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

Ionized jet deposition of silver nanostructured coatings: Assessment of chemico-physical and biological behavior for application in orthopedics

Infection is one of the main issues connected to implantation of biomedical devices and represents a very difficult issue to tackle, for clinicians and for patients. This study aimed at tackling infection through antibacterial nanostructured silver coatings manufactured by Ionized Jet Deposition (IJD) for application as new and advanced coating systems for medical devices. Films composition and morphology depending on deposition parameters were investigated and their performances evaluated by correlating these properties with the antibacterial and antibiofilm efficacy of the coatings, against Escherichia coli and Staphylococcus aureus strains and with their cytotoxicity towards human cell line fibroblasts. The biocompatibility of the coatings, the nanotoxicity, and the safety of the proposed approach were evaluated, for the first time, in vitro and in vivo by rat subcutaneous implant models. Different deposition times, corresponding to different thicknesses, were selected and compared. All silver coatings exhibited a highly homogeneous surface composed of nanosized spherical aggregates. All coatings having a thickness of 50 nm and above showed high antibacterial efficacy, while none of the tested options caused cytotoxicity when tested in vitro. Indeed, silver films impacted on bacterial strains viability and capability to adhere to the substrate, in a thickness-dependent manner. The nanostructure obtained by IJD permitted to mitigate the toxicity of silver, conferring strong antibacterial and anti-adhesive features, without affecting the coatings biocompatibility. At the explant, the coatings were still present although they showed signs of progressive dissolution, compatible with the release of silver, but no cracking, delamination or in vivo toxicity was observed.

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.

The microbial profile of infected endoprosthetic reconstructions after wide excision for patients with musculoskeletal tumors: A call for pathogen-based practices

BACKGROUND AND OBJECTIVES

Periprosthetic infection is a devastating complication following endoprosthetic reconstruction. This study utilized a large database of endoprostheses to describe the incidence, risk factors, and microbial profile of such infections to better catalogue and understand these catastrophic events.

METHODS

A retrospective review of endoprosthetic reconstructions for an oncologic indication from January 1, 1981 to December 31, 2020 was performed. Demographic, oncologic, procedural and outcome data was analyzed. Multivariable logistic regression was used to identify potential risk factors for infection with significance defined as p < 0.05.

RESULTS

Forty four out of 712 (6.2%) reconstructions resulted in infection at a mean time of 39.9 ± 44.5 months. Revision surgery (odds ratio [OR] 6.14, p < 0.001) or having a postoperative wound complication (OR 7.67, p < 0.001) were significantly associated with infection. Staphylococcus aureus and Staphylococcus epidermidis were the most commonly cultured organisms at a rate of 34.1% (15/44) and 22.7% (10/44), respectively. Ten infections resulted in amputation; five due to antimicrobial-resistant infections and three due to polymicrobial infections.

CONCLUSION

Understanding the microbial profile of patients undergoing endoprosthetic reconstruction is paramount. This study demonstrates a relatively high rate of polymicrobial and antibiotic-resistant infections that portend worse outcomes, thus suggesting that pathogen-specific infectious practices may be warranted.

LEVEL OF EVIDENCE

Retrospective cohort study, level III.

Limb salvage surgery reconstructive techniques following long-bone lower limb oncological resection: a systematic review and meta-analysis

BACKGROUND

Limb salvage surgery (LSS) is now considered the gold standard surgical treatment for lower limb bone sarcomas. However, there is a paucity of literature comparing the various LSS reconstructive options. The aim of this systematic review and meta-analysis was to compare functional outcomes and complications of LSS reconstructive techniques.

METHODS

The primary aim of the meta-analysis was to determine functional outcomes from the pooled data utilizing the Musculoskeletal Tumour Society score (MSTS). Comparisons could then made for this outcome between biological and prosthetic, vascularised and non-vascularised, and prosthetic and composite reconstructions. The secondary aim was to compare complication outcomes of each reconstruction. Standardized mean difference (Cohen's d) and odds ratios were estimated using a random effects model.

RESULTS

Fourteen studies with a total of 785 patients were included. We found structural failure was 75% less likely to occur in prosthetic reconstruction compared to biological (OR = 0.24; 95% CI: 0.07-0.79; P = 0.02). We did not find any evidence of difference in function (MSTS score) between vascularised verses non-vascularised reconstructions (Cohen's d = -1.14; 95% CI = -3.06 to 0.78; I2  = 87%). Other analyses comparing complications found no difference between the reconstructive groups.

