Articulating versus static spacers in revision total knee arthroplasty for sepsis. The Ranawat Award

Anterior tibial artery pseudoaneurysm secondary to articulating spacer use for infected knee arthroplasty: A case report

INTRODUCTION

Neurovascular compromise following primary or revision total knee arthroplasty is a rare but severe complication. To the best of our knowledge, there have been reports of pseudoaneurysm of the popliteal artery following primary and revision; however, an anterior tibial artery pseudoaneurysm with articulating spacer has not been described yet.

CASE PRESENTATION

We introduce a rare case of anterior tibial artery pseudoaneurysm and concomitant foot drop caused by an articulating spacer in a two-stage revision for infected knee replacement. Displacement of the articular spacer was observed on knee x-rays. Hematoma and pseudoaneurysm were detected. The patient was operated on urgently, and a pseudoaneurysm originating from the anterior tibial artery was intraoperatively observed.

DISCUSSION

Vascular complications following TKA are rare but could be limb-threatening and even life-threatening. If postoperative displacement of the articulating spacer is observed with neurovascular symptoms, orthopedic surgeons should be alerted to the possibility of a pseudoaneurysm.

CONCLUSION

Although rare, anterior tibial artery pseudoaneurysm should be considered among vascular injuries in revision knee arthroplasty cases.

Single-stage revision in the management of prosthetic joint infections after total knee arthroplasty - A review of current concepts

Introduction

Prosthetic joint infection (PJI) is a devastating complication following total knee arthroplasty (TKA); and the gold standard surgical approach involves a two-staged, revision TKA (TSR). Owing to the newer, emerging evidence on this subject, there has been gradual shift towards a single-stage revision approach (SSR), with the purported benefits of mitigated patient morbidity, decreased complications and reduced costs. However, there is still substantial lacuna in the evidence regarding the safety and outcome of the two approaches in chronic PJI. This study aimed to comprehensively review of the literature on SSR; and evaluate its role within Revision TKA post PJI.

Methods

The narrative review involved a comprehensive search of the databases (Embase, Medline and Pubmed), conducted on 20th of January 2024 using specific key words. All the manuscripts discussing the use of SSR for the management of PJI after TKA were considered for the review. Among the screened manuscripts, opinion articles, letters to the editor and non-English manuscripts were excluded.

Results

The literature search yielded a total 232 studies. Following a detailed scrutiny of these manuscripts, 26 articles were finally selected. The overall success rate following SSR is reported to range from 73 % to 100 % (and is comparable to TSR). SSR is performed in PJI patients with bacteriologically-proven infection, adequate soft tissue cover, immuno-competent host and excellent tolerance to antibiotics. The main difference between SSR and TSR is that the interval between the 2 stages is only a few minutes instead of 6 weeks. Appropriate topical, intraoperative antibiotic therapy, followed by adequate postoperative systemic antibiotic cover are necessary to ascertain good outcome. Some of the major benefits of SSR over TSR include reduced morbidity, decreased complications (such as arthrofibrosis or anesthesia-associated adverse events), meliorated extremity function, earlier return to activities, mitigated mechanical (prosthesis-associated) complications and enhanced patient satisfaction.

Conclusion

SSR is a reliable approach for the management of chronic PJI. Based on our comprehensive review of the literature, it may be concluded that the right selection of patients, extensive debridement, sophisticated reconstruction strategy, identification of the pathogenic organism, initiation of appropriate antibiotic therapy and ensuring adequate follow-up are the key determinants of successful outcome. To achieve this will undoubtedly require an MDT approach to be taken on a case-by-case basis.

Simple and cost-effective way to make mobile antibiotic cement spacer: hand-made silicone mold

BACKGROUND

Two-stage exchange arthroplasty is considered the most common approach for the management of prosthetic joint infections. There has been plentiful evidence to support the superiority of the mobile spacers over the static ones. Unfortunately, articulating options are not available in our low-resource environment, which motivated us to come up with an affordable way to create a mobile cement spacer. After experimenting with a variety of materials and producing methods, we realized that silicone is a favorable material for mold building and established a simple process of making a handmade silicone mold. We demonstrate the clinical outcomes of three prosthetic joint infections by using these spacers in the hope of spreading the idea to our colleagues who work in the circumstances of a developing country. Construction of the spacer molds: The molds, consisting of two parts, were shaped by using high viscosity addition silicone (elite HD+ putty soft, Zhermack SpA, Italy) as material, and previously removed implants as template. They were sterilized using ethylene oxide treatment before being ready for casting antibiotic-loaded bone cement spacer.

CASE REPORT

Three cases of prosthetic infection were treated with two-stage revision, using antibiotic-impregnated cement spacer cast in hand-made silicone molds. We sought to determine intraoperative complications, postoperative range of motion, and functional scores. All the patients were regularly followed up to identify fractures or dislocation of the spacer, and reinfection.

RESULTS

At the end of the follow-up, all three patients had the infection eradicated. The three patients could sit comfortably with bent knees, walk with partial weight-bearing, and achieve 75-80 degrees of knee flexion in the first week after surgery. Follow-up X-rays revealed no fractures or dislocation in any of the spacers.

CONCLUSION

Silicone molds offer a simple and cost-effective alternative to costly commercial products in producing articulating spacers. Treating infected joints arthroplasty with these spacers allows for early motion and partial weight bearing and improves patient satisfaction and life quality before reimplantation without significant complications.

Selecting a high-dose antibiotic-laden cement knee spacer

Prosthetic joint infection [PJI] after total knee arthroplasty (TKA) remains a common and challenging problem for joint replacement surgeons and patients. Once the diagnosis of PJI has been made, patient goals and characteristics as well as the infection timeline dictate treatment. Most commonly, this involves a two-stage procedure with the removal of all implants, debridement, and placement of a static or dynamic antibiotic spacer. Static spacers are commonly indicated for older, less healthy patients that would benefit from soft tissue rest after initial debridement. Mobile spacers are typically used in younger, healthier patients to improve quality of life and reduce soft-tissue contractures during antibiotic spacer treatment. Spacers are highly customizable with regard to antibiotic choice, cement variety, and spacer design, each with reported advantages, drawbacks, and indications that will be covered in this article. While no spacer is superior to any other, the modern arthroplasty surgeon must be familiar with the available modalities to optimize treatment for each patient. Here we propose a treatment algorithm to assist surgeons in deciding on treatment for PJI after TKA.

Management of Bilateral Synchronous Knee Prosthetic Joint Infection in a Patient with Infected Heart Transplant: A Case Report

CASE

A 74-year-old man presented with septic shock with infection of his heart transplant and bilateral prosthetic knee joints simultaneously. He underwent bilateral knee resection arthroplasties with placement of articulating spacers. At 3-year follow-up, the patient was alive and ambulating independently.

CONCLUSION

This case represents the first report of bilateral hematogenous prosthetic knee infections associated with concomitant enterococcal endocarditis of a heart transplant treated successfully and definitively with radical debridement and placement of articulating spacer with regular implants.

Mechanical complications of hip spacers: a systematic review of the literature

INTRODUCTION

Temporary spacers used in the staged revision of a hip prosthetic joint infection (PJI) have been associated with several mechanical complications with very variable reported general complications rates up to 73%. The aim of this systematic review was to assess the mechanical complications associated with hip antibiotic-loaded spacers when treating periprosthetic hip PJI.

METHODS

Through an electronic systematic search of PubMed, articles reporting mechanical complications of spacers used in the treatment of hip PJI were reviewed. Dislocations, spacer fracture, femoral fractures, and acetabular lysis rates were evaluated.

RESULTS

Forty studies were included. Standardized molded spacers had a significantly higher weighted mean of total mechanical complication rates (37.2%) when compared to standardized preformed spacers (13.8%, p = 0.039), while no significant difference was found between molded spacers and manually shaped spacers. Spacer dislocation was the most frequent complication. No significant difference in mechanical complication rate was found between spacers with and without any metallic component.

CONCLUSIONS

Spacer placement in chronic PJI of the hip with bone and soft-tissue defects is challenging and bears a high risk of mechanical failures and progressive bone loss during the interim period. A careful patient selection for spacer implantation is mandatory.

Articulating spacers: what are available and how to utilize them?

