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Rare cause of paediatric wrist pain unmasked by minor trauma

© BMJ Publishing Group Limited 2021. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION A 10yearold girl was referred to paediatric rheumatology with a 6month history of a painful, swollen left wrist associated with functional limitation and disturbed sleep. She initially had a minor fall, and Xrays at the time showed no bony abnormalities (figure 1). Blood tests were normal, including inflammatory markers and autoimmune screen. Wrist MRI showed significant synovial thickening and avascular necrosis of the left lunate (figure 2). She received nonsteroidal antiinflammatories and physiotherapy, but a year later, continues to have chronic regional pain with allodynia and hyperalgesia. Kienböck disease, an eponym for avascular necrosis of the lunate bone, is of unknown aetiology and incidence. The proposed trigger is trauma in those with a susceptibility due to natural skeletal and vascular variations. It is the most common cause of adult aseptic osteonecrosis of the upper extremity, usually in dominant hands of men aged 20–40 years. Paediatric Kienböck is rare, presenting as pain, stiffness, swelling and reduced power, often after an innocuous fall. Diagnostically, this is challenging because the mechanism suggests