Increasing risk of revision due to infection after primary total hip arthroplasty: results from the Nordic Arthroplasty Register Association

Choice of Bearings Influences the Implant Survival of Total Hip Arthroplasty in Patients Who Have Osteoarthritis Aged 55 Years or Older: Results of 158,044 Patients From the Nordic Arthroplasty Register Association From 2005 to 2017

BACKGROUND

The aim of our study was to compare implant survival rates of different total hip arthroplasty (THA) bearings in the Nordic Arthroplasty Register Association.

METHODS

All conventional primary THAs performed between 2005 and 2017 in patients aged more than 55 years who had primary osteoarthritis were studied. Metal-on-highly cross-linked polyethylene (MoXLP), ceramic-on-highly cross-linked polyethylene (CoXLP), ceramic-on-ceramic (CoC), and metal-on-metal (MoM) bearings were included. The outcome was a revision. Kaplan-Meier (KM) estimates were calculated at 5 and 10 years. The risk for revision was analyzed using a flexible parametric survival model adjusted for nation, age, sex, femoral head size, and femoral fixation.

RESULTS

A total of 158,044 THAs were included. The 5-year KM estimates were 95.9% (95% confidence interval [CI] 95.8 to 96.1) in MoXLP, 95.8% (95% CI 95.6 to 96.1) in CoXLP, 96.7% (95% CI 96.4 to 97.0) in CoC, and 93.9% (95% CI 93.5 to 94.4) in MoM. The 10-years KM estimates were 94.2% (94.0 to 94.5) in MoXLP, 94.3% (93.9 to 94.8) in CoXLP, 95.4% (95.0 to 95.9) in CoC, and 85.5% (84.9 to 86.2) in MoM. Compared with MoXLP, the adjusted risk for revision was lower in CoC (hazard ratio [HR] 0.6, CI 0.5 to 0.6), similar in CoXLP (HR 1.0, CI 0.9 to 1.0), and higher in MoM (HR 1.3, CI 1.2 to 1.4).

CONCLUSIONS

We found that MoXLP, CoXLP, and CoC bearings evinced comparably high implant survival rates up to 10 years, and they can all be regarded as safe options in this patient group. The MoM bearings were associated with clearly lower survivorship. The CoC bearings had the highest implant survival and a lower adjusted risk for revision compared with highly cross-linked polyethylene bearings.

The Association Between Postoperative Prophylactic Antibiotics and Severe Infections After Cochlear Implantation: A Retrospective Cohort Study

OBJECTIVE

To investigate the association between postoperative antibiotic prophylaxis and the risk of infections leading to implant explantation or hospitalization, with a follow-up of up to 12 years.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary medical institution.

PATIENTS

Adult patients (≥18 yr) receiving cochlear implant surgery between 2010 and 2022.

INTERVENTION

Postoperative oral prophylactic antibiotic treatment for 4 to 10 days.

MAIN OUTCOME MEASURES

The medical records of patients receiving cochlear implants were assessed (n = 927). Two groups were formed: group A, receiving postoperative oral antibiotic treatment (period: 2010-2015) (n = 526), and group B, not receiving postoperative oral antibiotic treatment (period: 2016-2022) (n = 401). The two groups were compared regarding infections leading to hospitalization or explantation, and baseline characteristics.

RESULTS

In total, 28 patients (3.0%) had infections requiring explantation or hospitalization. Of these, 13 were explantations (1.4%). The infection rate in group A was 2.9%, compared with 3.2% in group B, with an odds ratio of 1.2 in group B (p = 0.646). Group B had a 2.2 odds ratio of explantation caused by infection compared with group A (p = 0.179). We observed a significant correlation between severe infections in patients previously having otologic surgery (7.7%, p = 0.011) and in patients with previous issues of chronic otitis (16.7%, p = 0.005).

CONCLUSION

Occurrence of postoperative infection leading to explantation and hospitalization was not significantly associated with the use of postoperative antibiotic prophylaxis. However, infections were higher in patients not receiving antibiotic prophylaxis, despite having a lower risk of postoperative infection.

Never mind the bug: no differences in infection-free survival after periprosthetic joint infections with Staphylococcus aureus, Coagulase-negative Staphylococcus, or Streptococcus

Background

Periprosthetic joint infection (PJI) is a devastating complication following arthroplasty of the hip or knee joint and can be challenging to treat, depending on the underlying pathogen. There is still a debate whether streptococcal PJI are more difficult to treat than those caused by staphylococci. We aimed to investigate if the treatment results after PJI caused by Staphylococci aureus (S. aureus), Coagulase-negative Staphylococci spp. (CoNS) or Streptococci differ.