CONCLUSION

The study found no correlation between functional outcomes and the type of LSS reconstruction. Structural failure was more likely to occur in biological when compared with prosthetic reconstruction. There was no correlation between the incidence of other complications and the type of LSS technique. This suggests a role for improved approaches to reconstruction methods including bioprinting and bioresorbable devices.

Knee Arthrodesis with a Modular Silver-Coated Endoprosthesis for Infected Total Knee Arthroplasty with Extensive Bone Loss: A Retrospective Case-Series Study

INTRODUCTION

Knee arthrodesis is a limb salvage intervention for persistent periprosthetic joint infection (PJI) when revision total knee arthroplasty fails. Conventional arthrodesis techniques are associated with the increased rate of complications, especially in patients with extensive bone loss and extensor tendon deficiency.

METHODS

Eight patients with a modular silver-coated arthrodesis implant after failed exchange arthroplasty for infection, were retrospectively reviewed. All patients had significant bone loss, while 5 displayed extensor tendon deficiency. Survivorship, complications, leg length discrepancy, median Visual Analogue Scale (VAS) and Oxford Knee score (OKS) were evaluated.

RESULTS

The median follow up was 32 months (range 24-59 months). The survivorship rate of the prosthesis was 86% during the minimum time of follow up of 24 months. In one patient recurrence of the infection was observed and above-knee amputation was performed. The median postoperative leg length discrepancy was 2.07 ± 0.67 cm. Patients were able to ambulate with mild or no pain. The median VAS and OKS was 2.14 ± 0.9 and 34.7 ± 9.3, respectively.

CONCLUSIONS

The results of our study demonstrated that knee arthrodesis with a silver coated arthrodesis implant, performed for persistent PJI in patients with significant bone loss and extensor tendon deficit, provided a stable construct, allowed eradication of infection and was associated with good functional outcome.

Potential side effects of antibacterial coatings in orthopaedic implants: A systematic review of clinical studies

Objective: The systematic review aimed to determine the potential side effects of antibacterial coatings in orthopaedic implants. Methods: Publications were searched in the databases of Embase, PubMed, Web of Science and Cochrane Library using predetermined keywords up to 31 October 2022. Clinical studies reporting side effects of the surface or coating materials were included. Results: A total of 23 studies (20 cohort studies and three case reports) reporting the concerns about the side effects of antibacterial coatings were identified. Three types of coating materials, silver, iodine and gentamicin were included. All of studies raised the concerns regarding safety of antibacterial coatings, and the occurrence of adverse events was observed in seven studies. The main side effect of silver coatings was the development of argyria. For iodine coatings, only one anaphylactic case was reported as an adverse event. No systemic or other general side effects were reported for gentamicin. Conclusion: Clinical studies on the side effects of antibacterial coatings were limited. Based on the available outcomes, the most reported side effects of antibacterial coatings in clinical use were argyria with silver coatings. However, researchers should always pay attention to the potential side effects of antibacterial materials, such as systematic or local toxicity and allergy.

Prosthetic Joint Infection in Mega-Arthroplasty Following Shoulder, Hip and Knee Malignancy-A Prospective Follow-Up Study

INTRODUCTION

The risk of prosthetic joint infection (PJI) in mega-prosthesis for malignancy is increased compared with non-tumor cases. While several studies describe PJI in tumor-related arthroplasty, prospective studies comparing infection characteristics among different joints are limited. The present study analyzes mega-arthroplasty for hip, knee, and shoulder malignancy and compares the epidemiology, diagnosis, microbe spectrum, treatments, and outcomes between the different entities.

METHODS

The retrospective inclusion criteria were as follows: (1) mega-arthroplasty (2) in the hip, knee, or shoulder joint and a total femur arthroplasty (3) following a malignant bone tumor or metastasis (4) between 1996 and 2019. All included patients were prospectively followed and invited for a renewed hospital examination, and their PJI characteristics (if identified) were analyzed using both retrospective as well as newly gained prospective data. A PJI was defined according to the Infectious Disease Society of America (IDSA) and re-infection was defined according to the modified Delphi Consensus criteria.

