Abstract
Introduction: This study aimed to examine the changing trends in the reasons for total hip replacement (THR) revision surgery, in one country over a twenty-one-year period, in order to assess whether changes in arthroplasty practices have impacted revision patterns and whether an awareness of these changes can be used to guide clinical practice and reduce future revision rates.
Methods: The reason for revision THR performed between January 1999 and December 2019 was extracted from the New Zealand Joint Registry (NZJR). The results were then grouped into seven 3-year periods to allow for clearer visualization of trends. The reasons were compared across the seven time periods and trends in prosthesis use, patient age, gender, body mass index (BMI) and American Society of Anesthesiologist (ASA) grade were also reviewed. We compared the reasons for early revision, within one year, with the overall revision rates.
Results: There were 20,740 revision THR registered of which 7665 were revisions of hips with the index procedure registered during the 21-year period. There has been a statistically significant increase in both femoral fracture (4.1 - 14.9%, p<0.001) and pain (8.1 - 14.9%, p<0.001) as a reason for hip revision. While dislocation has significantly decreased from 57.6% to 17.1% (p<0.001). Deep infection decreased over the first 15 years but has subsequently seen further increases over the last 6 years. Conversely both femoral and acetabular loosening increased over the first 12 years but have subsequently decreased over the last 9 years. The rate of early revisions rose from 0.86% to 1.30% with a significant rise in revision for deep infection (13-33% of all causes, p<0.001) and femoral fracture (4-18%, p<0.001), whereas revision for dislocation decreased (59-30%, p<0.001). Adjusting for age and gender femoral fracture and deep infection rates remained significant for both (p<0.05). Adjusting for age, gender and ASA was only significant for infection.
Conclusions: The most troubling finding was the increased rate of deep infection in revision THR, with no obvious linked pattern, whereas the reduction in revision for dislocation, aseptic femoral and acetabular loosening can be linked to the changing patterns of the use of larger femoral heads and improved bearing surfaces.