Injury Vol. 26, No. 3, pp. 175-176, 1995 Copyright 0 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0020.1383/95/ $lO.OO+O.OO Painful bipartite patella following injury A. Iossifidis and R. N. Brueton Academic Unit, Department of Orthopaedic Surgery, St Thomas’ Hospital, London, UK We report nine rare casesof painful bipartife patella following inju y fo the knee, in seven non-athletic ad&s. Patients suffered with persisfent anferior knee pain and localized tenderness over the superolateral aspect of the pafella for an average of 2 years following injury. The clinical, radiugrnphic and arthroscopic findings are described. Excision of the accessory bipartite fragment resulted in satisfactory relief of pain and complete restoration of the knee function in all patients at ~7 mean follow-up of 10 months (range 3-36 months). Although p&z&l bipartite patella may be considered rare if should be recognized as a cause of post-traumafic anterior pain in the adult. Injury Vol. 26,No.3,175-176,199s Introduction Bipartite patella is usually asymptomatic, presenting as an incidental radiological finding and thus often dismissed as clinically insignificant. However, we have found that this congenital patella abnormality can be the origin of persist- ent and incapacitating anterior knee pain following injury. Painful bipartite patella is uncommon and has only been reported in adolescent and young athleteslb3. To our knowledge a seriesof painful bipartite patellae following injury in non-athletic adults has not been previously described. Patients and methods Seven patients with painful bipartite patella presented to the orthopaedic clinic. In two patients both patellae were symptomatic. Three patients were women and four men with a mean age at presentation of 30 years (range 21 to 46 years). All but one were over 27 and no patient was actively involved in sport. The onset of symptoms was related either to a direct impact on the knee such as a fall, kick or blow (four patients) or an indirect acute injury while cycling or hill climbing. All patients complained of anterior knee pain. The pain was increasedby walking and associated with giving way of the knee (six patients) and discomfort on climbing stairs (three patients). In all patients the pain was persistent resulting in continuing disability despite non-operative management. The mean duration of the symptoms from onset to presentation was 2 years (range 1 to 11 years). Anteroposterior, lateral and skyline radiographs of the patella were taken and bone scintigraphy was carried out in one patient. Following examination under general anaes- thesis and arthroscopy of the knee joint, the accessory superolateral fragment was excised. Findings and results Physical examination of the patients was unremarkable with the exception of localized tenderness over the superolateral patellar pole. Radiography showed bilateral bipartite patella in three patients, one of whom was symptomatic on one side, and unilateral abnormalities in four patients. In all cases the bipartite fragment was superolateral (Figure1 and Figure 2). A technetium 99 bone Figure I. Anteroposterior radiograph of a 31-year-old patient, showing a bipartite patella in the right knee. Figure2. Sky-line view of the bipartite patella shown in Figure 1.