RESULTS

In total, 83 cases of tumor mega-arthroplasty at a mean follow-up of 3.9 years could be included (32 knee, 30 hip, and 19 shoulder cases and 2 cases of total femur arthroplasty). In total, 14 PJIs were identified, with chondrosarcoma in 6 and osteosarcoma in 3 being the leading tumor entities. Knee arthroplasty demonstrated a significantly higher rate of PJI (p = 0.027) compared with hips (28.1% vs. 6.7%), while no significant difference could be found between the knee and shoulder (10.5%) (p = 0.134) or among shoulder and hip cases (p = 0.631). The average time of PJI following primary implantation was 141.4 months in knee patients, 64.6 in hip patients, and 8.2 months in shoulder patients. Age at the time of the primary PJI, as well as the time of the first PJI, did not show significant differences among the groups. Thirteen of the fourteen patients with PJI had a primary bone tumor. Statistical analysis showed a significant difference in the disadvantage of primary bone tumors (p = 0.11). While the overall cancer-related mortality in the knee PJI group (10%) was low, it was 50% in the hip and 100% in the shoulder group.

CONCLUSION

The risk of PJI in knee tumor arthroplasty is significantly increased compared with hips, while cancer-related mortality is significantly higher in hip PJI cases. At the same time, mega-prostheses appear to be associated with a higher risk of infection due to a primary bone tumor compared with metastases. The study confirms existing knowledge concerning PJI in tumor arthroplasty, while, being one of the few studies to compare three different joints concerning PJI characteristics.

Cemented vs uncemented megaprostheses in proximal femur metastases: a multicentric comparative study

BACKGROUND

Hip megaprostheses are a long known reconstructive method in the treatment of proximal femur metastases. The use of cemented or uncemented stems is still matter of debate. The aim of this study to compare cemented and uncemented megaprostheses on functional outcomes and complications, in order to establish the role of cementation.

METHODS

We retrospectively analysed 51 metastatic patients with proximal femur metastases treated with endoprosthetic reconstruction by megaprostheses, 25 with cementless stems and 26 with cemented ones with different megaprosthetic implants. The primary endpoint was MSTS score, and the secondary endpoint was to state the incidence of surgical and clinical complications in the two groups. An un-paired T test was used to compare anthropometric, anamnestic data, and MSTS. Chi-square test was performed for evaluation of complication in the two group. Multiple linear regression was used to match the functional outcomes and complications' incidence in the population study. Logistic regression was performed to analyse the odds ratio of different parameters and their role in the incidence of complications.

RESULTS

The mean follow-up was 50.1 months (+ 12.5). In thirty case right side was involved. No statistical differences were noticed between Group A and B regard the age, gender, active fracture/impending fracture. Comparing the MSTS results within the two groups at last follow-up, the score cemented group was higher than cementless one (17.9 + 7.8 vs 24.2 + 5.3; statistical significance p = 0.001). Regarding surgical complications a logistic regression was performed to analyse the odds ratio of age, cementation and length of resection; cementation confirm and odds ratio of 11 times in the incidence of surgical complications.

CONCLUSIONS

Cementation seems to be more liable to complications onset, while improves functional score in metastatic patients compared to uncemented megaprostheses. More studies have to be conducted in order to create a protocol and establish criteria to use cemented or uncemented stems in a frail population like metastatic patients.

Long-term outcomes of non-invasive expandable endoprostheses for primary malignant tumors around the knee in skeletally-immature patients

INTRODUCTION

Expandable endoprostheses are used to restore limb function and compensate for the sacrifice physis involved in carcinologic resection. Long-term outcomes of the last generation of knee "non-invasive" expandable endoprostheses are required. Objectives were to report on oncologic results of bone sarcoma resection around the knee with expandable endoprosthesis reconstruction and to compare the surgical outcomes of the "non-invasive" expandable endoprostheses used in our department.

MATERIALS AND METHODS

Retrospective study that included all children with bone sarcoma around the knee that underwent tumor resection reconstructed with non-invasive expandable prosthesis. Phenix-Repiphysis was used from 1994 to 2008 followed by Stanmore JTS non-invasive from 2008 to 2016. Survival and complications were recorded. Functional outcomes included Musculoskeletal Tumor Society (MSTS) score, knee range of motion, lower limb discrepancy (LLD).