Periprosthetic joint infection (PJI) is the most devastating complication following total joint arthroplasty (TJA) and is posing a global healthcare challenge as the demand for TJA mounts. Two-stage exchange arthroplasty with the placement of antibiotic-loaded spacers has been shown to be efficacious against chronic PJI. This study aimed to review the key concepts, types, and outcome evaluations of articulating spacers in the two-stage exchange for PJI. Previous studies indicated that articulating spacers have been widely used due to better functional improvement and a comparable infection control rate relative to static spacers. Several types of articulating spacers are reportedly available, including hand-made spacers, spacers fashioned from molds, commercially preformed spacers, spacers with additional metal or polyethylene elements, new or autoclaved prosthesis, custom-made articulating spacers, and 3D printing-assisted spacers. However, limited evidence suggested no significant difference in clinical outcomes among the different subtypes of articulating spacers. Surgeons should be familiar with different treatment strategies when using various spacers to know which is the most appropriate.

Antibiotic Prophylaxis in One-Stage Revision of Septic Total Knee Arthroplasty: A Scoping Review

BACKGROUND

Total knee replacement (TKA) is becoming a routine procedure in orthopedic surgery. One of the possible complications of this surgery is periprosthetic joint infection (PJI). The purpose of this study is to identify, through a literature review, which antibiotic is used as prophylaxis for septic one-stage revision TKA and what is the rationale for its use.

METHODS

We searched: MEDLINE, Embase, PsycINFO on Ovid, the Cochrane Library, and the Google Scholar Database. The searches were limited by date (January 2005 to September 2022) and to the English language. All types of original research were considered, including prospective or retrospective longitudinal studies, cross-sectional studies, and randomized trials. The specific search terms were ((antibiotic [MeSH]) AND (prophylaxis)) and (TKA OR TKR OR "Arthroplasty, Replacement, Knee" [MeSH] OR ((knee) adj2 (replace* OR arthroplasty* OR prosthe*))).

RESULTS

Despite our research efforts, we found no article capable of answering the question of which antibiotic to use as surgical prophylaxis for a septic revision one-stage TKA.

CONCLUSIONS

Although the research results are inconclusive, we would recommend using the same antibiotic prophylaxis as for primary joint replacement, i.e., cefazolin, as it was recommended for its low side effect rate and relative effectiveness.

Two-stage revision in periprosthetic knee joint infections

Periprosthetic joint infection (PJI) following total knee arthroplasty is one of the most catastrophic and costly complications that carries significant patient wellness as well as economic burdens. The road to efficiently diagnosing and treating PJI is challenging, as there is still no gold standard method to reach the diagnosis as early as desired. There are also international controversies with respect to the best approach to manage PJI cases. In this review, we highlight recent advances in managing PJI following knee arthroplasty surgery and discuss in depth the two-stage revision method.

Comparison of Static and Articulating Spacers After Periprosthetic Joint Infection

INTRODUCTION

There is no consensus on whether articulating or static spacers are superior during two-stage exchange arthroplasty for periprosthetic joint infection. We aimed to compare surgical time, need for extensile exposure, surgical costs, and treatment success for articulating and static spacers.

METHODS

This was a retrospective review of 229 periprosthetic joint infections treated with two-stage exchange with a minimum of one-year follow-up. For articulating and static spacers, we compared the need for extensile exposure during reimplantation and treatment failure based on an updated definition. Surgical time and costs at both stages were also compared. Subgroup analysis was performed for total knee and hip arthroplasties.

RESULTS

There was no difference in the surgical time for spacer insertion; however, articulating spacers demonstrated reduced surgical time during reimplantation (181 vs. 234 minutes, P < 0.001). In multivariate analysis, there was no difference in extensile exposures (odds ratio 2.20, P = 0.081), but treatment failure was more likely for static spacers (odds ratio 2.17, P = 0.009). Overall surgical costs for two-stage exchange were similar between groups (23,782 vs. 23,766, P = 0.495).

CONCLUSION

Articulating spacers demonstrated shorter surgical times and a trend toward decreased extensile exposures during reimplantation. They also had higher treatment success rates and similar surgical costs for overall two-stage exchange.

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.

C9 immunostaining as a tissue biomarker for periprosthetic joint infection diagnosis

Background

Culture-negative periprosthetic joint infections (PJI) are often false diagnosed as aseptic implant failure leading to unnecessary revision surgeries due to repeated infections. A marker to increase the security of e PJI diagnosis is therefore of great importance. The aim of this study was to test C9 immunostaining of periprosthetic tissue as a novel tissue-biomarker for a more reliable identification of PJI, as well as potential cross-reactivity.

Method

We included 98 patients in this study undergoing septic or aseptic revision surgeries. Standard microbiological diagnosis was performed in all cases for classification of patients. Serum parameters including C-reactive protein (CRP) serum levels and white blood cell (WBC) count were included, and the periprosthetic tissue was immunostained for C9 presence. The amount of C9 tissue staining was evaluated in septic versus aseptic tissue and the amount of C9 staining was correlated with the different pathogens causing the infection. To exclude cross-reactions between C9 immunostaining and other inflammatory joint conditions, we included tissue samples of a separate cohort with rheumatoid arthritis, wear particles and chondrocalcinosis.

Results

The microbiological diagnosis detected PJI in 58 patients; the remaining 40 patients were classified as aseptic. Serum CRP values were significantly increased in the PJI cohort. Serum WBC was not different between septic and aseptic cases. We found a significant increase in C9 immunostaining in the PJI periprosthetic tissue. To test the predictive value of C9 as biomarker for PJI we performed a ROC analyses. According to the Youden's criteria C9 is a very good biomarker for PJI detection with a sensitivity of 89% and a specificity of 75% and an AUC of 0.84. We did not observe a correlation of C9 staining with the pathogen causing the PJI. However, we observed a cross reactivity with the inflammatory joint disease like rheumatoid arthritis and different metal wear types. In addition, we did not observe a cross reactivity with chondrocalcinosis.

Conclusion

Our study identifies C9 as a potential tissue-biomarker for the identification of PJI using immunohistological staining of tissue biopsies. The use of C9 staining could help to reduce the number of false negative diagnoses of PJI.

Treatment of Periprosthetic Joint Infection in Total Knee Arthroplasty with a Temporary Intramedullary Nail: Is a Long or Short Nail Better?

To our knowledge, no studies have compared postoperative outcomes between patients who received a temporary short or long intramedullary (IM) nail in the setting of infected total knee arthroplasty (TKA). Therefore, the aim of this study was to compare short-term outcomes for patients who underwent long or short IM nail insertion for treatment of periprosthetic knee infection. Specifically, we compared: (1) success rates; (2) patient reported/functional outcomes; and (3) complications between patients implanted with a short or a long IM nail following PJI of the knee. A retrospective chart review was performed for patients who underwent two-stage exchange arthroplasty with a temporary long or short IM nail between November 2010 and June 2018 at our institution (n = 67). Continuous and categorical variables were assessed using t-test/Mann-Whitney U test and chi-squared test, respectively. Logistic regression analyses were conducted to assess the effect of IM nail length on success rate while adjusting for age, sex, body mass index, and race. A total of 36 patients underwent temporary treatment with a long IM nail, while 31 patients received a short IM nail. There were no differences in success rate for reimplanted patients treated with long and short IM nails (odds ratio 0.992; p = 0.847). Fewer patients with a long IM nail went on to reimplantation (52.8 vs. 83.9%; p = 0.007). There was no difference in satisfaction (7.86 vs. 7.68; p = 0.515), pain scores (3.39 vs. 4.45 points; p = 0.126), or Knee Society score outcome scores (150.61 vs. 166.26 points; p = 0.117) between long or short IM nail patients. Following reimplantation, there was no difference in the number of patients who became reinfected (15.8 vs. 11.5%; p = 0.679) or went on to amputation (0 vs. 7.7%; p = 0.210). Periprosthetic joint infection (PJI) is a rare but serious postoperative complication following TKA. Our findings suggest that the use of long and short IM nails during two-stage exchange can have equal utility in PJI patients with severe bone defects.

