Risk factors for revision due to infection after primary total hip arthroplasty. A population-based study of 80,756 primary procedures in the Danish Hip Arthroplasty Registry

Validation of the Incidence of Reported Periprosthetic Joint Infections in Total Hip and Knee Arthroplasty in the Dutch Arthroplasty Register

BACKGROUND

Arthroplasty registers underreport the incidence of periprosthetic joint infections (PJIs). We validated the incidence of reported PJIs in total hip arthroplasties (THAs) and total knee arthroplasties (TKAs) in the Dutch Arthroplasty Register (LROI) using data from the Dutch National Nosocomial Surveillance Network (PREZIES).

METHODS

All primary THAs and TKAs from the LROI and all primary THAs and TKAs performed in consenting hospitals from PREZIES between 2012 and 2018 were matched on date of birth, date of surgery, sex, hospital, and type of procedure (THA n = 91,208; TKA n = 80,304). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for PJIs registered in the LROI, using PREZIES as a reference.

RESULTS

The incidence of registered PJIs in THAs was 1.2% in PREZIES and 0.5% in the LROI. For TKAs, this was 0.7 and 0.4%, respectively. The PJIs in THAs in the LROI had a sensitivity of 0.32 (confidence interval [CI]: 0.29 to 0.35), specificity of 1.00 (CI: 1.00 to 1.00), PPV of 0.74 (CI: 0.70 to 0.78), and NPV of 0.99 (CI: 0.99 to 0.99). In TKAs, the sensitivity, specificity, PPV, and NPV were 0.38 (CI: 0.34 to 0.42), 1.00 (CI: 1.00 to 1.00), 0.65 (CI: 0.59 to 0.70), and 1.00 (CI: 1.00 to 1.00), respectively.

CONCLUSIONS

The LROI captures approximately one-third of the PJIs as revision within one year for infection or resection arthroplasty. The capture rate of PJIs can be improved by including all reoperations without component exchange and nonsurgical treatments with antibiotics only.

No Association Between Previous General Infection and Prosthetic Joint Infection After Total Hip Arthroplasty-A National Register-Based Cohort Study on 58,449 Patients Who Have Osteoarthritis

BACKGROUND

Prosthetic joint infection (PJI) following total hip arthroplasty (THA) is a complication associated with increased risk of death. There is limited knowledge about the association between infection before THA, and risk of revision due to PJI. We investigated the association between any previous hospital-diagnosed or community-treated infection 0 to 6 months before primary THA and the risk of revision.

METHODS

We obtained data on 58,449 patients who were operated with primary unilateral THA between 2010 and 2018 from the Danish Hip Arthroplasty Register. Information on previous infection diagnoses, redeemed antibiotic prescriptions up to 1 year before primary THA, intraoperative biopsies, and cohabitations was retrieved from Danish health registers. All patients had a 1-year follow-up. Primary outcome was revision due to PJI. Secondary outcome was any revision. We calculated the adjusted relative risk with 95% confidence intervals (CI), treating death as competing risk.

RESULTS

Among 1,507 revisions identified, 536 were due to PJI with a cumulative incidence of 1.0% ([CI] 0.9 to 1.2) and 0.9% ([CI] 0.8 to 1.0) for patients who did and did not have previous infection. For any revision, the cumulative incidence was 3.1% ([CI] 2.9 to 3.4) and 2.4% ([CI] 2.3 to 2.6) for patients who did and did not have previous infection. The adjusted relative risk for PJI revision was 1.1 ([CI] 0.9 to 1.4) and for any revision 1.3 ([CI] 1.1 to 1.4) for patients who did have previous infection compared to those who did not.

CONCLUSION

Previous hospital-diagnosed or community-treated infection 0 to 6 months before primary THA does not increase the risk of PJI revision. It may be associated with increased risk of any revision.

Management of septic arthritis and prosthetic joint infection

Management of joint infection is an evolving topic. This article reviews the literature on the management of native and prosthetic joint infection and suggests some areas of improvement in short- and long-term management which could lead to better patient outcomes. Surgical management is the mainstay of treatment for native or prosthetic knee infection and aspiration should only be used for diagnostic purposes. A multidisciplinary team approach and compliance with national guidelines, alongside referral networks and pooling of expertise, should be mandatory to improve patient outcomes.

Impact of spinal Anaesthesia versus general Anaesthesia on the incidence of surgical site infections after knee or hip arthroplasty: A meta-analysis

Postoperative Surgical Site Infections (SSIs) pose significant challenges to recovery after joint arthroplasty. This systematic review and meta-analysis aim to compare the incidence of SSIs after knee or hip arthroplasty under Spinal Anaesthesia (SA) versus general anaesthesia (GA). We conducted the systematic review and meta-analysis following the PRISMA guidelines, analysing data from 15 studies selected from PubMed, Embase, Web of Science, and Cochrane Library up to May 16, 2023. The analysis included studies comparing SSIs incidence in patients aged 18 years and above who underwent knee or hip arthroplasty under SA or GA. Quality assessment was performed using the Cochrane Collaboration's risk of bias tool. The effect size was calculated using random or fixed-effects models based on the observed heterogeneity. We assessed the heterogeneity between studies and conducted a sensitivity analysis. Of 1651 initially identified studies, 15 articles encompassing 353 169 patients were included in the final analysis. A total of 156 405 patients were under SA, while 196 764 received GA. The studies demonstrated substantial heterogeneity (p = 0.007, I2  = 53.7%), resulting in a random-effects model being employed. Patients receiving SA showed a 23% lower likelihood of developing SSIs postoperatively compared to GA patients (OR: 0.77, 95% CI: 0.70-0.86, p < 0.001). Sub-group analysis further confirmed these findings regardless of the type of joint arthroplasty. This meta-analysis indicated a significantly lower incidence of SSIs following knee or hip arthroplasty under SA compared to GA. Despite observed heterogeneity, the results underscore the potential benefit of SA over GA in orthopaedic surgeries to reduce the risk of SSIs.

Cost-effectiveness of a novel, fluoroscopy-based robotic-assisted total hip arthroplasty system: A Markov analysis

BACKGROUND

The purpose of this study was to assess the cost-effectiveness of a novel, fluoroscopy-based robotic-assisted total hip arthroplasty (RA-THA) system compared to a manual unassisted technique (mTHA) up to 5 years post-operatively.

METHODS

A Markov model was constructed to compare the cost-effectiveness of RA-THA and mTHA. Cost-effectiveness was defined as an Incremental Cost-Effectiveness Ratio (ICER) <$50 000 or $100 000 per Quality Adjusted Life Year (QALY).

RESULTS

RA-THA patients experienced lower costs compared to mTHA patients at 1 year ($20 865.12 ± 9897.52 vs. $21 660.86 ± 9909.15; p < 0.001) and 5 years ($23 124.57 ± 10 045.48 vs. $25 756.42 ± 10 091.84; p < 0.001) post-operatively. RA-THA patients also accrued more QALYs (1-year: 0.901 ± 0.117 vs. 0.888 ± 0.114; p < 0.001; 5-years: 4.455 ± 0.563 vs. 4.384 ± 0.537 p < 0.001). Overall, RA-THA was cost-effective (1-year ICER: $-61 210.77; 5-year ICER: $-37 068.31).

CONCLUSIONS

The novel, fluoroscopy-based RA-THA system demonstrated cost-effectiveness when compared to manual unassisted THA.

Patient-related risk factors of prosthetic joint infections following total hip and knee arthroplasty at King Abdulaziz Medical City, a 10-year retrospective study

BACKGROUND

Total joint arthroplasty (TJA) can be associated with the development of periprosthetic joint infection (PJI). It is necessary to determine the modifiable and non-modifiable risk factors of PJI to provide optimum healthcare to TJA candidates.

METHODS

This single-center retrospective review investigated 1198 patients who underwent TJA from 2012 to 2022. The data analysis comprised two stages. The first stage was a descriptive analysis, while the second stage was a bivariate analysis. The sociodemographic data, medical history, operative details, and presence of PJI postoperatively were evaluated.

RESULTS

The study sample consisted of 1198 patients who underwent TJA. The mean patient age was 63 years. Among the patients, only 1.3% had PJI. No comorbidity was significantly related to PJI. General anesthesia was used in almost 21% of the patients and was significantly associated with a higher risk of infection (p = 0.049). An increased operative time was also significantly related to PJI (p = 0.012). Conversely, tranexamic acid (TXA) administration was a protective factor against PJI (p = 0.017).

CONCLUSION

Although PJI is not a common complication of TJA, multiple risk factors such as general anesthesia and prolonged operative time play a significant role in its development. In contrast, TXA administration is thought to reduce the risk of PJI effectively.

