Risk stratified usage of antibiotic-loaded bone cement for primary total knee arthroplasty: short term infection outcomes with a standardized cement protocol

A systematic review and meta-analysis of antibiotic-loaded bone cement for prevention of deep surgical site infections following primary total joint replacement

BACKGROUND

The use of antibiotic-loaded bone cement (ALBC) as a mean for preventing deep surgical site infections (SSI) after total joint replacement is controversial. Therefore, we have conducted a meta-analysis to evaluate the prophylactic effect of ALBC for SSI prevention in patients undergoing arthroplasty. This study was conducted to revise treatment guidelines for MRSA infections in Japan.

METHODS

PubMed (Medline), Scopus, Embase, Web of Science and Cochrane library were searched for relevant articles comparing preventive effect of ALBC for patients undergoing primary total joint arthroplasty by August 2022. Primary outcome was the incidence of deep SSI. Subgroup analyses by type of surgery (total hip (THA) or knee (TKA) arthroplasty) and by causative pathogen (methicillin-resistant Staphylococcus aureus (MRSA)) were performed.

RESULTS

Of the 3379 studies identified for screening, six studies involving 5745 patients were included. The use of ALBC significantly reduced the incidence of deep SSI in overall patients (risk ratio [RR] 0.60, 95% confidential interval [CI] 0.39-0.92), but the evidence level was very low. There was no significant preventive effect for ALBC compared with non-ALBC in both THA and TKA (THA, RR 0.52, 95% CI 0.23-1.16; TKA, RR 0.64, 95% CI 0.38-1.06), and for preventing MRSA-SSI (RR 0.27, 95% CI 0.03-2.41).

CONCLUSIONS

Although the overall preventive effect of ALBC was significant, the evidence level was very low. Thus, the routine use of ALBC as a mean to prevent SSI in arthroplasty may not be suggested.

Impact of Manual Addition of Vancomycin to Polymethylmethacrylate (PMMA) Cements

(1) Background: The addition of antibiotics to bone cements is a common practice in the treatment of periprosthetic joint infections. In revision cases, the amount and type of antibiotic is often insufficient and additional antibiotics must be added. The addition, however, changes the product itself, and the surgeon becomes the "manufacturer" of the bone cement. PMMAe wished to clarify whether the admixture of antibiotics changes the mechanical stability of the bone cements used and if the added antibiotics were still functional and released in sufficient quantities. (2) Methods: We compared two industrially manufactured vancomycin-containing PMMA cements; the low-viscous VancogenX® (TECRES, Sommacampagna, Italy) and the high-viscous Copal® G+V (Heraeus Medical GmbH, Wehrheim, Germany), with two PMMA cements loaded with aminoglycosides, to which 2.0 g of vancomycin (Hexal CT1631) were manually added-the high-viscous Smartset® GHV and the medium-viscous Antibiotic Simplex with Tobramycin (antibiotic Simplex® T). Test specimens of the bone cements were used to determine mechanical stability (bending strength and bending module), and the release of the antibiotics was determined by HLPC and modified Kirby-Bauer assays. (3) Results: All tested bone cements showed an initial high release within the first hours. Repeated testing after 24 h showed a reduced efficacy of VancogenX® and Smartset® GHV in Kirby-Bauer assays. Long-time release over days showed a release of functional antimicrobial active ingredients over this period of time in anti-microbial assays, but no activity of VancogenX® from day 21 onward. No significant differences in the ISO bending modules could be detected, but in contrast to the bending module, the ISO bending strength was substantially reduced by 10-15 mPal in comparison to both cements of the reference group. The Simplex®T met just the ISO 5833; the Smartset® GHV did not after adding vancomycin. (4) Conclusions: In conclusion, the manual addition of 2 g of vancomycin to 40 g of PMMA powder is recommended for the treatment of methicillin-resistant staphylococci. Vancomycin is released over a period of 42 days with concentrations above the MIC for typical staphylococci. The mechanical properties of the PMMA just met, or did not fulfill, ISO mechanical specification. Copal® G+V showed a better elution than VancogenX® over time.

Demographics and Early Outcomes of Commercial Antibiotic Cement Usage for Infection Prophylaxis During Primary Total Knee Arthroplasty in Patients Older Than 65 Years: An American Joint Replacement Registry Study

INTRODUCTION

The use of antibiotic-laden bone cement (ALBC) for infection prophylaxis in the setting of primary total knee arthroplasty (TKA) remains controversial. Using data from the American Joint Replacement Registry (AJRR), (1) we examined the demographics of ALBC usage in the United States and (2) identified the effect of prophylactic commercially available ALBC on early revision and readmission for prosthetic joint infection (PJI) after primary TKA.

METHODS

This is a retrospective cohort study of the AJRR from 2017 to 2020. Patients older than 65 years undergoing primary cemented TKA with or without the use of commercially available antibiotic cement were eligible for inclusion (N = 251,506 patients). Data were linked to available Medicare claims to maximize revision outcomes. Demographics including age, sex, race/ethnicity, Charlson Comorbidity Index (CCI), preoperative inflammatory arthritis, region, and body mass index (BMI) class were recorded. Cox proportional hazards regression analysis was used to evaluate the association between the two outcome measures and ALBC usage.

RESULTS

Patients undergoing cemented TKA with ALBC were more likely to be Non-Hispanic Black ( P < 0.001), have a CCI of 2 or 3 ( P < 0.001), reside in the South ( P < 0.001), and had a higher mean BMI ( P < 0.001). In the regression models, ALBC usage was associated with increased risk of 90-day revision for PJI (hazards ratio 2.175 [95% confidence interval] 1.698 to 2.787) ( P < 0.001) and was not associated with 90-day all-cause readmissions. Male sex, higher CCI, and BMI >35 were all independently associated with 90-day revision for PJI.

DISCUSSION

The use of commercial ALBC in patients older than 65 years for primary TKA in the AJRR was not closely associated with underlying comorbidities suggesting that hospital-level and surgeon-level factors influence its use. In addition, ALBC use did not decrease the risk of 90-day revision for PJI and was not associated with 90-day readmission rates.

Effectiveness of antibiotic-loaded bone cement in total joint arthroplasty at a tertiary medical center: A retrospective cohort study

Background

Data regarding the effectiveness of antibiotic-loaded bone cement (ALBC) in preventing prosthetic joint infections (PJI) after total joint arthroplasty (TJA) is inconsistent. The objective of this study was to evaluate if the routine use of ALBC influenced the risk of revision surgery due to PJI.

Methods

This is a retrospective cohort study performed between January 2018 and September 2020. Adult patients aged ≥ 18 years who underwent TJA (knee or hip) and received either ALBC or plain cement (PC) were included. The outcome of this study was the rate of revision due to PJI. Multivariate analysis using logistic regression was used to identify factors that may be associated with increased risk of PJI, using STATA 15.1 (StataCorp LP, College Station, Texas, USA).