First Stage Revision of Infected TKR: A Technique of Handcrafted Articulating Spacers and Cement Pancake Soft Tissue Spacers

This is a study to see if improvised 'articulating antibiotic cement spacers' work in two-stage revisions for infected TKRs with bone defects in the condyles. The second objective is to see if adhesions can be prevented between intra-articular bone and soft tissue around it after the first stage to make exposure of the joint easy and quick in the second stage. Six cases were selected which had moderate defects of femoral or tibial condyles and a modified technique was used to prepare articulating cement spacers. Antibiotic cement moulded like pancakes was placed on the exposed raw areas of the femur and tibia. Patients were mobilised with protected weight-bearing after the surgery and active knee flexion was encouraged. Patients regained a mean of 80 degrees of knee flexion during the interval between the stages and a mean of 100 degrees of flexion following the second stage. There was no bone loss while removing the modified cement spacers. Patients had no significant intra-articular adhesions and hence the exposure of the knee joint during the second stage did not require further intra-articular dissection. Standard articulating spacers are not suitable in the cases with bone loss of the condyles. Our modified technique allowed us to use it in cases with moderate bone loss also where static spacers are used otherwise. This helped to mobilise these knees between the two stages of revision instead of keeping immobilised with static spacers. Antibiotic cement pancakes prevented intra-articular adhesions and carried an extra dose of antibiotic into the joint.

Which serum markers predict the success of reimplantation after periprosthetic joint infection?

Purpose

In clinical practice, serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels are routinely used to screen for periprosthetic joint infection (PJI), but the effectiveness of predicting the success of reimplantation is variable. This study aimed to evaluate the diagnostic effectiveness of serum CRP, ESR, plasma D-dimer, and fibrinogen values in groups achieving treatment success or failure for PJI.

Methods

A total of 119 PJI cases between January 2012 and January 2017 were identified and included in this study. The most recent serum CRP, ESR, plasma D-dimer, and fibrinogen values obtained prior to performing second-stage revision or spacer exchange were collected for analysis. Treatment failure was defined as having been unable to undergo reimplantation due to clinically persistent infection or reinfection after reimplantation.

Results

All these tests showed significantly lower values in the treatment success group than in the treatment failure group. The optimal cutoff serum CRP, ESR, plasma D-dimer, and fibrinogen levels for predicting the success of reimplantation were 9.4 mg/L, 29 mm/h, 1740 ng/mL, and 365.6 mg/dL, respectively. All tests had the same sensitivity (72.7%) except for ESR (63.6%), while their specificities were 92.6%, 88.0%, 72.3%, and 83.2%, respectively. Plasma fibrinogen had the highest AUC value of 0.831 [95% confidence interval (CI), 0.685 to 0.978], followed by serum CRP (0.829) and ESR (0.795); plasma D-dimer had the lowest AUC value of 0.716 (95% CI, 0.573 to 0.859).

Conclusion

Plasma CRP and fibrinogen are good tests for predicting reimplantation success after two-stage revision procedures for patients with PJI.

Against the Norm: Do Not Rely on Serum C-Reactive Protein and White Blood Cell Count Only When Assessing Eradication of Periprosthetic Joint Infection

Introduction: Periprosthetic joint infections (PJI) following primary arthroplasty continue to be a serious complication, despite advances in diagnostics and treatment. Two-stage revision arthroplasty has been commonly used as the gold standard for the treatment of PJI. However, much discussion persists regarding the interim of the two-stage procedure and the optimal timing of reimplantation. Serology markers have been proposed as defining parameters for a successful reimplantation. The objective of this matched-pair analysis was to assess the role of serum C-reactive protein (CRP) and white blood cell count (WBC) in determining infection eradication and proper timing of reimplantation. We investigated the delta (∆) change in CRP and WBC values prior to both stages of two-stage revision arthroplasty as a useful marker of infection eradication. Methods: We analyzed 39 patients and 39 controls, matched by propensity score matching (BMI, age, ASA-classification), with a minimum follow-up of 24 months and treated with a two-stage revision THA or TKA in our institution. Data of serum CRP and WBC values were gathered at two selected time points: prior to the explantation of the implant (preexplantation) and following the completion of antibiotic treatment regimen, both systemic and with a drug-eluting cement spacer (prereimplantation). Patient records were reviewed electronically for preexisting comorbidities, overall health status, synovial fluid cultures, inflammatory serologies, revision surgeries, and recurrent or persistent infection based on the modified Musculoskeletal Infection Society criteria. Patient demographics, ∆CRP, ∆WBC, and time interval to reimplantation were statistically analyzed using receiver operator curves (ROC), Pearson’s correlation coefficient, Levene’s test, and Student’s t-test. Results: Infection-free patients exhibited higher mean CRP and WBC than did patients who were reinfected at both time points. When comparing preexplantation with prereimplantation values, the median ∆CRP was 9.48 mg/L (interquartile range (IQR) 2.3−36.6 mg/L) for patients who did not develop a reinfection versus 2.74 mg/L (IQR 1.4−14.2 mg/L) for patients who developed reinfection (p = 0.069). The median ∆WBC was 1.5 × 109/L (IQR 0.6−4.0 × 109/L) for patients who remained infection-free versus 1.2 × 109/L (IQR 0.8−2.2 109/L) for patients who developed reinfection (p = 0.072). Analysis of areas under the curve (AUC) using ROC demonstrated poor prediction of persistent infection by ∆CRP (AUC = 0.654) and ∆WBC (AUC = 0.573). Although a highly significant correlation was found between the interim interval and infection persistence (r = 0.655, p < 0.01), analysis using ROC failed to result in a specific threshold time to reimplantation above which patients are at significantly higher risk for reinfection (AUC = 0.507). Conclusion: No association could be determined between the delta change in serum CRP and WBC before and after two-stage revision arthroplasty for PJI and reinfection risk. Even though inflammatory serologies demonstrate a downtrending pattern prior to reimplantation, the role of CRP and WBC in determining the optimal timing of reimplantation seems to be dispensable. Planning a second-stage reimplantation requires assessing multiple variables rather than relying on specific numeric changes in these inflammatory marker values.

Are Static Spacers Superior to Articulated Spacers in the Staged Treatment of Infected Primary Knee Arthroplasty? A Systematic Review and Meta-Analysis

In the treatment of knee periprosthetic joint infection with a two-stage protocol, static spacers allow for the local delivery of high doses of antibiotics and help to preserve soft tissue tension. Articulated spacers were introduced to better preserve flexion after the reimplantation. The aim of this systematic review is to provide a comprehensive data collection of the results of these different spacers. An in-depth search on the main clinical databases was performed concerning the studies reporting data on the topic. A total of 87 studies and 4250 spacers were included. No significant differences were found both in pooling data analysis and meta-analysis of comparative studies about infection recurrences, complications, and clinical scores. Mean active knee flexion at last follow-up after total knee reimplantation was found to be significantly higher using articulated spacers (91.6° ± 7° for static spacers vs. 100.3° ± 9.9° for articulated spacers; p < 0.001). Meta-analysis also recognized this strong significant difference (p < 0.001). This review has confirmed that articulated spacers do not appear to be inferior to static spacers regarding all clinical outcomes, while they are superior in terms of active flexion. However, the low quality of the studies and the risk for selection bias with complex patients preferentially treated with static spacers need to be accounted for.

A Mid-term Follow-up Study on the Reimplantation of Autoclaved Femoral and Tibial Components as Spacers for Treating Infected Total Knee Arthroplasty

Objective

Infection after total knee arthroplasty (TKA) is a rare but devastating complication. Different types of spaces have been used in two‐stage revision. The study aimed to evaluate the effect of autoclaved femoral and tibial components as spacers for treating periprosthetic infections after TKA.

Methods

A retrospective study was performed for 13 patients (five males, eight females) with a mean age of 69 ± 6 (range, 57–80) years and suffering from periprosthetic infection after TKA. They were treated with unconventional two‐stage revision from May 2008 to June 2017. In the first‐stage surgery, the autoclaved femoral and tibial components were reimplanted with a new liner as a spacer after a thorough debridement. After 4–6 months, the second‐stage surgery was performed according to the patients' requirements. The knee society score (KSS) and knee range of motion (ROM) were assessed before and after surgery. The reinfection rate was calculated.

