Abstract
Introduction
Infection remains a serious complication following primary total hip arthroplasty (THA). Many factors including primary diagnosis, comorbidities and duration of procedure are known to influence the rate of infection. Although the association between patient and surgical factors is increasingly well understood, little is known about the role of the prosthesis. This analysis from the Australian Registry (AOANJRR) was undertaken to determine if revision for infection varied depending on the type of bearing surface used.
Methods
Three different bearing surfaces, ceramic on ceramic (CoC), ceramic on cross-linked polyethylene (CoXP) and metal on cross-linked polyethylene (MoXP) were compared. The study population included all primary THA undertaken for OA using these bearing surfaces and reported to the AOANJRR between 1999 and 2013. Kaplan-Meier survivorship curves were compiled with revision for infection as the end point. Hazard Ratios (HR) from Cox proportional hazards models were used to compare revision rates. Sub analysis examining the effect of age, gender, fixation of the femoral stem and femoral head size. To ensure there was no confounding due to differences in femoral and acetabular component selection a further analysis was undertaken which compared the three different bearings with the same stem and acetabular component combinations.
Results
During the study period there were 177,237 primary THA's reported to the registry that met the inclusion criteria (57,839 CoC, 24,269 CoXP and 95129 MoXP). When all procedures were included Both MoXP and CoXP had a higher revision rate for infection compared to CoC (HR 1.46 (1.25, 1.72) p<0.001 and HR 1.42 (1.15, 1.75) p=0.001 respectively). There was no difference in the revision rate for infection when MoXP and CoXP were compared.
There was an age variation with the lower revision rate for infection rate being evident in patient's age 70 years or younger but not older patients. Both men and women had a lower revision rate when CoC was used. The difference was evident when a cementless femoral stem was used but not when the stem was cemented. The difference was also evident for most head sizes with the exception of 28 mm heads.
CoC also had a lower revision rate for infection when the same femoral stem and acetabular component combinations were compared.
Conclusion
Patients aged 70 years or less have a lower revision rate for infection when a CoC bearing is used compared to both CoXP and MoXP. This difference was independent of gender, and femoral and acetabular prostheses selection. No difference was evident if the femoral component was cemented or a head size of 28 mm was used.
