Summary

Largest series in the literature to investigate the incidence of infection in hip and knee periprosthetic fractures

Abstract

Introduction

Unexpected positive intra-operative cultures are reported in the literature following aseptic revision hip and knee surgery. There is no consensus in the literature on how to treat this finding. Periprosthetic joint infection is a significant complication following revision surgery. The purpose of this study is to investigate the prevalence of unexpected positive cultures (UEPC) in hip and knee periprosthetic fracture (PPF) and study its clinical significance.
 
Methodology 
This is a retrospective review of patients admitted to the Endo Klinik with hip and knee PPF, during the period of December 2010 to 2021. Patients were only included in the study if the diagnosis of infection was not expected preoperatively. Data collection included patients’ demographics, patients’ related factors predisposing to infection, preoperative investigations to rule out infection, postoperative microbiology or histology results of infection and how patients with UEPC were treated.
 

Results

 
220 patients were admitted during the study period. Average age was 70 years (range 32-93 years). Female to male ratio was 1.3:1. 61 presented with knee PPF and 159 with hip PPF. In all cases, 3-5 samples were taken for culture. Of the 220 patients, 14 patients (6.4%) had unexpected positive cultures diagnosed postoperative on cultures and/or histopathology. Preoperative aspiration results were only available for 73 patients. 6 of the 14 patients with UEPC had preoperative aspiration. Serum inflammatory markers were not suggestive of infection. The most prevalent organisms were Staphylococcus epidermidis (35.0%), Cutibacterium acnes (15.0%) and Staphylococcus aureus (10.0%). Two of the 14 patients (14.3%) required a single stage revision, and the rest were treated conservatively. None of the patient related risk factors were found to be associated with an increased risk of UEPC.
 

Conclusion

To our knowledge this is the first series in the literature to investigate this research question. The incidence of UEPC is 6.4%. Although surgical treatment may be required, this was not the case for the majority. We propose routine preoperative aspiration for patients admitted with periprosthetic fracture, especially if there is a history of infection. Larger series are required to investigate the clinical significance of this uncommon event.