Results

The mean duration of follow‐up was 5.7 ± 2.1 (range, 3.1–8.8) years. Culture‐positive infections comprised 69% of the cohort. All patients were able to walk 24 h after the first stage surgery, and the knee ROM could reach 90° in 1 week. Two patients (15.4%) experienced an infection recurrence. One patient was reinfected 1 year after the first stage surgery. Another patient developed reinfection 3 years after surgery but did not choose re‐revision and died of pneumonia. Only one patient underwent the second stage revision. The remaining 10 patients refused to receive a new prosthesis. At the time of the final follow‐up, six patients had slight pain in the knee while walking, and one patient required crutches to walk. There were no signs of prosthesis dislocation, rupture, deep vein thrombosis, pulmonary embolism, or delayed wound healing. No radiolucent lines or osteolysis were found. The mean KSS improved from 51 ± 10 (range, 35–63) points preoperatively to 79 ± 5 (range, 60–85) points at the final follow‐up. The average ROM before and after the first stage surgery were 62° ± 29° (range, 10°–100°) and 104° ± 9° (range, 90°–120°) (t = 4.659, P < 0.01) respectively. The infection control rate was 84.6%.

Conclusion

Reimplantation of the autoclaved original femoral and tibial components as an articulating spacer during the first stage surgery is a valuable addition for treating an infected TKA.

Nephrotoxicity Related to Antibiotic-Loaded Spacers in a 2-Stage Revision for Periprosthetic Joint Infection

Antibiotic-loaded bone cement (ALBC) spacers are the mainstay in 2-stage revision, but antibiotics (vancomycin plus aminoglycosides) may undergo systemic absorption, resulting in acute kidney injury (AKI). Data on spacer antibiotics are heterogeneous. Our objective was to review risk factors for AKI and dosage of antibiotics. Significant AKI risk factors were antibiotic concentration greater than 3 or 3.6 g per cement batch, comorbidities, chronic kidney disease, and hypovolemia. Despite similar spacer antibiotic dosing, there was remarkable variability in serum concentrations. To err on the side of caution, it appears that antibiotic dose below 3 g per cement batch might be relatively safe until more evidence surfaces. Consideration of risk factors for AKI calls for appropriate antibiotic use in 2-stage revision. [Orthopedics. 20XX;XX(X):xx-xx.].

Comparison of dynamic and static spacers for the treatment of infections following total knee replacement: a systematic review and meta-analysis

Background

Revision surgery is the most common treatment for patients who develop infection after total knee arthroplasty (TKA). Two types of spacers are often used in revision surgery: dynamic spacers and static spacers. The comparative efficacy of these two types of spacers on knee prosthesis infections is not well established. Therefore, we carried out a systematic evaluation and meta-analysis with the aim of comparing the difference in efficacy between dynamic and static spacers.

Methods

We conducted the literature search in PubMed, Web of Science, Cochrane Library, and Embase databases. The articles searched were clinical study comparing the difference in efficacy between dynamic spacers and static spacers for the treatment of prosthetic infections occurring after total knee arthroplasty.

Results

We conducted a literature search and screening based on the principles of PICOS. Ultimately, 14 relevant clinical studies were included in our current study. We use infection control rate as the primary evaluation indicator. The KSS knee scores (KSSs), KSS functional scores, bone loss and range of motion (ROM) are secondary indicators of evaluation. Thirteen of these included studies reported the infection control rates, with no significant difference between dynamic and static shims (RR: 1.03; 95% Cl 0.98, 1.09; P = 0.179 > 0.05). The KSSs were reported in 10 articles (RR: 5.98; 95% CI 0.52, 11.43; P = 0.032 < 0.05). Six articles reported the KSS functional scores (RR: 13.90; 95% CI 4.95, 22.85; P = 0.02 < 0.05). Twelve articles reported the ROM (RR: 17.23. 95% CI 10.18, 24.27; P < 0.0001). Six articles reported the bone loss (RR: 2.04; 95% CI 1.11, 3.77; P = 0.022 < 0.05).

Conclusion

Current evidence demonstrates that dynamic spacers are comparable to static spacers in controlling prosthetic joint infection. In terms of improving the functional prognosis of the knee joint, dynamic spacers are more effective than static spacers.

Utilizing a Prefabricated Antibiotic-Impregnated Articular Spacer Combined With an Intramedullary Device for Significant Femoral Bone Loss in Periprosthetic Hip Infection

Periprosthetic joint infection can be a devastating complication following total hip arthroplasty, which often requires a lengthy treatment course that is fraught with complications. There are various types of antibiotic-impregnated spacers that can be used to treat periprosthetic hip infections, with articulating spacers being utilized frequently with the goal of preserving patient range of motion and functionality. Many of these articulating spacers have pre-set sizes and stem options, which accommodate the majority of patients. However, when significant femoral bone loss is evident at the time of revision surgery, many articulating spacer options are not sufficient to provide stability, and custom modifications of available spacer constructs may be needed to fill the bony void. The goal of this article is to report a surgical technique that can be used in the salvage of failed antibiotic-impregnated spacers where severe femoral bone loss is present.

New Primary Total Knee Arthroplasty Components Versus Other Contemporary Types of Spacers for the Treatment of Chronic Periprosthetic Knee Infection With a Two-Stage Protocol

The optimal type of antibiotic spacer for the treatment of a knee periprosthetic joint infection (PJI) remains a topic of debate. Although the ultimate goal of an antibiotic spacer is infection control, contemporary spacer iterations, such as the use of a new femoral component (NFC), may offer unique advantages. The primary goal of this study was to compare rates of infection control and functional outcomes between contemporary spacer types. We retrospectively reviewed 96 patients who underwent removal of a total knee arthroplasty with insertion of an antibiotic spacer for knee PJI over a 14-year period at a single institution with a minimum 1-year follow-up. Three patient cohorts were defined based on spacer type: NFC (n=30), cement-on-cement (n=19), and static (n=47). There was no association between spacer type and the odds of infection clearance (P=.60). The NFC spacers resulted in increased knee range of motion before replantation and improved ambulatory status at 8 weeks postre-plantation, although no difference was seen at final follow-up. The use of NFC spacers may provide functional advantages over their contemporary counterparts, and the potential of NFC spacers to be used in single-stage exchange arthroplasty remains an appealing area of investigation. Future high-powered, prospective, noninferiority studies between contemporary spacer types are needed. [Orthopedics. 2022;45(2):109-115.].

Outcomes of Modular Knee Arthrodesis for Challenging Periprosthetic Joint Infections

Background

Methods

Results

Discussion

Diagnosis and management of infected arthroplasty

Periprosthetic joint infection (PJI) is one of the most dreadful complications after THA and TKA. Though prevention is of utmost importance in PJI management, the last decade has seen many remarkable developments in PJI diagnosis, including the introduction of several standardized PJI diagnostic definitions and biomarkers. Depending on the specific clinical situation, a myriad of treatment options for PJI are offered. Our review aims to summarize the pertinent information on PJI diagnosis and synthesize literature on the different treatment methods currently used in clinical practice. One of the most accepted PJI diagnostic definitions was developed by the Musculoskeletal Infection Society (MSIS) in 2011, later modified in the 2013 International Consensus Meeting (ICM). After promising results from studies, alpha-defensins and D-dimer were recently incorporated into the 2018 ICM PJI definition. The management choices for PJI include irrigation and debridement (DAIR), one-stage exchange arthroplasty, or two-stage exchange arthroplasty, to name a few. While two-stage revision has traditionally been the treatment of choice in the United States, there has been a growing body of evidence framing one-stage revision as a comparable choice. One-stage revision should be offered in patients meeting strict selection criteria: no sinus tract, proper soft tissue available for wound closure, appropriate bone stock, a favorable identifiable organism with encouraging antibiotic sensitivities (for cement and oral suppression later), and robust immunological status. DAIR can be considered in case of early infections with sensitive infecting organisms. Patients with multiple unsuccessful revisions or those who refuse further surgical intervention for PJI can be offered antibiotic suppression. If nothing seems to work, salvage procedures (resection arthroplasty and arthrodesis) are available as a last resort. Further research is encouraged to improve on diagnostic capabilities and develop evidence on the best treatment of choice for PJI.