Patients and methods

This study was designed as a retrospective observational study on patients with PJI caused by either streptococci or staphylococci in the hip or knee treated at a tertiary referral center between 1998 and 2021. Patients were identified in the local PJI register and data were collected by medical chart review performed minimum 1 year after the index PJI. Patients with polymicrobial infections or incomplete data were excluded, leaving 299 patients with streptococcal or staphylococcal PJI for final analysis. These patients were categorized according to the underlying pathogen: 114 were S. aureus 121 were CoNS, and 64 Streptococci. Infection-free survival was defined as the absence of (1) further surgery to the index joint due to PJI, (2) suppressive antibiotic therapy, and (3) death due to PJI and was assessed using the Kaplan-Meier method. Cox regression models were fitted to estimate the risk of infection relapse adjusted for relevant confounders.

Results

We found no statistically or clinically significant difference in unadjusted survival between the three groups. Infection-free survival at 2 years was 71% (95%CI: 63-80) for S. aureus, 75% (95%CI: 67-84) for CoNS, and 60% (95%CI: 60-84) for Streptococci. The adjusted hazard ratios (HR) for the risk of infection relapse with S. aureus as the reference were 1.2 (95%CI: 0.7-2.0) for CoNS and 1.1 (95%CI: 0.6-2.0) for Streptococci. For all three groups of bacteria, survival was lower when DAIR was performed in comparison to exchange surgery.

Discussion

In our cohort, there was no difference in infection-free survival between the three groups. Albeit limitations due to the study design, it seems that streptococcal PJI do not have to be considered more difficult to treat than their staphylococcal counterparts. Exchange surgery shows favorable results in all groups compared to DAIR.

Treatment of Periprosthetic Joint Infection with Intravenous Vancomycin: Do We Hit the Target?

Background/objectives: Vancomycin is commonly used in the treatment of periprosthetic joint infection (PJI), and trough concentrations are measured to ascertain that they are within the therapeutic range. It has not been investigated what proportion of vancomycin concentrations during treatment of PJI patients is accurately within this range, how many dose adjustments are commonly needed, and which patient factors predispose towards aberrations from the desired range. Method: In this single-center cohort study, we investigated vancomycin trough concentrations in 108 patients with surgically treated PJI who received IV administered vancomycin treatment post-operatively. Patients were identified in our local arthroplasty register, and data beyond what was available in the register were collected from electronic medical charts. Results: Of the final study cohort, 41% were women, and the median age was 71 (IQR 63-79) years. Most patients had PJI of the hip (73%), the majority (54%) underwent a debridement, antibiotics and implant retention (DAIR) procedure prior to vancomycin treatment, and 39% received vancomycin-loaded bone cement during the preceding revision procedure. Of 791 vancomycin trough measurements, only 58.2% were within the target range of 15-20 mg/L, 18.5% were below, and 23.4% were above. A total of 71% of all patients required at least one dose adjustment, and the median length of vancomycin treatment was 8 days. We observed positive correlations of vancomycin trough concentrations with both age (Spearman's rho = 0.35, p < 0.001) and pre-treatment creatinine concentrations (Spearman's rho = 0.34, p < 0.001), but no statistically significant difference between patients who had received vancomycin-loaded bone cement and those who had not. Conclusions: In our PJI patients, a high proportion of vancomycin trough concentrations were outside the therapeutic range, despite adherence to local and national guidelines. We can also confirm that caution needs to be exerted in patients of advanced age and those with compromised kidney function. Alternative broad-spectrum antibiotics that do not require as extensive therapeutic drug monitoring should be further explored.

Sex-based differences in risk of revision for infection after hip, knee, shoulder, and ankle arthroplasty in osteoarthritis patients: a multinational registry study of 4,800,000 implants

BACKGROUND AND PURPOSE

 We aimed to determine sex differences for periprosthetic joint infections after primary arthroplasty of the hip, knee, ankle, and shoulder in osteoarthritis patients in an international perspective.

METHODS

 This is a multinational combined arthroplasty registry study. Each arthroplasty registry performed Cox-regression analysis of their data and reported the crude and adjusted hazard ratios (HR) with an a priori designed data form. A random-effects model was used to pool these HRs to estimate an overall HR with 95% confidence interval (CI). Adjustment was undertaken for patient age, BMI, ASA grade, type of fixation, and type of implant. 9 arthroplasty registries participated. Patients who received primary total joint arthroplasty for primary osteoarthritis were considered: 2,134,313 hip arthroplasties, 2,658,237 knee arthroplasties, 57,889 shoulder arthroplasties, and 8,445 ankle arthroplasties. We calculated hazard ratios (HR) for the overall risk of complete revision due to infection for each implant type and follow-up.

RESULTS

The pooled HR for revision due to infection for men compared with women at 1-year follow-up was 1.60 (95% confidence interval [CI] 1.42-1.80) for hip arthroplasties; 2.06 (CI 1.90-2.46) for knee arthroplasties; 4.51 (CI 2.99-6.80) for shoulder arthroplasties; and 0.87 (CI 0.46-1.62) for ankle arthroplasties. These results remained consistent over time and were identified in both unadjusted and adjusted models.

CONCLUSION

 Men have a higher risk of revision due to infection than women after primary hip, knee, and shoulder arthroplasty. No evidence of difference was found for ankle arthroplasty. These elevated relative risks persist in the fully adjusted investigations and over the 10-year postoperative period studied.

