Two-stage revision of infected uncemented lower extremity tumor endoprostheses

Can Periprosthetic Joint Infection of Tumor Prostheses Be Controlled With Debridement, Antibiotics, and Implant Retention?

BACKGROUND

Two-stage revision for periprosthetic joint infection (PJI) in patients who have undergone segmental replacement of the distal femur or proximal tibia after tumor resection can be associated with considerable morbidity, pain, and risk of complications because the procedure often results in removal of long, well-fixed stems from the diaphysis. A less-aggressive surgical approach, such as debridement, antibiotics, and implant retention (DAIR), may be attractive to patients and surgeons because of less morbidity, but the likelihood of eradicating infection in comparison to the traditional two-stage revision is not well established for oncology patients. Furthermore, the relative risk of subsequent amputation for DAIR versus two-stage revision has not been defined for this population.

QUESTIONS/PURPOSES

(1) How does DAIR compare with two-stage revision in terms of infection control for patients with distal femoral or proximal tibial segmental modular endoprostheses? (2) Is DAIR as an initial procedure associated with an increased risk of amputation compared with two-stage revision for infection?

METHODS

From the longitudinally maintained orthopaedic oncology surgical database at our institution, we identified 69 patients who had been treated for a clinical diagnosis of PJI at the knee between 1993 and 2015. We excluded 32% (22) of patients who did not meet at least one of the major criteria of the Musculoskeletal Infection Society (MSIS) for PJI, 3% (2) of patients who underwent immediate amputation, 3% (2) of patients who had a follow-up time of < 24 months, and 7% (5) of patients who did not have a primary tumor of the distal femur or proximal tibia. The study consisted of 38 patients, of whom eight underwent two-stage revision, 26 underwent DAIR, and four underwent extended DAIR (removal of all segmental components but with retention of stems and components fixed in bone) for their initial surgical procedure. To be considered free of infection, patients had to meet MSIS standards, including no positive cultures, drainage, or surgical debridement for a minimum of 2 years from the last operation. Factors associated with time-dependent risk of infection relapse, clearance, amputation, and patient survival were analyzed using Kaplan-Meier survivorship curves and the log-rank test to compare factors. Association of demographic and treatment factors was assessed using chi-square and Fisher exact tests.

RESULTS

Continuous infection-free survival at 5 years was 16% (95% CI 2% to 29%) for patients undergoing DAIR compared with 75% (95% CI 45% to 100%) for patients undergoing two-stage revision (p = 0.006). The median (range) number of total surgical procedures was 3 per patient (1 to 10) for DAIR and 2 (2 to 5) for two-stage revision. Twenty-nine percent (11 of 38) of patients eventually underwent amputation. Survival without amputation was 69% (95% CI 51% to 86%) for DAIR compared with 88% (95% CI 65% to 100%) for two-stage revision at 5 years (p = 0.34). The cumulative proportion of patients achieving infection-free status (> 2 years continuously after last treatment) and limb preservation was 58% (95% CI 36% to 80%) for patients initially treated with DAIR versus 87% (95% CI 65% to 100%) for patients first treated with two-stage revision (p = 0.001).

CONCLUSION

Infection control was better with two-stage revision than DAIR. The chance of eventual clearance of infection with limb preservation was better when two-stage revision was chosen as the initial treatment. However, the loss to follow-up in the two-stage revision group would likely make the true proportion of infection control lower than our estimate. Our experience would suggest that the process of infection eradication is a complex and difficult one. Most patients undergo multiple operations. Nearly one-third of patients eventually underwent amputation, and this was a serious risk for both groups. While we cannot strongly recommend one approach over the other based on our data, we would still consider the use of DAIR in patients who present with acute short duration of symptoms (< 3 weeks), no radiographic signs of erosion around fixed implants, and organisms other than Staphylococcus aureus. We would advocate the extended DAIR procedure with removal of all segmental or modular components, and we would caution patients that there is a high likelihood of needing further surgery. A prospective trial with strict adherence to indications may be needed to evaluate the relative merits of an extended DAIR procedure versus a two-stage revision.

LEVEL OF EVIDENCE

Level III, therapeutic study.

High Rates of Treatment Failure and Amputation in Modular Endoprosthesis Prosthetic Joint Infections Caused by Fungal Infections With Candida

BACKGROUND

Fungal prosthetic joint infections (PJIs) are rare yet severe events associated with high rates of recurrent infection. Although bacterial PJIs associated with megaprostheses are known to be associated with higher rates of recurrence and amputation, little is known about fungal PJIs near megaprostheses.

QUESTIONS/PURPOSES

In patients with fungal megaprosthesis PJIs from one institutional registry, we asked: (1) What were the most common microorganisms isolated? (2) What were the reoperation-, revision-, and amputation-free survival rates 1 and 2 years after surgery?

