions of increased signal on fluid sensitive-sensitive sequences, adjacent to the physis of long bones.

Plain films are unremarkable. 

Treatment and prognosis

This entity requires no invasive diagnostic procedure and does not need imaging follow up-up ¹. 

Differential diagnosis

Imaging differential considerations include:

• Salter-Harris fractures
• Stress fracture
• contusional bone marrow oedema
• chronic recurrent multifocal osteomyelitis