This is one of a series of occasional articles highlighting conditions that may be more common than many doctors realise or may be missed at first presentation. The series advisers are Anthony Harnden, university lecturer in general practice, Department of Primary Health Care, University of Oxford, and Richard Lehman, general practitioner, Banbury. To suggest a topic for this series, please email us at easilymissed@bmj.comA 30 year old, right hand dominant mechanic presented to the emergency department with a swollen, painful right wrist after he fell on to an outstretched right hand from a motorcycle travelling at high speed. Radiographs were interpreted as normal and the patient was discharged with a diagnosis of a wrist sprain. The next morning he presented again to the same emergency department with a new symptom: numbness of the right thumb and index, middle, and ring fingers. The radiographs were reviewed and a perilunate dislocation with median nerve compression was diagnosed. That afternoon the patient had median nerve decompression and open reduction and stabilisation of the perilunate dislocation with ligament repair. PRACTICE Key points• Remain vigilant about the possibility of perilunate dislocation in patients who sustain high energy hyperextension wrist injuries with or without carpal bone fractures• Delay in diagnosis can result in injury to the median nerve in the acute setting and post-traumatic arthritis• Confirm the diagnosis with posteroanterior and lateral plain wrist radiography, which would show the "spilled teacup" sign (lunate angulated volarly) and disruption of the smooth borders of the carpal rows (Gilula's lines)• Immediate management involves closed reduction, followed by early surgical repair (stabilisation and fixation)