One-Stage Exchange Arthroplasty: A Surgical Technique Update

Review of recent advances in the diagnosis and management of periprosthetic joint infection after total knee arthroplasty part 2: single-stage or two-stage surgical technique?

Periprosthetic joint infection (PJI) after total knee arthroplasty is a complication that affects approximately 2-3% of patients. The management of this issue is complicated and expensive for both the patients and the healthcare system. Multiple management options are available including antibiotic suppressive therapy, surgical management, and salvage procedures. Surgical management is considered a popular option for treating PJI, with multiple available surgical techniques, including single-stage revision arthroplasty and two-stage revision arthroplasty among others. Two-stage revision has been considered the gold standard for treating PJI. This method consists of two surgical procedures with a time interval in between, the first procedure aims to eradicate the infection along with implanting either a static or a mobile spacer, while the second intervention aims to remove the spacer and implant a new prothesis. During the interval period the patient is closely monitored through a handful of laboratory tests and clinical signs that help in assessing the optimal time of undertaking the second stage. However, in recent years, the single-stage method has gained much attention for its comparable outcomes and fewer complications. Contrary to the two-stage method, the single-stage approach consists only of one procedure in which the old infected prosthesis is removed and a new one is implanted. Many articles have compared the two methods over the years but have not agreed on a particular approach to be more potent in eliminating infection and providing better outcomes. Plenty of questions are yet to be answered regarding the two methods, including the superior type of spacer, interim period duration, and single-stage revision inclusion criteria. We herein, aim to address these issues, highlighting recent advances in managing this morbid complication and discussing controversial topics in the staged procedures.

Single-stage revision for chronic periprosthetic joint infection after knee and hip arthroplasties: indications and treatments

Single-stage revision for chronic periprosthetic joint infection has been introduced 40 years ago. This option is gaining more and more attention as well as popularity. It is a reliable treatment for the chronic periprosthetic joint infection after knee and hip arthroplasties when implemented by an experienced multi-disciplinary team. However, its indications and corresponding treatments remain controversial. This review focused on the indications and specific treatments related to the option, with an attempt to help surgeons to use this method with more favorable outcomes.

Successful eradication rate following one-stage septic knee and hip exchange in selected pre-operative culture-negative periprosthetic joint infections

PURPOSE

The main requirement for performing the one-stage septic exchange is the pre-operative identification of the pathogen and its susceptibility. The purpose of this study is to evaluate the success rate with special focus on reinfection in a cohort of patients who underwent one-stage septic knee or hip revision for pre-operative culture-negative PJI.

METHODS

We retrospectively analyzed 640 patients treated by one-stage revision for chronic knee or hip PJI between January 1, 2016, and December 31, 2018. Only cases with pre-operative culture-negative PJI, with culture-negative synovial aspirations and one negative open biopsy, were analyzed. We evaluated the septic and aseptic complication and the rate of complication-free survival defined as the time from the date of first operation and the date of complication events.

RESULTS

A total of 22 patients fulfilled the inclusion and were enrolled. The mean age of the group was 73.2 ± 9.8 years, with a median ASA score of 3 (range 3-4). After mean follow-up of 3.6 ± 2.6 years, 86.4% (19 out of 22) of patients reported no complications. Two patients (9.1%) after one-stage hip required revision arthroplasty due to septic failure, while one patient (4.5%) with one-stage knee had revision for femoral component aseptic loosening.

CONCLUSION

Our analysis suggests that the absence of pre-operative pathogen detection may not be contraindication to the one-stage revision in selected patients. The one-stage exchange might be considered in patients with pre-operative negative cultures in presence of ASA > 3 and multiple comorbidities that are not able to tolerate multiple surgeries.

One- or two-stage reimplantation for infected total knee prosthesis?