RESULTS

Forty children (Sex Ratio = 1) aged a mean 8.8 years (range, 5.6-13.8) at surgery were included in the study. There were 36 osteosarcoma and 4 Ewing sarcoma that involved 33 distal femur and 7 proximal tibia. Cohort (n = 40) consisted of 28 Phenix-Repiphysis and 12 Stanmore with a mean follow-up of 9.8 ± 5.8 years and 6.1 ± 3.1 years, respectively. Postoperative infection rate was 7.5% in the cohort (3 Repiphysis). Functional results were significantly better in the Stanmore group with a mean MSTS of 87.6 ± 5.4% and knee flexion of 112 ± 38°. At last follow-up, implant survival was 100% in Stanmore group, whereas all living Phenix-Repiphysis were explanted. Mechanical failure was the primary cause for revision of Phenix-Repiphysis. Limb length equality was noted in 79% patients with Phenix-Repiphysis and 84% with Stanmore at last follow-up.

CONCLUSION

Chemotherapy and limb-salvage surgery yield good oncologic outcomes. Expandable endoprostheses are effective in maintaining satisfactory function and lower limb equality. With improvements made in the last generation of "non-invasive" prostheses, implants' survival has been substantially lengthened.

Can "domino" therapy effectively treat the infection around the prosthesis after the limb salvage surgery of bone tumor? - A study of sequential therapy

BACKGROUND

Tumor resection and prosthetic replacement have become the treatments of choice for malignant bone tumors. Infections are the leading cause of failure of limb salvage surgeries. Therefore, treating infections around prostheses after limb salvage is essential and challenging. Our research team designed a "domino" sequential treatment plan to treat postoperative infections around tumor prostheses and evaluated its efficacy.

PURPOSE

To introduce the new domino sequential treatment plan for postoperative infections of tumor prostheses, and evaluate the technical points of the plan and prognosis in medium- and long-term follow-ups.

METHODS

Between January 2015 and August 2021, 14 patients were treated with prosthesis-preserving domino sequential therapy for peripheral prosthesis infections after bone-tumor limb salvage. The sample included eight cases of distal femur tumor, two of proximal tibia tumor, three of pelvic tumor, and one of middle femur tumor. We evaluated routine blood test results, C-reactive protein level, the erythrocyte sedimentation rate, and other indicators. X-rays and CT scans of the surgical site were obtained and the Musculoskeletal Tumor Society (MSTS) score was calculated. Treatment involved debridement and lavage of the prosthesis, and systemic and local antibiotics.

RESULTS

The positivity rate of microbial culture was 78.6%. There were three cases of Staphylococcus aureus, one of Staphylococcus epidermidis, two of methicillin-resistant Staphylococcus epidermidis, one of methicillin-resistant Staphylococcus aureus, two of Acinetobacter baumannii, one of Streptococcus lactis (group C), one of Streptococcus mitis, and three with negative cultures. In three cases, sequential treatment failed to control the infection. The operation success rate was 78.6% (11/14). One case eventually required amputation, and another required long-term wound dressings. To control the infection, a third had to be treated using antibiotic bone cement combined with the "intramedullary nail reverse double insertion" technique. The MSTS scores of patients before infection debridement and at the last follow-up showed statistically significant differences (t = 5.312, p = 0.02).

CONCLUSIONS

The prosthesis-preserving domino sequential method has certain advantages for treating bone-tumor limb salvage infections around the prosthesis.

LEVEL OF EVIDENCE

Level IV, therapeutic.

Development of Silver-Containing Hydroxyapatite-Coated Antimicrobial Implants for Orthopaedic and Spinal Surgery

The prevention of surgical site infections is directly related to the minimization of surgical invasiveness, and is in line with the concept of minimally invasive spine therapy (MIST). In recent years, the incidence of postoperative infections has been increasing due to the increased use of spinal implant surgery in patients at high risk of infection, including the elderly and easily infected hosts, the limitations of poor bone marrow transfer of antibiotics, and the potential for contamination of surgical gloves and instruments. Thus, the development of antimicrobial implants in orthopedic and spinal surgery is becoming more and more popular, and implants with proven antimicrobial, safety, and osteoconductive properties (i.e., silver, iodine, antibiotics) in vitro, in vivo, and in clinical trials have become available for clinical use. We have developed silver-containing hydroxyapatite (Ag-HA)-coated implants to prevent post-operative infection, and increase bone fusion capacity, and have successfully commercialized antibacterial implants for hip prostheses and spinal interbody cages. This narrative review overviews the present status of available surface coating technologies and materials; describes how the antimicrobial, safety, and biocompatibility (osteoconductivity) of Ag-HA-coated implants have been demonstrated for commercialization; and reviews the clinical use of antimicrobial implants in orthopedic and spinal surgery, including Ag-HA-coated implants that we have developed.