Economic advantage of ‘self-made’ antibiotic-loaded spacer compared to prefabricated antibiotic-loaded spacer and spacer molds in two-staged revision arthroplasty

Infection after total hip or total knee arthroplasty is a serious complication implying great costs for the health care system. Amongst the different treatment options, the two-step exchange using a spacer in the interval is a valid option. We evaluate the economic impact of our self-made antibiotic-loaded hip and knee cement spacers compared with prefabricated spacers and spacer molds. Costs to prepare self-made cement spacers are detailed for each spacer type. We also assess the intraoperative time spent for fabricating our self-made hip and knee spacers. The price of these self-made knee spacer is 514 CHF (450 EUR / 505 USD) if non-articulated and 535 CHF (470 EUR / 525 USD) if articulated ; the price for the self-made hip spacer is 749 CHF (760 EUR / 735 USD). Our average preparation time is 14 minutes for our self-made knee spacers and 16 minutes for our self-made hip spacers. While the senior surgeon is fabricating the self-spacers, another surgeon of the team continues intensive irrigation and debridement. Thus, no time is lost waiting for the self-spacer to be fabricated. In our hands, self-made hip and knee spacers are at least 40-50% cheaper than prefabricated spacers and spacer-molds. This is a serious economic advantage in this already expensive surgery. When done in teamwork, self-spacer fabrication does not increase the surgery time. The economic advantage is added to the main and most important advantage of self- made spacers, which remains the possibility of patient adapted anatomical reconstruction of the joint.

Cruciate-Retaining vs Posterior-Stabilized Antibiotic Cement Articulating Spacers for Two-Stage Revision of Prosthetic Knee Infection: A Retrospective Cohort Study

BACKGROUND

Antibiotic cement articulating spacers are recommended during 2-stage revision for prosthetic knee infection because of increased range of motion (ROM) and improved function; however, spacer mechanical complications have been reported. We aimed to determine the association between different constraints of articulating spacers and the rate of complications and infection eradication, functional outcomes, and ROM.

METHODS

A retrospective study of prosthetic knee infection using cruciate-retaining (CR) or posterior-stabilized (PS) spacers was conducted between 2011 and 2018. The rate of spacer mechanical complications, infection eradication after reimplantation and reoperation, Hospital of Special Surgery (HSS) knee score, and ROM during the interim stage were analyzed. All patients were regularly followed up for 2 years.

RESULTS

One hundred forty-one patients were included, with 66 CR and 75 PS spacers. Overall mechanical complication rate was lower in PS (9.3%) than in CR spacers (45.5%) (P < .001), especially in joint dislocation (1.3% vs 30.3%, respectively, P < .001). Overall reoperation rate was lower in PS (16.0%) than in CR spacers (36.4%) (P < .001), especially for mechanical complications (1.3% vs 24.2%, respectively, P < .001). HSS knee score was higher in PS (72.3) than in CR spacers (63.8) (P < .001). ROM was greater in PS (90.3°) than in CR spacers (80.6°) (P = .005), especially at maximum flexion (102.4° vs 89.6°, respectively, P = .003). Infection eradication was comparable between the spacers.

CONCLUSION

Both spacers can control infection; however, PS spacers had a lower rate of mechanical complications and reoperation, better HSS knee scores, and greater ROM than CR spacers.

On the Necessity of a Customized Knee Spacer in Peri-Prosthetic Joint Infection Treatment: 3D Numerical Simulation Results

Peri-prosthetic joint infections (PJIs) dramatically affect human health, as they are associated with high morbidity and mortality rates. Two-stage revision arthroplasty is currently the gold standard treatment for PJI and consists of infected implant removal, an accurate debridement, and placement of antimicrobial impregnated poly-methyl-metha-acrylate (PMMA) spacer. The use of antibiotic-loaded PMMA (ALPMMA) spacers have showed a success rate that ranges from 85% to 100%. ALPMMA spacers, currently available on the market, demonstrate a series of disadvantages, closely linked to a low propensity to customize, seen as the ability to adapt to the patients’ anatomical characteristics, with consequential increase of surgical complexity, surgery duration, and post-operative complications. Conventionally, ALPMMA spacers are available only in three or four standard sizes, with the impossibility of guaranteeing the perfect matching of ALPMMA spacers with residual bone (no further bone loss) and gap filling. In this paper, a 3D model of an ALPMMA spacer is introduced to evaluate the cause- effect link between the geometric characteristics and the correlated clinical improvements. The result is a multivariable-oriented design able to effectively manage the size, alignment, stability, and the patients’ anatomical matching. The preliminary numerical results, obtained by using an “ad hoc” 3D virtual planning simulator, clearly point out that to restore the joint line, the mechanical and rotational alignment and the surgeon’s control on the thicknesses (distal and posterior thicknesses) of the ALPMMA spacer is mandatory. The numerical simulations campaign involved nineteen patients grouped in three different scenarios (Case N° 1, Case N° 2 and Case N° 3) whose 3D bone models were obtained through an appropriate data management strategy. Each scenario is characterized by a different incidence rate. In particular, the observed rates of occurrence are, respectively, equal to 17% (Case N° 1), 74% (Case N° 2), and 10% (Case N° 3).

Two-Stage Exchange Using a Short Intramedullary Nail for Treatment of Periprosthetic Knee Infections: A Technique Worth Questioning

Periprosthetic joint infections (PJIs) following total knee arthroplasty (TKA) are serious orthopaedic complications that pose marked burdens to both patients and health care systems. At our institution, two-stage exchange with a temporary short antibiotic cement-coated intramedullary nail was utilized for the treatment of repeat PJIs in a series of compromised patients with considerable bone loss. This study reports on (1) success rates, (2) functional and pain outcomes, (3) and complications for patients receiving a temporary short intramedullary nail for the treatment of PJI. Our institutional database was queried for all repeat knee PJI patients between March 1st, 2009 and February 28th, 2015. Patients with type II/III Anderson Orthopaedic Research Institute (AORI) bone defects who underwent two-stage exchange arthroplasty with a short antibiotic-coated intramedullary nail were included for analysis (n = 31). Treatment success was determined using the Delphi-based consensus definition of a successfully treated PJI: infection eradication (healed wound with no recurrence of infection by the same organism), no further surgical intervention for infection after reimplantation, and no PJI-related mortality. A paired t-test was performed to assess for continuous variables. A total of 26 patients went on to reimplantation, while 5 patients retained the intramedullary nail. Overall treatment success was 74.2%. Range of motion significantly decreased postoperatively (102.1 vs. 87.3 degrees; p < 0.001), while Knee Society Scores (function) significantly increased (55.6 vs. 77.7, p < 0.001). A majority of patients were full weight-bearing immediately following surgery (38.7%). Treating poor health status patients with PJI of the knee can be difficult after multiple revisions. With a success rate similar to conventional methods, our results demonstrate that two-stage exchange with a temporary short intramedullary nail may be a desirable treatment option for patients with bony defects wishing to avoid amputation or permanent arthrodesis. However, this method does not outperform other treatment modalities, and may not be suitable for all patients. Patient expectations and health status should be carefully assessed to determine if this procedure is appropriate in this complex patient population.

Flash Sterilization and Component Reimplantation Is a Viable Option for Articulating Antibiotic Spacers in Periprosthetic Knee Infections

The articulating antibiotic spacer is a treatment utilized for two-stage revision of an infected total knee arthroplasty. The original femoral component is retained and reused in one described variation of this technique. The purpose of this study is to determine the safety and efficacy of flash sterilization of the femoral component for reimplantation in an articulating antibiotic spacer for the treatment of chronic periprosthetic joint infection. A total of 10 patients were identified prospectively with a culture positive infected total knee arthroplasty. The patients underwent explantation, debridement, and placement of an articulating antibiotic spacer consisting of the explanted and sterilized femoral component and a new polyethylene tibial insert. The explanted tibial components were cleaned and flash-sterilized with the femoral components, but the components were then aseptically packaged and sent to our microbiology laboratory for sonication and culture of the sonicate for 14 days. Ten of 10 cleaned tibial components were negative for bacterial growth of the infecting organism after final testing and analysis. At 18-month follow-up, 9 of 10 of patients remained clear of infection. Among the 10 patients, 7 were pleased with their articulating spacer construct and had no intention of electively pursuing reimplantation. Also, 3 of 10 of patients were successfully reimplanted at a mean of 6.5 months after explantation. Autoclave sterilization and reimplantation of components may be a safe and potentially resource-sparing method of articulating spacer placement in two-stage treatment of PJI. Patient follow-up demonstrated clinical eradication of infection in 90% of cases with good patient tolerance of the antibiotic spacer.