A prosthetic joint infection (PJI) is possibly the most significant potential complication of total knee arthroplasty (TKA) and is associated with substantial morbidity and socioeconomic burden. It is a devastating complication for both the patient and the surgeon alike. A two-stage revision approach for infected TKA has been the standard for surgical management; however, there is growing interest in single-stage revision surgery due to fewer procedures, reduced inpatient hospital stay and reduced costs to healthcare systems. A one-stage exchange is indicated when there is no sign of systemic sepsis and in cases where a microorganism has been isolated. It involves removal of the old prosthesis, debridement of all infected tissue, a copious washout and re-draping, and finally, re-implantation of a new prosthesis. The two-stage approach involves the use of an antibiotic spacer before the second stage is carried out. The length of time between the stages is discussed. Patients with a PJI should be managed by a multidisciplinary team. We recommend these patients are managed in specialist arthroplasty centres by high volume revision arthroplasty specialists.

Nontuberculous mycobacteria peri-prosthetic joint infection: An outcome analysis for two stage revision arthroplasty

PURPOSE

Nontuberculous mycobacteria periprosthetic joint infection (NTMPJI) is a rare complication of hip or knee joint arthroplasty. The experience for outcomes of NTMPJI treatment is still limited. The objective of this study was to investigate the outcome of hip or knee nontuberculous mycobacteria periprosthetic joint infection following treatment with two-stage exchange arthroplasty.

MATERIAL AND METHODS

From 1995 to 2020, 12 patients with NTMPJI were treated with two-stage exchange arthroplasty at our institution. We collected and analyzed variables including demographic data, comorbidity, microbiological data, treatment outcome and antibiotic formula in bone cement.

RESULTS

Mycobacterium abcessus (n = 6) and Mycobacterium chelonae (n = 2) constitute the majority of the cases. Five patients had early-onset PJIs and the other seven patients were late onset. The success rate of two-stage exchange arthroplasty was 66.7% (8 of 12). Three patients experienced infection relapse, and one patient had soft tissue compromise complication. Post-operative antibiotic therapy may not improve the success rate (4 of 6 cases, 66.7%). Based on in vitro study, the most commonly used effective antibiotic in bone cement spacer for nontuberculous mycobacteria was amikacin.

CONCLUSIONS

nontuberculous mycobacteria is a rare cause of PJIs and should be suspected especially in relatively immunocompromised patients. Resection arthroplasty with staged reimplantation is the preferred approach. Prolonged post-operative antibiotic therapy before reimplantation may not improve the success rate. Delayed revision surgery may not be needed and can be performed once C-reactive protein level is normal after a drug holiday.

Is a preoperative pathogen detection a prerequisite before undergoing one-stage exchange for prosthetic joint infection of the hip?

BACKGROUND

A preoperative pathogen detection is considered a prerequisite before undergoing one-stage exchange for prosthetic joint infection (PJI) according to most guidelines. This study compares patients with and without preoperative pathogen detection undergoing one-stage exchange for PJI of the hip. The authors put up the hypothesis that a preoperative pathogen detection is no prerequisite in selected cases undergoing one-stage exchange.

METHODS

30 consecutive patients with PJI of the hip, treated with one-stage exchange, between 2011 and 2021, were retrospectively included. Mean age was 70 years and mean follow-up 2.1 ± 1.8 years. PJI was defined according to the European Bone and Joint Infection Society. One-stage exchange was performed in (1) chronic PJI longer than 4 weeks, (2) well-retained bone condition, (3) absence of multiple prior revisions for PJI (≤ 2) with absence of difficult-to-treat pathogens in the past, and (4) necessity/preference for early mobility due to comorbidities/age.

RESULTS

One-stage exchange was performed in 20 patients with and in 10 without a preoperative pathogen detection. Age (71 years, 68 years, p = 0.519), sex (50% and 30% males, p = 0.440), American Society of Anesthesiologists Score (2.2, 2.4, p = 0.502), and Charlson Comorbidity Index (3, 4, p = 0.530) did not differ among the two groups. No significant differences were noted concerning preoperative CRP (15 mg/l, 43 mg/l, p = 0.228), synovial cell count (15.990/nl, 5.308/nl, p = 0.887), radiological signs of loosening (55%, 50%, p = 0.999), and intraoperative histopathology. Except a higher rate of coagulase-negative staphylococci (70%, 20%, p = 0.019) in patients with a preoperative pathogen detection, no significant differences in pathogen spectrum were identified among groups. Revision for PJI recurrence was performed in one patient with an initial preoperative pathogen detection (3.3%). Additional revisions were performed for dislocation in two and postoperative hematoma in one patient. Revision rate for both septic and aseptic causes (p = 0.999), stay in hospital (16 and 15 days, p = 0.373) and modified Harris Hip Score (60, 71, p = 0.350) did not differ between groups.