METHODS

We conducted a retrospective analysis of megaprostheses in our institutional database. Between 2000 and 2022, 86 patients with a diagnosis of PJI after megaprosthesis implantation were surgically treated at our institution. We considered patients with microbiological cultures that were positive for fungal organisms and who had a minimum follow-up of 2 years from the initial treatment for PJI. Ten patients with fungal megaprosthesis PJIs were included. Although four patients had a follow-up shorter than 2 years, all reached one of the study endpoints at that earlier interval, and therefore were included. All included patients were treated between 2016 and 2022, and the diagnosis of PJI was made in accordance with the 2011 Musculoskeletal Infection Society criteria. Patients were treated with either debridement, antibiotics, and implant retention (DAIR), DAIR-plus (debridement, antibiotics, modular implant component exchange, and stem retention), or one-stage or two-stage revision. In general, DAIR was used for acute PJIs, while DAIR-plus was performed in patients with chronic PJIs who were deemed medically unfit to endure the high morbidity associated with removal of the stems. In cases of prior unsuccessful DAIR-plus or patients with fewer comorbidities, one-stage or two-stage revision was the main treatment approach. The median age at diagnosis was 67 years (range 32 to 84 years), 5 of 10 patients were female, and the median BMI was 31 kg/m 2 (range 20 to 43 kg/m 2 ). The median follow-up was 26 months (range 1 to 54 months). A Kaplan-Meier survival analysis was performed to calculate reoperation-, revision-, and amputation-free survival at 1 and 2 years from the index surgery for PJI.

RESULTS

The two most common organisms were Candida albicans (5 of 10 patients) and C.parapsilosis (3 of 10). Six of 10 patients had coinfection with a bacterial organism. One-year reoperation-free and revision-free survival were 35% (95% CI 9% to 64%) and 42% (95% CI 11% to 71%), respectively. Two-year reoperation-free and revision-free survival were 12% (95% CI 1% to 40%) and 14% (95% CI 1% to 46%), respectively. Amputation-free survival was 74% (95% CI 30% to 93%) at the 1-year interval and 40% at the 2-year interval (95% CI 7% to 73%). At the final follow-up interval, four patients had undergone amputations and four were being administered chronic antifungal suppression.

CONCLUSION

Megaprosthesis fungal PJIs are rare but devastating. Arthroplasty surgeons should consider treatment efficacy, which appears to be low across surgical strategies, and the patient's capacity to withstand it. A lower decision threshold for performing amputation may be considered in patients who require rapid infection control to initiate immunosuppressive treatments. Future studies should aim to compare the surgical and clinical outcomes of fungal PJIs with those of other etiologies while controlling for potential variables. Efforts should be made to establish multi-institutional collaborations to achieve larger study samples.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Controversies in orthopaedic oncology

Chondrosarcoma is the second most common surgically treated primary bone sarcoma. Despite a large number of scientific papers in the literature, there is still significant controversy about diagnostics, treatment of the primary tumour, subtypes, and complications. Therefore, consensus on its day-to-day treatment decisions is needed. In January 2024, the Birmingham Orthopaedic Oncology Meeting (BOOM) attempted to gain global consensus from 300 delegates from over 50 countries. The meeting focused on these critical areas and aimed to generate consensus statements based on evidence amalgamation and expert opinion from diverse geographical regions. In parallel, periprosthetic joint infection (PJI) in oncological reconstructions poses unique challenges due to factors such as adjuvant treatments, large exposures, and the complexity of surgery. The meeting debated two-stage revisions, antibiotic prophylaxis, managing acute PJI in patients undergoing chemotherapy, and defining the best strategies for wound management and allograft reconstruction. The objectives of the meeting extended beyond resolving immediate controversies. It sought to foster global collaboration among specialists attending the meeting, and to encourage future research projects to address unsolved dilemmas. By highlighting areas of disagreement and promoting collaborative research endeavours, this initiative aims to enhance treatment standards and potentially improve outcomes for patients globally. This paper sets out some of the controversies and questions that were debated in the meeting.

Surgical Management of Periprosthetic Joint Infections in Hip and Knee Megaprostheses

Periprosthetic joint infection is a feared complication after the megaprosthetic reconstruction of oncologic and non-oncologic bone defects of including the knee or hip joint. Due to the relative rarity of these procedures, however, optimal management is debatable. Considering the expanding use of megaprostheses in revision arthroplasty and the high revision burden in orthopedic oncology, the risk of PJI is likely to increase over the coming years. In this non-systematic review article, we present and discuss current management options and the associated results focusing on studies from the last 15 years and studies from dedicated centers or study groups. The indication, surgical details and results in controlling infection are presented for debridement, antibiotics, irrigation and retention (DAIR) procedure with an exchange of the modular components, single-stage implant exchange, two-stage exchanges and ablative procedures.

