B.P. Chalmers, J.T. Weston, D.R. Osmon, A.D. Hanssen, D.J. Berry, M.P. Abdel
The Bone and Joint Journal, July 2019
Summary: Daniel Corr, BS
Prosthetic joint infection (PJI) is a significant concern following total knee arthroplasty (TKA), as this deep infection complication often requires a revision arthroplasty procedure.1,2 Therefore, it is important to understand and mitigate risk factors for postoperative PJI whenever possible. While the PJI event rate after TKA is somewhat rare – reported between 0.5-1.8%1-3 – a previous history of arthroplasty with PJI in another joint may make subsequent PJI more likely.
The authors evaluated a matched cohort of primary TKA patients who had undergone previous THA or TKA of the contralateral side. Departmental joint registries identified 102 TKAs between 2000-2014 with previous treatment for PJI after other THA/TKA. This cohort was matched in a 1:3 ratio to 306 TKAs with prior THA/TKA without PJI based on age, sex, BMI, and date of primary TKA. The authors investigated infection and clinical functional outcomes, with the incidence of PJI at 10 years being the primary endpoint. Student’s t-tests were used to analyze continuous variables, while Fischer’s exact tests were used to compare dichotomous variables between groups. Cox regression analysis was undertaken to calculate unmatched comparison hazard ratios (HR) with 95% confidence intervals (CI) in order to identify differences in rates of PJI.
Compared with the matched cohort, the study cohort had a significantly increased risk of PJI at 10 years, with 6.1% of study subjects and 2.6% of matched subjects reporting PJI (HR=3.25, CI 1.18 – 8.97; p=0.03). There were no significant differences in the risk of PJI within the study cohort for variables including age, sex, BMI, time from previous PJI to the primary TKA surgery, or history of PJI coming from previous TKA versus THA. However, multivariate analysis revealed that patients on chronic antibiotic suppression at the time of primary TKA had significantly increased risk of PJI, as 21% of these patients reported PJI versus 1.4% of those not on chronic suppression (HR=15.2, CI 8.4-23.2; p=0.002). Finally, there was no significant difference in final postoperative Knee Society Score (KSS) between the study and match groups (88 vs 90, p=0.8).
This study indicates that patients undergoing primary TKA with a history of PJI from previous other arthroplasty are at a 3x greater risk for PJI following the procedure. Patients taking chronic antibiotic suppression had the greatest risk of PJI. Limitations of this study include a low PJI event rate that makes a robust data comparison – especially within a single institution – challenging.
- Galat DD, McGovern SC, Larson DR, et al. Surgical Treatment of Early Wound Complications following Primary Total Knee Arthroplasty. J Bone Joint Surg (Am) 2009;91-A:48-54.
- Namba RS, Inacio MC, Paxton EW. Risk Factors Associated with Deep Surgical Site Infections after Primary Total Knee Arthroplasty: an analysis of 56,212 Knees. J Bone Joint Surg (Am) 2013;95-A:775-782.
- Kurtz SM, Lau E, Schmier J, et al. Infection Burden for Hip and Knee Arthroplasty in the United States. J Arthroplasty 2008; 23:984-991.