CONCLUSION

Patients with and without a preoperative pathogen detection did not show significant differences concerning baseline characteristics, clinical and functional outcomes at 2 years. An absent preoperative pathogen detection is no absolute contraindication for one-stage exchange in chronic PJI, if involving good bone quality and absence of multiple prior revisions.

External validation study of hip peri-prosthetic joint infection with cemented custom-made articulating spacer (CUMARS)

INTRODUCTION

Peri-prosthetic joint infection (PJI) is a devastating complication after total hip arthroplasty (THA). The use of custom-made articulating spacers (CUMARS) has been described for use in the first of 2-stage treatment. We report our outcomes of managing PJI using CUMARS.

METHODS

Patients undergoing 1st-stage revision using the Exeter standard stem, all-polyethylene acetabulum and antibiotic-loaded cement were identified. Medical records were assessed for demographics, microbiological and operative treatment, complications, eradication of infection and reoperations. No postoperative restrictions were enforced. 2nd-stage revision was undertaken in the presence of pain or subsidence.

RESULTS

53 patients underwent 1st-stage revision using this technique. The average follow-up was 3.9 (range 0.5-7.2) years. Infection was eradicated in 47 (88.7%) patients. 2 patients had chronic infection managed with suppressive antibiotics, 2 patients died before eradication confirmed, 1 patient had raised inflammatory markers but no positive aspiration cultures, 1 patient was lost to follow-up. Complications occurred in 5 (9.4%) patients - 4 dislocations and 1 infected haematoma. 4 patients required a repeated 1st stage. 2nd-stage revision was performed in 19 patients (35%).

CONCLUSIONS

The CUMARS technique is an effective way of eradicating PJI after THA. It maintains function by providing a stable construct that permits weight-bearing. It delays or negates the need for 2nd-stage revision. Furthermore, it allows surgeons to choose between managing patients prospectively as a single-stage revision with the option of reverting to a 2nd stage.

Engineered photo-chemical therapeutic nanocomposites provide effective antibiofilm and microbicidal activities against bacterial infections in porous devices

Today, prosthetic joint infection (PJI) is still a relatively rare but devastating complication following total hip and/or knee arthroplasty. The treatment of PJI is difficult due to a number of obstacles, such as microbial drug resistance, biofilm protection, and insufficient immune activity, which dramatically diminish the cure rate of PJI to <50%. To efficiently eradicate the bacteria hiding in the implant, photo-chemical joint antibacterial therapeutics based on indocyanine green (ICG) and rifampicin (RIF) co-loaded PLGA nanoparticles (IRPNPs) were developed in this study. The IRPNPs were first characterized as a spherical nanostructure with a size of 266 ± 18.2 nm and a surface charge of -28 ± 1.6 mV. In comparison with freely dissolved ICG, the IRPNPs may confer enhanced thermal stability to the encapsulated ICG and are able to provide a comparable hyperthermic effect and increased production of singlet oxygen under 808 nm near infrared (NIR) exposure with an intensity of 6 W cm-2. Based on the spectrophotometric analysis, the IRPNPs with ≥20-/3.52 μM ICG/RIF were able to provide remarkable antibiofilm and antimicrobial effects against bacteria in a porous silicon bead upon NIR exposure in vitro. Through the analysis of the microbial population index in an animal study, ≥70% Staphylococcus capitis subsp. urealyticus grown in a porous silicon bead in vivo can be successfully eliminated without organ damage or inflammatory lesions around the implant by using IRPNPs + NIR irradiation every 72 h for 9 days. The resulting bactericidal efficacy was approximately three-fold higher than that resulting from using an equal amount of free RIF alone. Taken together, we anticipate that IRPNP-mediated photochemotherapy can serve as a feasible antibacterial approach for PJI treatment in the clinic.