The Role of Single Positive Cultures in Presumed Aseptic Total Hip and Knee Revision Surgery-A Systematic Review of the Literature

(1) Background: Prior to revision hip (THA) or knee arthroplasty (TKA), periprosthetic low-grade infection (PJI) should be ruled out. Despite advances in preoperative diagnosis, unsuspected positive cultures (UPCs) may occur in initially planned aseptic revisions. Particularly, single UPCs pose a diagnostic and therapeutic dilemma, as their impact on outcome is unclear and recommendations are heterogeneous. This review investigates the frequency of single UPCs and their impact on implant survivorship. (2) Methods: In July 2022, a comprehensive literature search was performed using PubMed and Cochrane Library search. In total, 197 articles were screened. Seven retrospective studies with a total of 5821 cases were able to be included in this review. (3) Results: Based on the cases included, UPCs were found in 794/5821 cases (14%). In 530/794 cases (67%), the majority of the UPCs were single positive. The most commonly isolated pathogens were coagulase negative Staphylococci and Cutibacterium acnes. Five of seven studies reported no influence on revision- or infection-free survival following a single positive culture. In two studies, single UPCs following THA revision were correlated with subsequent re-revision for PJI. (4) Conclusions: Single UPCs of a non-virulent pathogen following presumed aseptic TKA revision may be interpreted as contaminants. A single UPC following THA revision may be a risk factor for subsequent PJI. The role of systemic antibiotic treatment remains unclear, but it should be considered if other risk factors for PJI are present.

A retrospective study of risk factors, causative micro-organisms and healthcare resources consumption associated with prosthetic joint infections (PJI) using the Clinical Practice Research Datalink (CPRD) Aurum database

BACKGROUND

Prosthetic joint infection (PJI) is a serious complication after joint replacement surgery and it is associated with risk of mortality and morbidity along with high direct costs.

METHODS

The Clinical Practice Research Datalink (CPRD) data were utilized to quantify PJI incidence after hip or knee replacement up to 5 years after implant and a variety of risk factors related to patient characteristics, medical and treatment history along with characteristics of the original surgery were analyzed through Cox proportional hazard.

RESULTS

221,826 patients (individual joints 283,789) met all the inclusion and exclusion criteria of the study; during the study follow-up period (5 years), 707 and 695 PJIs were diagnosed in hip and knee, respectively. Patients undergoing joint replacement surgery during an unscheduled hospitalization had greater risk of PJI than patients whose surgery was elective; similarly, the risk of developing PJI after a secondary hip or knee replacement was about 4 times greater than after primary arthroplasty when adjusted for all other variables considered. A previous diagnosis of PJI, even in a different joint, increased the risk of a further PJI. Distribution of average LoS per each hospitalization caused by PJI exhibited a right skewed profile with median duration [IQR] duration of 16 days [8-32] and 13 days [7.25-32] for hip and knee, respectively. PJIs causative micro-organisms were dependent on the time between initial surgery and infection offset; early PJI were more likely to be multispecies than later (years after surgery); the identification of Gram- pathogens decreased with increasing post-surgery follow-up.

CONCLUSIONS

This study offers a contemporary assessment of the budgetary and capacity (number and duration of hospitalizations along with the number of Accident and Emergency (A&E) visits) posed by PJIs in UK for the national healthcare system (NHS). The results to provide risk management and planning tools to health providers and policy makers in order to fully assess technologies aimed at controlling and preventing PJI. The findings add to the existing evidence-based knowledge surrounding the epidemiology and burden of PJI by quantifying patterns of PJI in patients with a relatively broad set of prevalent comorbidities.

Getting it right first time: national survey of surgical site infection 2019

Introduction

Surgical site infections (SSIs) are associated with increased morbidity and mortality. Deep SSI, or prosthetic joint infection (PJI), is associated with revision surgery involving longer operative times with higher infection rates, longer length of stay (LoS) and high costs in addition to the catastrophic effect on the patient. The surveillance of SSI is important for patient decision making, identification of outliers for support and maximising focussed improvement. This paper reports the findings of the second Getting it Right First Time (GIRFT) national SSI survey for orthopaedic and spinal surgery.

Methods

Data were submitted prospectively by 67 orthopaedic units and 22 spinal units between 1 May 2019 and 31 October 2019. For a patient to be included, they had to present with SSI within the study period and within 1 year of the index procedure.

Results

A total of 309 SSIs were reported from primary and revision, total hip, knee, shoulder, elbow and ankle replacements, and 58 SSIs were reported from lumbar spine single level discectomy or decompression, lumbar spine single-level instrumented posterior fusion, posterior cervical spine decompression and instrumented fusion and posterior correction of adolescent idiopathic scoliosis. SSIs rates have remained low compared with the 2017 survey. There were variations in SSI rates by procedure, with primary shoulder replacement reporting the lowest (0.4%) and revision shoulder replacement the highest (2.5%) rates.

Conclusions

The authors recommend that the elective surgical restart following the COVID-19 pandemic provides a unique opportunity for all units to implement a full SSI prevention bundle to minimise the risk of infection and improve patient outcomes.

Preoperative anemia and deep vein thrombosis in patients with perioperative bone trauma: a cohort study

Background

In current active prevention (including physical and drug prevention), the incidence of perioperative deep vein thrombosis (DVT) of the lower extremities remains high in patients with bone trauma. Risk factors need to be further optimized, and high-risk patients must be identified early. Preoperative comorbidities, especially preoperative anemia, and DVT in patients with perioperative bone trauma are not clear. The purpose of this study was to explore the causal relationship between preoperative anemia and DVT in patients with perioperative bone trauma, and further reduce the incidence of DVT in patients with bone trauma.

Objectives

To analyze the relationship between preoperative anemia and perioperative DVT in patients with femoral and pelvic fractures and provide a reference for the optimization of risk factors for DVT.

Methods

The clinical data of 1049 patients with femoral and pelvic fractures who received surgical treatment from May 2018 to June 2021 were retrospectively analyzed. Propensity score matching (PSM) was performed for the covariates of DVT. Modified Poisson regression was used to analyze the relationship between preoperative anemia and DVT.

Results

After matching 1:1 propensity scores in 1049 patients included in this study, there were 258 patients in the anemic and non-anemic groups. Preoperative anemia was statistically significant for the formation of DVT in patients with perioperative bone trauma (P = 0.000, RR = 1.567 [95% CI 1.217–2.017]). This conclusion remained true after PSM (P = 0.009, RR = 1.500 [95% CI 1.105–2.036]). Preoperative anemia has some predictive value for perioperative DVT, with DVT-associated preoperative anemia thresholds of 125 g/L and area under the receiver operating characteristic curve of 0.5877 (95% CI 0.5345 to 0.6408). On this basis, sensitivity and specificity were 89.2 and 30.3%, respectively, with a Youden index of 0.195. In addition, we conducted an E-value determination of the propensity score; the E-value analysis showed robustness to unmeasured confounding.

Conclusions

Preoperative anemia is highly correlated with perioperative DVT in patients with bone trauma, which is the cause of perioperative DVT in these patients.

Unsuspected Positive Cultures in Planned Aseptic Revision Knee or Hip Arthroplasty-Risk Factors and Impact on Survivorship

BACKGROUND

Unsuspected positive cultures (UPCs) may be found at the time of planned aseptic revision surgery and have previously been associated with decreased implant survival. However, reported rates vary greatly, and potential risk factors are widely unknown. This study investigates the rate of UPCs, implant survival, as well as potential risk factors for UPCs and revision.

METHODS

This is a retrospective, single-center study on 434 cases of total hip arthroplasty (THA 277) and knee revision arthroplasty (TKA 157) performed between 2010 and 2017. Microbiology culture results, revision-free survival (RFS) and infection-free (IFS) survival, and the potential impact of UPCs as well as patient- or procedure-related risk factors were investigated at a minimum follow-up of 24 months (median 41 months).

RESULTS

A total of 37% of patients had a positive culture (160/434). 27% (119/434) had a solitary positive culture, and 9% (41/434) had ≥2 positive cultures of the same species. Most commonly, coagulase-negative staphylococci were cultured. Overall, 32% (13/41) of patients with ≥2 positive cultures underwent revision for infection compared with 6% (17/274) of patients with negative cultures. RFS and IFS were reduced if ≥2 cultures were positive. Single positive cultures had no impact on RFS or IFS. Male sex, elevated serum C-reactive protein, and obesity were independently associated with finding ≥2 UPCs in revision THA.

CONCLUSION

Appearance of ≥2 UPCs in aseptic revision leads to reduced RFS and IFS. Males, obese patients, and patients with elevated serum C-reactive protein planned for THA revision should be considered for extended diagnostics to rule out periprosthetic joint infection.