[Use of custom-made acetabular components (CMAC) as part of a two-stage procedure in patients with severe periacetabular bone loss]

OBJECTIVE

Implantation of custom-made acetabular components (CMAC) with load transmission onto the remaining bone stock and reconstruction of the "center of rotation" (COR) in cases of severe periacetabular bone defects.

INDICATIONS

Severe periacetabular bone loss (Paprosky type IIIA/B) with or without pelvic discontinuity after septic or aseptic loosening with inadequate load capacity of the dorsal pillar and/or large supraacetabular defects.

CONTRAINDICATIONS

Acute or local infections, lack of compliance, taking into account the risks and complications: missing or limited expected postoperative functional gain, multimorbid patients with potential inoperability during the first and/or second intervention.

SURGICAL TECHNIQUE

Lateral transgluteal or posterolateral approach while protecting neurovascular and muscular structures. Preparation of the implant site based on preoperative planning with augmentation of bone defects as far as possible. Primarily stable anchoring with 2 angle-stable pole screws in the ilium, an optional pole screw in the pubic bone for determination of COR, and stabilization screws in the iliac wing (optionally angle-stable). Use of dual mobility cup according to the soft tissue tension and intraoperative stability.

POSTOPERATIVE MANAGEMENT

For the first 6 weeks postoperative partial weight-bearing (20 kg), followed by a gradual increase of the load (10 kg per week).

RESULTS

Between 2008 and 2018, 47 patients with a Paprosky type III defect underwent implantation of a monoflanged CMAC. Main complication was a periprosthetic joint infection with subsequent need for implant removal in 9 of 10 cases. Harris Hip Score improved from 21.1 to 61.5 points. X‑ray imaging displayed an angle of inclination of 42.3 ± 5.3°, an anteversion of 16.8 ± 6.2°, a ∆ H of 0.5 ± 0.2 mm and a ∆ V of 17.7 ± 1.1 mm according to Roessler et al.

Mid-term implant survival, functional and radiological results and mechanical complications of mega-prosthetic reconstruction around the knee with the PENTA® system

AIM

Mega-prosthetic reconstruction is the most common treatment method for massive osteoarticular defects caused by tumor resection around the knee. The new implant is a highly modular rotational-hinged megaprosthesis system with a distinct pentagonal stem geometry and variable implantation options. The aim of this study is to present the mid-term implant survival characteristics, functional and radiological results and mechanical complication profile of the new megaprosthesis.

METHODS

One hundred and one mega-prosthetic knee reconstruction procedures in 90 patients (M/F: 51/39) utilizing the new implant system were retrospectively analyzed. In 68 patients, the megaprosthesis was used for primary reconstruction following tumor resection while it was used for revision of other implants in 22. The mean age was 28.5 (7-66) years and the mean follow-up was 59.2 (24-124) months. The most common primary pathology was osteosarcoma with 63-70% patients, the most common anatomical site of involvement was the distal femur with 56-62% patients.

RESULTS

Henderson Type 2 failure (aseptic loosening) was seen in only 2-2.2% patients while Type 3 (structural failure) was seen in 29-32.2% Although the 5-year anchorage survival rate was 94.3%, overall mechanical implant survival was 76.1% at 5 years due to a relatively high failure rate in the first-generation hinge mechanism of the implant. The 5-year hinge survival rate demonstrated a significant improvement rate from 61.7% to 87.2% between the first and second generations of the implant (p = 0.027). The mean MSTS score was 24 out of 30 (14-29). The mean cumulative ISOLS radiographic score for index megaprosthesis operations was 19.7 (12-24), which corresponded to excellent outcome.

CONCLUSION

The new megaprosthesis system is a reliable choice for the reconstruction of tumor-related massive osteoarticular defects around the knee. Although long-term follow-up is necessary for a definitive evaluation of the implant's survival characteristics, midterm follow-up yields exceptional anchorage properties related to pentagonal stem geometry with very good functional outcomes.