Results

A total of 844 patients were screened and 319 patients were included. There were 247 patients in ALBC group and 72 patients in the PC group. Only vancomycin powder was used in all ALBC cases, with a 2 g dose in 50% of the cases (dose ranged between 1 g and 8 g). The status of the prosthetic joint was assessed and recorded up to 2 years of the TJA. Overall, the difference in the rates of PJI between the two groups after primary arthroplasty was not statistically significant (5.6% vs 1.4%; p = 0.173; OR, 4.2; 95% CI, 0.5-33).

Conclusion

ALBC was not associated with a reduction in PJI rates after primary TJA. More research is needed to further evaluate the effectiveness of ALBC in preventing PJI.

Comprehensive meta-analysis of antibiotic-impregnated bone cement versus plain bone cement in primary total knee arthroplasty for preventing periprosthetic joint infection

PURPOSE

Antibiotic-loaded bone cement (ALBC) was usually used to prevent periprosthetic joint infection (PJI) in primary total knee arthroplasty (PTKA), but whether to use ALBC or plain bone cement in PTKA remains unclear. We aimed to compare the occurrence rate of PJI using two different cements, and to investigate the efficacy of different antibiotic types and doses administered in preventing surgical site infection (SSI) with ALBC.

METHODS

The availability of ALBC for preventing PJI was evaluated by using a systematic review and meta-analysis referring to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Existing articles until December 2021 involving PTKA patients with both ALBC and plain bone cement cohorts were scanned by searching "total knee arthroplasty", "antibiotic-loaded cement", "antibiotic prophylaxis", "antibiotic-impregnated cement" and "antibiotic-laden cement" in the database of PubMed/MEDLINE, Embase, Web of Science and the Cochrane Library. Subgroup analysis included the effectiveness of different antibiotic types and doses in preventing SSI with ALBC. The modified Jadad scale was employed to score the qualities of included articles.

RESULTS

Eleven quantitative studies were enrolled, including 34,159 knees undergoing PTKA. The meta-analysis results demonstrated that the use of prophylactic ALBC could significantly reduce the prevalence of deep incisional SSI after PTKA, whereas there was no significant reduction in the rate of superficial incisional SSI. Moreover, gentamicin-loaded cement was effective in preventing deep incisional SSI, and the use of high-dose ALBC significantly reduced the rate of deep incisional SSI after PTKA. Besides, no significant adverse reactions and complications were stated during the use of ALBC in PTKA.

CONCLUSION

The preventive application of ALBC during PTKA could reduce the rates of deep PJI. Furthermore, bone cement containing gentamicin and high-dose ALBC could even better prevent deep infection after PTKA. However, the existing related articles are mostly single-center and retrospective studies, and further high-quality ones are needed for confirmation.

Effectiveness of antibiotics loaded bone cement in primary total knee arthroplasty: A systematic review and meta-analysis

INTRODUCTION

The application of antibiotics loaded bone cement (ALBC) in the revision of failed total knee arthroplasty (TKA) has been widely accepted to reduce risk of peri-prosthetic infection. However, the prophylactic use of ALBC in primary TKA remains controversial. This study was aimed to identify the prophylactic effect on peri-prosthetic infection and safety of ALBC in primary TKA.

HYPOTHESIS

The application of ALBC could reduce the risk of peri-prosthetic infection in primary TKA.

MATERIALS AND METHODS

Electronic platforms including PubMed, EMBASE, and CENTRAL were retrieved to identify studies comparing outcomes of prophylactic ALBC and plain cement in primary TKA. For outcomes reported as dichotomous variable and continuous variable, risk ratio (RR) and weighted mean difference (WMD) as well as their 95% confidence intervals (95% CI) were selected as the effect sizes for pooling. While for those outcomes reported the adjusted effect sizes such as odds ratio (OR, derived from multivariate logistic regression), and hazard ratio (HR, derived from multivariate COX proportional hazard model), the reported effect sizes were selected for pooling.

RESULTS

A total of 17 studies with 2,074,844 patients (1,093,920 in ALBC group and 980,924 in plain cement group) were eligible for final inclusion. No significant difference was found between ALBC and plain cement groups both for the unadjusted (RR=1.02, 95% CI: 0.86∼1.21, p=0.832) and adjusted (OR=0.94, 95% CI: 0.76∼1.17, p=0.596) peri-prosthetic infection rate. ALBC application was related to significantly increased length of hospital stay (WMD=0.13, 95% CI: 0.10∼0.17, p<0.001). There was no significance on the difference of operation related adverse events between two groups (RR=1.31, 95% CI: 0.68∼2.52, p=0.420). Significantly increased risks of acute renal failure and readmission, and temporarily increased ototoxicity in ALBC group were reported in one of the primary study.

DISCUSSION

There is no sufficient evidence supporting decreased peri-prosthetic infection rate with ALBC application in primary TKA. What's more, it must be taken into consideration about the safety and added cost of additional impregnated antibiotics.

LEVEL OF EVIDENCE

III; meta-analysis.

Antibiotic-free antimicrobial poly (methyl methacrylate) bone cements: A state-of-the-art review

Prosthetic joint infection (PJI) is the most serious complication following total joint arthroplasty, this being because it is associated with, among other things, high morbidity and low quality of life, is difficult to prevent, and is very challenging to treat/manage. The many shortcomings of antibiotic-loaded poly (methyl methacrylate) (PMMA) bone cement (ALBC) as an agent for preventing and treating/managing PJI are well-known. One is that microorganisms responsible for most PJI cases, such as methicillin-resistant S. aureus, have developed or are developing resistance to gentamicin sulfate, which is the antibiotic in the vast majority of approved ALBC brands. This has led to many research efforts to develop cements that do not contain gentamicin (or, for that matter, any antibiotic) but demonstrate excellent antimicrobial efficacy. There is a sizeable body of literature on these so-called "antibiotic-free antimicrobial" PMMA bone cements (AFAMBCs). The present work is a comprehensive and critical review of this body. In addition to summaries of key trends in results of characterization studies of AFAMBCs, the attractive features and shortcomings of the literature are highlighted. Shortcomings provide motivation for future work, with some ideas being formulation of a new generation of AFAMBCs by, example, adding a nanostructured material and/or an extract from a natural product to the powder and/or liquid of the basis cement, respectively.

Timely explantation of tobramycin-impregnated beads and bone cement to avoid haemodialysis in a patient with worsening renal failure

A male patient with right total knee arthroplasty complicated by prosthetic joint infection on intravenous antimicrobials developed an acute kidney injury (AKI) with creatinine up to 7.3 mg/dL ('normal' range (0.5-1.2 mg/dL)) after hardware removal and tobramycin loaded polymethylmethacrylate beads and spacer placement. The AKI was initially attributed to intravenous vancomycin. Despite discontinuing vancomycin, the AKI worsened. A tobramycin level was collected and resulted at 5.5 µg/mL. Due to high suspicion for aminoglycoside-induced renal toxicity and to prevent haemodialysis, the antibiotic cement spacer with tobramycin-impregnated beads was removed. After the removal, tobramycin level rapidly decreased and renal functions improved. AKI is an increasingly recognised complication related to antibiotic-loaded bone cement (ALBC) due to the systemic absorption of antibiotics. With this case we highlight the early recognition of ALBC-induced renal toxicity necessitating explantation of ALBC and beads in order to prevent haemodialysis and emphasise monitoring aminoglycoside levels in the early postoperative period.