Inhaled Corticosteroids, Vitamin K Antagonists and Amlodipine Were Associated with an Increased Risk of Acute Periprosthetic Joint Infection in Patients with Total Hip Arthroplasty: A Retrospective Case–Cohort Study

The perioperative use of certain medication may influence the risk of developing a periprosthetic joint infection (PJI). Inhaled corticosteroids (ICSs) and cardiovascular drugs are widely used against pulmonary and cardiovascular diseases. While oral corticosteroids and anticoagulants have been shown to increase the risk of developing PJI, this is not clear for ICSs. In contrast, some cardiovascular drugs, such as amlodipine, nifedipine and statins, have been documented to show an antimicrobial effect, suggesting a synergistic effect with antibiotics in the treatment of (multi-resistant) microorganisms. We performed a case–cohort study to assess the association between the occurrence of PJI after THA and the use of inhaled corticosteroids, anticoagulants, or previously mentioned cardiovascular agents. In a cohort of 5512 primary THAs, we identified 75 patients with a PJI (1.4%), and randomly selected 302 controls. A weighted Cox proportional hazard regression model was used for the study design and to adjust for potential confounders (age, sex, smoking, and cardiovascular/pulmonary disease). We found ICS use (HR 2.6 [95% CI 1.1–5.9]), vitamin K antagonist use (HR 5.3 [95% CI 2.5–11]), and amlodipine use (HR 3.1 [95% CI 1.4–6.9]) to be associated with an increased risk of developing PJI after THA. The effect remained after correction for the mentioned possible confounders. The underlying diseases for which the medications are prescribed could also play a role in the mentioned association; we believe, however, that the usages of ICSs, vitamin K antagonists and amlodipine appear to be potential modifiable risk factors for PJI, and therefore have to be questioned during preoperative screening and consultation.

Prediction of Early Periprosthetic Joint Infection After Total Hip Arthroplasty

Purpose

To develop a parsimonious risk prediction model for periprosthetic joint infection (PJI) within 90 days after total hip arthroplasty (THA).

Patients and Methods

We used logistic LASSO regression with bootstrap ranking to develop a risk prediction model for PJI within 90 days based on a Swedish cohort of 88,830 patients with elective THA 2008–2015. The model was externally validated on a Danish cohort with 18,854 patients.

Results

Incidence of PJI was 2.45% in Sweden and 2.17% in Denmark. A model with the underlying diagnosis for THA, body mass index (BMI), American Society for Anesthesiologists (ASA) class, sex, age, and the presence of five defined comorbidities had an area under the curve (AUC) of 0.68 (95% CI: 0.66 to 0.69) in Sweden and 0.66 (95% CI: 0.64 to 0.69) in Denmark. This was superior to traditional models based on ASA class, Charlson, Elixhauser, or the Rx Risk V comorbidity indices. Internal calibration was good for predicted probabilities up to 10%.

Conclusion

A new PJI prediction model based on easily accessible data available before THA was developed and externally validated. The model had superior discriminatory ability compared to ASA class alone or more complex comorbidity indices and had good calibration. We provide a web-based calculator (https://erikbulow.shinyapps.io/thamortpred/) to facilitate shared decision making by patients and surgeons.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/T0qfHTvBEs4

First Detection of Methanogens in Orthopedic Prosthesis Infection: A Four-Case Founding Series

Orthopedic prosthesis infection must be medically managed after appropriate microbiological documentation. While bacteria and fungi are acknowledged to be causative opportunistic pathogens in this situation, the potential role of methanogens in orthopedic prosthesis infections is still unknown. In a retrospective study, a total of 100 joint and bone samples collected from 25 patients were screened by specific PCR assays for the detection of methanogens. PCR-positive samples were observed by autofluorescence, electron microscopy and tentatively cultured under specific culture conditions. Methanogens were detected by quantitative PCR in 4/100 samples, in the presence of negative controls. Sequencing identified Methanobrevibacter oralis in two cases, Methanobrevibacter smithii in one case and Methanobrevibacter wolinii in one case. Microscopic methods confirmed molecular findings and bacterial culture yielded two strains of Staphylococcus aureus, one strain of Staphylococcus epidermidis and one strain of Proteus mirabilis. These unprecedented data highlight the presence of methanogens in joint and bone samples of patients also diagnosed with bacterial orthopedic prosthesis infection, questioning the role of methanogens as additional opportunistic co-pathogens in this situation.

Differences in Infection Rates by Surgical Approach in Total Hip Arthroplasty and Patient Sex: A Systematic Review

Background

There exists conflicting data that patient sex may influence complication and revision rates when undergoing total hip arthroplasty (THA), specifically when comparing different surgical approaches. Differences in body fat or muscular distribution are proposed mechanisms, but these are poorly understood and not well described in current literature.

Methods

A systematic review of the literature was conducted from PubMed, Embase, and Web of Science from inception of the database through September 15, 2020. Studies were included if they included patients undergoing primary elective unilateral THA, delineated infections by surgical approach, and delineated infections by patient sex. Basic science, cadaveric, and animal studies were excluded as were case reports. Two authors screened abstracts and then extracted data from the full text article.

Results

Three studies, including 1,694 patients undergoing 1,811 THA were included. 80 infections were included. No study reported a statistically significant difference in infection risk by patient sex or surgical approach, though there was substantial heterogeneity in study design, approach, and analysis.

Conclusion

Limited data suggests no relationship between sexes across surgical approaches for infection rates. However, poor reporting and small sample sizes preclude definitive conclusions from being drawn. Future studies should emphasize reporting differences in outcomes by patient sex to better elucidate differences, if any, in adverse outcomes between sexes following THA across surgical approaches. Level of Evidence: IV.

Risk factors for prosthetic joint infections following total hip arthroplasty based on 33,337 hips in the Finnish Arthroplasty Register from 2014 to 2018

Background and purpose - Periprosthetic joint infection (PJI) is a devastating complication and more information on risk factors for PJI is required to find measures to prevent infections. Therefore, we assessed risk factors for PJI after primary total hip arthroplasty (THA) in a large patient cohort.Patients and methods - We analyzed 33,337 primary THAs performed between May 2014 and January 2018 based on the Finnish Arthroplasty Register (FAR). Cox proportional hazards regression was used to estimate hazard ratios with 95% confidence intervals (CI) for first PJI revision operation using 25 potential patient- and surgical-related risk factors as covariates.Results - 350 primary THAs were revised for the first time due to PJI during the study period. The hazard ratios for PJI revision in multivariable analysis were 2.0 (CI 1.3-3.2) for ASA class II and 3.2 (2.0-5.1) for ASA class III-IV compared with ASA class I, 1.4 (1.1-1.7) for bleeding > 500 mL compared with < 500 mL, 0.4 (0.2-0.7) for ceramic-on-ceramic bearing couple compared with metal-on-polyethylene and for the first 3 postoperative weeks, 3.0 (1.6-5.6) for operation time of > 120 minutes compared with 45-59 minutes, and 2.6 (1.4-4.9) for simultaneous bilateral operation. In the univariable analysis, hazard ratios for PJI revision were 2.3 (1.7-3.3) for BMI of 31-35 and 5.0 (3.5-7.1) for BMI of > 35 compared with patients with BMI of 21-25.Interpretation - We found several modifiable risk factors associated with increased PJI revision risk after THA to which special attention should be paid preoperatively. In particular, high BMI may be an even more prominent risk factor for PJI than previously assessed.

The reasons for and mortality of patients unable to receive reimplantation after resection arthroplasty for chronic hip periprosthetic infection

BACKGROUND

Two-stage exchange arthroplasty is a feasible treatment for chronic PJI (periprosthetic joint infection) of total hip arthroplasty (THA). However, there are large numbers of patients who are unable to ultimately receive reimplantation after resection arthroplasty owing to uncontrolled infection and multiple comorbidities. The purpose of the current study was to identify patient-related risk factors and reasons for being unable to undergo revision THA.

METHODS

Individuals undergoing resection arthroplasty for chronic PJI treatment from 2013 to 2020 at our institution were retrospectively reviewed. A variety of patient comorbidities, laboratory data, isolated pathogens, and follow-up status were collected for analysis.

RESULTS

A total of 84 patients (46 men and 38 women) with a 2.7 ± 2.1-year follow-up were analyzed. Thirty-eight (45.2%) patients eventually underwent revision THA, while the other 46 (54.8%) did not receive reimplantation during follow-up. The patients without receiving reimplantation had higher Charlson comorbidity index (CCI) score (3.1 ± 2.9 versus 1.2 ± 1.5; p = 0.001). Lower cumulative incidence of receiving reimplantation was observed in patients with chronic kidney disease (log-rank test, p = 0.019), anemia (p = 0.011), presence of initial fever (p = 0.030), and oxacillin-resistant strain infection (p = 0.030). The most common reasons for not receiving reimplantation were uncontrolled infection, unstable medical conditions, and death. The patients without reimplantation had a relatively higher mortality rate (log-rank test, p = 0.002).

