Abstract
Background
Dislocation is a major complication following total hip arthroplasty (THA). Aetiology is multi-factorial, but increasing femoral head size may result in lower dislocation rates. The latest England and Wales National Joint Registry (NJR) annual report has highlighted a statistically significant increase in the use of femoral heads of size 36mm+ from 5% in 2005 to 26% in 2009, together with an increase in the use of the posterior approach. The aim of this study was to determine whether national dislocation rates have fallen over the same period.
Methods
Hospital episode statistics (HES) data for England was analysed so as to determine trends in national rates of 3-, 6-, 12- and 18-month dislocation rates following primary THA performed between 2005 and 2009 (247,546 THAs). 18-month revision rates were also examined.
Results
Significant decreases in cumulative dislocation rates were seen at each time interval (3-month: 1.117% (2005) to 0.863% (2009), p< 0.001, 6-month: 1.247% to 0.955%. p< 0.001, 12-month: 1.423% to 1.112%, p< 0.001, 18-month: 1.556% to 1.309% (2008), p< 0.001). 18-month revision rates did not significantly change (1.26% to 1.39%, OR=1.10, 0.98–1.24, p=0.118). An analysis of hemiarthroplasty patients over the same period showed no evidence of changes in the coding of dislocations.
Discussion
This data has revealed a significant reduction in dislocations associated with a rapid increase in the use of large femoral head sizes, despite an increase in the use of the posterior approach. 18-month revision rates remained unchanged.