The risk factors for mechanical complication in endoprosthetic reconstruction of knee osteosarcoma

BACKGROUND

The increased limb survival rates and higher functional demands have also increased the mechanical complication rates of megaprostheses. This study aimed to analyse possible risk factors which can predispose patients to mechanical complications.

METHODS

Patients with knee osteosarcoma referred to our clinic from 1992 to 2014 were investigated retrospectively. The patients who underwent surgical resection and endoprosthetic reconstruction with at least 5 years of follow up were analysed. The revision of the megaprosthesis due to a mechanical complication was accepted as an endpoint. The possible risk factors, including cement usage, implant material, joint mechanism, neoadjuvant radiotherapy, and anatomical localization of the lesion, were analysed for any association with mechanical complication rates.

RESULTS

A total of 118 patients were included for final analysis. The average age was 24.5 years (standard deviation ±10.1, range: 15-64). Mechanical complication rate was 22% which included 19 aseptic loosenings and seven implant failures. The average time to mechanical complication was 32.5 months. Overall, 5-year implant survival was 78%. Multiple regression analysis revealed that cement usage is an independent risk factor for mechanical complication (P = 0.007). Although the 5-year implant survival was higher in rotating hinge and titanium implants compared with fixed hinge and cobalt chrome, the multiple regression model did not yield a correlation with mechanical complication rates.

CONCLUSION

Cemented implants showed significantly higher mechanical complication rates compared with cementless ones in this series of knee osteosarcoma patients who underwent megaprosthetic reconstruction. Hinge mechanism and implant material did not have a significant effect on mechanical complication rates.

A long-term experience with Mutars tumor megaprostheses: analysis of 187 cases

PURPOSE

Modular megaprostheses have widely replaced allografts, as a reconstructive option; however, failures of these devices remain high. Aim of this study was to analyze outcomes, survival of the implants, incidence and types of complications with Mutars modular endoprostheses at long term.

METHODS

Between 2000 and 2019, 187 Mutars prostheses were implanted in two dedicated centers: 72 upper limbs and 115 lower limbs reconstructions. Diagnoses included 107 primary malignant bone or soft tissue tumors, 65 metastases, 8 benign bone tumors and 7 non-oncologic cases. Silver-coated prostheses were used in 118/187 (63%) cases.

RESULTS

At last follow-up, 76.5% of patients had retained their implant. The overall failure rate was 23.5% at a mean of 1.7 years. There were 22 mechanical failures and 22 non-mechanical failures. The overall implant survival to all types of failure was 68% and 52% at 5 and 10 years, respectively. Infection was the most common mode of failure with an incidence of 6.9%. Implant survival to infection was better for silver-coated implants than for standard implants even if with no significant difference (p = 0.56). Functional results were satisfactory in 97% of patients.

CONCLUSIONS

The overall implant survival at long term was satisfactory with Mutars prostheses. The incidence of complications with Mutars prosthesis is in line with the incidence reported in the literature with other types of tumor prosthesis. The most frequent cause of failure was infection with a lower incidence in silver-coated prostheses; silver coating seems to prevent infection in distal femur and proximal tibia. The silver coating seems to be particularly useful in two-stage revisions with a lower incidence of secondary amputation. In higher risk patients, silver-coated prostheses are the preferable choice for the reduction of the reinfection rate. The functional results of Mutars prostheses were excellent or good in most of cases. The current paper is design to enhance the literature on megaprosthesis in tumor surgery, proven that this system is one of the most used all over the word and one of the best performing.

Antibiotics- and Heavy Metals-Based Titanium Alloy Surface Modifications for Local Prosthetic Joint Infections

Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due to the high number of patients that will eventually receive a prosthesis, PJI incidence is increasing exponentially. As these infections are provoked by microorganisms, mainly bacteria, and as such can develop a biofilm, which is in turn resistant to both antibiotics and the immune system, prevention is the ideal approach. However, conventional preventative strategies seem to have reached their limit. Novel prevention strategies fall within two broad categories: (1) antibiotic- and (2) heavy metal-based surface modifications of titanium alloy prostheses. This review examines research on the most relevant titanium alloy surface modifications that use antibiotics to locally prevent primary PJI.