CONCLUSION

Chronic hip PJI with poor medical conditions or oxacillin-resistant strain infection decreased the chance of undergoing revision surgery. These patients had unfavourable outcomes and a higher mortality rate after resection arthroplasty.

Patients' risk factors for periprosthetic joint infection in primary total hip arthroplasty: a meta-analysis of 40 studies

BACKGROUND

Periprosthetic joint infection (PJI) is a catastrophic complication after total hip arthroplasty (THA). Our meta-analysis aimed to identify the individual-related risk factors that predispose patients to PJI following primary THA.

METHODS

Comprehensive literature retrieval from Pubmed, Web of Science, and the Cochrane Library was performed from inception to Feb 20th, 2021. Patient-related risk factors were compared as per the modifiable factors (BMI, smoke and alcohol abuse), non-modifiable factors (gender, age), and medical history characteristics, such as diabetes mellitus (DM), avascular necrosis (AVN) of femoral head, femoral neck fracture, rheumatoid arthritis (RA), cardiovascular disease (CVD), and osteoarthritis (OA) etc. The meta-analysis was applied by using risk ratios with 95% corresponding intervals. Sensitivity analysis and publication bias were performed to further assess the credibility of the results.

RESULTS

Overall, 40 studies with 3,561,446 hips were enrolled in our study. By implementing cumulative meta-analysis, higher BMI was found associated with markedly increased PJI risk after primary THA [2.40 (2.01-2.85)]. Meanwhile, medical characteristics including DM [1.64 (1.25-2.21)], AVN [1.65 (1.07-2.56)], femoral neck fracture [1.75 (1.39-2.20)], RA [1.37 (1.23-1.54)], CVD [1.34 (1.03-1.74)], chronic pulmonary disease (CPD) [1.22 (1.08-1.37)], neurological disease [1.19 (1.05-1.35)], opioid use [1.53 (1.35-1.73)] and iron-deficiency anemia (IDA) [1.15 (1.13-1.17)] were also significantly correlated with higher rate of PJI. Conversely, dysplasia or dislocation [0.65 (0.45-0.93)], and OA [0.70 (0.62-0.79)] were protective factors. Of Note, female gender was protective for PJI only after longer follow-up. Besides, age, smoking, alcohol abuse, previous joint surgery, renal disease, hypertension, cancer, steroid use and liver disease were not closely related with PJI risk.

CONCLUSION

Our finding suggested that the individual-related risk factors for PJI after primary THA included high BMI, DM, AVN, femoral neck fracture, RA, CVD, CPD, neurological disease, opioid use and IDA, while protective factors were female gender, dysplasia/ dislocation and OA.

Proton-pump inhibitors are associated with increased risk of prosthetic joint infection in patients with total hip arthroplasty: a case-cohort study

Background and purpose - Proton-pump inhibitors (PPI) have previously been associated with an increased risk of infections such as community-acquired pneumonia, gastrointestinal infections and central nervous system infection. Therefore, we evaluated a possible association between proton-pump inhibitor use and prosthetic joint infection (PJI) in patients with total hip arthroplasty (THA), because they can be stopped perioperatively or switched to a less harmful alternative.Patients and methods - A cohort of 5,512 primary THAs provided the base for a case-cohort design; cases were identified as patients with early-onset PJI. A weighted Cox proportional hazard regression model was used for the study design and to adjust for potential confounders.Results - There were 75 patients diagnosed with PJI of whom 32 (43%) used PPIs perioperatively compared with 75 PPI users (25%) in the control group of 302 patients. The risk of PJI was 2.4 times higher (95% CI 1.4-4.0) for patients using PPI. This effect remained after correction for possible confounders.Interpretation - The use of PPIs was associated with an increased risk of developing PJI after THA. Hence, the use of a PPI appears to be a modifiable risk factor for PJI.

Increasing but levelling out risk of revision due to infection after total hip arthroplasty: a study on 108,854 primary THAs in the Norwegian Arthroplasty Register from 2005 to 2019

Background and purpose - Focus on prevention, surveillance, and treatment of infection after total hip arthroplasty (THA) in the last decade has resulted in new knowledge and guidelines. Previous publications have suggested an increased incidence of surgical revisions due to infection after THA. We assessed whether there have been changes in the risk of revision due to deep infection after primary THAs reported to the Norwegian Arthroplasty Register (NAR) over the period 2005-2019.Patients and methods - Primary THAs reported to the NAR from January 1, 2005 to December 31, 2019 were included. Adjusted Cox regression analyses with the first revision due to deep infection after primary THA were performed. We investigated changes in the risk of revision as a function of time of primary THA. Time was stratified into 5-year periods. We studied the whole population of THAs, and the subgroups: all-cemented, all-uncemented, reverse hybrid (cemented cup), and hybrid THAs (cemented stem). In addition, we investigated factors that were associated with the risk of revision, and changes in the time span from primary THA to revision.Results - Of the 108,854 primary THAs that met the inclusion criteria, 1,365 (1.3%) were revised due to deep infection. The risk of revision due to infection, at any time after primary surgery, increased through the period studied. Compared with THAs implanted in 2005-2009, the relative risk of revision due to infection was 1.4 (95% CI 1.2-1.7) for 2010-2014, and 1.6 (1.1-1.9) for 2015-2019. We found an increased risk for all types of implant fixation. Compared to 2005-2009, for all THAs, the risk of revision due to infection 0-30 days postoperatively was 2.2 (1.8-2.8) for 2010-2014 and 2.3 (1.8-2.9) for 2015-2019, 31-90 days postoperatively 1.0 (0.7-1.6) for 2010-2014 and 1.6 (1.0-2.5) for 2015-2019, and finally 91 days-1 year postoperatively 1.1 (0.7-1.8) for 2010-2014 and 1.6 (1.0-2.6) for 2015-2019. From 1 to 5 years postoperatively, the risk of revision due to infection was similar to 2005-2009 for both the subsequent time periodsInterpretation - The risk of revision due to deep infection after THA increased throughout the period 2005-2019, but appears to have levelled out after 2010. The increase was mainly due to an increased risk of early revisions, and may partly have been caused by a change of practice rather than a change in the incidence of infection.

The possible effect of different types of ventilation on reducing operation theatre infections: a meta-analysis

INTRODUCTION

The relation between type of ventilation used in the operating theatre and surgical site infection has drawn considerable attention. It has been reported that there is a possible relationship between the type of ventilation used in the operation theatre and surgical site infection. This meta-analysis was performed to evaluate this relationship.

METHODS

Through a systematic literature search up to May 2020, 14 studies describing 590,121 operations, 328,183 were performed under laminar airflow ventilation and 2,611,938 were performed under conventional ventilation. Studies were identified that reported relationships between type of ventilation with its different categories and surgical site infection (10 studies were related to surgical site infection in total hip replacement, 7 in total knee arthroplasties and 3 in different abdominal and open vascular surgery). Odds ratios with 95% confidence intervals were calculated comparing surgical site infection prevalence and type of theatre ventilation using the dichotomous method with a random or fixed-effect model.

FINDINGS

No significant difference was found between surgery performed under laminar airflow ventilation and conventional ventilation in total hip replacement (OR 1.23; 95% CI 0.97-1.56, p = 0.09), total knee arthroplasties (OR 1.14; 95% CI 0.62-2.09, p = 0.67) or different abdominal and open vascular surgery (OR 0.75; 95% CI 0.43-1.33, p = 0.33). The impact of the type of theatre ventilation may have no influence on surgical site infection as a tool for decreasing its occurrence.

CONCLUSIONS

Based on this meta-analysis, operating under laminar airflow or conventional ventilation may have no independent relationship with the risk of surgical site infection. This relationship forces us not to recommend the use of laminar airflow ventilation since it has a much higher cost compared with conventional ventilation.

Contemporary indications for first-time revision surgery after primary cementless total hip arthroplasty with emphasis on early failures

BACKGROUND

To clarify contemporary indications for first-time revision surgery after primary cementless total hip arthroplasty (THA) for addressing potential issues with cementless THA.

METHODS

Data for 101 consecutive hips in 94 patients who underwent primary cementless THA at our institution and subsequently underwent first-time revision surgery were retrospectively reviewed. Baseline characteristics, indications for first-time revision surgery, and time from the primary THA to first-time revision surgery were evaluated.