Risk Factors and Management of Prosthetic Joint Infections in Megaprostheses-A Review of the Literature

Prosthetic joint infection (PJI) is the most common mode of failure of megaprostheses, yet the literature on the topic is scarce, and studies report conflicting data regarding the optimal treatment strategy. Patients with megaprostheses PJI are often immunosuppressed, and surgeons must balance the trade-off between treatment efficacy and morbidity associated with the surgery aiming for infection eradication. Our review on megaprostheses PJI focuses on two axes: (1) risk factors and preventative strategies; and (2) surgical strategies to manage this condition. Risk factors were classified as either unmodifiable or modifiable. Attempts to decrease the risk of PJI should target the latter group. Strategies to prevent PJI include the use of silver-coated implants, timely discontinuation of perioperative antibiotic prophylaxis, and adequate soft tissue coverage to diminish the amount of dead space. Regarding surgical treatment, main strategies include debridement, antibiotics, implant retention (DAIR), DAIR with modular component exchange, stem retention (DAIR plus), one-stage, and two-stage revision. Two-stage revision is the "gold standard" for PJI in conventional implants; however, its success hinges on adequate soft tissue coverage and willingness of patients to tolerate a spacer for a minimum of 6 weeks. DAIR plus and one-stage revisions may be appropriate for a select group of patients who cannot endure the morbidity of two surgeries. Moreover, whenever DAIR is considered, exchange of the modular components should be performed (DAIR plus). Due to the low volume of megaprostheses implanted, studies assessing PJI should be conducted in a multi-institutional fashion. This would allow for more meaningful comparison of groups, with sufficient statistical power. Level of evidence: IV.

Prophylactic antibiotics for massive endoprostheses in orthopaedic oncology

The recently published Prophylactic Antibiotic Regimens In Tumor Surgery (PARITY) trial found no benefit in extending antibiotic prophylaxis from 24 hours to five days after endoprosthetic reconstruction for lower limb bone tumours. PARITY is the first randomized controlled trial in orthopaedic oncology and is a huge step forward in understanding antibiotic prophylaxis. However, significant gaps remain, including questions around antibiotic choice, particularly in the UK, where cephalosporins are avoided due to concerns of Clostridioides difficile infection. We present a review of the evidence for antibiotic choice, dosing, and timing, and a brief description of PARITY, its implication for practice, and the remaining gaps in our understanding.

Infections of Tumor Prostheses: An Updated Review on Risk Factors, Microbiology, Diagnosis, and Treatment Strategies

Several causes contribute to the high infection rate in tumor prostheses, including extensive tissue dissection and patients' immunosuppression due to the neoplastic disease. Most of these infections develop within the first 2 years following surgery with 70% of them occurring during the first year, while they are often associated with a low pathogen burden. The pathogenesis of infections in tumor prostheses is linked to bacteria developing in biofilms. Approximately half of them are caused by Staphylococcus spp., followed by Streptococcus spp., Enterococcus spp., and Enterobacteriaceae spp., while multiple pathogens may be isolated in up to 25% of the cases, with coagulase-negative Staphylococci (CoNS) and Enterococccus spp. being the most frequent pair. Although early detection and timely management are essential for complete resolution of these challenging infections, prompt diagnosis is problematic due to the highly varying clinical symptoms and the lack of specific preoperative and intraoperative diagnostic tests. Surgical management with one- or two-stage revision surgery is the mainstay for successful eradication of these infections. The recent advances in laboratory diagnostics and the development of biofilm-resistant prostheses over the past years have been areas of great interest, as research is now focused on prevention strategies. The aim of this study is to review and consolidate the current knowledge regarding the epidemiology, risk factors, microbiology, and diagnosis of infections of tumor prostheses, and to review the current concepts for their treatment and outcomes.

Risk factors for recurrent infection in the surgical treatment of infected massive endoprostheses implanted for musculoskeletal tumours

BACKGROUND

Infection is a devastating complication of endoprosthetic replacement (EPR) in orthopaedic oncology. Surgical treatments include debridement and/or one- or two-stage exchange. This study aims to determine the infection-free survival after surgical treatment for first and recurrent EPR infections and identify the risk factors associated with infection recurrence.

METHODS

This single-centre cohort study included all patients with primary bone sarcomas or metastatic bone disease treated for infected EPR between 2010 and 2020. Variables included soft tissue status using McPherson classification, tumour type, silver coating, chemotherapy, previous surgery and microorganisms identified. Data for all previous infections were collected. Survival analysis, with time to recurrent infection following surgical treatment, was calculated at 1, 2 and 4 years. Cox regression analysis was used to assess the influence of different variables on recurrent infection.

RESULTS

The cohort included 99 patients with a median age of 44 years (29-58 IQR) at the time of surgical treatment. The most common diagnoses were osteosarcoma and chondrosarcoma. One hundred and thirty-three surgical treatments for first or subsequent infections were performed. At 2 years of follow-up, overall success rates were as follows: two-stage exchange 55.3%, one-stage exchange 45.5%, DAIR with an exchange of modular components 44.6% and DAIR without exchange of modular components 24.7%. Fifty-one (52%) patients were infection-free at the most recent follow-up. Of the remaining 48 patients, 27 (27%) were on antibiotic suppression and 21 (21%) had undergone amputation. Significant risk factors for recurrent infection were the type of surgical treatment, with debridement alone as the highest risk (HR 4.75: 95%CI 2.43-9.30; P < 0.001); significantly compromised soft tissue status (HR 4.41: 95%CI 2.18-8.92; P = 0.001); and infections due to Enterococcus spp.. (HR 7.31: 95%CI 2.73-19.52); P = 0.01).

CONCLUSIONS

Two-stage exchange with complete removal of all components where feasible is associated with the lowest risk of recurrent infection. Poor soft tissues and enterococcal infections are associated with higher risks of recurrent infection. Treatment demands an appropriate multidisciplinary approach. Patients should be counselled appropriately about the risk of recurrent infection before embarking on complex treatment.