Infection after primary total knee arthroplasty: a randomized controlled prospective study of the addition of antibiotics to bone cement

Objective  The present prospective, randomized and controlled study was conducted with 286 patients submitted to primary total knee arthroplasty (TKA) with the objective of evaluating the efficacy of the addition of antibiotics to bone cement as a way to prevent post arthroplasty infection (PAI).

Methods  The patients were randomized into two groups: bone cement without antibiotic (No ATB, n  = 158) or cement with antibiotic (ATB, n  = 128), in which 2 g of vancomycin was added to 40 g of cement. The patients were followed up for 24 months after surgery.

Results  Regarding preoperative demographic data, the distribution of patients between groups was homogeneous ( p  < 0.05). In the 24-month period, the overall infection rate was of 2.09% (6/286), with no difference (odds ratio [OR] = 1.636; 95% confidence interval [CI]: 0.294–9.080; p  = 0.694) between the ATB group (1.56%; 2/128) and the No ATB group (2.53%; 4/158). In the No ATB group, the infection was caused by methicillin-resistant Staphylococcus aureus (MRSA) ( n  = 2), methicillin-sensitive S. aureus (MSSA) ( n  = 1) and Eschirichia coli ( n  = 1). Proteus mirabilis and MSSA were isolated from patients in the ATB group. Among the comorbidities, all patients with PAI were hypertensive and nondiabetic. Two rheumatoid arthritis patients who developed PAI were from the ATB group.

Conclusion  The use of cement with ATB reduced the absolute number of infections, but without statistical difference between the groups; thus, routine use should not be encouraged.

Intra-articular administration of vancomycin and tobramycin during primary cementless total knee arthroplasty : determination of intra-articular and serum elution profiles

AIMS

Intra-articular administration of antibiotics during primary total knee arthroplasty (TKA) may represent a safe, cost-effective strategy to reduce the risk of acute periprosthetic joint infection (PJI). Vancomycin with an aminoglycoside provides antimicrobial cover for most organisms isolated from acute PJI after TKA. However, the intra-articular doses required to achieve sustained therapeutic intra-articular levels while remaining below toxic serum levels is unknown. The purpose of this study is to determine the intra-articular and serum levels of vancomycin and tobramycin over the first 24 hours postoperatively after intra-articular administration in primary cementless TKA.

METHODS

A prospective cohort study was performed. Patients were excluded if they had poor renal function, known allergic reaction to vancomycin or tobramycin, received intravenous vancomycin, or were scheduled for same-day discharge. All patients received 600 mg tobramycin and 1 g of vancomycin powder suspended in 25 cc of normal saline and injected into the joint after closure of the arthrotomy. Serum from peripheral venous blood and drain fluid samples were collected at one, four, and 24 hours postoperatively. All concentrations are reported in µg per ml.

RESULTS

A total of 22 patients were included in final analysis. At one, four, and 24 hours postoperatively, mean (95% confidence interval (CI)) serum concentrations were 2.4 (0.7 to 4.1), 5.0 (3.1 to 6.9), and 4.8 (2.8 to 6.9) for vancomycin and 4.9 (3.4 to 6.3), 7.0 (5.8 to 8.2), and 1.3 (0.8 to 1.8) for tobramycin; intra-articular concentrations were 1,900.6 (1,492.5 to 2,308.8), 717.9 (485.5 to 950.3), and 162.2 (20.5 to 304.0) for vancomycin and 2,105.3 (1,389.9 to 2,820.6), 403.2 (266.6 to 539.7), and 98.8 (0 to 206.5) for tobramycin.

CONCLUSION

Intra-articular administration of 1 g of vancomycin and 600 mg of tobramycin as a solution after closure of the arthrotomy in primary cementless TKA achieves therapeutic intra-articular concentrations over the first 24 hours postoperatively and does not reach sustained toxic levels in peripheral blood. Cite this article: Bone Joint J 2021;103-B(11):1702-1708.

Adjuvant antibiotic-loaded bone cement: Concerns with current use and research to make it work

Antibiotic-loaded bone cement (ALBC) is broadly used to treat orthopaedic infections based on the rationale that high-dose local delivery is essential to eradicate biofilm-associated bacteria. However, ALBC formulations are empirically based on drug susceptibility from routine laboratory testing, which is known to have limited clinical relevance for biofilms. There are also dosing concerns with nonstandardized, surgeon-directed, hand-mixed formulations, which have unknown release kinetics. On the basis of our knowledge of in vivo biofilms, pathogen virulence, safety issues with nonstandardized ALBC formulations, and questions about the cost-effectiveness of ALBC, there is a need to evaluate the evidence for this clinical practice. To this end, thought leaders in the field of musculoskeletal infection (MSKI) met on 1 August 2019 to review and debate published and anecdotal information, which highlighted four major concerns about current ALBC use: (a) substantial lack of level 1 evidence to demonstrate efficacy; (b) ALBC formulations become subtherapeutic following early release, which risks induction of antibiotic resistance, and exacerbated infection from microbial colonization of the carrier; (c) the absence of standardized formulation protocols, and Food and Drug Administration-approved high-dose ALBC products to use following resection in MSKI treatment; and (d) absence of a validated assay to determine the minimum biofilm eradication concentration to predict ALBC efficacy against patient specific micro-organisms. Here, we describe these concerns in detail, and propose areas in need of research.

Antibiotic-Loaded Bone Cement in Prevention of Periprosthetic Joint Infections in Primary Total Knee Arthroplasty: A Register-based Multicentre Randomised Controlled Non-inferiority Trial (ALBA trial)

INTRODUCTION

The current evidence on the efficacy of antibiotic-loaded bone cement (ALBC) in reducing the risk of periprosthetic joint infections (PJI) after primary joint reconstruction is insufficient. In several European countries, the use of ALBC is routine practice unlike in the USA where ALBC use is not approved in low-risk patients. Therefore, we designed a double-blinded pragmatic multicentre register-based randomised controlled non-inferiority trial to investigate the effects of ALBC compared with plain bone cement in primary total knee arthroplasty (TKA).

METHODS AND ANALYSIS

A minimum of 9,172 patients undergoing full-cemented primary TKA will be recruited and equally randomised into the ALBC group and the plain bone cement group. This trial will be conducted in Norwegian hospitals that routinely perform cemented primary TKA. The primary outcome will be risk of revision surgery due to PJI at 1-year of follow-up. Secondary outcomes will be: risk of revision due to any reason including aseptic loosening at 1, 6, 10 and 20 years of follow-up; patient-related outcome measures like function, pain, satisfaction and health-related quality of life at 1, 6 and 10 years of follow-up; risk of changes in the microbial pattern and resistance profiles of organisms cultured in subsequent revisions at 1, 6, 10 and 20 years of follow-up; cost-effectiveness of routine ALBC versus plain bone cement use in primary TKA. We will use 1:1 randomisation with random permuted blocks and stratify by participating hospitals to randomise patients to receive ALBC or plain bone cement. Inclusion, randomisation and follow-up will be through the Norwegian Arthroplasty Register.