RESULTS

The overall mean time to first-time revision surgery was 10.3 years (range, 0-33 years). The indications for first-time revision surgery were polyethylene wear and osteolysis in 33 hips, aseptic loosening in 25 hips, infection in 17 hips, periprosthetic fracture in 13 hips, instability in 8 hips, and component failure (liner dissociation or stem fracture) in 5 hips. Thirty-seven hips (37%) had undergone first-time revision surgery within 5 years of primary THA, of which the most common indications were infection and periprosthetic fracture.

CONCLUSION

The current results suggested that reducing the number of early failures seems to be essential form improving THA outcomes.

Robotic Arm-assisted Total Hip Arthroplasty is More Cost-Effective Than Manual Total Hip Arthroplasty: A Markov Model Analysis

BACKGROUND

Total hip arthroplasty (THA) is the benchmark surgical treatment of advanced and symptomatic hip osteoarthritis. Preliminary evidence suggests that the robotic arm-assisted (RAA) technology yields more accurate and reproducible acetabular cup placement, which may improve survival rate and clinical results, but economic considerations are less well-defined. The purpose of this study was to compare the cost effectiveness of the RAA THA with manual THA (mTHA) modalities, considering direct medical costs and utilities from a payer's perspective.

METHODS

A Markov model was constructed to analyze two potential interventions for hip osteoarthritis and degenerative joint disorder: RAA THA and mTHA. Potential outcomes of THA were categorized into the transition states: infection, dislocation, no major complications, or revision. Cumulative costs and utilities were assessed using a cycle length of 1 year over a time horizon of 5 years.

RESULTS

RAA THA cohort was cost effective relative to mTHA cohort for cumulative Medicare and cumulative private payer insurance costs over the 5-year period. RAA THA cost saving had an average differential of $945 for Medicare and $1,810 for private insurance relative to mTHA while generating slightly more utility (0.04 quality-adjusted life year). The preferred treatment was sensitive to the utilities generated by successful RAA THA and mTHA. Microsimulations indicated that RAA THA was cost effective in 99.4% of cases.

CONCLUSIONS

In the Medicare and private payer scenarios, RAA THA is more cost effective than conventional mTHA when considering direct medical costs from a payer's perspective.

LEVEL OF EVIDENCE

Economic Level III. Computer simulation model (Markov model).

The effect of type of ventilation used in the operating room and surgical site infection: A meta-analysis

BACKGROUND

The relation between type of ventilation used in the operating room and surgical site infection has drawn considerable attention with its conflicting results. A possible relationship between the type of ventilation used in the operating room and surgical site infection has been reported. This meta-analysis was performed to evaluate this relationship.

METHODS

A systematic literature search up to May 2020 identified 14 studies with 590,121 operations, 328,183 operations of which were performed under laminar airflow ventilation and 261,938 of which were performed operations under conventional ventilation. These articles reported relationships between type of operating-room ventilation with its different categories and surgical site infection: 10 studies were related to surgical site infection in the total hip replacement; 7 studies in total knee arthroplasties; and 3 studies in different abdominal and open vascular surgery. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated comparing surgical site infection prevalence and type of operating room ventilation using the dichotomous method with a random-effects or fixed-effects model.

RESULTS

No significant difference was found between operation performed under laminar airflow ventilation and conventional ventilation in total hip replacement (OR, 1.23; 95% CI, 0.97-1.56, P = .09), in total knee arthroplasties (OR, 1.14; 95% CI, 0.62-2.09; P = .67), and in different abdominal and open vascular surgery (OR, 0.75; 95% CI, 0.43-1.33; P = .33). The impact of the type of operating room ventilation may have no influence on surgical site infection as a tool for decreasing its occurrence.

CONCLUSIONS

Based on this meta-analysis, operating under laminar airflow or conventional ventilation may have no independent relationship with the risk of surgical site infection. This relationship forces us not to recommend the use of laminar airflow ventilation because it has a much higher cost compared to conventional ventilation.

Symptomatic Benign Prostatic Hyperplasia: A Risk Factor for Periprosthetic Joint Infection in Male Patients

BACKGROUND

Male patients undergoing total joint arthroplasty have a higher risk of periprosthetic joint infection (PJI) compared with female patients. The exact reason for this finding is not well known. This study aimed to determine if patients with symptomatic benign prostatic hyperplasia (BPH) are at increased risk of PJI.

METHODS

A total of 12,902 male patients who underwent primary or revision total joint arthroplasty from January 2006 to April 2017 were retrospectively identified. The mean patient age was 62.47 years and the mean patient body mass index was 30.1 kg/m. The majority of patients were Caucasian or African American. Most surgical procedures involved the hip joints (57.8%) and were primary arthroplasties (86%). Of these patients, 386 (3%) had symptomatic BPH. Among this group, 250 patients with symptomatic BPH were identified and were matched in an approximate 1:3 ratio with 708 control patients. Using the International Consensus Meeting criteria, patients who developed PJI were identified.

RESULTS

The PJI rate was 7.9% in the symptomatic BPH group and 2.8% in the control group. Multivariate regression analysis in unmatched groups showed that symptomatic BPH was a strong independent risk factor for PJI. After matching for variables related to outcomes, symptomatic BPH remained a significant risk factor for PJI (p = 0.01).

CONCLUSIONS

Patients with symptomatic BPH had a higher risk of PJI compared with the control patients. This may partly explain the higher rate of PJI that is seen in male patients.

LEVEL OF EVIDENCE

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

Timing of hip hemiarthroplasty and the influence on prosthetic joint infection

Introduction

Previous research suggested that patients have increased risk of infection with increased time from presentation with a femoral neck fracture to treatment with a hip hemiarthroplasty (HHA). The purpose of this study was to determine if rates of prosthetic joint infections within 3 months of surgery was affected by the time from patient presentation with a femoral neck fracture to the time of treatment with HHA.

Materials and methods

Acute hip fractures treated with HHA between 2005 and 2017 at three centres in Norway were enrolled in the study. Multi-trauma patients were excluded. Univariable analysis was performed to determine any significant effect of pre-operative waiting time on infection rate. Two pre-planned analyses dichotomizing pre-operative waiting time cut-offs were performed.

Results

There were 2300 patients with an average age of 82 (range, 48–100) years included of which 3.4% experienced a prosthetic joint infection within 3 months. The primary analysis found no significant difference in infection rate depending on time to surgery (OR = 1.06 (95% CI 0.94–1.20, p = 0.33)). The secondary analyses showed no significant differences in infection rates when comparing pre-operative waiting time of <24 hours vs ≥24 hours (OR = 0.92 (95% CI 0.58–1.46, p = 0.73)) and <48 hours vs ≥48 hours (OR = 1.39 (95% CI 0.81–2.38, p = 0.23)).

Conclusion

Based off of a large retrospective Norwegian database of hip fractures there did not appear to be a significant difference in infection rate based on pre-operative wait time to surgery.

Implant Survival of Constrained Acetabular Device in Primary Total Hip Arthroplasty Based on Data From the Finnish Arthroplasty Register

BACKGROUND

Constrained acetabular devices were developed to prevent dislocations after total hip arthroplasty (THA). However, the data on their success have been contradictory. In this study, we aimed to assess implant survival of the constrained acetabular device in primary THA based on the Finnish Arthroplasty Register data.

METHODS

A total of 373 primary THAs with constrained acetabular devices inserted from 2006 to 2017 were included. A reference group was formed on a 1:3 basis and matched for age, sex, and diagnosis, consisting of 1118 conventional THAs. Implant survival estimates using death as a competing risk were assessed with revision for any reason and for any aseptic reason as the endpoints. The Cox multiple regression models were adjusted for age, sex, and diagnosis. The mean follow-up time was 3.3 (0-12.4) years for the constrained device group and 3.8 (0-12.0) years for the reference group.

RESULTS

Overall, there were 21 revisions in the constrained device group and 49 in the reference group. The 8-year survivorship for any reason was 94% (confidence interval [CI]: 91-96) for the constrained device group and 93% (CI: 89-97) for the reference group. With revision for any aseptic reason as the endpoint, the 8-year survivorships were 97% (CI: 95-99) and 94% (CI: 90-98), respectively. During the first 1.5 years, the constrained acetabular device group had a similar revision risk (hazard ratio: 1.09 [CI: 0.57-2.07], P = .8) to that of the reference group.

CONCLUSION

The constrained acetabular device had good survival in primary THA, and our results support its continued use even in high-risk patients.