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.

Risk Factors of Periprosthetic Infection in Patients with Tumor Prostheses Following Resection for Musculoskeletal Tumor of the Lower Limb

Tumor prostheses for the lower limb following resection of musculoskeletal tumors is useful limb salvage management; however, as compared with routine total joint replacement, an increased incidence of deep periprosthetic infection of tumor prosthesis has been observed. The risk factors for periprosthetic infection of tumor prosthesis remain unclear. This study examines the risk factors and outcomes of periprosthetic infection. This was a retrospective observational study including 121 patients (67 males and 54 females) who underwent tumor prosthesis of the lower limb after resection of musculoskeletal tumors between 1 January 2000 and 30 November 2018. Among a total of 121 tumor prostheses, 7 were total femurs, 47 were proximal femurs, 47 were distal femurs, and 20 were proximal tibias. The incidence of postoperative infection and its risk factors were analyzed. Forty-five patients (37%) had osteosarcoma, 36 patients (30%) had bone metastasis, and 10 patients (8%) had soft-tissue tumors invading the bone. The mean operating time was 229 min, and the mean follow-up duration was 5.9 years. Deep periprosthetic infection was noted in 14 patients (12%). In the multivariate analysis, the risk factors for postoperative infection were identified as being male (hazard ratio [HR], 11.2316; p = 0.0100), soft-tissue tumor (HR, 52.2443; p = 0.0003), long operation (HR, 1.0056; p = 0.0184), and radiotherapy (HR, 6.5683; p = 0.0476). The incidence of periprosthetic infection in our institution was similar to that of previous reports. Patients undergoing tumor prosthesis of the lower limb who were male, had a soft-tissue tumor, were predicted to have a long operation, and who underwent radiation, had an increased possibility of postoperative infection.

Guideline for Limb-Salvage Treatment of Osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor, occurring mainly in children and adolescents, and the limbs are the main affected sites. At present, limb‐salvage treatment is considered as an effective basic standard treatment for osteosarcoma of the limb. China has a vast territory, but the development of technology is not balanced,which requires sufficient theoretical coverage, strong technical guidance and the application of limb‐salvage treatment guidelines to the treatment of osteosarcoma. Therefore, to standardize and promote the development of limb‐salvage surgery technology and improve the success rate of limb‐salvage treatment, this guide systematically introduces limb‐salvage techniques for the treatment of patients with limb osteosarcoma through definition of limb‐salvage treatment, surgical methods, efficacy evaluation, postoperative treatment and prevention of complications, rehabilitation guidance, and follow‐up advice.

Silver-coated (PorAg®) endoprosthesis can be protective against reinfection in the treatment of tumor prostheses infection

INTRODUCTION

We aim to evaluate the use of silver (PorAg^®) coated compared to uncoated prosthesis in two-stage revision for prosthetic joint infection (PJI) of distal femur and proximal tibia megaprosthesis in oncological patients.

MATERIALS AND METHODS

In total, 68 patients were retrospectively evaluated. Median age was 30 years (range 14-83). In total, 29 patients were re-implanted with PorAg^® prosthesis and 39 with uncoated prosthesis (Megasystem C^®, Waldemar Link GmbH & Co. KG, Hamburg, Germany). All patients had PJI confirmed according to Musculoskeletal Infection Society (MSIS) criteria. In 10 cases, no microorganism was identified at the time of first-stage revision, but all had a sinus communicating with the prosthesis. Successful eradication of the infection was defined by the absence of clinical/serologic evidence of infection at 6 months after the second stage or at latest follow-up. Infection was again defined according to the MSIS criteria.

RESULTS

At 3-year follow-up, estimated reinfection rate in the silver group was slightly lower than in uncoated EPR (10.3% vs. 17.5%, p = 0.104). Among reinfected patients, only one out of three patients (33%) in the silver group required an amputation compared to 80% in the nonsilver group (p = 0.047).

CONCLUSIONS

Our results show the efficacy of PorAg^® coating in the two-stage revision of knee EPR. PorAg^®-coated EPR may have possible advantages over this traditional strategy, in particular when applied to patients with a higher risk of reinfection.

Management of infected extremity endoprostheses: a systematic review

BACKGROUND

Endoprosthetic reconstructions have become increasingly common in the setting of significant bone loss. Indications include revision arthroplasty, trauma, and reconstruction in the setting of primary malignancies or bony metastases. Although the use of endoprostheses has several advantages, they carry a high risk of infection. The purpose of this review is to determine the success rates of surgical management of infected endoprostheses.

METHODS

The authors searched databases for relevant studies and screened in duplicate. Data extracted included overall infection rate, timing of infection, follow-up, isolated pathogen and operative treatment strategy, and subsequent failure rate. The overall quality of the evidence with the Methodological Index for non-randomized studies criteria.

RESULTS

A total of 16 studies and 647 patients met the inclusion criteria. 400 patients had operative management and reported outcomes. Failure rates of patients undergoing debridement, antibiotics, and implant retention (DAIR) were 55.1%. Failure rates of patients who underwent one-stage revision were 45.5%. Failure rates of patients undergoing two-stage revision were 27.3%. Failure occurred at 31.4 months (range, 0-228) postoperatively.