How good are surgeons at disclosing periprosthetic joint infection at the time of revision, based on pre- and intra-operative assessment? A study on 16,922 primary total hip arthroplasties reported to the Norwegian Arthroplasty Register

BACKGROUND AND PURPOSE

Revision due to infection, as reported to the Norwegian Arthroplasty Register (NAR), is a surrogate endpoint to periprosthetic joint infection (PJI). We aimed to find the accuracy of the reported causes of revision after primary total hip arthroplasty (THA) compared with PJI to see how good surgeons were at disclosing infection, based on pre- and intraoperative assessment.

PATIENTS AND METHODS

We investigated the reasons for revision potentially caused by PJI following primary THA: infection, aseptic loosening, prolonged wound drainage, and pain only, reported to the NAR from surgeons in the region of Western Norway during the period 2010-2020. The electronic patient charts were investigated for information on clinical assessment, treatment, biochemistry, and microbiological findings. PJI was defined in accordance with the Musculoskeletal Infection Society (MSIS) definition. Sensitivity, specificity, and accuracy were calculated.

RESULTS

363 revisions in the NAR were eligible for analyses. Causes of revision were (reported/validated): infection (153/177), aseptic loosening (139/133), prolonged wound drainage (37/13), and pain only (34/40). The sensitivity for reported revision due to infection compared with PJI was 80%, specificity was 94%, and accuracy-the surgeons' ability to disclose PJI or non-septic revision at time of revision-was 87%. The accuracy for the specific revision causes was highest for revision due to aseptic loosening (95%) and pain only (95%), and lowest for revision due to prolonged wound drainage (86%).

CONCLUSION

The accuracy of surgeon-reported revisions due to infection as representing PJI was 87% in the NAR. Our study shows the importance of systematic correction of the reported cause of revision in arthroplasty registers, after results from adequately taken bacterial samples.

Incidence of Rifampicin Resistance in Periprosthetic Joint Infection: A Single-Centre Cohort Study on 238 Patients

BACKGROUND

Rifampicin is a pillar in the treatment of periprosthetic joint infection (PJI). However, rifampicin resistance is an increasing threat to PJI treatment. This study explores the incidence of rifampicin-resistant bacteria over time in a Swedish tertiary referral centre and the association of rifampicin resistance with infection-free survival after PJI.

METHODS

The study included 238 staphylococcal PJIs treated between 2001 and 2020 for which susceptibility data for rifampicin were available. Data on causative bacteria, rifampicin resistance, treatment, and outcome were obtained. Kaplan-Meier survival analysis and Cox regression modelling estimated the infection-free cumulative survival and adjusted hazard ratios (HRs) for the risk of treatment failure.

RESULTS

Rifampicin-resistant causative bacteria were identified in 40 cases (17%). The proportion of rifampicin-resistant agents decreased from 24% in 2010-2015 to 12% in 2016-2020. The 2-year infection-free survival rates were 78.6% (95% CI, 66.4-93.1%) for the rifampicin-resistant group and 90.0% (95% CI, 85.8-94.4%) for the rifampicin-sensitive group. Patients with PJI caused by rifampicin-resistant bacteria had an increased risk of treatment failure (adjusted HR, 4.2; 95% CI, 1.7-10.3).

CONCLUSIONS

The incidence of PJI caused by rifampicin-resistant bacteria did not increase over the past 20 years. The risk of treatment failure in PJI caused by rifampicin-resistant bacteria is more than four times that caused by rifampicin-sensitive bacteria, highlighting the importance of limiting the development of rifampicin resistance.

Increased mortality after total hip prosthetic joint infection is mainly caused by the comorbidities rather than the infection itself

BACKGROUND AND PURPOSE

Periprosthetic joint infection (PJI) is a feared complication of arthroplasty surgery. There is controversy as to whether PJI also correlates with increased mortality. Our aim was to investigate in a nationwide cohort if PJI is an independent risk factor for dying.

PATIENTS AND METHODS

We performed a retrospective cohort study based on data from the Swedish Hip Arthroplasty Register (SHAR). All patients with a revision THA performed between 1998 and 2017 were included. The outcome is mortality; exposure is PJI according to SHAR. The control group was study participants who underwent aseptic revision. Confounders were age, sex, diagnosis, and comorbidity according to the Elixhauser index. The outcome was analyzed with a Cox proportional hazards model.

RESULTS

4,943 PJI revisions and 12,529 non-infected revisions were included in the analysis. The median follow-up time was 4.1 years. In the PJI group, 1,972 patients died and in the control group, 4,512. The incidence rate ratio was 1.19 (95% confidence interval [CI] 1.13-1.25), the crude hazard ratio (HR) 1.19 (CI 1.13-1.25), and the adjusted HR 1.05 (CI 0.99-1.12) for the exposed versus the unexposed group. The strongest confounder was comorbidity.

CONCLUSION

The increased mortality risk after revision due to PJI is mainly caused by the comorbidity of the patient, rather than by the infection itself.