Air quality in the operating room: Surgical site infections, HVAC systems and discipline - position paper of the German Society of Hospital Hygiene (DGKH)

In recent years, there has been an ongoing discussion about the value of laminar airflow (LAF=low turbulence displacement ventilation) in the operating room for prevention of surgical site infections (SSI). Some publications, e.g., from the WHO, issued the demand to no longer build LAF ceilings in operating rooms. The present statement deals critically with this position and justifies the use of LAF ceilings in different ways: Many of the papers cited by the WHO and others for the case against LAF do not provide reliable data.The remaining studies which might be used for answering the question give quite different results, also in favor of LAF.The size of the LAF ceiling in many studies is not given or mostly too small in comparison to actual technical requirements.LAF in different countries can mean quite different techniques (e.g., the US in comparison to Germany) so that the results of studies that do not take this into account may not be comparable.LAF has positive effects in terms of reducing particulate and bacterial load, associated with increased airflow in the surgical working area. A reduction of carcinogenic substances in the air may also be assumed, which would increase workers' safety. Thus, this paper recommends building LAF ceilings in the future as well, depending on the operations intended. Further, this paper gives an overview of possible reasons for surgical site infections and highlights the importance of discipline in the operating theatre.

Have We Actually Reduced Our 30-Day Short-Term Surgical Site Infection Rates in Primary Total Hip Arthroplasty in the United States?

BACKGROUND

The purpose of this study is to track the 30-day postoperative annual rates and trends of (1) overall, (2) deep, and (3) superficial surgical site infections (SSIs) following total hip arthroplasty (THA) using a large nationwide database.

METHODS

The National Surgical Quality Improvement Program database was queried for all THA cases performed between 2012 and 2016. After an overall 5-year correlation and trends analysis, univariate analysis was performed to compare the most recent year, 2016, with the preceding 4 years. Correlation coefficients and chi-squared tests were used to determine correlation and statistical significance.

RESULTS

The lowest incidence of SSIs was in the most recent year, 2016 (0.81%), while the greatest incidence was in the earliest year, 2012 (1.12%), marking a 31% decrease (P < .01). The lowest rate was in the most recent year, 2016 (0.23%), marking a 26% decrease from 2012. The lowest superficial SSI incidence occurred in the most recent year, 2016 (0.58%), while greatest incidence was in 2012 (0.83%), marking a 31% decrease over time (P < .05). There was an inverse correlation among overall, deep, and superficial SSI rates with operative year.

CONCLUSION

The findings from this study suggest a decreasing trend in SSIs within 30 days following THA. Furthermore, deep SSIs, which can pose substantial threats to implant survivorship, have also decreased throughout the years. These results highlight that potentially through improved medical and surgical techniques, we are winning the fight against short-term infections, but that more can still be done.

Are Patients Who Undergo THA for Infection at Higher Risk for 30-day Complications?

BACKGROUND

Value-based payment models, such as bundled payments, continue to become more widely adopted for total joint arthroplasty. However, concerns exist regarding the lack of risk adjustment in these payment and quality reporting models for THA. Providers who care for patients with more complicated problems may be financially incentivized to screen out such patients if reimbursement models fail to account for increased time and resources needed to care for these more complex patients.

QUESTIONS/PURPOSES

(1) Are patients who undergo revision THA for infectious causes at greater adjusted risk of 30-day short-term major complications, return to the operating room, readmission, and mortality compared with patients undergoing aseptic revision? (2) What are other independent factors associated with the risk of 30-day major complications, readmission, and mortality in this patient population?

METHODS

We queried the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database for all patients undergoing revision THA from 2012 to 2015. The NSQIP database allows for the analysis of 30-day surgical outcomes, including postoperative complications, return to the operating room, readmission, and mortality of patients from approximately 400 participating institutions. The NSQIP was selected over other larger databases, such as the National Impatient Sample (NIS), because the NSQIP includes readmission data and 30-day complications rates that were relevant to our study. Patients undergoing aseptic revision THA and those undergoing revision THA with a diagnosis of periprosthetic joint infection were identified. We identified 8973 patients who underwent revision THA and excluded six patients due to a diagnosis of malignancy leaving 8967 patients; 726 (8%) of these were due to infection. Demographic variables, medical comorbidities, and 30-day major complications, hospital readmissions, reoperations, and mortality were compared among patients undergoing aseptic and infected revision THA. A major complication was defined as myocardial infarction, postoperative mortality, sepsis, septic shock, and stroke. A multivariate logistic regression analysis was then performed to identify factors independently associated with the primary outcome of 30-day hospital readmission, and secondary endpoints of 30-day major complications, return to operating room, and mortality.

RESULTS

Controlling for medical comorbidities and demographic factors, the patients who underwent THA for infection were more likely to experience a major complication (odds ratio [OR], 4.637; 95% confidence interval [CI], 2.850-7.544; p < 0.001) within 30 days of surgery and more likely to return to the operating room (OR = 1.548; 95% CI, 1.062-2.255; p = 0.023). However, there were no greater odds of 30-day readmission (OR, 1.354; 95% CI, 0.975-1.880; p = 0.070) or 30-day mortality (OR, 0.661; 95% CI, 0.218-2.003; p = 0.465). Preoperative malnutrition was associated with an increased risk of return to the operating room (OR, 1.561; 95% CI, 1.152-2.115; p = 0.004), 30-day readmission (OR, 1.695; 95% CI, 1.314-2.186; p < 0.001), and 30-day mortality (OR, 7.240; 95% CI, 2.936-17.851; p < 0.001).

CONCLUSIONS

Patients undergoing revision THA for infection undergo reoperation and experience major complications more frequently in a 30-day episode of care than patients undergoing aseptic revision THA. Without risk adjustment to existing alternative payment and quality reporting models, providers may experience a disincentive to care for patients with infected THAs, who may face difficulties with access to care.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Implant Fixation and Risk of Prosthetic Joint Infection Following Primary Total Hip Replacement: Meta-Analysis of Observational Cohort and Randomised Intervention Studies

Prosthetic joint infection (PJI), although uncommon, is a dreaded and devastating complication of total hip replacement (THR). Whether implant-related factors, such as the fixation method, influences the risk of PJI following THR is contentious. We conducted a systematic review and meta-analysis to evaluate the body of evidence linking fixation methods (cemented, uncemented, hybrid, or reverse hybrid) with the risk of PJI following primary THR. Observational studies and randomised controlled trials (RCTs) comparing fixation methods, and reporting PJI incidence following THR, were identified through MEDLINE, Embase, Web of Science, Cochrane Library, and reference lists of relevant studies up to 24 April 2019. Summary measures were relative risks (RRs) (95% confidence intervals, CIs). We identified 22 eligible articles (based on 11 distinct observational cohort studies comprising 2,260,428 THRs and 4 RCTs comprising 945 THRs). In pooled analyses of observational studies, all cemented fixations (plain and antibiotic combined), plain cemented fixations, hybrid fixations, and reverse hybrid fixations were each associated with an increased overall PJI risk when compared with uncemented fixations: 1.10 (95% CI: 1.04–1.17), 1.50 (95% CI: 1.27–1.77), 1.49 (95% CI: 1.36–1.64), and 1.49 (95% CI: 1.14–1.95), respectively. However, in the first six months, uncemented fixations were associated with increased PJI risk when compared to all cemented fixations. Compared to antibiotic-loaded cemented fixations, plain cemented fixations were associated with an increased PJI risk (1.52; 95% CI: 1.36–1.70). One RCT showed an increased PJI risk comparing plain cemented fixations with antibiotic-loaded cemented fixations. Uncemented and antibiotic-loaded cemented fixations remain options for the prevention of PJI in primary THR.

Radical scavenging of poly(methyl methacrylate) bone cement by rifampin and clinically relevant properties of the rifampin-loaded cement

Objectives

The objective of this study was to characterize the effect of rifampin incorporation into poly(methyl methacrylate) (PMMA) bone cement. While incompatibilities between the two materials have been previously noted, we sought to identify and quantify the cause of rifampin’s effects, including alterations in curing properties, mechanical strength, and residual monomer content.

Methods

Four cement groups were prepared using commercial PMMA bone cement: a control; one with 1 g of rifampin; and one each with equimolar amounts of ascorbic acid or hydroquinone relative to the amount of rifampin added. The handling properties, setting time, exothermic output, and monomer loss were measured throughout curing. The mechanical strength of each group was tested over 14 days. A radical scavenging assay was used to assess the scavenging abilities of rifampin and its individual moieties.

Results

Compared with control, the rifampin-incorporated cement had a prolonged setting time and a reduction in exothermic output during polymerization. The rifampin cement showed significantly reduced strength and was below the orthopaedic weight-bearing threshold of 70 MPa. Based on the radical scavenging assay and strength tests, the hydroquinone structure within rifampin was identified as the polymerization inhibitor.