CONCLUSIONS

Rates of periprosthetic joint infection remain high in endoprosthetic reconstructions. Although DAIR procedures were found to have a low success rate, they remain a reasonable option in acute infections given the morbidity of staged revisions. There is a lack of comparative data in the current literature and the heterogeneity and low level of evidence does not allow for between group comparisons of results.

[Silver coating on tumour prostheses]

BACKGROUND

Modular endoprostheses, so-called "tumour or megaprostheses" are mainly used for limb salvage surgery after resection of malignant soft tissue or a bone tumour. Sometimes, this type of prosthesis is also used for revision surgeries after failed primary joint arthroplasty. Despite continuously improving techniques and quality management systems, periprosthetic infection is one of the most serious complications.

AIM OF THE STUDY

Review of the literature in the PubMed data base with the main focus on silver coatings in joint arthroplasty and their effect on infection rate, outcome and patients' safety.

RESULTS

The current literature shows that there is a beneficial role of silver coatings in megaprostheses in terms of revision rates for septic complications, especially following tumour resection with bad soft tissue coverage or in (multimorbid) high-risk patients, compared to uncoated implants.

DISCUSSION

Based on the results of previous publications examining blood or serum silver concentrations or silver levels in urine, silver coatings do not appear to have side effects, except for local argyria. Continuous monitoring of silver levels in blood or serum is still recommended, and additional long-term studies will be necessary to verify the effectiveness and safety of silver coatings.

Sonication Improves the Diagnosis of Megaprosthetic Infections

Limited data are available for the diagnosis of patients with tumors with infected endoprosthetic reconstructions. The purpose of this study was to evaluate whether sonication is effective for the diagnosis of infection and to compare it with tissue cultures. The files of 58 patients who underwent revision surgery for suspected infected endoprosthetic reconstructions were reviewed. Cultures were performed on 5 tissue samples obtained from each patient and on fluid obtained by sonication of the megaprosthesis. The sensitivity, specificity, and negative and positive predictive values of tissue and sonication fluid cultures were evaluated. Overall, tissue and sonication fluid cultures confirmed an infection in 42 of the 58 patients. In 36 of the 42 infected endoprosthetic reconstructions, tissue and sonication fluid cultures identified the same bacterial isolate. In 5 cases, a bacterial isolate was identified only in sonication fluid cultures, and in 1 case, a bacterial isolate was identified only in tissue cultures. The sensitivity and negative predictive value of sonication fluid cultures were statistically significantly better than those of tissue cultures, while the specificity and positive predictive value were not different between the 2 culture types. Compared with tissue cultures for the diagnosis of infected megaprostheses in patients with tumors, sonication fluid cultures are associated with a better sensitivity and negative predictive value and a similar specificity and positive predictive value. Therefore, sonication should be considered a useful adjunct for the optimal diagnosis and management of these patients. [Orthopedics. 2019; 42(1):28-32.].

Efficacy of different revision procedures for infected megaprostheses in musculoskeletal tumour surgery of the lower limb

Purpose

The incidence of recurrent infections in patients following one or two stage revision for infected megaprostheses after resection of bone tumours was investigated. The difference between retaining at least one well fixed stem and a complete removal of the megaprosthesis during a two stage revision was also analysed.

Methods

627 patients who experienced a replacement of a musculoskeletal tumour by megaprostheses were recorded. An infection occurred in 83 of 621 patients available for follow-up. 61 patients underwent one stage revision, and 16 patients two stage revision for the first revision surgery. In the entire study period, two stage revision was performed 32 times (first, second, and third revision).

Results

The cumulative incidence analysis showed a reinfection probability after one stage revision of 18% at one year, 30% at two years, 39% at five years, 46% at ten years, and 56% at 15 years. After two stage revision, a reinfection probability of 28% at two years, and 48% at five years was calculated. Cumulative incidence curves did not differ significantly (Gray’s test; p = 0.51) between one and two stage revision (with and without complete removal of the stems). In two stage revision (n = 32), a statistically significant difference in infection rates between patients treated with complete removal of the megaprosthesis (n = 18) including anchorage stems and patients with at least one retained stem (n = 14) was shown (Fisher’s exact test, p = 0.029).

Conclusion

Two stage revisions with complete removal of the megaprosthesis showed the best results among limb salvage procedures for the treatment of infected megaprosthesis.

