Abstract
INTRODUCTION
Dislocation is a major complication post total hip replacement (THR) and a common cause for revision. Jameson et al (2012) studied 35,000 cemented Exeter (Stryker) THRs demonstrating the risk of revision was significantly influenced by the acetabular component design. This led 3 surgeons in a single hospital group to make a mass move from using the hooded Exeter Low Profile (LP) cup to the better performing Contemporary Flanged (CF) component. The purpose of this study was to show whether this change was associated with a fall in dislocation rates.
PATIENTS/MATERIALS & METHODS
Locally held National Joint Registry data between 2010 and 2015 was used to ascertain implants used in all primary THRs by 3 experienced high volume surgeons. This was linked to local Hospital Episode Statistics to identify patients who had undergone closed or open reduction of a dislocated hip replacement in theatre.
RESULTS
From January 2010 to March 2015 there were 611 primary THRs using the LP cup and 790 primary THRs using the CF, after the surgeons had switched. Between the two groups there was no significant difference in age, ASA grade, BMI, approach, grade of first surgeon or grade of assistant. The dislocation rate of the LP was 2.64%, CF 0.71% (p=0.003). After adjustment for co-variables the odds risk ratio of dislocating with a LP compared to a CF cup was 3.5 (95% CIs 1.3–9.2, p=0.01).
The trust wide dislocation rate has dropped from 2.5% in 2010 to 0.8% in 2015.
DISCUSSION
Rate of dislocation was significantly influenced by acetabular component design. The absence of a hood in the flanged cup may allow easier positioning; the hood in itself may also act as an impingement site causing dislocation.
CONCLUSION
This project demonstrates a significant improvement in local services after implementing a change based on a national clinical audit.
