Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: rationale and methods of the shoulder subgroup

Does retained cement or hardware during 2-stage revision shoulder arthroplasty for infection increase the risk of recurrent infection?

BACKGROUND

When treating chronic prosthetic joint infection after shoulder arthroplasty, removal of the implants and cement is typically pursued because they represent a potential nidus for infection. However, complete removal can increase morbidity and compromise bone stock that is important for achieving stable revision implants. The purpose of this study is to compare the rates of repeat infection after 2-stage revision for prosthetic joint infection in patients who have retained cement or hardware compared to those who had complete removal.

MATERIALS AND METHODS

We retrospectively analyzed all two-stage revision total shoulder arthroplasties performed for infection at 2 institutions between 2011 and 2020 with minimum 2-year follow-up from completion of the two-stage revision. Patients were included if they met the International Consensus Meeting criteria for probable or definite infection. Postoperative radiographs after the first-stage of the revision consisting of prosthesis and cement removal and placement of an antibiotic spacer were reviewed to evaluate for retained cement or hardware. Repeat infection was defined as either ≥2 positive cultures at the time of second-stage revision with the same organism cultured during the first-stage revision or repeat surgery for infection after the two-stage revision in patients that again met the International Consensus Meeting criteria for probable or definite infection. The rate of repeat infection among patients with retained cement or hardware was compared to the rate of infection among patients without retained cement or hardware.

RESULTS

Thirty-seven patients met inclusion criteria and were included in the analysis. Six (16%) patients had retained cement and 1 patient (3%) had 2 retained broken glenoid baseplate screws after first-stage revision. Of the 10 cases of recurrent infection, 1 case (10%) involved retained cement/hardware. Age at revision (60.9 ± 10.6 vs. 65.0 ± 9.6, P = .264), body mass index (33.4 ± 7.2 vs. 29.7 ± 7.3, P = .184), Charlson Comorbidity Index (2 (0-8) vs. 3 (0-6), P = .289), male sex (7 vs. 16, P = .420), and presence of diabetes (1 vs. 3, P = .709) were not associated with repeat infection. Retained cement or hardware was also not associated with a repeat risk of infection (1 vs. 6, odds ratio = 0.389, P = .374).

DISCUSSION

We did not find an increased risk of repeat infection in patients with retained cement or hardware compared to those without. Therefore, we believe that surgeons should consider leaving cement or hardware that is difficult to remove and may lead to increased morbidity and future complications.

Establishing a Consensus Definition of a Knee Fracture-Dislocation (Schenck Knee Dislocation V) Using a Global Modified Delphi Method

BACKGROUND

Knee fracture-dislocations are complex injuries; however, there is no universally accepted definition of what constitutes a fracture-dislocation within the Schenck Knee Dislocation (KD) V subcategory. The purpose of this study was to establish a more precise definition for fracture patterns included within the Schenck KD V subcategory.

METHODS

A series of clinical scenarios encompassing various fracture patterns in association with a bicruciate knee ligament injury was created by a working group of 8 surgeons. Utilizing a modified Delphi technique, 46 surgeons from 18 countries and 6 continents with clinical and academic expertise in multiligamentous knee injuries undertook 3 rounds of online surveys to establish consensus. Consensus was defined as ≥70% agreement with responses of either "strongly agree" or "agree" for a positive consensus or "strongly disagree" or "disagree" for a negative consensus.

RESULTS

There was a 100% response rate for Rounds 1 and 2 and a 96% response rate for Round 3. A total of 11 fracture patterns reached consensus for inclusion: (1) nondisplaced articular fracture of the femur; (2) displaced articular fracture of the femur; (3) tibial plateau fracture involving the weight-bearing surface (with or without tibial spine involvement); (4) tibial plateau peripheral rim compression fracture; (5) posterolateral tibial plateau compression fracture, Bernholt type IIB; (6) posterolateral tibial plateau compression fracture, Bernholt type IIIA; (7) posterolateral tibial plateau compression fracture, Bernholt type IIIB; (8) Gerdy's tubercle avulsion fracture with weight-bearing surface involvement; (9) displaced tibial tubercle fracture; (10) displaced patellar body fracture; and (11) displaced patellar inferior pole fracture. Fourteen fracture patterns reached consensus for exclusion from the definition. Two fracture patterns failed to reach consensus for either inclusion or exclusion from the definition.

CONCLUSIONS

Using a modified Delphi technique, this study established consensus for specific fracture patterns to include within or exclude from the Schenck KD V subcategory.

LEVEL OF EVIDENCE

Prognostic Level V . See Instructions for Authors for a complete description of levels of evidence.

Extensor Mechanism Disruption Impacts Treatment of Dislocated and Multiligament Injured Knees: Treatment and Schenck Classification Recommendations Based on a Global Delphi Method

BACKGROUND

Multiligament knee injury (MLKI) with associated extensor mechanism (EM) involvement is a rare injury, with limited evidence to guide optimal treatment. The purpose of this study was to identify areas of consensus among a group of international experts regarding the treatment of patients with MLKI and concomitant EM injury.

METHODS

Utilizing a classic Delphi technique, an international group of 46 surgeons from 6 continents with expertise in MLKI undertook 3 rounds of online surveys. Participants were presented with clinical scenarios involving EM disruption in association with MLKI, classified using the Schenck Knee-Dislocation (KD) Classification. Positive consensus was defined as ≥70% agreement with responses of either "strongly agree" or "agree," and negative consensus was defined as ≥70% agreement with "strongly disagree" or "disagree."

RESULTS

There was a 100% response rate for rounds 1 and 2 and a 96% response rate for round 3. There was strong positive consensus (87%) that an EM injury in combination with MLKI significantly alters the treatment algorithm. For an EM injury in conjunction with a KD2, KD3M, or KD3L injury, there was positive consensus to repair the EM injury only and negative consensus regarding performing concurrent ligamentous reconstruction at the time of initial surgery.