Sonication culture improves microbiological diagnosis of modular megaprostheses

Modular megaprostheses are known for high infection rates followed by high rates of revisions. Microbial biofilms growing adherently on prosthetic surfaces may inhibit the detection of the pathogens causing prosthetic joint infections. We sought to answer the following questions: Does sonication culture (SC) improve the microbiological diagnosis of periprosthetic infections of megaprostheses compared to conventional tissue culture (TC)? Which pathogens were detected on the surface of megaprostheses with either SC or TC and do the findings help to identify low-grade infections? Included were 31 patients with modular megaprostheses, whose implant had been explanted due to suspected joint infection or revision surgery. SCs were performed according to the protocol by Trampuz et al. The diagnosis of infection was evaluated according to the definition of the Musculoskeletal Infection Society. The sensitivity of SC was 91.3% compared to 52.2% for TC and the specificity was 100% for SC and TC (p = 0.004). Under preoperative antibiotic therapy, the sensitivity of SC was 83.3% while the sensitivity of TC was 50%. Without preoperative antibiotic therapy the sensitivity of SC was 100% compared to 54.5% for TC. In nine cases, SCs detected microorganisms, while TC was negative. Detected bacteria were Staphylococcus epidermidis in four, Micrococcus species in one, Finegoldia magna in one, Brevibacterium casei in one, Pseudomonas fluorescens in one, and Enterococcus faecium in one. SC is a reliable method for dislodging pathogens from orthopedic implants. The SC of modular megaprostheses showed significantly higher pathogen detection than the periprosthetic TC, especially for low virulence pathogens. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1383-1387, 2017.

Lower limb reconstruction in tumor patients using modular silver-coated megaprostheses with regard to perimegaprosthetic joint infection: a case series, including 100 patients and review of the literature

PURPOSE AND OBJECTIVE

Bone resection regarding adequate surgical margins is the treatment of choice for malignant bone tumors. In the case of metastasis-related complications, so-called skeletal-related events, it is highly important to achieve pain relief and a stable joint situation to re-mobilize the patients immediately following surgery. To bridge the often large osseous defect zones after tumor resection, both cemented and uncemented modular endoprosthetic systems are widely used. Patients undergoing tumor-related endoprosthetic orthopedic surgery are facing high risk for developing a periprosthetic joint infection (PJI). The immunocompromised condition due to anti-neoplastic treatment and long operation time with large exposure of tissue contributes to a high risk of infection.

METHODS

The authors present a case series of 100 patients (31% primary bone tumor and 69% metastasis-related surgery) undergoing tumor-related lower limb salvage surgery with special regard to periprosthetic joint infection and the management of this "difficult to treat" situation. Furthermore, a review of the current literature regarding infection following bone tumor resection and endoprosthetic reconstruction is performed and discussed.

RESULTS

The median follow-up was 24 months (range 12-108 months). Ten patients (10%) suffered from a periprosthetic joint infection. We recorded six acute infections (type I) <4 weeks after surgery, one infection >4 weeks after surgery (type II), and three late infections (type III). According to the definition of Laffer et al., three of our patients (30%) are probably free of infection, one patient died of PJI-associated sepsis, and five patients were free of infection, but without restoration of the affected joint.

CONCLUSION

In conclusion, our own results show that perimegaprosthetic joint infection among silver-coated implants, in patients undergoing tumor-related surgery of the lower limb, is lower compared to non-silver-coated implants. Due to heterogeneity of patients and potential treatment options, the treatment regime should be tailored for the patients' individual situation.

Levels of silver ions in body fluids and clinical results in silver-coated megaprostheses after tumour, trauma or failed arthroplasty

INTRODUCTION

Infection in megaprostheses remains an unsolved problem, with a rate of occurrence ranging from 5% to 12%. Silver coating of medical devices has recently been proposed to reduce infection rate because of the antibacterial effect of silver. This innovation could be particularly interesting for megaprostheses, but few data have been reported in the literature.

MATERIALS AND METHODS

From June 2010 to August 2014 a modified MegaC System megaprosthesis with an innovative peripheral silver-added layer of titanium alloy ('Porag') was implanted in 33 patients after previous infection (21 patients) or at high risk for infection because of local or general conditions (12 patients). Previous infection followed megaprosthesis or standard arthroplasty procedures in 14 patients and trauma surgery in seven patients. A proximal femur replacement was performed in 13 patients, distal femur replacement in 13, total femur in one, and knee arthrodesis in six. Clinical results and levels of silver in blood, urine and wound drains were examined.

RESULTS

Minimum follow-up of the patients was one year (average 25.9 months). There was no infection during the first two years after surgery in the 12 patients who received a silver-coated megaprosthesis and had no previous history of infection. An infection developed in one patient at 25 months after surgery following two further surgical procedures. Infection recurred at seven months and 24 months in two out of the 21 patients (9.5%) who had received the implant because of previous septic complications. There was no clinical evidence of argyria, and no local or systemic side effects related to silver were detected. Mean levels of silver ranging from 0.41 to 5.33μg/L in blood and from 0.28 to 0.86μg/L in urine were detected at 24h to 36 months after surgery.

CONCLUSIONS

Silver-coated megaprostheses showed promising results in this series in terms of prevention of infection in a high-risk group of patients, many of whom had a history of infection. No side-effects were detected. The circulating silver levels confirm both the persistence of silver-coating activity after three years and the safety of silver-coated implants. Longer follow-up and larger series are needed.