Conclusion

The incorporation of rifampin into PMMA bone cement interferes with the cement’s radical polymerization. This interference is due to the hydroquinone moiety within rifampin. This combination alters the cement’s handling and curing properties, and lowers the strength below the threshold for weight-bearing applications. Additionally, the incomplete polymerization leads to increased toxic monomer output, which discourages its use even in non-weight-bearing applications.

Cite this article: G. A. Funk, E. M. Menuey, K. A. Cole, T. P. Schuman, K. V. Kilway, T. E. McIff. Radical scavenging of poly(methyl methacrylate) bone cement by rifampin and clinically relevant properties of the rifampin-loaded cement. Bone Joint Res 2019;8:81–89. DOI: 10.1302/2046-3758.82.BJR-2018-0170.R2.

Dual Mobility Cups: Effect on Risk of Revision of Primary Total Hip Arthroplasty Due to Osteoarthritis: A Matched Population-Based Study Using the Nordic Arthroplasty Register Association Database

BACKGROUND

The dual mobility acetabular cup (DMC) was designed to reduce prosthetic instability and has gained popularity for both primary and revision total hip arthroplasty (THA). We compared the risk of revision of primary THA for primary osteoarthritis between patients treated with a DMC and those who received a metal-on-polyethylene (MoP) or ceramic-on-polyethylene (CoP) bearing.

METHODS

A search of the Nordic Arthroplasty Register Association (NARA) database identified THAs performed with a DMC during 1995 to 2013. With use of propensity score matching, 2,277 of these patients were matched (1:1), with regard to sex, age, component fixation, and year of surgery, with patients with an MoP or CoP bearing. We estimated the cumulative incidence of revision taking death as a competing risk into consideration and performed competing risk regression with revision or death as end points.

RESULTS

There was no difference in the overall risk of revision between the DMC group and the propensity-score-matched MoP/CoP group (adjusted hazard ratio [HR] = 1.18; 95% confidence interval [95% CI] = 0.87 to 1.62). Patients with a DMC bearing had a lower risk of revision due to dislocation (adjusted HR = 0.09; 95% CI = 0.03 to 0.29) but a higher risk of revision caused by infection (adjusted HR = 3.20; 95% CI = 1.49 to 6.85).

CONCLUSIONS

There was no difference in overall risk of revision between the DMC and MoP/CoP groups. The DMCs protected against revision due to dislocation but THAs performed with this bearing were more commonly revised because of infection. There may have been a selection bias toward placing DMC implants in patients with greater frailty as the mortality rates were higher in the DMC group than in the age and sex-matched MoP/CoP group.

LEVEL OF EVIDENCE

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

Incise Draping Reduces the Rate of Contamination of the Surgical Site During Hip Surgery: A Prospective, Randomized Trial

BACKGROUND

Iodophor-impregnated adhesive incise drapes are widely used during surgeries for reducing surgical site contamination. There is little evidence to support the latter belief. This study evaluated the efficacy of iodophor-impregnated adhesive drapes for reducing bacterial contamination and counts at the incision site during hip surgery.

METHODS

In this prospective, randomized clinical trial, we enrolled 101 patients undergoing open joint preservation procedure of the hip. Half the patients had the adhesive drape applied to the skin prior to incision, while the remainder underwent the same surgery without a drape. Culture swabs were taken from the surgical site at 5 points (preskin preparation, after skin preparation, postincision, before subcutaneous closure, prior to dressing application) and sent for culture and colony counts. Mixed-effects logistic regressions were used to estimate effects of time and drape application on contamination rate.

RESULTS

At the conclusion of surgery, 12.0% of incisions with adhesive drapes and 27.4% without adhesive drapes were positive for bacterial colonization. When controlling for preoperative colonization and other factors, patients without adhesive drapes were significantly more likely to have bacteria present at the time of skin closure, and at all time points when swab cultures were taken.

CONCLUSION

It appears that the iodophor-impregnated adhesive draping significantly reduces bacterial colonization of the incision. Bacterial count at the skin was extremely high in some patients in whom adhesive drapes were not used, raising the possibility that a subsequent surgical site infection or periprosthetic joint infection could arise had an implant been utilized.

The Impact of Patient and Surgical Factors on the Rate of Postoperative Infection After Total Hip Arthroplasty-A New Zealand Joint Registry Study

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication after total hip arthroplasty (THA). The potential to define and modify risk factors for infection represents an important opportunity to reduce the incidence of PJI. This study uses New Zealand Joint Registry data to identify independent risk factors associated with PJI after primary THA.

METHODS

Data on 91,585 THAs performed between 2000 and 2014 were analyzed. Factors associated with revision for PJI within 12 months were identified using univariate and multivariate analyses.

RESULTS

Revision rates for PJI were 0.15% and 0.21% at 6 and 12 months, respectively. Multivariate analysis showed significant associations with the American Society of Anesthesiologists grade (odds ratio [OR] 6.13, 95% confidence interval [CI] 1.28-29.39), severe or morbid obesity (OR 2.15, CI 1.01-4.60 and OR 3.73, CI 1.49-9.39), laminar flow ventilation (OR 1.98, CI 1.38-2.85), consultant-supervised trainee operations (OR 1.94, CI 1.22-3.08), male gender (OR 1.68, CI 1.23-2.30) and anterolateral approach (OR 1.62, CI 1.11-2.37). Procedures performed in the private sector were protective for revision for infection (OR 0.68, CI 0.48-0.96).

CONCLUSIONS

The PJI risk profile for patients undergoing THA is constituted of a complex of patient and surgical factors. Several patient factors had strong independent associations with revision rates for PJI. Although surgical factors were less important, these may be more readily modifiable in practice.

A biocompatible sol-gel derived titania coating for medical implants with antibacterial modification by copper integration

Implant-associated infections are dangerous complications and may cause dramatic illness with hematogeneous spread of bacteria and secondary infections. Since treatment of these infections remains most challenging and commonly requires implant removal, prevention is of utmost importance. In the present work a titania-sol was equipped with a copper salt resulting after calcination in a titania coating (TiO2) with antibacterial properties combined with good cytocompatibility. In vitro tests with bacteria as well as tissue cells were carried out under corresponding conditions. Mouse fibroblasts and different staphylococcal strains were used for growth inhibition assays with serial dilutions of CuCl2. Cultivation on the surface of bare Ti6Al4V, TiO2-coated and copper-filled TiO2-coated Ti6Al4V samples was performed with both bacteria and tissue cells. Bacterial and cellular proliferation and mitochondrial activity were hereby determined. Coating of Ti6Al4V with pure TiO2 significantly improved cytocompatibility compared to the uncoated alloy. In the growth inhibition assays, fibroblasts tolerated higher concentrations of copper ions than did bacteria. Nevertheless, copper integration reduced fibroblast proliferation and mitochondrial activity on the surface coating. On the other hand, integration of copper into the TiO2-coating significantly reduced adhesion of viable bacteria resulting in a promising combination of cytocompatibility and antibacterial properties. Additionally, significant bacterial growth inhibition by antibacterial amounts of copper was also demonstrated in the supernatant. In conclusion, the copper-loaded TiO2-coatings for medical implants may be a promising approach to reduce the rate of implant-associated infections.

Patient and surgical factors affecting procedure duration and revision risk due to deep infection in primary total knee arthroplasty

BACKGROUND

The aim of this study was to assess which patient and procedure factors affected both the risk of infection as well as procedure duration. Additionally, to assess if procedure duration affected the revision risk due to deep infection in total knee arthroplasty (TKA) patients and in a subgroup of low-risk patients.

METHODS

28,262 primary TKA with 311 revisions due to deep infection were included from the Norwegian Arthroplasty Register (NAR) and analysed from primary surgery from 2005 until 31st December 2015 with a 1 and 4 year follow up. The risk of revision due to deep infection was calculated in a multivariable Cox regression model including patient and procedure related risk factors, assessing Hazard Ratio (HR) with 95% confidence interval (CI).

RESULTS

Multivariate analysis showed statistically significant associations with revision due to deep infection and increased procedure duration for male patients, ASA3+ (American Society of Anesthesiologists) and perioperative complications. Procedure duration ≥110 min (75 percentile) had a higher risk of deep infection compared to duration <75 min (25 percentile), in the unadjusted analysis (HR = 1.8, 95% CI 1.3-2.5, p = 0.001) and in the adjusted analysis (HR = 1.5, 95% CI 1.0-2.1, p = 0.03). For low-risk patients, procedure duration did not increase the risk of infection.

CONCLUSION

Male patients, ASA 3+ patients and perioperative complications were risk factors both for longer procedure duration and for deep infection revisions. Patients with a high degree of comorbidity, defined as ASA3+, are at risk of infection with longer procedure durations. The occurrence of perioperative complications potentially leading to a more complex and lengthy procedure was associated with a higher risk of infection. Long procedure duration in itself seems to have minor impact on infection since we found no association in the low-risk patient.