Management of Large Segmental Bone Defects at the Knee With Intramedullary Stabilized Antibiotic Spacers During Two-Stage Treatment of Endoprosthetic Joint Infection

BACKGROUND

Following debridement of infected prostheses that require reconstruction with an endoprosthetic replacement (EPR), instability related to segmental residual bone defects present a challenge in management with 2-stage reimplantation.

METHODS

We retrospectively reviewed all patients treated for revision total joint or endoprosthetic infection at the knee from 1998 to 2018. At our institution, patients with skeletal defects >6 cm following explant of prosthesis and debridement (stage 1) were managed with intramedullary nail-stabilized antibiotic spacers. Following stage 1, antimicrobial therapy included 6 weeks of intravenous antibiotics and a minimum of 6 weeks of oral antibiotics. Following resolution of inflammatory markers and negative tissue cultures, reimplantation (stage 2) of an EPR was performed.

RESULTS

Twenty-one patients at a mean age of 54 ± 21 years were treated for prosthetic joint infection at the knee. Polymicrobial growth was detected in 38% of cases, followed by coagulase-negative staphylococci (24%) and Staphylococcus aureus (19%). Mean residual skeletal defect after stage 1 treatment was 20 cm. Prosthetic joint infection eradication was achieved in 18 (86%) patients, with a mean Musculoskeletal Tumor Society score of 77% and mean knee range of motion of 100°. Patients with polymicrobial infections had a greater number of surgeries prior to infection (P = .024), and were more likely to require additional debridement prior to EPR (odds ratio 12.0, P = .048).

CONCLUSION

Management of large segmental skeletal defects at the knee following explant using intramedullary stabilized antibiotic spacers maintain stability and result in high rates of limb salvage with conversion to an endoprosthesis.

Aspect ratio of nano/microstructures determines Staphylococcus aureus adhesion on PET and titanium surfaces

AIMS

Joint infections cause premature implant failure. The avoidance of bacterial colonization of implant materials by modification of the material surface is therefore the focus of current research. In this in vitro study the complex interaction of periodic structures on PET and titanium surfaces on the adhesion of Staphylococcus aureus is analysed.

METHODS AND RESULTS

Using direct laser interference patterning as well as roll-to-roll hot embossing methods, structured periodic textures of different spatial distance were produced on surfaces and S. aureus were cultured for 24 h on these. The amount of adhering bacteria was quantified using fluorescence microscopy and the local adhesion behaviour was investigated using scanning electron microscopy. For PET structures, minimal bacterial adhesion was identified for an aspect ratio of about 0·02. On titanium structures, S. aureus adhesion was significantly decreased for profile heights of < 200 nm. Our results show a significantly decreased bacterial adhesion for structures with an aspect ratio range of 0·02 to 0·05.

CONCLUSIONS

We show that structuring on surfaces can decrease the amount of S. aureus on titanium and PET as common implant materials.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study highlights the immense potential of applying specific structures to implant materials to prevent implant colonization with pathogen bacteria.

Articulating vs Static Spacers for Native Knee Infection in the Setting of Degenerative Joint Disease

Background

Patients with advanced knee arthritis who develop a septic joint are not adequately treated with irrigation and debridement and intravenous antibiotics because of antecedent cartilage damage. The gold standard treatment has been a 2-stage approach. The periprosthetic joint infection literature has demonstrated the superiority of articulating spacers, and metal-on-poly (MOP) spacers are being used with increasing frequency. The purpose of this study was to compare the postoperative outcomes of patients with infected, arthritic knees treated by a 2-stage approach to those of patients who received single-stage treatment with a MOP spacer.

Methods

Sixteen patients with native knee septic arthritis treated with an antibiotic spacer between 1998 and 2019 were reviewed. Demographic data, clinical data, knee motion, Knee Society score, Timed-Up-and-Go, and pain scores were collected. Survivorship of final implants was compared.

Results

Six of 16 knees (38%) received single-stage treatment, and 10 received 2-stage treatment (62%). Five of 6 MOP spacers (83%) were retained at a mean follow-up of 3 ± 1.2 years. Nine of 10 (90%) receiving static spacers had subsequent reconstruction, with 9 (100%) surviving at mean follow-up of 7 ± 3.2 years. The patients who received MOP spacers trended toward greater terminal flexion, higher Knee Society score, and faster Timed-Up-and-Go at final follow-up.

Conclusion

Infection in a native, arthritic knee may be effectively treated using single-stage MOP spacer. Postoperative outcomes of single-stage MOP spacers compare favorably to staged static spacers and with those undergoing revision surgery for other indications. Longer follow-up is needed to evaluate durability of MOP spacers.

Küntscher nails with static cement spacer: A simple technique in periprosthetic knee infections with massive bone loss and instability

BACKGROUND

Two-stage revision for periprosthetic knee infection is challenging in cases of massive bone loss and instability. The present study aims to describe our experience with an alternative technique of reinforced cement spacer, usually necessary in these situations, focusing on its advantages and clinical results.

METHODS

We retrospectively identified all patients who underwent a two-stage revision for periprosthetic knee infection using two intramedullary Küntscher nails as reinforcement from January 2010 to September 2018. From each medical record, we extracted the type of explanted prosthesis, isolated micro-organism, number of cement spacers before index procedure (and related episodes of spacer dislocation) and final treatment.

RESULTS

Twelve patients were identified, mean age of 64.0 years (range 39-85). In four of them, the reinforced spacer was used twice for persistent infection, with a total of 16 procedures performed and no cases of dislocation. Ten patients were finally treated with reimplantation or arthrodesis with intramedullary nails, whereas an above-knee amputation was necessary for two patients. Infection was eradicated in 10 patients out of 12 (83%) at a mean follow up of 34.3 months (range 10-62).

CONCLUSIONS

This technique is an effective alternative to traditional spacers in cases of massive bone loss, producing a mechanically stable joint and preserving adequate tissue tensions. The construct is technically easy to perform and, not less importantly, to remove during stage 2. Further studies, with larger groups, are necessary to determine its validity.

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.

Acute kidney failure after total knee arthroplasty revision with antibiotic-impregnated cement spacer

Gentamicin-impregnated cement beads and spacers are frequently used in case of infective complications after Total Knee Arthroplasty (TKA). A great number of studies in the literature demonstrated that the local administration of gentamicin produces high local antibiotic levels but low serum and urine gentamicin concentrations. Gentamicin-impregnated cement spacer can induce nephrotoxicity in patients presenting major renal impairment susceptibility. We report a case of acute renal failure using a gentamicin-impregnated block spacer. An 83-year-old woman underwent a gentamicinimpregnated bone-cement spacer implant because of an infected TKA removal. Three days later patient clinical status got worse reporting a decreased urine output and increasing C-reactive protein (CRP), Serum Creatinine (SCr) and Blood Urea Nitrogen (BUN). Because the symptoms could be related to the knee spacer lead us to the decision of gentamicin-impregnated cement spacer removal. The day following the removal procedure showed progressive improvement of general condition with evidence of SCr and BUN normalization. Gentamicin-impregnated cement spacer can induce nephrotoxicity in patients presenting major renal impairment susceptibility.

Cemented prosthesis as spacer for two-stage revision of infected hip prostheses: a similar infection remission rate and a lower complication rate

Aims

To explore the effect of different types of articulating antibiotic-loaded cement spacers in two-stage revision for chronic hip prosthetic joint infection (PJI).

Methods

A retrospective cohort study was performed involving 36 chronic PJI patients treated with different types of articulating antibiotic-loaded cement spacers between January 2014 and December 2017. The incidence of complications and the therapeutic effects of different types of antibiotic-loaded articulating cement spacers were compared.

Results

A total of 36 patients with chronic hip PJI were included. Of these, 13 patients were treated with spacers with Kirschner wires as an endoskeleton (group I), ten patients were treated with spacers with a cemented femoral prosthesis as an endoskeleton (group II), and 13 patients were treated with cemented femoral prostheses combined with polyethylene sockets as a spacer (group III). All patients were followed for 12 to 60 months, with a mean follow-up period of 26.44 months (SEM 14.09). Infection was controlled in 34 patients (94.44%), and there were no significant differences in the eradication rate among the three groups (p = 0.705), but the risk of complications related to the spacer in group III was significantly lower than that in groups I and II (p = 0.006).