Management of infection following reconstruction in bone tumors

Limb salvage surgery in bone tumors has evolved in recent years and includes all of the surgical procedures designed to accomplish removal of a malignant tumor and reconstruction of the limb with an acceptable oncologic, functional, and cosmetic result. This dramatic change came about as the result of three important developments, i.e. effective chemotherapy, improved precision imaging techniques and advances in reconstructive surgery. Reconstruction with a modular custom-made oncological endoprosthesis (megaprosthesis) has become a common procedure nowadays. These large foreign bodies make infection a common and feared complication. However, the occurrence of complications may be multifactorial, including a poor nutritional and compromised immune status due to chemotherapy and/or radiotherapy, a lengthy operation, extensive dissection and resection of soft tissues, inadequate soft-tissue coverage, a longer exposure of the wound resulting in infection, etc. Management of postoperative infection in these cases remains a challenge. This article analyses the current literature available for these cases and summarizes the cause and different available methods of treatment.

Retrospective evaluation of the incidence of early periprosthetic infection with silver-treated endoprostheses in high-risk patients: case-control study

We conducted a case-control study to examine the merit of silver-coated tumour prostheses. We reviewed 85 patients with Agluna-treated (silver-coated) tumour implants treated between 2006 and 2011 and matched them with 85 control patients treated between 2001 and 2011 with identical, but uncoated, tumour prostheses. In all, 106 men and 64 women with a mean age of 42.2 years (18.4 to 90.4) were included in the study. There were 50 primary reconstructions (29.4%); 79 one-stage revisions (46.5%) and 41 two-stage revisions for infection (24.1%). The overall post-operative infection rate of the silver-coated group was 11.8% compared with 22.4% for the control group (p = 0.033, chi-square test). A total of seven of the ten infected prostheses in the silver-coated group were treated successfully with debridement, antibiotics, and implant retention compared with only six of the 19 patients (31.6%) in the control group (p = 0.048, chi-square test). Three patients in the silver-coated group (3.5%) and 13 controls (15.3%) had chronic periprosthetic infection (p = 0.009, chi-square test). The overall success rates in controlling infection by two-stage revision in the silver-coated group was 85% (17/20) compared with 57.1% (12/21) in the control group (p = 0.05, chi-square test). The Agluna-treated endoprostheses were associated with a lower rate of early periprosthetic infection. These silver-treated implants were particularly useful in two-stage revisions for infection and in those patients with incidental positive cultures at the time of implantation of the prosthesis. Debridement with antibiotic treatment and retention of the implant appeared to be more successful with silver-coated implants.

[Management of complications following resection and defect reconstruction of tumors near the hip joint]

BACKGROUND

Tumorous destruction of the periacetabular region and the proximal femur are a consequence of either primary malignant bone tumor manifestation or metastatic disease, which is observed much more frequently and occurs typically in these skeletal segments. Pathological fractures of the proximal femur and periacetabular regions of the pelvis have a high incidence and ultimately lead to severe pain and immobilization.

TREATMENT METHODS

Advanced resection techniques and different types of defect reconstruction, allowing for oncologically sufficient resection of extensive tumors have contributed to a marked increase in the limb salvage rate. However, these procedures are associated with an increasing rate of several, sometimes severe intraoperative and postoperative complications.

COMPLICATIONS

Compared to elective total hip arthroplasty, the rate of postoperative deep infections, dislocations, the incidence of pathological and periprosthetic fractures and the prevalence of deep vein thrombosis are increased with high rates of postoperative mortality and local tumor recurrence, being the most serious complications. Pelvic involvement and subsequent periacetabular resection have the highest complication rate when compared to proximal femur resection with endoprosthetic treatment.

CONCLUSION

In order to minimize the risk of these intraoperative and postoperative complications wide resection and advanced reconstruction as well as complicated palliative stabilization due to malignant bone tumor growth around the hip joint should be performed in musculoskeletal tumor centers with profound expertise in osteosynthetic and endoprosthetic reconstruction of the pelvis and the proximal femur. Only in specialized centers an effective, multidisciplinary emergency management of these complications and, more importantly, reliable prevention of complications can be ensured.

Treatment solutions are unclear for perimegaprosthetic infections

BACKGROUND

Infection about a megaprosthesis is a dreaded complication. Treatment options vary from débridement alone to staged revisions, arthrodesis, and amputation. Indications for how to treat this complication are unclear.

QUESTIONS/PURPOSES

We therefore determined (1) the incidence of perimegaprosthetic infections, (2) the methods of treatment, (3) the number of patients who failed their original treatment plan, and (4) the characteristics of the infection.

METHODS

We retrospectively identified 291 patients who had megaprostheses implanted between 2001 and 2011 and identified all those surgically treated for a perimegaprosthetic infection during that time. We defined a treatment failure as any unplanned reoperation or death due to uncontrolled infection. All patients with failure had a minimum followup of 1 year (mean, 3.3 years; range, 1-8 years).

RESULTS

Of the 291 patients, 31 (11%) had subsequent infections. Surgical management varied among irrigation and débridement (n=15), single-stage revisions (n=11), two-stage revisions (n=4), and amputations (n=1). Sixteen patients failed their original treatment plan: 13 required additional surgery and three died. Infections were mostly chronic and single organism with five being methicillin-resistant Staphylococcus aureus.

