Papers of the Week

Primary bone marrow edema (BME) of the knee is still an elusive condition. This retrospective study was undertaken to gain insight into its characteristic features. The records of 48 patients with primary BME of the knee diagnosed by magnetic resonance imaging were reviewed. Demographic data, medical history, current medications, pain type, smoking and drinking habits, allergies, occupation, sports practiced, environmental factors, and life events predating symptom onset were examined. Data analysis demonstrated that 56.3% of patients had experienced a stressful event before BME pain onset and that 50% suffered from thyroid disorders. Standard conservative treatment resulted in pain resolution irrespective of the use of anti-inflammatories. However, most patients reported new persistent symptoms: dysesthesia/hypoesthesia on palpation in the skin area overlying the previous edema and a reduced ipsilateral patellar reflex. To our knowledge, this is the first study characterizing a substantial cohort of patients with BME. We found that middle-aged, sedentary, and slightly overweight women smokers are the typical patients with primary BME of the knee. The appearance and persistence of cutaneous dysesthesia/hypoesthesia at the site of the earlier lesion and ipsilateral patellar hyporeflexia implicate an autonomous nervous system dysfunction in BME pathogenesis and warrant further investigation.