**1. Introduction**

Periprosthetic joint infection (PJI) of the shoulder represents a devastating complication and is the main cause of revision within the first few years after shoulder arthroplasty [1–3]. Its treatment continues to pose a challenge for the orthopedic community [3,4]. Although the preferred surgical treatment of chronic shoulder PJI is still unknown and pooled data demonstrate single-stage exchange may be superior to two-stage exchange in selected cases, two-stage exchange arthroplasty with implant removal, insertion of an antibiotic spacer, followed by reimplantation of an arthroplasty, continues to be the most common treatment strategy for shoulder PJI [5,6]. The reported infection eradication rate of two-stage exchange arthroplasty varies in literature between 63% and 100% [4,6]. However,

**Citation:** Akgün, D.; Wiethölter, M.; Maziak, N.; Paksoy, A.; Karczewski, D.; Scheibel, M.; Moroder, P. Two-Stage Exchange Arthroplasty for Periprosthetic Shoulder Infection Is Associated with High Rate of Failure to Reimplant and Mortality. *J. Clin. Med.* **2021**, *11*, 5186. https://doi.org/ 10.3390/jcm10215186

Academic Editor: Johannes C. Reichert

Received: 17 October 2021 Accepted: 2 November 2021 Published: 6 November 2021

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the majority of these studies focus on the clinical outcomes after successful reimplantation and overlook a substantial number of patients who undergo resection arthroplasty alone and do not complete the second stage of an attempted two-stage exchange arthroplasty [7,8]. Thus, these studies may not accurately reflect the overall success rate of two-stage exchange arthroplasty for shoulder PJI. Furthermore, most studies are limited to small case series and most importantly, there is a lack of data and high variability of how these studies define diagnosis and treatment success of shoulder PJI, which could result in an overestimation of the outcome parameters. An improved understanding of the interstage period and application of a standardized, multidimensional definition of shoulder PJI diagnosis and also treatment success is crucial to accurately depict the clinical outcome of two-stage exchange arthroplasty.

The purpose of the current study was to assess the clinical course of patients after implant removal in the process of an attempted two-stage exchange arthroplasty for shoulder PJI including infection eradication, successful reimplantation, and patient survival as main outcome parameters.

#### **2. Materials and Methods**

#### *2.1. Study Design and Cohort*

We conducted a retrospective analysis of all patients who were scheduled for a twostage exchange arthroplasty in our institution between 2008 and 2018 due to a shoulder PJI. A total of 49 patients were identified from our prospectively collected institutional database and were included in the study. The study protocol was reviewed and approved by the institutional ethics committee (EA4/040/14).

The mean age of the patients at the time of the first stage of the two-stage exchange arthroplasty was 70 ± 11 years (range: 37–88 years) and 30 patients (61%) were female. The main reasons for primary shoulder arthroplasty were cuff arthropathy (10 patients), primary osteoarthritis (17 patients), fracture (19 patients), or posttraumatic osteoarthritis (3 patients). A total of 10 patients (20.4%) had undergone at least one previous septic revision in another hospital, 10 (20.4%) had undergone at least one aseptic revision, and 29 (59%) had developed a shoulder PJI after the initial arthroplasty. The type of arthroplasty at the time of the first stage revision surgery was hemiarthroplasty in 17 (35%), anatomic total shoulder arthroplasty in 9 (18%), and reverse shoulder arthroplasty in 23 patients (47%). The mean interval between the primary arthroplasty and implant removal surgery at our institution was 4.1 ± 3.7 years.