ETHICS AND DISSEMINATION

The trial was approved by the Western Norway Regional Committees on Medical and Health Research Ethics (reference number: 2019/751/REK vest) on 21 June 2019. The findings of this trial will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT04135170.

Vancomycin Powder Use in Fractures at High Risk of Surgical Site Infection

OBJECTIVES

To determine if the use of intrawound vancomycin powder reduces surgical-site infection after open reduction and internal fixation of bicondylar tibial plateau, tibial pilon, and calcaneus fractures.

DESIGN

Retrospective analysis.

SETTING

Level I trauma center.

PATIENTS

All fractures operatively treated from January 2011 to February 2015 were reviewed; 583 high-risk fractures were included, of which 35 received topical vancomycin powder. A previously published prospectively collected cohort of 235 similar high-risk fractures treated at our center from 2007 through 2010 served as a second comparison group.

INTERVENTION

Topical vancomycin powder at wound closure.

MAIN OUTCOME MEASUREMENTS

Deep surgical-site infection. Analyses used both univariate comparison of all patients and 1:2 matching analysis using both nearest neighbor and propensity-based matching.

RESULTS

Compared with a control group of fractures treated during the same time period without vancomycin powder, the infection rate with vancomycin powder was significantly lower [0% (0/35) vs. 10.6% (58/548), P = 0.04]. Compared with our previously published historical infection rate of 13% for these injuries, vancomycin powder was also associated with significantly decreased deep surgical-site infection (0% vs. 13%, P = 0.02). These results agreed with the matched analyses, which also showed lower infection in the vancomycin powder group (0% vs. 11%-16%, P ≤ 0.05).

CONCLUSIONS

Vancomycin powder may play a role in lowering surgical-site infection rates after fracture fixation. A larger randomized controlled trial is needed to validate our findings.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Antibiotic-Laden Bone Cement Use and Revision Risk After Primary Total Knee Arthroplasty in U.S. Veterans

BACKGROUND

It is controversial whether the use of antibiotic-laden bone cement (ALBC) in primary total knee arthroplasty (TKA) affects periprosthetic joint infection (PJI) or revision rates. The impact of ALBC on outcomes of primary TKA have not been previously investigated in U.S. veterans, to our knowledge. The purposes of this study were to quantify utilization of ALBC among U.S. veterans undergoing primary TKA and to determine if ALBC usage is associated with differences in revision TKA rates.

METHODS

Patients who had TKA with cement from 2007 to 2015 at U.S. Veterans Health Administration (VHA) hospitals with at least 2 years of follow-up were retrospectively identified. Patients who received high-viscosity Palacos bone cement with or without gentamicin were selected as the final study cohort. Patient demographic and comorbidity data were collected. Revision TKA was the primary outcome. All-cause revisions and revisions for PJI were identified from both VHA and non-VHA hospitals. Unadjusted and adjusted regression analyses were performed to identify variables that were associated with increased revision rates.

RESULTS

The study included 15,972 patients who had primary TKA with Palacos bone cement at VHA hospitals from 2007 to 2015. Plain bone cement was used for 4,741 patients and ALBC was used for 11,231 patients. Utilization of ALBC increased from 50.6% in 2007 to 69.4% in 2015. At a mean follow-up of 5 years, TKAs with ALBC had a lower all-cause revision rate than those with plain bone cement (5.3% versus 6.7%; p = 0.0009) and a lower rate of revision for PJI (1.9% versus 2.6%; p = 0.005). On multivariable regression, ALBC use was associated with a lower risk of all-cause revision compared with plain bone cement (hazard ratio [HR]: 0.79, 95% confidence interval [CI]: 0.68 to 0.92; p = 0.0019). Seventy-one primary TKAs needed to be implanted with ALBC to avoid 1 revision TKA.

CONCLUSIONS

The utilization of ALBC for primary TKAs performed at VHA hospitals has increased over time and was associated with a lower all-cause revision rate and a lower rate of revision for PJI.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Antibiotics and cement: what I need to know?

We conducted a systematic review about antibiotic-loaded bone cement (ALBC) with a focus on clinical evidence about ALBC in general, concerns about ALBC and ALBC cost.

The role of antibiotic-loaded bone cement in complicated knee arthroplasty: relevance of gentamicin allergy and benefit from revision surgery - a case control follow-up study and algorithmic approach

BACKGROUND

Antibiotic-loaded (particularly gentamicin) bone cement (BC) is widely used in total joint arthroplasty (TJA) to prevent periprosthetic infections (PPIs), but may itself cause implant failure. In light of a complete lack in literature, the objective was to assess the clinical relevance of gentamicin allergy for failure of cemented total knee arthroplasties in 25 out of 250 patients with positive patch test reactions to gentamicin and otherwise unexplained symptoms by evaluating benefits from revision with change to gentamicin-free cement.

METHODS

Fifteen of these 25 patients and their treating orthopaedic surgeons agreed to a re-assessment. They were surveyed regarding interim course of therapy and symptoms, including re-assessment of the Knee Injury and Osteoarthritis Outcome Score (KOOS), and underwent follow-up clinical and radiographic investigations. The initial use of gentamicin-loaded BC was reaffirmed by review of the primary implantation operative reports and respective implant passports. Primary and follow-up KOOS scores were analyzed regarding benefits from revision surgery by comparing nine patients with revision to six without revision.

RESULTS

Mean follow-up time was 38 months. The entirety of patients experienced an improvement of self-reported symptoms, with revision surgery (i.e., switching to gentamicin-free BC or uncemented total knee arthroplasty) yielding significantly greater improvement (p = 0.031): the nine revised patients reported a significant symptom relief (p = 0.028), contrary to the six unrevised patients (p = 0.14). Interestingly, the decision to proceed with revision surgery was significantly correlated with higher symptom severity (p = 0.05).

CONCLUSION

In symptomatic total knee arthroplasty with gentamicin allergy, uncemented revision arthroplasty or change to gentamicin-free BC provides significant symptom relief.

Antibiotic containing bone cement in prevention of hip and knee prosthetic joint infections: A systematic review and meta-analysis

BACKGROUND

Prosthetic joint infection (PJI) is the most serious total joint arthroplasty (TJA) complication despite several aseptic and antiseptic preventive measures. There is no clear evidence or even consensus, whether antibiotic-loaded bone cement (ALBC) should be used, in addition to systemic short-term routine antibiotic prophylaxis, to reduce the risk of PJI in primary TJA. We aimed to analyze the efficacy of ALBC for prevention of PJI in patients undergoing primary TJA.

