Abstract
Background
A few patients undergoing a total hip replacement need a subsequent revision of the cup. In some of these cases, the treating surgeon may be confronted with Unexpected Positive Intraoperative Cultures (UPIC). The exact incidence of this finding is unclear. Moreover, it is unknown what the clinical outcome of these patients is when the stem is left in situ. The aim of our study was to describe the incidence of UPIC in patients undergoing cup revision and to determine the need for total revision in this patient group during follow-up.
Methods/design
In this retrospective multicenter cohort study, we included all consecutive patients that underwent a cup revision between 2015–2017 and had a minimal follow-up of 2 years. Patients were divided in 3 cohorts: i) no positive intra operative cultures; ii) one UPIC; iii) two or more UPIC. Cases in whom 2 or fewer cultures were obtained during cup revision were excluded from the analysis.
Results
From the 334 evaluated cases, 77 were excluded because an inadequate number of cultures were obtained. From the total of 257 included cases, the incidence of UPIC was 16% (n=39). 21 cases had one (8%), and 18 cases had two or more UPIC (7%). After two years of follow up, implant survival in the no UPIC group was 88% (95% CI 0.83 – 0.93), in the one UPIC group 95% (95% CI 0.86 – 1.0), and in the two or more UPIC group 77% (95% CI 0.57 – 0.97). Survival analysis showed no statistically significant differences between the cohorts as determined by cox regressive analysis and log rank test (P = 0.19).
Conclusion
The incidence of UPIC in patients who undergo cup revision is relatively high but does not seem to have a major influence on the need for total revision of the hip during a follow-up of 2 years.