Treatment options in PJI - is two-stage still gold standard?

Total knee arthroplasty (TKA) is a successful treatment for osteoarthritis with good clinical outcomes 1,2. Periprosthetic joint infection (PJI) in TKA has a low incidence between 0.5 and 3% but it is nevertheless one of the most dreadful complications 3-6. Two-staged revisions are considered to be the gold standard for revision in chronic PJI with infection eradication rates of over 90% 7. Recently, similar infection eradication rates after one-staged revision arthroplasty have been reported 8-10, raising the question whether the two-staged approach can still be considered the gold standard. We therefore performed a literature review to analyse the correlation of one-staged and two-staged TKA revisions with recurrent infection rates and functional outcomes. Studies concerning PJI treated by one- or two-staged revision published between 2000 and 2020 were retrieved by searching the databases PubMed/Medline and the Cochrane Database of Systematic Reviews. 29 studies were included in this qualitative synthesis. Mean follow-up was at 4.9 ± 2.6 years. The mean infection eradication rate after one-staged revision vs. two-staged revision in TKA was 87 ± 8.8% vs. 83 ± 11.7%. The functional outcome measured by the mean Knee Society Score (KSS) of one-staged revision vs. two-staged revision in TKA was 80 ± 5.9 vs. 80 ± 3.9 points. One-staged revision arthroplasty in TKA appears to have similar infection eradication rates and functional outcomes compared to two-staged revision arthroplasty. However, these results should be interpreted with caution, since selection bias may have played a significant role. Several criteria to guide the surgeon in selecting the appropriate procedure have been described, but the current recommendations are based on poor evidence as randomized controlled trials are lacking 11,12. Two-staged revision remains a successful treatment option which is rightly the gold standard. However, there is a variety of cases in which one-staged revision is a viable alternative, where similar success rates and functional outcome can be expected 7,13.

[Periprosthetic joint infections : Latest developments, strategies and treatment algorithms]

BACKGROUND

Due to their multidimensional consequences, periprosthetic joint infections are a serious complication in arthroplasty. There are disagreements in the literature regarding their classification. At the same time, a consequence for the practical procedure cannot always be derived.

THERAPEUTIC PROCEDURES

In addition to debridement with antibiotics and implant retention, there are options for a one or two-stage change in the therapeutic procedure. Although the preservation of implants is only possible in the case of acute infections with a short duration of symptoms, prosthesis changes are indicated with a longer symptom duration. For both procedures, there are interinstitutional deviating indication criteria, weighing pros and cons. Both have specific problems, such as, in particular, the duration of the antibiotics course, the question of anchoring the prosthesis and, in the case of a two-stage procedure, the shape of the spacer.

A Low Percentage of Patients Satisfy Typical Indications for Single-stage Exchange Arthroplasty for Chronic Periprosthetic Joint Infection

BACKGROUND

Periprosthetic joint infection (PJI) is a leading cause of revision arthroplasty. Considerable controversy still exists whether single- or two-stage exchange is the better approach for patients with chronic PJI. Historically, single-stage exchange arthroplasty was thought to have an unacceptably high risk of reinfection compared with two-stage exchange but recent studies have demonstrated that this may not be the case. To be considered for single-stage exchange, patients should meet certain criteria including a preoperatively identified nonvirulent pathogen in an immunocompetent host with an uncompromised soft tissue envelope. It is unclear what proportion of patients with chronic PJI actually meet these criteria. Additionally, patients who meet the criteria for single-stage exchange are selected because, in principle, they may be more likely to be able to overcome the infection, but it is unknown what the reinfection risk is in patients undergoing two-stage exchange who might have met selection criteria for single-stage exchange.

QUESTIONS/PURPOSES

(1) What percentage of patients with chronic PJI treated at our institution met the International Consensus Meeting criteria for single-stage exchange arthroplasty? (2) Is the risk of persistent or recurrent infection lower for patients treated with two-stage exchange who met International Consensus Meeting criteria for single-stage exchange than it is among those who did not meet those inclusion criteria?