METHODS

We searched systematically for randomized controlled trials (RCTs) in PubMed, Scopus, Embase, Web of Science and Cochrane library. Two reviewers independently screened potentially eligible studies according to predefined selection criteria and assessed the risk of bias using a modified version of the Cochrane risk of bias tool. PJI was prespecified as the primary outcome of interest. The meta-analyses were based on risk ratios using random-effects model per default. For the purpose of sensitivity, the corresponding fixed effects model odds ratios were calculated with the use of the Peto method as well. To evaluate a potential difference in effect sizes using different types (subgroups) of antibiotics used in bone cement, and at different follow-up periods, we performed stratified meta-analyses.

RESULTS

Thirty-seven studies were eligible for the systematic review and qualitative synthesis, and 9 trials (6507 total joint arthroplasties) were included in this meta-analysis. Overall ALBC significantly reduced the risk of PJI following primary TJAs (RRs, 0.36; 95% CIs, 0.16 to 0.80; P = 0.01) with a moderate degree of inconsistency (I2 = 47%). Based on stratified meta-analyses the use of gentamicin appeared to have a better effect (P = 0.0005) in the total hip arthroplasty. Pooled data of different antibiotics used in knee arthroplasties showed a significant association of cefuroxime (RRs, 0.08; 95% CIs, 0.01 to 0.63; P = 0.02). Further, ALBCs significantly reduced the PJI at one and two years of follow-up (P = 0.03 and P = 0.005 respectively).

CONCLUSIONS

The evidence suggests that ALBCs are effective in reducing the PJI following primary TJA; i.e. between 20 and 84% reduced risk. However, the clear limitations of the available trial evidence highlight the need for joint-specific confirmatory trials, that will need to be designed as cluster-randomized trials of clinics in countries with well-functioning arthroplasty registries.The translational potential of this article: This meta-analysis highlights the prophylactic potential of ALBCs in lowering the risk of infection following primary hip or knee arthroplasties but emphasizes the need for more recent confirmatory trials.

Local delivery of tobramycin and vancomycin in primary total knee arthroplasty achieves minimum inhibitory concentrations for common bacteria causing acute prosthetic joint infection

AIMS

The aim of this study was to determine if the local delivery of vancomycin and tobramycin in primary total knee arthroplasty (TKA) can achieve intra-articular concentrations exceeding the minimum inhibitory concentration thresholds for bacteria causing acute prosthetic joint infection (PJI).

METHODS

Using a retrospective single-institution database of all primary TKAs performed between January 1 2014 and May 7 2019, we identified patients with acute PJI that were managed surgically within 90 days of the initial procedure. The organisms from positive cultures obtained at the time of revision were tested for susceptibility to gentamicin, tobramycin, and vancomycin. A prospective study was then performed to determine the intra-articular antibiotic concentration on postoperative day one after primary TKA using one of five local antibiotic delivery strategies with tobramycin and/or vancomycin mixed into the polymethylmethacrylate (PMMA) or vancomycin powder.

RESULTS

A total of 19 patients with acute PJI after TKA were identified and 29 unique bacterial isolates were recovered. The mean time to revision was 37 days (6 to 84). Nine isolates (31%) were resistant to gentamicin, ten (34%) were resistant to tobramycin, and seven (24%) were resistant to vancomycin. Excluding one Fusobacterium nucleatum, which was resistant to all three antibiotics, all isolates resistant to tobramycin or gentamicin were susceptible to vancomycin and vice versa. Overall, 2.4 g of tobramycin hand-mixed into 80 g of PMMA and 1 g of intra-articular vancomycin powder consistently achieved concentrations above the minimum inhibitory concentrations of susceptible organisms.

CONCLUSION

One-third of bacteria causing acute PJI after primary TKA were resistant to the aminoglycosides commonly mixed into PMMA, and one-quarter were resistant to vancomycin. With one exception, all bacteria resistant to tobramycin were susceptible to vancomycin and vice versa. Based on these results, the optimal cover for organisms causing most cases of acute PJI after TKA can be achieved with a combination of tobramycin mixed in antibiotic cement, and vancomycin powder. Cite this article: Bone Joint J 2020;102-B(6 Supple A):163-169.

A review of calcium phosphate cements and acrylic bone cements as injectable materials for bone repair and implant fixation

Treatment of bone defects caused by trauma or disease is a major burden on human healthcare systems. Although autologous bone grafts are considered as the gold standard, they are limited in availability and are associated with post-operative complications. Minimally invasive alternatives using injectable bone cements are currently used in certain clinical procedures, such as vertebroplasty and balloon kyphoplasty. Nevertheless, given the high incidence of fractures and pathologies that result in bone voids, there is an unmet need for injectable materials with desired properties for minimally invasive procedures. This paper provides an overview of the most common injectable bone cement materials for clinical use. The emphasis has been placed on calcium phosphate cements and acrylic bone cements, while enabling the readers to compare the opportunities and challenges for these two classes of bone cements. This paper also briefly reviews antibiotic-loaded bone cements used in bone repair and implant fixation, including their efficacy and cost for healthcare systems. A summary of the current challenges and recommendations for future directions has been brought in the concluding section of this paper.

The cost-effectiveness of antibiotic-loaded bone cement versus plain bone cement following total and partial knee and hip arthroplasty

Background

Postoperative infection is one of the most prevalent complications following total joint arthroplasty (TJA). As such procedures become more prevalent, it is imperative that we develop new prophylactic methods to prevent the need for revision procedures. In recent years, surgeons have opted to use antibiotic-loaded bone cement (ALBC) rather than plain bone cement (PBC) in primary hip and knee replacements due to its theoretical potential of lowering infection rates. However, the cost-effectiveness of this intervention remains in question.Questions/Purposes: To determine the rate of infection and cost-effectiveness of antibiotic-loaded bone cement as compared to plain bone cement in hip and knee arthroplasty.

Patients and methods

We reviewed 4116 primary hip and knee arthroplasty cases performed between 2016 and 2018 at Morristown Medical Center in New Jersey. Data regarding demographics, complications, and any readmissions due to deep infection were collected retrospectively. During that time period there were a total of 4016 knee cases (423 ALBC, 3593 PBC) and 123 hip cases (63 ALBC, 60 PBC). The average cost for one bag of antibiotic-loaded bone cement and plain bone cement for hip and knee arthroplasty was $336.42 and $72.14, respectively. A statistical analysis was performed using Fisher's exact test; the National Healthcare Safety Network (NHSN) surgical site infection guidelines were used to distinguish between superficial and deep infections.

Results

Ten patients were readmitted due to deep infection, all of whom had undergone total knee arthroplasty. Of those cases, plain bone cement was used for the index procedure in seven instances and antibiotic-loaded cement was used in three. This resulted in an infection rate of 0.19% and 0.62%, respectively, p = 0.103. There was no statistically significant difference in infection rates between the two groups. A total of 778 bags of ALBC were used in 423 knee surgeries, and 98 bags of ALBC were used in 63 hip cases. The total cost for ALBC in TKA and THA procedures was $261,734.76 (778*336.42) and $32,969.16 (98*336.42), respectively. If PBC had been used during all index procedures, it would have resulted in a total savings of $231,509.28.

