Focal Periphyseal Edema (FOPE) Zone on MRI of the Adolescent Knee: A Potentially Painful Manifestation of Physiologic Physeal Fusion?

Abstract

On knee MRI, a FOPE zone can be seen in adolescents and likely relates to the early stages of physiologic physeal closure. It may be associated with pain particularly when no other MRI abnormalities are present. When the characteristic appearance of a FOPE zone is observed on MRI, we suggest that it not be mistaken for an abnormality, requires no invasive diagnostic procedure, and does not need imaging follow-up.

Magnetic Resonance Imaging of the Pediatric Knee

“…Areas of fused physis have relatively less flexibility, possibly resulting in localized microtrauma, accounting for the pain that some patients experience. 4 Variation in epiphyseal ossification and signal intensity is most evident along the distal femoral condyles. The development of low signal intensity along the weight-bearing surface of the epiphyseal cartilage begins as soon as the child becomes ambulatory.…”

“…This increase in signal intensity becomes more focal as the child grows, and appears radiographically as single or multiple ossification centers that eventually coalesce with the underlying bone. 4 Gebarski and Hernandez 5 have described 4 different normal variations in ossification of the posterior femoral condyles. The first they describe as a puzzle-piece configuration whereby an osseous defect in the posterior femoral condyle is filled with an ossification that fills the defect.…”

The Lower Extremity: Acquired Disorders

“…14.19 ). Termed "focal periphyseal edema" (or "FOPE" zone), this marrow edema may be associated with pain but requires no further evaluation [ 20 ]. …”

Case report: imaging the clinical course of FOPE—a cause of adolescent knee pain

“…FOPE is a term used to describe the MRI finding of bone marrow oedema situated around a physis at the time of its fusion, and affects lower limb bones of the adolescent skeleton in either sex [1]. This is a rare finding of uncertain aetiology and significance that has shown itself to be a self-limiting condition [1, 2].…”

“…This is a rare finding of uncertain aetiology and significance that has shown itself to be a self-limiting condition [1, 2]. …”