METHODS

Between 2012 and 2016, one referral center treated 120 patients with chronic PJI as determined by Musculoskeletal Infection Society (MSIS) criteria. During this time, we used single-stage exchange only rarely in patients with chronic PJI (3%; four of 120), and only in oncologic patients with mega-prosthesis implants; 7% (eight of 120) underwent other procedures (resection arthroplasty or arthrodesis). Of the remaining 108, 16% (17) were lost to follow-up; the remaining 91 were evaluated in this retrospective study. To answer our first question, we applied the International Consensus Meeting indications for single-stage exchange, which were a known nonvirulent preoperative organism, an immunocompetent host, and a healthy soft-tissue envelope without a sinus tract; we then calculated the percentage of patients who would have met those criteria. To answer our second question, we compared those who would and would not have met those criteria in terms of the proportion who were determined to be infection-free at 2 years using the MSIS criteria.

RESULTS

Only 19% (20 of 108) of patients met the International Consensus Meeting criteria for single-stage exchange. With the numbers available, there was no difference between those who met and did not meet those criteria in terms of the proportion of patients who had persistent or recurrent infection 2 years after treatment (three of 15 versus 32% [24 of 76]; p = 0.38).

CONCLUSIONS

We found that only a small proportion of patients who presented with chronic PJI to a referral center would have been suitable for single-stage direct exchange; with the numbers available, we found no difference in the reinfection risk after two-stage revision in those patients compared with those who would not have met those criteria. Consequently, it is possible that a small proportion of patients may benefit from single-stage exchange, but our small sample size may have missed important differences in reinfection risk, and so our findings on that question must be considered preliminary. Larger studies randomizing patients who meet single-stage criteria to either single- or two-stage exchange will better elucidate the true reinfection risk in this patient population.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The Changing Face of Infection, Diagnosis, and Management in the United Kingdom

Prosthetic joint infection is still a rare but devastating complication following total hip and knee arthroplasty. The incidence of prosthetic joint infection ranges from 2% to 4% in primary procedures as opposed to nearly 20% in revisions. The challenges that arise here include mainly diagnostic uncertainty, management in immunocompromised patients, recurrent infection, infection around a well-fixed implant, and substantial bone loss, and require careful preoperative assessment and well-defined management plans. This article summarizes recent developments in the diagnosis and management of this increasingly prevalent issue specifically focusing on outcomes following debridement, antibiotics, and implants retention and one-stage revision procedures.

Single vs 2-Stage Revision for the Treatment of Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is one of the most devastating complications following total joint arthroplasty, accounting for a projected 10,000 revision surgeries per year by 2030. Chronic PJI is complicated by the presence of bacterial biofilm, requiring removal of components, thorough debridement, and administration of antibiotics for effective eradication. Chronic PJI is currently managed with single-stage or 2-stage revision surgery. To date, there are no randomized, prospective studies available evaluating eradication rates and functional outcomes between the 2 techniques. In this review, both treatment options are described with the most current literature to guide effective surgical decision-making that is cost-effective while decreasing patient morbidity.

Persistent Fistula for Treatment of a Failed Periprosthetic Joint Infection: Relic From the Past or a Viable Salvage Procedure?

BACKGROUND

New treatment algorithms for periprosthetic joint infections (PJIs) show high success rates in achieving permanent infection eradication with some degree of failure. Different salvage procedures are described, but there is no evidence for persistent fistula (PF). The purpose of this study was to analyze PF as a salvage procedure in patients with therapy-resistant PJIs.

METHODS

This retrospective analysis included all patients treated with PF (2005-2018) in a maximum care center with PJI (knee or hip). The baseline parameters (age, sex, BMI) and other data (number of surgeries, pathogen spectrum, American Society of Anesthesiologists classification) were recorded. The function was documented using the Harris Hip Score, the Knee Society Score, and the quality of life using the SF-36 Health Survey.