Conclusions

Antibiotic-loaded cement did not significantly reduce the rate of infection for either knee or hip arthroplasty. Thus, the routine use of antibiotic-loaded cement in primary hip and knee arthroplasty may be an unnecessary financial burden to the healthcare system. A larger sample size and a randomized controlled trial would help confirm our findings and would provide further information on the cost-effectiveness of ALBC cement versus PBC.Significance/Clinical Relevance: In this review of cases performed from 2016 to 2018 there was no statistically significant difference between the rate of infection and the need for revision surgeries for patients treated with ALBC versus PBC. As hospital systems continue to transition towards a bundled payment model, it becomes imperative for providers to reduce any unnecessary costs in order to increase quality and efficiency. We estimate that our hospital system could save nearly $120,000/year by using plain bone cement instead of antibiotic-loaded cement.

Antibiotic-loaded bone cement is associated with a lower risk of revision following primary cemented total knee arthroplasty: an analysis of 731,214 cases using National Joint Registry data

AIMS

Antibiotic-loaded bone cements (ALBCs) may offer early protection against the formation of bacterial biofilm after joint arthroplasty. Use in hip arthroplasty is widely accepted, but there is a lack of evidence in total knee arthroplasty (TKA). The objective of this study was to evaluate the use of ALBC in a large population of TKA patients.

MATERIALS AND METHODS

Data from the National Joint Registry (NJR) of England and Wales were obtained for all primary cemented TKAs between March 2003 and July 2016. Patient, implant, and surgical variables were analyzed. Cox proportional hazards models were used to assess the influence of ALBC on risk of revision. Body mass index (BMI) data were available in a subset of patients.

RESULTS

Of 731 214 TKAs, 15 295 (2.1%) were implanted with plain cement and 715 919 (97.9%) with ALBC. There were 13 391 revisions; 2391 were performed for infection. After adjusting for other variables, ALBC had a significantly lower risk of revision for any cause (hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.77 to 0.93; p < 0.001). ALBC was associated with a lower risk of revision for all aseptic causes (HR 0.85, 95% CI 0.77 to 0.95; p < 0.001) and revisions for infection (HR 0.84, 95% CI 0.67 to 1.01; p = 0.06). The results were similar when BMI was added into the model, and in a subanalysis where surgeons using only ALBC over the entire study period were excluded. Prosthesis survival at ten years for TKAs implanted with ALBC was 96.3% (95% CI 96.3 to 96.4) compared with 95.5% (95% CI 95.0 to 95.9) in those implanted with plain cement. On a population level, where 100 000 TKAs are performed annually, this difference represents 870 fewer revisions at ten years in the ALBC group.

CONCLUSION

After adjusting for a range of variables, ALBC was associated with a significantly lower risk of revision in this registry-based study of an entire nation of primary cemented knee arthroplasties. Using ALBC does not appear to increase midterm implant failure rates. Cite this article: Bone Joint J 2019;101-B:1331-1347.

Effect of Antibiotic-Impregnated Bone Cement in Primary Total Knee Arthroplasty

BACKGROUND

The purpose of this study is to evaluate the effect of commercially available antibiotic-impregnated bone cement (AIBC) on (1) prosthetic joint infections (PJIs) and (2) surgical site infections (SSIs) after primary total knee arthroplasty (TKA).

METHODS

A review of primary TKAs between 2014 and 2017 from an institutional database was conducted. This identified 12,541 cases which were separated into AIBC (n = 4337) and non-AIBC (8,164) cohorts. Medical records were reviewed for PJIs and SSIs (mean 2-year postoperative period). Infection rates between the cohorts were compared with univariate analyses followed by subanalysis of high risk patients (defined as having 2 or more of the following characteristics: >65 years, body mass index >40, or Charlson Comorbidity Index score >3). To control for confounders, multivariate analyses were performed with regression models adjusted for age, gender, body mass index, comorbidities, year, operative times, and lengths of stay.

RESULTS

On univariate analysis, PJI rates were higher in the AIBC cohort (1.0%) compared to the non-AIBC cohort (0.5%, P < .001). Subanalysis of the high risk patients also showed that PJI rates were higher in the AIBC cohort (1.9% vs 0.6%, P < .01). After adjusting for potential confounders, no significant associations between PJIs and AIBC use were found (odds ratio 1.4, 95% confidence interval 0.9-2.3, P = .133). Similarly, no significant differences in SSI rates were observed between the AIBC (2.9%) and non-AIBC cohorts (2.4%, P = .060) and no significant associations between SSIs and AIBC were found with multivariate analysis (odds ratio 1.0, 95% confidence interval CI 0.8-1.3, P = .948).

CONCLUSION

This study found that there was no clinically or statistically significant decrease in infection rates with AIBC in primary TKAs.

Antibiotic-Loaded Bone Cement in Primary Total Knee Arthroplasty: Utilization Patterns and Impact on Complications Using a National Database

BACKGROUND

The routine usage of antibiotic-loaded bone cement (ALBC) in primary total knee arthroplasty (TKA) is controversial. Its effectiveness in reducing infection risk remains unclear while high-dose antibiotics can lead to multiple adverse effects. The purpose of this population-based study is to evaluate utilization patterns of ALBC in primary TKA and its impact on clinical outcomes.

METHODS

This retrospective cohort study used data from the nationwide Premier Healthcare claims database (2006-2016). Multivariable models estimated associations between ALBC use and early postoperative infection, kidney injury, allergic reaction, hospital readmission, cost, and length of stay.

RESULTS

ALBC was used in 27.2% of all primary TKAs (N = 1,184,270). Usage increased from 17.3% to 30.2% in 2006-2010, then plateaued. Study covariates differed minimally between groups, suggesting nonselective ALBC use. Utilization was lower in rural (21.4%) and higher in large (>500 beds; 29.4%) hospitals. After adjusting for relevant covariates, ALBC use was associated with significantly decreased odds for early postoperative infection (odds ratio, 0.89; confidence interval, 0.83-0.96) and increased odds for acute kidney injury (odds ratio, 1.06; confidence interval, 1.02-1.11).

CONCLUSION

With utilization rates of around 30%, we found that ALBC reduced odds for early postoperative infection and increased odds for kidney injury. Strong consideration should be given for selective use of ALBC in primary TKA.

