Bilateral Stress Fractures Of The Proximal Tibia - A Rare Differential Diagnosis Of Atraumatic Knee Pain A Case Report

Bone marrow edemas at the knee joint are diagnosed with increasing frequency due to the broad availability of MRI. These can be an expression of stress fracture. SF comprise both, fatigue and insufficiency fractures. In most cases, localized pain first occurs under load-bearing activities. Later on, there may be a progression to immobilizing pain. Up to 95 % of stress fractures are found in the lower extremity. The proximal tibia is rarely affected and usually there is a one-sided manifestation. As a differential diagnosis a transient bone marrow edema syndrome, secondary osteonecrosis as well as a spontaneous osteonecrosis of the knee (M. Ahlback) should be considered. These can be accompanied by secondary damage to the joint surfaces. MRI represents the gold standard in the diagnosis and assessment of stress fractures.We report about a 24-year old female patient with partially immobilizing, atraumatic pain of the hip and knee joints. Laboratory diagnostics showed no evidence of rheumatoid arthritis, a reactive arthritis or osteomyelitis. MRI of the knee joints showed bilateral bone marrow edema of the proximal tibia with signs of stress fractures. After conservative therapy with stress reduction and analgesia according to pain level, MRI showed complete regression of signs of the stress fracture eight weeks later. The load-bearing capacity