MRI findings in regional migratory osteoporosis of the knee migrating from the femur to the tibia.

Regional migratory osteoporosis (RMO) is an uncommon self-limiting disease characterized by migrating bone marrow edema and osteoporosis. RMO of the knee with intra-articular migration is very rare. In such cases, different parts of the femur are usually involved. We report a case of intra-articular RMO of the knee migrating from the femur to the tibia--a pattern of migration that has not been previously described in the literature.