Influence of Fixation Methods on Prosthetic Joint Infection Following Primary Total Knee Replacement: Meta-Analysis of Observational Cohort and Randomised Intervention Studies

The type of fixation used in primary total knee replacement (TKR) may influence the risk of prosthetic joint infection (PJI). We conducted a systematic review and meta-analysis to assess published evidence linking type of fixation (cemented, uncemented, or hybrid) with the risk of PJI following primary TKR. Randomised controlled trials (RCTs) and observational cohort studies comparing fixation methods and reporting PJI incidence following primary TKR were identified in MEDLINE, Embase, Web of Science, and Cochrane Library up until November 2018. Summary measures were relative risks (RR) with 95% confidence intervals (CIs). We identified 32 eligible articles (24 observational studies and 8 RCTs) involving 1,161,292 TKRs. In pooled analysis of observational studies, uncemented fixation was associated with a decreased overall PJI risk when compared with cemented fixation at 0.76 (0.64–0.89). Comparing antibiotic-loaded cemented fixation with plain cement, there was no significant difference in overall PJI risk at 0.95 (0.69–1.31), but PJI risk was increased in the first 6-month postoperative period to 1.65 (1.12–2.43). Limited data from RCTs showed no differences in PJI risk among the fixation types. Observational evidence suggests uncemented fixation may be associated with lower PJI risk in primary TKR when compared with cemented fixation. In the early postoperative period, antibiotic-loaded cemented fixation may be associated with increased PJI risk when compared with plain cement. This may either reflect appropriate selection of higher risk patients for the development of PJI to cemented and antibiotic-loaded cement or may reflect a lower PJI risk in uncemented TKR due to factors such as shorter operative time.

The Hidden Cost of Commercial Antibiotic-Loaded Bone Cement: A Systematic Review of Clinical Results and Cost Implications Following Total Knee Arthroplasty

BACKGROUND

The purpose of this systematic review is to compare deep prosthetic joint infections (PJIs) between total knee arthroplasty (TKA) patients treated with either antibiotic-loaded bone cement (ALBC) or plain bone cement, and to explore the potential cost implications of commonly used bone cement regimens. We hypothesized that ALBC would not substantially reduce PJIs and would thereby present an unnecessary cost to the healthcare system.

METHODS

Using the PRISMA guidelines, we reviewed articles through May 2017 involving primary TKA patients with both ALBC cohort and plain bone cement cohort. A meta-analysis was performed comparing the prevalence of deep infections between cohorts. A cost comparison for a hypothetical setting with an annual volume of 1000 TKAs was performed to compare 3 commonly used cement regimens: 2 bags of ALBC used during each case, 1 bag of ALBC with 1 bag of plain cement, and 2 bags of plain cement. Pricing at our institution is $215/bag for commercial ALBC and $60/bag for plain cement.

RESULTS

Eight articles were included with a total of 34,664 patients. ALBC did not reduce the PJI (ALBC = 93/8189, 1.1% vs plain = 251/26,475, 0.9%; P = .09). The estimated costs for the 3 bone cement regimens per 1000 primary TKAs were as follows: 2 bags of ALBC = $430,000/y, 1 bag of ALBC +1 bag of plain cement = $275,000/y, and 2 bags of plain cement = $120,000/y.

CONCLUSION

ALBC did not reduce the prevalence of PJI suggesting that ALBC may be an unnecessary cost to the healthcare system. Hospital systems that perform 1000 TKAs/y could save between $155,000 and $310,000/y by switching to plain cement.

Standardization of Acrylic Bone Cement Mixing Protocols for Total Knee Arthroplasty Results in Cost Savings

Cost reduction is important in total joint replacement surgery. Bone cement is used to fixate implants in most knee replacement procedures. The authors instituted a 4-pronged approach to reduce the cost of cement. Their approach included reducing the cost of the cement powder, changing the type of mixing method, using less antibiotic cement, and decreasing the amount of cement required for smaller implants. The authors evaluated the implementation of this program and measured the overall costs of cementation during knee replacement. A retrospective review of total knee replacement cementation technique and cost was performed before and after the cost-reduction program was implemented. The type of cement and cement mixing equipment used, the amount of cement used, and the cost of cement and cement mixing equipment were examined. The authors also reported the short-term complication rate including 90-day readmission rate and 30-day revision rate. The program resulted in an overall decrease in cement-related costs from approximately $310 to $105 per case. Reductions in the amount of cement used and the use of antibiotic cement were shown. Among the 3 surgeons, adoption of the program varied. Bone cement is an expense of modern total knee replacement. Implementing a cost-reduction program can reduce cement costs without changing quality of cementation. [Orthopedics. 2018; 41(5):e671-e675.].

Intraoperative Considerations for Treatment/Prevention of Prosthetic Joint Infection

PURPOSE OF REVIEW

Innovative measures have recently been proposed to prevent periprosthetic joint infection following total hip and knee arthroplasty. We sought to review these recent innovations to determine the reported reduction in periprosthetic joint infection.

RECENT FINDINGS

The most recent literature demonstrates promising results in regard to hydrofiber dressings as an independent risk factor for primary prosthetic joint infection reduction, which in turn is also linked with cost savings. As our understanding of safe yet effective concentrations of antiseptic solutions develops, dilute betadine in particular has demonstrated encouraging efficacy which warrants continued investigation through controlled trials. In summary, we found that the application of a hydrofiber dressing may prove beneficial in decreasing the risk of prosthetic joint infection following primary total hip and knee arthroplasty. The gold standard for an infection prevention protocol continues to be explored and optimized.

What is the Intraarticular Concentration of Tobramycin Using Low-dose Tobramycin Bone Cement in TKA: An In Vivo Analysis?

BACKGROUND

Antibiotic-impregnated bone cement has increased in popularity as an effort to reduce the risk of infection in high-risk TKAs. However, limited data has been reported regarding antibiotic levels achieved when using tobramycin-impregnated bone cement after implanting total knee components.

QUESTIONS/PURPOSES

We asked: (1) What is the tobramycin serum and knee intraarticular levels in patients undergoing primary TKA using tobramycin cement? (2) What is the intraarticular tobramycin level for patients receiving only intravenous tobramycin?

METHODS

All patients undergoing primary TKA by one of the two study surgeons (GV, JP) during a 6-month period were evaluated for inclusion and invited to participate. The study enrolled 15 patients undergoing primary TKA by one of two surgeons (GV, JP) who met inclusion criteria; treatment allocation was assigned randomly through blinded envelope. The study group consisted of 10 patients whose components were implanted using a commercially prepared low-dose tobramycin bone cement mixture (1 g/40 g). The control group consisted of five patients who received standard weight-based dose intravenous tobramycin. Samples of serum and Hemovac^® drain-collected intraarticular hematoma were analyzed at 6, 24, and 48 hours postoperatively. Tobramycin levels were measured using an immunoassay technique with a low-end sensitivity of 0.28 μg/mL. Mann-Whitney U tests were performed to compare the serum and intraarticular tobramycin concentrations at each time in the independent variable of group (Control and Study).

RESULTS

The median (interquartile range [IQR]) intraarticular tobramycin concentrations for the study group, with tobramycin-impregnated bone cement, was 31.8 (29.0) μg/mL at 6 hours, 17.1 (13.1) μg/mL at 24 hours, and 6.8 (6.8) μg/mL at 48 hours. The intraarticular tobramycin concentrations of this study group were larger than those for the control group at 6 hours (median = 1.3; IQR = 0.7; p = 0.002), 24 hours (median = 1.3, IQR = 1.0; p = 0.002), and 48 hours (median = 1.4; IQR = 1.0; p = 0.02). The serum concentrations for the tobramycin-impregnated bone cement group were 0.3 μg/mL or less for all samples whereas serum concentrations and median (IQR) for the control group were 1.2 (2.6) μg/mL, 1.6 (4.4) μg/mL, and 2.0 (3.3) μg/mL at 6, 24, and 48 hours respectively. The serum levels for the tobramycin-impregnated cement group were less than those for the control group at 6 hours (p = 0.001), 24 (p = 0.001), and 48 hours (p < 0.001).

