Abstract
Northern Ireland has previously demonstrated high incidence of Perthes' disease (11.6 per 100,000). The aim of this study is to confirm a declining incidence in this diagnosis in Northern Ireland.
Methods
A reduction in new Perthes' patients had been noted by the senior author. A retrospective study was designed to identify patients with a new diagnosis of this disease over a 7 year period (2004–10). Clinical notes were interrogated using word searches. Further cross referencing with x-ray system reports were utilised to capture all new patients presenting with subsequently proven Perthes'. Patients not resident in Northern Ireland at the time of diagnosis were excluded. Patients with epiphyseal dysplasia or avascular necrosis secondary to treatment of developmental dysplasia of the hip were also excluded.
A previous study from this unit had demonstrated 313 new cases over the 7 year period 1992–1998, with average incidence of approximately 45/year for the population.
Results
All years in our study (2004–10) have had less than 30 for the entire population (<8.3 per 100,000). Significant variation between years with some years much less detected, so further searches are been undertaken to ensure completeness if data capture.
Conclusions
Perthes' disease incidence appears to have reduced significantly. Factors such as a lower threshold for investigation, better radiological diagnostics and better understanding of Perthes' should artificially increase the incidence. However, these study findings suggest a decrease. Passive smoking has long been debated as a possible cause in Perthes' disease. The prevalence of smoking is falling in N. Ireland. The 2007 introduction of a workplace smoking ban coincided with a statistically significant fall in smoking behaviour from 25% in 2006/07 to 23% in 2007/08. The cause of Perthes' is undoubtedly multifactorial, but these findings do coincide with decreasing smoking habits in this captive population.
