A rare cause of paediatric wrist pain unmasked by minor trauma

ABSTRACT

Introduction: A 10 year-old girl was referred to paediatric rheumatology with a six-month history of a painful, swollen left wrist associated with functional limitation and disturbed sleep. She initially had a minor fall, X-rays at the time showed no bony abnormalities. Objectives: Blood tests were normal including inflammatory markers and autoimmune screen. Wrist MRI showed significant synovial thickening and avascular necrosis of the left lunate (figure 1). Methods: Our patient received non-steroidal anti-inflammatories and physiotherapy, but a year later continued to have chronic regional pain with allodynia and hyperalgesia. Despite this, she remains upbeat and continues to live a normal childhood and has coped well with the recent increase in computer usage and typing associated with remote-schooling as a consequence of closures during the COVID-19 pandemic. Results: Kienböck disease;an eponym for avascular necrosis of the lunate bone, is of unknown aetiology and incidence[1]. The proposed trigger is trauma in those with a susceptibility due to natural skeletal and vascular variations[2]. It is the commonest cause of adult aseptic osteonecrosis of the upper extremity, usually in dominant hands of men aged 20-40[3]. 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 a soft-tissue injury whereas the chronicity mimics Juvenile Idiopathic Arthritis. Radiographic severity is defined by Lichtman classification and used to guide non-curative surgical or conservative management[4]. This aims to relieve pressure on the lunate bone and restore perfusion. Anti-inflammatory medications are offered prior to surgical jointlevelling to reduce pain, swelling and deformity[5]. Conclusion: We emphasise that clinicians consider this rare, destructive pathology in their differential diagnosis for paediatric chronic wrist pain and swelling, especially in those presenting weeks after a seemingly innocuous hand trauma.