Conclusion

Articulating antibiotic-loaded cement spacers is effective in the treatment of chronic hip PJI, but we must pay attention to the occurrence of spacer fracture and dislocation, which can lead to poor joint function. The risk of spacer-related mechanical complications is low, and better joint function can be achieved when using cemented femoral prostheses combined with polyethylene sockets as spacers.

Cite this article: Bone Joint Res 2020;9(8):484–492.

The 'apple core' cement spacer for the management of massive bone loss in two-stage revision knee arthroplasty for infection

Antibiotic-loaded cement spacers are used in two-stage revision knee arthroplasty for infection, but commercially available spacers may not always be suitable for significant bone loss or soft tissue failure in multiply revised cases. We describe a technique for producing an on-table, static, reinforced cement spacer - the 'apple core' spacer - with the intended outcome of providing joint stability in such patients, prior to undertaking a second-stage procedure. Following a radical debridement, the spacer is made of three components: (1) a 'central bar' of external fixator connecting rods, combined using cerclage wires as needed; (2) a standard polymethylmethacrylate cement 'apple core'; and (3) a covering 'skin' of high dose antibiotic-loaded cement, which is stippled as it sets, to increase the surface area and facilitate antibiotic elution. This technique was performed in nine patients who underwent two-stage salvage revision for complex, recurrent infected total knee arthroplasty at a single institution. All patients successfully went on to definitive second-stage reimplantation and have retained their limbs. The 'apple core' cement spacer allows massive bone defects to be effectively managed between staged revision procedures.

A Novel Technique for Creating an Articulating Cement Spacer for Ankle Prosthetic Joint Infections

Total ankle arthroplasty has been increasing as a treatment for end-stage ankle arthritis. With this increase, the incidence of total ankle prosthetic infections will also increase. Treatment of these infections depends on the duration of symptoms and whether the infection is acute or chronic in presentation. The treatment of choice for chronic infections is a 2-stage procedure, the removal of implants and placement of a static cement spacer. We describe a technique for creating an articulating antibiotic cement spacer through an anterior approach in a patient with an infected total ankle arthroplasty. The articulating antibiotic cement spacer allows high doses of local antibiotics, decreases soft tissue contractures, and allows continued motion of the joint.

Complications in the treatment of prosthetic joint infection

AIMS

Two-stage exchange arthroplasty is the most common definitive treatment for prosthetic joint infection (PJI) in the USA. Complications that occur during treatment are often not considered. The purpose of this study was to analyze complications in patients undergoing two-stage exchange for infected total knee arthroplasty (TKA) and determine when they occur.

METHODS

We analyzed all patients that underwent two-stage exchange arthroplasty for treatment of PJI of the knee from January 2010 to December 2018 at a single institution. We categorized complications as medical versus surgical. The intervals for complications were divided into: interstage; early post-reimplantation (three months); and late post-reimplantation (three months to minimum one year). Minimum follow-up was one year. In total, 134 patients underwent a first stage of a two-stage exchange. There were 69 males and 65 females with an mean age at first stage surgery of 67 years (37 to 89). Success was based on the new Musculoskeletal Infection Society (MSIS) definition of success reporting.

RESULTS

Overall, 70 (52%) patients experienced a complication during the planned two-stage treatment, 36 patients (27%) experienced a medical complication and 47 (41%) patients experienced a surgical complication. There was an 18% mortality rate (24/134) at a mean of 3.7 years (0.09 to 8.3). During the inter-stage period, 28% (37/134) of patients experienced a total of 50 complications at a median of 47 days (interquartile range (IQR) 18 to 139). Of these 50 complications, 22 were medical and 28 required surgery. During this inter-stage period, four patients died (3%) and an additional five patients (4%) failed to progress to the second stage. While 93% of patients (125/134) were reimplanted, only 56% (77/134) of the patients were successfully treated without antibiotic suppression (36%, 28/77) or with antibiotic suppression (19%, 15/77) at one year.

CONCLUSION

Reported rates of success of two stage exchanges for PJI have not traditionally considered complications in the definition of success. In our series, significant numbers of patients experienced complications, more often after reimplantation, highlighting the morbidity of this method of treatment. Cite this article: Bone Joint J 2020;102-B(6 Supple A):145-150.

Calcium sulfate-containing glass polyalkenoate cement for revision total knee arthroplasty fixation

Poly(methyl methacrylate) (PMMA) bone cement is used as a minor void filler in revision total knee arthroplasty (rTKA). The application of PMMA is indicated only for peripheral bone defects with less than 5 mm depth and that cover less than 50% of the bone surface. Treating bone defects with PMMA results in complications as a result of volumetric shrinkage, bone necrosis, and aseptic loosening. These concerns have driven the development of alternative bone cements. We report here on novel modified glass polyalkenoate cements (mGPCs) containing 1, 5 and 15 wt% calcium sulfate (CaSO₄ ) and how the modified cements' properties compare to those of PMMA used in rTKA. CaSO₄ is incorporated into the mGPC to improve both osteoconductivity and bioresorbability. The results confirm that the incorporation of CaSO₄ into mGPCs decreases the setting time and increases release of therapeutic ions such as Ca²⁺ and Zn²⁺ over 30 days of maturation in deionized (DI) water. Moreover, the compressive strength for 5 and 15 wt% CaSO₄ addition increased to over 30 MPa after 30 day maturation. Although the overall initial compressive strength of the mGPC (~ 30 MPa) is less than PMMA (~ 95 MPa), the compressive strength of mGPC is closer to that of cancellous bone (~ 1.2-7.8 MPa). CaSO₄ addition did not affect biaxial flexural strength. Fourier transform infrared analysis indicated no cross-linking between CaSO₄ and the GPC after 30 days. in vivo tests are required to determine the effects the modified GPCs as alternative on PMMA in rTKA.

A Randomized Trial of Static and Articulating Spacers for the Treatment of Infection Following Total Knee Arthroplasty

BACKGROUND

There is no consensus whether the interim antibiotic spacer utilized in the 2-stage exchange arthroplasty should immobilize the joint or allow for motion. The purpose of this multicenter, randomized clinical trial was to compare static and articulating spacers as part of the 2-stage exchange arthroplasty for the treatment of chronic periprosthetic joint infection complicating total knee arthroplasty as defined with use of Musculoskeletal Infection Society criteria.

METHODS

Sixty-eight patients undergoing 2-stage exchange arthroplasty were randomized to either a static (32 patients) or an articulating (36 patients) spacer. An a priori power analysis determined that 28 patients per group would be necessary to detect a 13° difference in range of motion between groups. Six patients were excluded after randomization, 6 died, and 7 were lost to follow-up before 2 years.

RESULTS

Patients in the static group had a hospital length of stay that was 1 day greater than the articulating group after stage 1 (6.1 compared with 5.1 days; 95% confidence interval [CI], 5.3 to 6.9 days and 4.6 to 5.6 days, respectively; p = 0.032); no other differences were noted perioperatively. At a mean of 3.5 years (range, 2.0 to 6.4 years), 49 patients were available for evaluation. The mean motion arc was 113.0° (95% CI, 108.4° to 117.6°) in the articulating spacer group, compared with 100.2° (95% CI, 94.2° to 106.1°) in the static spacer group (p = 0.001). The mean Knee Society Score was higher in the articulating spacer cohort (79.4 compared with 69.8 points; 95% CI, 72.4 to 86.3 and 63.6 to 76.1, respectively; p = 0.043). Although not significantly different with the sample size studied, static spacers were associated with a greater need for an extensile exposure at the time of reimplantation (16.7% compared with 4.0%; 95% CI, 0.6% to 38.9% and 0.5% to 26.3%, respectively; p = 0.189) and a higher rate of reoperation (25.0% compared with 8.0%; 95% CI, 9.8% to 46.7% and 1.0% to 26.0%, respectively; p = 0.138).

CONCLUSIONS

Articulating spacers provided significantly greater range of motion and higher Knee Society scores at a mean of 3.5 years. Static spacers were associated with a longer hospital stay following removal of the infected implant. When the soft-tissue envelope allows and if there is adequate osseous support, an articulating spacer is associated with improved outcomes.