CONCLUSIONS

An 11% incidence of perimegaprosthetic infections is consistent with the increased risk of infection seen in other studies. A variety of surgical methods were employed at our institution and by those contributing to the literature without clear evidence of superiority of one method over another. Given the complicated medical and surgical histories of these patients, individualization in decision making is necessary.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Infected tumor prostheses

Infection of tumor prostheses has been a major concern because of the extensive soft tissue dissection, long operating times, and patients' immunosuppression by cancer and adjuvant treatments. Infections most often present within 2 years postoperatively, with approximately 70% of postoperative deep infections presenting within 12 months after surgery. They are typically low organism burden infections, the pathogenesis of which is related to bacteria growing in biofilms. Staphylococci are the most common pathogens involved in prosthetic joint infections, accounting for approximately 50% of infections overall, followed by streptococci, enterococci, Enterobacteriaceae species, Pseudomonas aeruginosa, and anaerobe species. Multiple pathogens may be isolated in approximately 25% of cases, with the most common combination being coagulase-negative Staphylococcus and group-D Streptococcus. Early diagnosis and appropriate treatment are necessary. However, diagnosis may be challenging because clinical symptoms are highly variable and numerous preoperative and intraoperative diagnostic laboratory tests are nonspecific. In most cases, a 1- or 2-stage revision surgery is necessary for eradicating the megaprosthetic infection. Prevention of infection is important. The future will see technical advances for infections of tumor prostheses in areas such as microbiological diagnostics and biofilm-resistant prostheses.

Perioperative infection rate in patients with osteosarcomas treated with resection and prosthetic reconstruction

BACKGROUND

The incidence of perioperative infection after segmental tumor endoprosthetic replacement in previous reports varies from a high of 7.4% to a low of 2.6%. Appropriate antibiotic use for this group is unknown and controversial, whereas the relationship of antibiotic use and perioperative infection is unclear.

QUESTIONS/PURPOSES

We determined the incidence of perioperative infection in patients with osteosarcoma treated with segmental prosthetic replacement using a standard perioperative antibiotic regimen and the incidence of late infections and wound complications.

PATIENTS AND METHODS

We retrospectively reviewed the records of 53 patients with osteosarcoma undergoing segmental prosthetic replacements from 1993 to 2008. There were 30 males and 23 females ranging from 10 to 78 years of age. All patients were given intraoperative antibiotics (intravenous cefazolin), continued for 3 days postoperatively and then given orally for 5 days. Patients who were allergic to penicillin or cefazolin were given vancomycin followed by clindamycin. A perioperative infection was defined as a deep infection within 2 months after prosthetic reconstruction. The minimum followup was 1 year (range, 1-15 years).

RESULTS

We identified one confirmed perioperative prosthetic infection (1/53; 1.9%) (Enterobacter cloacae and methicillin-resistant Staphylococcus) in a 78-year-old woman after proximal tibial replacement, gastrocnemius flap, and skin graft. Her infection was controlled with débridement, drainage, and intravenous antibiotics. Three patients had late infections, two of which were culture negative. Four patients had wound complications that required further surgery.

CONCLUSION

The antibiotic regimen we used is longer than that recommended for patients having routine total joint arthroplasty. Its appropriateness will require comparison with alternate regimens, including those of shorter duration.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Management of septic complications following modular endoprosthetic reconstruction of the proximal femur

In a retrospective single-centre study 170 consecutive patients were included who received a Kotz modular prosthesis after resection of bone tumours of the proximal femur to evaluate the management of prosthetic infection. Infection occurred in 12 of 166 patients available for follow-up (six males; six females; mean age, 47 years; range, ten to 75 years) after a mean of 39 months (range, one to 166 months; infection rate, 7.2%). Mean follow-up was 54 months (range, four to 200 months). One patient died of septic shock. Two patients were treated by wound revision only. Treatment of infection in the remaining patients was one-stage revision in eight and hip disarticulation in one. Infection control by one-stage revision was achieved in five of eight patients; re-infection occurred in three patients and was successfully treated by further revision in all of them. The overall success rate for controlling infection was 83.3%.

O uso de espaçadores com antibiótico no tratamento das infecções em endopróteses de joelho

OBJETIVO: O objetivo do estudo é avaliar a utilização dos espaçadores de cimento acrílico com antibiótico no tratamento das infecções em endopróteses não convencionais de joelho. MÉTODO: Desde de 2004 foram tratados sete pacientes (seis pacientes operados no nosso serviço e um paciente que havia sido submetido a cirurgia primária do tumor em outro serviço) com infecção peri-endoprótese não convencional de joelho. Todos pacientes foram submetidos a retirada da endoprótese e reconstrução com espaçador com cimento acrílico com antibiótico. Todos os pacientes foram monitorados clínica e laboratorialmente quanto ao controle da evolução, sendo considerados aptos para a revisão e recolocação de endoprótese após 06 (seis) meses sem sinais infecciosos RESULTADOS: Notamos um discreto predomínio do do processo infeccioso nas próteses realizadas na tíbia proximal em comparação com o fêmur distal (57,1% x 42,9%). O seguimento médio dos pacientes foi 68,2 meses. Durante o seguimento, um paciente faleceu devido a doença de base. Dos sete pacientes, 6 foram considerados curados e um persistiu com sinais e sintomas de infecção. CONCLUSÃO: Os resultados obtidos até o momento tem motivado a continuidade deste método de tratamento.