CONCLUSIONS

Tobramycin-impregnated bone cement provides a way to deliver antibiotics in patients undergoing TKA. This supratherapeutic short-term prophylactic perioperative antibiotic local delivery can be achieved with limited systemic absorption, whereas joint tobramycin levels were less than therapeutic levels when given intravenously alone. In the control group, with only intravenous tobramycin, a subtherapeutic (< 2.0 μg/mL) level of tobramycin was found in all the intraarticular samples at 6, 24, and 48 hours. Based on the evidence obtained in this study, commercially prepared low-dose tobramycin bone cement can be used to obtain short-term supratherapeutic local concentrations in the knee while maintaining serum tobramycin levels at a minimum.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Antibiotic-loaded bone cement reduces risk of infections in primary total knee arthroplasty? A systematic review

PURPOSE

Antibiotic-loaded bone cement has been widely used for the treatment of infected knee replacement, but its routine use in primary TKA remains controversial. The aim of this systematic review was to analyze the literature about the antimicrobial efficacy and safety of antibiotic-loaded bone cement for its prophylactic use in primary TKA.

METHODS

A detailed and systematic search of the Pubmed, Medline, Cochrane Reviews and Google Scholar databases had been performed using the keyword "total knee arthroplasty" "total knee replacement" "total knee prosthesis" and "antibiotic-loaded bone cement" with no limit regarding the year of publication. We used modified Coleman scoring methodology (mCMS) to identify scientifically sound articles in a reproducible format. The review was limited to the English-language articles.

RESULTS

Six articles met inclusion criteria. In total, 6318 arthroplasties were included in our study. 3217 of these arthroplasties received antibiotic-loaded bone cement and 3101 arthroplasties served as the control. There was no statistical difference between the two groups in terms of the incidence of deep or superficial surgical site infection. The average mCMS score was 67.6, indicating good methodological quality in the included studies.

CONCLUSIONS

Present review did not reveal any significant difference in terms of rate of deep or superficial surgical site infection in patients receiving antibiotic-loaded bone cement compared with the control (plain bone cement) during primary TKA. The clinical relevance of this study was that the use of antibiotic-loaded bone cement did not significantly reduce the risk of infection in primary TKA.

LEVEL OF EVIDENCE

III.

The impact of patient and surgical factors on the rate of infection after primary total knee arthroplasty: an analysis of 64,566 joints from the New Zealand Joint Registry

AIMS

The aim of this study was to identify risk factors for prosthetic joint infection (PJI) following total knee arthroplasty (TKA).

PATIENTS AND METHODS

The New Zealand Joint Registry database was analysed, using revision surgery for PJI at six and 12 months after surgery as primary outcome measures. Statistical associations between revision for infection, with common and definable surgical and patient factors were tested.

RESULTS

A total of 64 566 primary TKAs have been recorded on the registry between 1999 and 2012 with minimum follow-up of 12 months. Multivariate analysis showed statistically significant associations with revision for PJI between male gender (odds ratio (OR) 1.85, 95% confidence interval (CI) 1.24 to 2.74), previous surgery (osteotomy (OR 2.45 95% CI 1.2 to 5.03), ligament reconstruction (OR 1.85, 95% CI 0.68 to 5.00)), the use of laminar flow (OR 1.6, 95% CI 1.04 to 2.47) and the use of antibiotic-laden cement (OR 1.93, 95% CI 1.19 to 3.13). There was a trend towards significance (p = 0.052) with the use of surgical helmet systems at six months (OR 1.53, 95% CI 1.00 to 2.34).

CONCLUSION

These findings show that patient factors remain the most important in terms of predicting early PJI following TKA. Furthermore, we found no evidence that modern surgical helmet systems reduce the risk of PJI and laminar flow systems may actually increase risk in TKA. The use of this registry data assists the estimation of the risk of PJI for individual patients, which is important for both informed consent and the interpretation of infection rates at different institutions.

TAKE HOME MESSAGE

Infection rates in TKA are related to both individual patient and surgical factors, and some modern methods of reducing infection may actually increase infection risk.

Use of antibiotic-loaded cement in total knee arthroplasty

Bone cement has the capacity to release antibiotic molecules if any antibiotic is included in it, and these elution properties are improved as cement porosity is increased. In vitro studies have shown high local antibiotic concentration for many hours or few days after its use. Antibiotic loaded bone cement (ALBC) is helpful when treating an infection in total knee arthroplasty (TKA) revision surgery. The purpose of this paper was to review the evidence for the routine use of ALBC in TKA in the literature, its pros and cons. Many authors have recommended the use of ALBC also in primary TKA for infection prophylaxis, but the evidence based on data from National Registries, randomized clinical trials and meta-analysis suggest a protective effect of ALBC against infection when used in hips, but not (or only mild) in knees. A possible explanation to this finding is that the duration and quantity of locally elevated antibiotic levels after surgery are smaller in TKA, due to the smaller amount of cement used for fixation in TKA-only a layer in the bone surface. There are some concerns about the routine use of ALBC in primary TKA as prophylaxis against infection: Firstly, there is a risk of hypersensivity or toxicity even when the chance is highly improbable. Secondly, there is a reduction in the mechanical properties of the cement, but this can be probably neglected if the antibiotic is used in low doses, not more than 1 g per 40 g cement package. Another significant concern is the increased economic cost, which could be overlooked if there were enough savings in treating fewer prosthetic infections. Finally, there is also a risk of selection of antibiotic-resistant strains of bacteria and this could be the main concern. If used, the choice of the antibiotic mixed in ALBC should consider microbiological aspects (broad antimicrobial spectrum and low rate of resistant bacteria), physical and chemical aspects (thermal stability, high water solubility), pharmacological characteristics (low risk to allergic reactions or toxicity) and economic aspects (not too expensive). The most commonly used antibiotics in ALBC are gentamicin, tobramycin and vancomycin. In conclusion, there is a paucity of randomized clinical trials in the use of ALBC in primary TKAs and the actual evidence of the effect of ALBC in reducing the risk of infection is insufficient. This, in addition to concerns about patient safety, risks of increase in the antibiotic resistance of microorganisms and the increase in costs in the procedure, lead us to recommend a cautious use of ALBC, perhaps only in high-risk patients (immunocompromised, morbidly obese, diabetic and patients with previous history of fracture or infection around the knee) unless the benefits of ALBC use were fully proven. Meanwhile, the rigorous use of peri-operative prophylactic systemic antibiotics and adoption of efficient antiseptic procedures and improved surgical techniques must be considered the gold standard in infection prevention in TKA surgery.