Periprosthetic infection is the major indication for TKA revision – experiences from a university referral arthroplasty center

Total knee arthroplasty (TKA) is the treatment of choice for symptomatic arthrosis. Patient satisfaction with TKA has improved from 81.2% between the years 1990 and 1999 to 85% between the years 2000 and 2012 [1], but still absolute revision numbers are increasing. Although revision rates after TKA remain constantly low, data from the Nationwide Inpatient Sample (NIS) showed an increase of TKA revisions of 39% from 48,260 in 2006 to 67,534 in 2010 in the US [2]. In the first annual report of the German joint registry an increase of 144% was demonstrated from 7238 in 2004 to 17,658 in 2014 [3]. Recent clinical studies focusing solely on primary revisions found aseptic reasons such as instability with 19 and 22%, and aseptic loosening with 31 and 22% the two most common indications [4, 5]. The analysis of the Swedish, Norwegian, Finnish, Danish, Australian and the New Zealand registry by Sadoghi et al. stated, that the two most common reasons for TKA revisions between 1979 and 2009 were aseptic and septic loosening with 29.8% and 14.8%, respectively [6]. In contrast to aseptical revisions, management of periprosthetic joint infections (PJI) necessitates an interdisciplinary setting and special care [7]. This peculiarity of PJI management leads to a pooling of the affected patients at specialized referral arthroplasty centers, as the study institution is.

That is why we hypothesized, that PJI accounts for the major proportion of primary and secondary revisions at our institution. Additionally, we hypothesized that, in contrast to primary revision, the frequency of PJI is not related to time of revision for secondary revision.

We found PJI to be the most common indication for both, primary and secondary TKA revision at a university referral arthroplasty center. This result is in accordance with the numbers published from the NIS for knee arthroplasty revisions, without discriminating primary from secondary revisions [17]. The odds ratio from the current study demonstrates, that PJI is particularly the major revision indication for secondary revisions. The few other available studies on reasons for re-revisions report comparable rates of PJI as revision indication for secondary revisions. Suarez et al. had a re-revision rate of 46% for PJI in their 68 knees that underwent secondary revision [18]. Mortazavi et al. described this rate to be 44% in their study of 102 knees [19]. However, in contrast to previous publications, we found PJI to be the most common indication for primary revisions, too. In the study of 358 primary revisions by Thiele et al. PJI was the fourth most common indication with a proportion of 15% [5]. In their study, revisions with component retention were excluded. However, debridement and irrigation with retention of the fixed components is a warranted treatment regime for early postoperative or acute periprosthetic infection [14, 20]. These cases are included in our study and are represented by the finding, that PJI was predominantly found for primary revision within 1 year after index operation. Schroer et al. described PJI the third most common reason with a proportion of 16.2% of 844 patients treated at six different institutions [4]. However, we present monocentric results based on standardized diagnostic algorithms.

In contrast to PJI, retropatellar arthrosis and instability are specific issues of primary TKA. In accordance with our results, instability is consistently reported a major failure mechanism after primary TKA [4, 5, 21]. However, retropatellar arthrosis was the most common revision reason 1–3 years after the implantation, what reflects the development of clinically relevant and radiographically obvious retropatellar wear.

This study has limitations because of its retrospective design and the complexity of TKA revision.

If the treatment of PJI failed and the patient was readmitted, the following revision was considered a new case. In this study with 345 primary and secondary revisions, about 10% were repeatedly revised for reinfection. Thus, the proportion of PJI might be biased by patient specific characteristics.

Further, we did not investigate the proportion of resurfaced patellae before revision. These cases were not excluded from the analysis because the proportion of failures due to patellar arthrosis is clinically relevant and the discussion of the best treatment is still going on [22]. The significantly higher proportion of retropatellar arthrosis in the primary revision group is highly likely to be owed to the fact, that the secondary revisions had a higher rate of resurfaced patella before re-revision.

The 14th NJR annual reported aseptical failure mechanisms the most frequent reasons for primary revision [23]. The current monocenter study at a university referral arthroplasty center found PJI the leading failure mechanism irrespectively whether after primary or revised TKA. This discrepancy is owed the pooling of patients. It displays the enormous challenge of referral arthroplasty centers to especially ensure the management of PJI as a potentially life threating TKA failure with the danger of devastating sequela.

PJI is the most common indication for secondary TKA revision and within one year after primary TKA. Aseptical failures such as instability, retropatellar arthrosis and aseptical loosening are the predominant reasons for revision more than one year after primary TKA.