LEVEL OF EVIDENCE

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

The Role of Poly(Methyl Methacrylate) in Management of Bone Loss and Infection in Revision Total Knee Arthroplasty: A Review

Poly(methyl methacrylate) (PMMA) is widely used in joint arthroplasty to secure an implant to the host bone. Complications including fracture, bone loss and infection might cause failure of total knee arthroplasty (TKA), resulting in the need for revision total knee arthroplasty (rTKA). The goals of this paper are: (1) to identify the most common complications, outside of sepsis, arising from the application of PMMA following rTKA, (2) to discuss the current applications and drawbacks of employing PMMA in managing bone loss, (3) to review the role of PMMA in addressing bone infection following complications in rTKA. Papers published between 1970 to 2018 have been considered through searching in Springer, Google Scholar, IEEE Xplore, Engineering village, PubMed and weblinks. This review considers the use of PMMA as both a bone void filler and as a spacer material in two-stage revision. To manage bone loss, PMMA is widely used to fill peripheral bone defects whose depth is less than 5 mm and covers less than 50% of the bone surface. Treatment of bone infections with PMMA is mainly for two-stage rTKA where antibiotic-loaded PMMA is inserted as a spacer. This review also shows that using antibiotic-loaded PMMA might cause complications such as toxicity to surrounding tissue, incomplete antibiotic agent release from the PMMA, roughness and bacterial colonization on the surface of PMMA. Although PMMA is the only commercial bone cement used in rTKA, there are concerns associated with using PMMA following rTKA. More research and clinical studies are needed to address these complications.

Point/Counterpoint: Nonarticulating vs Articulating Spacers for Resection Arthroplasty of the Knee or Hip

Two-stage exchange arthroplasty remains the gold standard for chronic total knee arthroplasty (TKA) and total hip arthroplasty infections in North America. Cement spacers impregnated with high-dose antibiotics have been successfully used in the interim period of the 2-stage exchange process. A number of spacers have been described; however, this article will focus on articulating spacers. In the presence of an intact extensor mechanism (for TKA), reasonable soft tissue envelope, and adequate bone, articulating antibiotic spacers provide several advantages. These include an infection eradication rate of approximately 90%, higher range of motion after reimplantation, and lower complication rates when compared with nonarticulating spacers. In the appropriate patient, articulating antibiotic spacers are an effective and a safe treatment for infected TKAs and total hip arthroplasties.

Comparison of Traditional Molded, First-Generation Premolded, and Second-Generation Premolded Antibiotic-Loaded Polymethylmethacrylate Articulating Spacers for Treatment of Chronic Prosthetic Joint Infection of the Knee

BACKGROUND

The purpose of this study was to compare patients who had chronic prosthetic joint infection treated using three methods of articulating polymethylmethacrylate spacers in two-stage reimplantation.

METHODS

We identified 77 patients who had chronic prosthetic joint infection with a minimum of one-year follow-up. Reinfection rates were determined using modified International Consensus group criteria.

RESULTS

The overall reinfection rate was 18% (14 of 77 patients). Despite a higher medical comorbidity in the second-generation spacer cohort, there were no statistical differences in reinfection rates between articulating spacer types.

CONCLUSION

This study suggests that there were no differences in efficacy between the traditional molded, first-generation premolded, and second-generation premolded articulating spacers, but more studies with high level of evidence are needed.

Loading capacity of dynamic knee spacers: a comparison between hand-moulded and COPAL spacers

Background

The two-stage revision protocol represents the current gold standard for treating infected total knee replacement implants. Allowing early mobility with weight-bearing between staged procedures will enable early restoration to knee function. So, the mechanical performance of knee spacers is a key issue. Commercially available moulds are often used as they are easy to prepare and produce smoother surfaces of the articulating parts. However, they are costly, and only for single use. A cost-effective alternative is the surgeon-made hand-moulded spacers. In this study, we wanted to determine how the hand-moulded spacers will compare biomechanically with the commercially available COPAL spacers.

Methods

Seven cadaveric knees were implanted with knee spacers fabricated using COPAL knee moulds. The same surgeon implanted eight cadaveric knees with hand-moulded spacers. In the first test protocol, an axial load was applied at 200 mm/min till failure. In the second test protocol, the knees were cyclically loaded in five steps of 1000 cycles each from 30-400 N, 30-600 N, 30-800 N, 30-1000 N, 30-1200 N at 1.5 Hz.

Results

COPAL knee spacers demonstrated a maximum load and mean stiffness of 5202 (± 486.9) N and 1098 (± 201.5) N/mm respectively. The hand-moulded knee spacers demonstrated a mean stiffness of 4509 (± 1092.6) N and 1008.7 (± 275.4) N/mm respectively. The maximum axial displacement was 1.19 ± 0.57 mm and 0.89 ± 0.30 mm for specimens implanted with COPAL knee spacers and hand-moulded spacers respectively. The differences between COPAL and hand-moulded knee spacers were not statistically different.

Conclusions

Our study demonstrated that dynamic knee spacers may be able to withstand more than the touch-down load permitted in previous studies, and this may allow more weight-bearing during ambulation. Previous studies have demonstrated that hand-moulded knee spacers have similar advantages to commercially available dynamic spacers with respect to mobility, pain, bone loss, and reinfection rate. Given that ambulation with weight-bearing up to 1200 N is permitted during rehabilitation, it may be more cost-effective to fabricate hand-moulded spacers in revision total knee arthroplasty.

[Research progress of two-stage revision for periprosthetic joint infection after hip and knee arthroplasties]

Objective

To summarize the research progress of two-stage revision for periprosthetic joint infection (PJI) after hip and knee arthroplasties.

Methods

The related literature on two-stage revision for PJI was summarized, and the new progress in the choice of spacers, systemic antibiotic therapy, and risk factors were analyzed.

Results

Two-stage revision is a common way to treat infection after hip and knee arthroplasties. The types of spacers used in the one-stage operation are diverse and each has its own advantages and disadvantages. Non-articular spacers are mainly used for the patients with poor soft tissue conditions around the joints and severe bone defects. But the joint mobility is not good after the placement of the spacer. Articular spacers can restore the affected joint movement after operation, which is beneficial to the joint mobility after two-stage operation. The use of antibiotics is an indispensable part of the treatment process, and the effectiveness of short-term antibiotic treatment is similar to long-term treatment. Identifying the relevant risk factors that influence the prognosis of the two-stage revision can help preoperative management and reduce the recurrence rate of infection.

Conclusion

There are still controversies about the choice of spacers and systemic antibiotic therapy during the two-stage revision and treatment of PJI. The factors affecting the prognosis of the two-stage revision need to be explored and the further high-quality research is needed.

Two-Stage Exchange Arthroplasty for Periprosthetic Joint Infection: The Rate and Reason for the Attrition After the First Stage

BACKGROUND

Two-stage exchange arthroplasty remains a popular surgical treatment for patients with chronic periprosthetic joint infection (PJI). Patients who do not receive reimplantation were largely overlooked in the current literature. We aimed at investigating the clinical outcomes of these patients.

METHODS

Our institutional PJI database was retrospectively reviewed to identify 616 patients (237 hips, 379 knees) who were treated with an intended 2-stage exchange. Of them, 111 (18%) did not receive reimplantation within a minimum follow-up of 1 year. Chart review and targeted interviews were performed to elucidate the cause of attrition. Patients were considered to have failed treatment in the absence of reimplantation if they remained medically unfit for reimplantation, underwent a salvage procedure, or died during the study period.

RESULTS

Of the 111 patients without reimplantation, 29 (26.1%) did well with their retained spacer and were unwilling to proceed with reimplantation, 23 (20.7%) underwent salvage procedures, and the remaining 59 (53.2%) were considered medically unfit for reimplantation, with 34 of them dying within 1 year of initial spacer insertion. The overall success rate for 2-stage exchange cohort at 2 years was 65.7% when treatment failure without reimplantation was taken into account. Several factors associated with increased risk of treatment failure without reimplantation were identified using a multivariate regression model.

CONCLUSION

Almost 1 in 5 patients may never receive the intended reimplantation. Among many reasons for attrition, mortality appears to be a relatively common event. The current definition of treatment success does not take into account the attrition group and thus inflates the relative success of 2-stage exchange arthroplasty.