CONCLUSIONS

In the setting of bicruciate MLKI, there was overall agreement on the significant impact of EM injury on the treatment algorithm. We therefore recommend that the Schenck KD Classification be updated with the addition of the modifier suffix "-EM" to highlight this impact. Treatment of the EM injury was judged to have the highest priority, and there was consensus to treat the EM injury only. However, given the lack of clinical outcome data, treatment decisions need to be made on a case-by-case basis with consideration of the numerous clinical factors that are encountered.

CLINICAL RELEVANCE

Little clinical evidence exists to guide the surgeon on the management of EM injury in the setting of a multiligament injured or dislocated knee. This survey highlights the impact that EM injury has on the treatment algorithm and provides some guidance for management until a further large case series or prospective studies are undertaken.

Factors Associated With Elevated Inflammatory Markers Prior to Shoulder Arthroplasty

Background: Preoperative erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) ranges for several shoulder arthroplasty indications are not well understood. Purpose: We sought to compare preoperative ESR and CRP values for a variety of shoulder arthroplasty indications and evaluate risk factors for elevated preoperative ESR and CRP values. Methods: We conducted a retrospective cohort study of shoulder arthroplasty cases performed at a single academic medical institution from 2013 to 2018. Preoperative ESR and CRP values for 235 shoulder arthroplasties with various indications were recorded. Independent risk factors for elevated values (CRP > 10.0 mg/L and ESR > 30.0 mm/h) were determined via multiple variable logistic regression. Results: Patients undergoing shoulder arthroplasty for osteoarthritis had an ESR (mean ± SD) of 22.6 ± 17.8, with 29.8% of patients elevated, and a CRP of 6.5 ± 6.4, with 25.5% of patients elevated. Arthroplasty for acute fracture and prosthetic joint infection (PJI) had higher preoperative ESR and CRP values. Multivariate analysis identified several predictors of elevated ESR, including infection, acute fracture, diabetes, and female sex. It also identified predictors of elevated CRP, including infection, acute fracture, and younger age. Conclusions: Preoperative ESR and CRP values may be elevated in 25% to 30% of patients undergoing primary shoulder arthroplasty. Arthroplasty for both acute fracture and PJI, along with several other patient factors, was associated with elevated preoperative ESR and CRP. Thus, routine collection of ESR and CRP preoperatively may not be of benefit, as elevated values are common. Further study is warranted.

Does the Alpha Defensin ELISA Test Perform Better Than the Alpha Defensin Lateral Flow Test for PJI Diagnosis? A Systematic Review and Meta-analysis of Prospective Studies

BACKGROUND

Periprosthetic joint infection (PJI) following total joint arthroplasty is a serious complication that causes severe morbidity and adds a major financial burden to the healthcare system. Although there is plenty of research on the alpha-defensin (AD) test, a meta-analysis consisting of only prospective studies investigating AD's diagnostic efficacy has not been performed. Additionally, some important subgroups such as THA and TKA have not been separately analyzed, particularly regarding two commonly used versions of the AD test, the laboratory-based (ELISA) and lateral-flow (LF).

QUESTIONS/PURPOSES

(1) Does the AD ELISA test perform better in the detection of PJI than the AD LF test, in terms of pooled sensitivity and specificity, when including prospective studies only? (2) Are there differences in sensitivity or specificity when using AD ELISA and AD LF tests for PJI diagnosis of THA or TKA PJI separately?

METHODS

Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, we included prospective studies describing the use of either AD test in the workup of pain after total joint arthroplasty (primary or revision, but not after resection arthroplasty). Fifteen studies (AD ELISA: 4; AD LF: 11) were included, with 1592 procedures. Subgroup data on THA and TKA could be retrieved for 1163 procedures (ELISA THA: 123; LF THA: 257; ELISA TKA: 228; LF TKA: 555). Studies not describing THA or TKA, those not using Musculoskeletal Infection Society (MSIS) criteria as the standard for determining the presence or absence of PJI, those not clearly reporting data for the AD test for the total cohort, and those describing data published in another study were excluded. Studies were not excluded based on follow-up duration; the MSIS criteria could be used within a few weeks, when test results were available. Quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 criteria. Study quality was generally good. The most frequent sources of bias were related to patient selection (such as unclear inclusion and exclusion criteria) and flow and timing (uncertainty in place and time of aspiration, for example). Heterogeneity was moderate to high; a bivariate random-effects model therefore was used. To answer both research questions, sensitivity and specificity were calculated for AD ELISA and LF test groups and THA and TKA subgroups, and were compared using z-test statistics and meta-regression analysis.

RESULTS

No differences were found between the AD ELISA and the AD LF for PJI diagnosis in the pooled cohorts (THA and TKA combined), in terms of sensitivity (90% versus 86%; p = 0.43) and specificity (97% versus 96%; p = 0.39). Differences in sensitivity for PJI diagnosis were found between the THA and TKA groups for the AD ELISA test (70% versus 94%; p = 0.008); pooled AD LF test sensitivity did not differ between THA and TKA (80% versus 87%; p = 0.20). No differences in specificity were found in either subgroup.

CONCLUSIONS

Both the AD ELISA and AD LF test can be used in clinical practice because both have high sensitivity and very high specificity for PJI diagnosis. The lower sensitivity found for diagnosis of PJI in THA for the AD ELISA test must be carefully interpreted because the pooled data were heterogenous and only two studies for this group were included. Future research should analyze TKAs and THAs separately to confirm or disprove this finding.

LEVEL OF EVIDENCE

Level II diagnostic study.