RESULTS

A total of 159 patients were included (80 ± 12 years) and subdivided into four groups: hip (n = 66), knee (n = 13), Girdlestone resection arthroplasty (n = 50), knee arthrodesis (n = 27). Patients stayed 111 ± 87 days in the hospital, underwent six operations and three revisions after establishing PF. The mean American Society of Anesthesiologists score was 2.7. The BMI was 31 ± 3 kg/m² (P = .1). The follow-up was 2.8 ± 0.5 years including 27 patients. The Harris Hip Score and Knee Society Score were 38 and 34, respectively. SF-36 showed no significant difference.

CONCLUSION

The study showed poor outcomes regarding quality of life and the function of the infected joint. Therefore, the indication for establishing a PF in the treatment of PJI must be assessed very critically. PF is only an option for multimorbid patients with a limited life expectancy.

Rates of periprosthetic infection and surgical revision in Beijing (China) between 2014 and 2016: a retrospective multicenter cross-sectional study

Background

Periprosthetic joint infection (PJI) is a rare but devastating complication after total joint arthroplasty. There is a paucity of data on the incidence and prevalence of periprosthetic infection in mainland China. This study aimed to analyze the rates of surgical revision after arthroplasty due to PJI and the procedures followed in Beijing, China.

Methods

The study involved a retrospective multicenter cross-sectional survey of patients undergoing revisions for periprosthetic infection after hip/knee arthroplasty at nine hospitals in Beijing from 2014 to 2016. Age, gender, body mass index, primary diagnosis, comorbidity, primary surgery, treatment methods, and post-revision complications were analyzed.

Results

A total of 38,319 hip/knee arthroplasties and 366 (0.96%) revisions for PJI were identified. Of these, 161 (161/14,110; 1.14%) revisions involved hip arthroplasty, whereas 205 (205/24,209; 0.85%) revisions were due to knee arthroplasty. Procedures for revisions of infected hip included 7 (4.3%) cases of open debridement and prosthesis retention, 32 (19.9%) cases of one-stage exchange, 121 (75.2%) cases of two-stage exchange, and 1 (0.007%) case of hip dissection. As for the infected knee, the procedures included 45 (22.0%) cases of open debridement and prosthesis retention, 13 (6.3%) cases of one-stage exchange, 143 (69.8%) cases of two-stage exchange, and 4 (0.02%) cases of knee fusion.

Conclusions

The study found the rates of revision due to PJI to be low. Nonetheless, the incidence of PJI in mainland China could be higher and calls for more elaborate studies in geographically and socioeconomically diverse health institutions.

Risk factors, diagnosis and management of prosthetic joint infection after total hip arthroplasty

Introduction: Although a relatively rare complication, the incidence and prevalence of prosthetic joint infection (PJI) is certainly rising. This is mainly due to the number of arthroplasties performed each year and our ability to capture more cases. There is currently no consensus in the optimal diagnosis and management of the infected total hip arthroplasty. Various management techniques have been described in literature.Areas covered: We discuss and summarize the literature in diagnosing prosthetic joint infection (PJI) including next-generation sequencing. An in-depth critical analysis of the biomarkers and the novel tests available in the market is reviewed including the evolving nature of the diagnostic criteria for PJI. The key issues in managing infected THA are identified.Expert commentary: The senior authors' expert opinion on diagnostic criteria is discussed. We also stress the importance of tissue/fluid analysis of microbiology and histology being key to diagnosis of PJI. The indications of one-stage versus two-stage revision arthroplasty is examined, including techniques for successful one-stage revision.

Outcome of single-stage versus two-stage exchange for revision knee arthroplasty for chronic periprosthetic infection

The gold standard for treating chronic periprosthetic joint infection is still considered to be double-stage exchange revision. The purpose of this review is to analyse the difference in terms of eradication rates and functional outcome after single- and double-stage prosthetic exchange for chronic periprosthetic joint infection around the knee.

We reviewed full text articles written in English from 1992 to 2018 reporting the success rates and functional outcomes of either single-stage exchange or double-stage exchange for knee arthroplasty revision performed for chronic infection. In the case of double-stage exchange, particular attention was paid to the type of spacer: articulating or static.