Role of fast-setting cements in arthroplasty: A comparative analysis of characteristics

AIM

To evaluate the behaviour of two fast-setting polymethylmethacrylate (PMMA) cements CMW^® 2G and Palacos^® fast R + G, as reference: Standard-setting Palacos^® R + G.

METHODS

The fast-setting cements CMW^® 2G and Palacos^® fast R + G were studied, using standard-setting high viscosity Palacos^® R + G as a reference. Eleven units (of two batch numbers) of each cement were tested. All cements were mixed as specified by the manufacturer and analysed on the following parameters: Handling properties (mixing, waiting, working and hardening phase) according to Kuehn, Mechanical properties according to ISO 5833 and DIN 53435, Fatigue strength according to ISO 16402, Benzoyl Peroxide (BPO) - Content by titration, powder/liquid-ratio by weighing, antibiotic elution profile by High Performance Liquid Chromatography. All tests were done in an acclimatised laboratory with temperatures set at 23.5 °C ± 0.5 °C and a humidity of > 40%.

RESULTS

Palacos^® fast R + G showed slightly shorter handling properties (doughing, hardening phase, n = 12) than CMW^® 2G, allowing to reduce operative time and to optimise cemented cup implantation. Data of the quasistatic properties of ISO 5833 and DIN 53435 of both cements tested was comparable. The ISO compressive strength (MPa) of Palacos^® fast R + G was significantly higher than CMW^® 2G, resulting in ANOVA (P < 0.01) and two sample t-test (P < 0.01) at 0.05 level of significance (n = 20). Palacos^® fast R + G showed a higher fatigue strength of about 18% mean (ISO 16402) of 15.3 MPa instead of 13.0 MPa for CMW^® 2G (n = 5 × 10⁶ cycles). Palacos^® fast R + G and CMW^® 2G differed only by 0.11% (n = 6) with the former having the higher content. The BPO-content of both cements were therefore comparable. CMW^® 2G had a powder/liquid ratio of 2:1, Palacos^® fast R + G of 2.550:1 due to a higher powder content. Despite its higher gentamicin content, CMW^® 2G showed a significantly lower antibiotic elution over time than Palacos^® fast R + G (n = 3).

CONCLUSION

Both cements are compliant with international standards and are highly suitable for their specified surgical indications, affording a time-saving measure without detriment to the mechanical properties.

[Does the certification according to EndoCert lead to a better quality of treatment?]

BACKGROUND

Certification according to EndoCert in the field of arthroplasty in Germany aims at standardization of treatment and with this optimization of its quality. However, huge capital investment and efforts are necessary. There are currently more than 400 certified centres in Germany. Our Department of Orthopaedics at a German medical school was certified in the pilot phase. The aim of this study was to analyse whether there was a difference in the quality in the year after the certification. A second aim was to analyse whether the defined quality criteria are adequate for a university hospital.

MATERIALS AND METHODS

The quality criteria as defined by EndoCert were analysed in the year before (2011) and after certification (2012). The observed complications were noted for 1 year postoperatively. The clinical outcome was analysed with Western Ontario and McMaster University Osteoarthritis Index Score (WOMAC) 1 year postoperatively.

RESULTS

There was no difference concerning the criteria analysed, including the clinical outcome in the year before and that after certification. In both years, nearly all criteria could be reached except the operation time and the infection rate in hip and knee revision surgery.

CONCLUSION

Certification did not lead to a measurable change of the quality of care. Nearly all criteria, except the infection rate in revision arthroplasty (required: less than 3% at 1 year postop.) and the operation duration could be fulfilled. This rate as well as the operation duration should be revised. Certification according to EndoCert is an important tool to prove quality care, however big efforts and capital are needed. The criteria should be constantly revised and reduced, as these resources should not be missed in patient care.

Comparison of Short-Term Outcomes After Total Hip Arthroplasty Between an Orthopedic Specialty Hospital and General Hospital

BACKGROUND

The purpose of this study is to compare perioperative outcomes for total hip arthroplasty (THA) at an orthopedic specialty hospital (OSH) and a general hospital (GH).

METHODS

A retrospective study of all primary THAs was performed at an OSH and GH in 2014. A cohort of GH patients was manually matched to the OSH by clinical and demographic variables blinded to outcome. These matched groups were then unblinded and compared by length of stay (LOS), 90-day readmissions, mortality, reoperations, and inpatient rehabilitation utilization.

RESULTS

The 329 THAs at the OSH were matched with 329 THAs at the GH. Average LOS for THA at the OSH was 1.10 ± 0.51 days compared with 1.27 ± 0.93 (P = .004) at the GH. There were 2 OSH readmissions vs 5 GH readmissions (P = .25). There were 3 OSH reoperations vs 4 GH reoperations (P = .70). There were no mortalities. Three OSH patients used inpatient rehabilitation vs 13 GH patients (P = .011). When GH outlier and rehabilitation patients were excluded, the difference in LOS was not significant (1.08 ± 0.47 vs 1.13 ± 0.55 days; t = 1.331; P = .184). Two OSH patients required transfer to a GH postoperatively (angina and gastrointestinal bleed).

CONCLUSION

This study found that perioperative outcomes for THA were equally good at the OSH and GH. Rehabilitation utilization was higher at the GH. The LOS at both facilities was lower than the national average of 2.9 days. When rehabilitation patients and outliers were excluded, there was no significant difference in LOS between the two.

Atomic Layer Deposition of a Silver Nanolayer on Advanced Titanium Orthopedic Implants Inhibits Bacterial Colonization and Supports Vascularized de Novo Bone Ingrowth

Joint replacement surgery is associated with significant morbidity and mortality following infection with either methicillin-resistant Staphylococcus aureus (MRSA) or Staphylococcus epidermidis. These organisms have strong biofilm-forming capability in deep wounds and on prosthetic surfaces, with 10³ -10⁴ microbes resulting in clinically significant infections. To inhibit biofilm formation, we developed 3D titanium structures using selective laser melting and then coated them with a silver nanolayer using atomic layer deposition. On bare titanium scaffolds, S. epidermidis growth was slow but on silver-coated implants there were significant further reductions in both bacterial recovery (p < 0.0001) and biofilm formation (p < 0.001). MRSA growth was similarly slow on bare titanium scaffolds and not further affected by silver coating. Ultrastructural examination and viability assays using either human bone or endothelial cells, demonstrated strong adherence and growth on titanium-only or silver-coated implants. Histological, X-ray computed microtomographic, and ultrastructural analyses revealed that silver-coated titanium scaffolds implanted into 2.5 mm defects in rat tibia promoted robust vascularization and conspicuous bone ingrowth. We conclude that nanolayer silver of titanium implants significantly reduces pathogenic biofilm formation in vitro, facilitates vascularization and osseointegration in vivo making this a promising technique for clinical orthopedic applications.

One-year incidence of prosthetic joint infection in total hip arthroplasty: a cohort study with linkage of the Danish Hip Arthroplasty Register and Danish Microbiology Databases

OBJECTIVE

To examine the trend of Prosthetic Joint Infections (PJI) following primary total hip arthroplasty (THA) and the antimicrobial resistance of the bacteria causing these infections.

MATERIALS AND METHODS

We identified a population-based cohort of patients in the Danish Hip Arthroplasty Register (DHR) who had primary THA and received their surgery in Jutland or Funen between 2005 and 2014. We followed the patients until revision, emigration, death, or up to 1-year of follow-up. Data from the DHR were combined with those from microbiology databases, the National Register of Patients, and the Civil Registration System. We estimated the cumulative 1-year incidence of PJI for two 5-year periods; 2005-2009 and 2010-2014. The hazard ratio of PJI as a measure of relative risk after adjusting for multiple risk factors was calculated.

RESULTS

Of 48,867 primary THAs identified, 1120 underwent revision within 1 year. Of these, 271 were due to PJI. The incidence of PJI was 0.53% (95% confidence interval (CI): 0.44; 0.63) during 2005-2009 and 0.57% (95% CI: 0.49; 0.67) during 2010-2014. The adjusted relative risk was 1.05 (95% CI: 0.82; 1.34) for the 2010-2014 period vs the 2005-2009 period. The most common micro-organisms identified in the 271 PJI were Staphylococcus aureus (36%) and coagulase-negative staphylococci (CoNS) (33%); others commonly identified included Enterobacteriaceae, enterococci, and streptococci. Antimicrobial resistance to beta-lactams and gentamicin did not change during the study period.

CONCLUSION

The risk of PJI within 1-year after primary THA and the antimicrobial resistance of the most prevalent bacteria remained unchanged during the 2005-2014 study period.