In all, 32 articles were analysed: 14 articles for single-stage including 687 patients and 18 articles for double-stage including 1086 patients. The average eradication rate was 87.1% for the one-stage procedure and 84.8% for the two-stage procedure. The functional outcomes were similar in both groups: the average Knee Society Knee Score was 80.0 in the single-stage exchange group and 77.8 in the double-stage exchange. The average range of motion was 91.4° in the single-stage exchange group and 97.8° in the double-stage exchange group.

Single-stage exchange appears to be a viable alternative to two -stage exchange in cases of chronic periprosthetic joint infection around the knee, provided there are no contra-indications, producing similar results in terms of eradication rates and functional outcomes, and offering the advantage of a unique surgical procedure, lower morbidity and reduced costs.

Cite this article: EFORT Open Rev 2019;4:495-502. DOI: 10.1302/2058-5241.4.190003

Significant increase of pathogen detection rate by dry arthroscopic biopsies at suspected low-grade infection following total knee arthroplasty: a prospective observational study

INTRODUCTION

The differentiation between stiff-knee and low-grade periprosthetic joint infection (PJI) is the current diagnostic challenge in total knee (TKA) revision arthroplasty. The aim of this study was to investigate the additional value of dry biopsies, compared to wet biopsies, in patients presenting with knee stiffness following primary TKA.

MATERIALS AND METHODS

Single center, prospective observational study. Consecutive patients with joint stiffness of unknown origin following primary TKA were enrolled. Patient assessment followed the diagnostic standard algorithm. During diagnostic arthroscopy, synovial fluid (synovial WBC, PMN%) and five dry biopsies (dry) were collected. Then fluid was infused and another five microbiology (wet) and five histological biopsies gathered, all from identical locations. The primary outcome parameter was the difference between the pathogens in wet and dry biopsies.

RESULTS

71 patients (61% females, 67 ± 10 years) were eligible. Preoperative blood serology mean CRP (0.7 ± 1.5 mg/dl; p = 0.852), WBC (6.6 ± 1.7 G/l; p = 0.056), and synovial fluid mean WBC (1639 ± 2111; p = 0.602), PMN% (38 ± 28; p = 0.738) did not differ between patients with negative, positive wet or dry biopsies. The histology was in 11% positive (p = 0.058). In 32% at least one pathogen was detected, 48% from wet, 44% from dry biopsies. An inhomogeneous distribution was found. Cutibacterium acnes (100%) was solely found in wet, Micrococcus luteus (75%), Staphylococcus capitis (67%), and Micrococcus lylae (100%) were predominantly found in dry biopsies. Additional dry biopsies increased the pathogen detection rate by 49%.

CONCLUSION

The addition of dry biopsies to the current standard diagnostic algorithm for PJI increased the pathogen detection rate by 49%.

The Role of One-Stage Exchange for Prosthetic Joint Infection

PURPOSE OF REVIEW

In an era of increasing numbers of hip and knee replacements, strategies to manage prosthetic joint infection (PJI) that are effective at infection control with good patient-reported outcomes and cost containment for health systems are needed. Interest in single-stage exchange for PJI is rising and we assess evidence from the last 5 years related to this treatment strategy.

RECENT FINDINGS

Only five series for total knee replacement and ten series for total hip replacement have been reported in the last five years. More review articles and opinion pieces have been written. Reinfection rates in these recent studies range from 0 to 65%, but a meta-analysis and systematic review of all studies showed a reinfection rate of 7.6% (95% CI 3.4-13.1) and 8.8% (95% CI 7.2-10.6) for single-stage and two-stage revisions respectively. There is emerging evidence to support single-stage revision in the setting of significant bony deficiency and atypical PJIs such as fungal infections. Prospective randomised studies are recruiting and are necessary to guide the direction of single-stage revision selection criteria. The onus of surgical excellence in mechanical removal of implants, necrotic tissue, and biofilms lies with the arthroplasty surgeon and must remain the cornerstone of treatment. Single-stage revision may be considered the first-line treatment for all PJIs unless the organism is unknown, the patient is systemically septic, or there is a poor tissue envelope.