Distal femoral replacement - Does length matter? Mid-term results for distal femoral replacements

BACKGROUND

Review of mid-term results (five years) for tumour and revision arthroplasty surgery using the Stanmore METS® distal femoral replacement.

METHODS

Data were collected retrospectively for 90 patients for procedures performed between 2002 and 2019. Kaplan-Meier survivorship for implant was estimated at five years post-op. Endpoints for survivorship analysis included revision for any cause and as per Henderson classification. Log rank test was used to compare implant survival for different categorical variables. Musculo-Skeletal Tumour Society (MSTS) score was used to estimate function.

RESULTS

Overall implant survival at five years was 76% (95% CI 66-86). Implants with a short body (<= 45 mm) had significantly better implant survival [87% (95% CI 78-99)] compared to those with larger bodies [63% (95% CI 48-82)] (logrank test, p = 0.031). There was no significant difference in implant survival for tumour and revision arthroplasty patients (logrank test, p = 0.61). Mean MSTS scores (median follow-up = 3.5 years) for tumour and revision arthroplasty patient were 71% and 63% respectively (Wilcoxon rank test, p < 0.05). Higher total number of surgeries was a significant predictor of patient mortality [HR = 0.7 (95% CI 0.49-0.99)]. Longer bodies were a significant predictor of implant failure [HR = 3.2 (95% CI 1.05-10.53), p < 0.05].

CONCLUSION

Overall outcome of Stanmore METS® distal femoral replacement at five years following tumour and revision arthroplasty reconstruction is comparable to the other implants.

Risk factors for implant failure of custom-made acetabular implants in patients with Paprosky III acetabular bone loss and combined pelvic discontinuity

BACKGROUND

Severe acetabular bone loss in revision total hip arthroplasty (RTHA), both with or without pelvic discontinuity, remains a great challenge in orthopaedic surgery.

OBJECTIVE

The aim of this study was to evaluate risk factors for failure of custom-made acetabular implants in RTHA.

METHODS

Seventy patients with severe acetabular bone loss (Paprosky Type III) and pelvic discontinuity, who required RTHA, were included in our study. All prostheses were constructed based on a thin-layer computed-tomography (CT) scan of the pelvis. The treatment was considered unsuccessful in the event of periprosthetic joint infection (PJI) or aseptic loosening (AL) with need for explantation of the custom-made acetabular implant.

RESULTS

The average follow-up was 41.9 ± 34.8 months (range 1.5-120). Implant survival at last follow-up was 75.7% (53 of 70). Explantation was necessary in 17 cases (15 PJI; 2 AL). Previous PJI as reason for RTHA (p= 0.025; OR 3.56 (95% CI: 1.14; 11.21)), additional revision of femoral components (p= 0.003; OR 8.4 (95% CI: 1.75; 40.42)), rheumatoid disease (p= 0.039; OR 3.43 (95% CI: 1.01; 11.40)), elevated preoperative CRP > 15.2 mg/l (p= 0.015; AUC: 0.7) and preoperative haemoglobin < 10.05 (p= 0.022; AUC: 0.69) were statistically significant risk factors associated with treatment failure. Age and BMI were not statistically significant contributing to implant failure.

CONCLUSION

Risk factors for treatment failure were a previous PJI, additional revision of femoral component, rheumatoid disease, elevated preoperative CRP and low preoperative haemoglobin. Awareness of these risk factors will help to improve future treatment standards.

Osseointegration for Amputees: Current Implants, Techniques, and Future Directions

Osseointegrated prostheses provide a rehabilitation option for amputees offering greater mobility, better satisfaction, and higher use than traditional socket prostheses. There are several different osseointegrated implant designs, surgical techniques, and rehabilitation protocols with their own strengths and limitations. The 2 most prominent risks, infection and periprosthetic fracture, do not seem unacceptably frequent or insurmountable. Proximal amputations or situations leading to reduced mobility are exceptionally infrequent. Osseointegrated implants can be attached to advanced sensory and motor prostheses.

The role of silver coating for arthroplasty components

Periprosthetic joint infection (PJI) is one of the most dreaded complications after arthroplasty surgery; thus numerous approaches have been undertaken to equip metal surfaces with antibacterial properties. Due to its antimicrobial effects, silver is a promising coating for metallic surfaces, and several types of silver-coated arthroplasty implants are in clinical use today. However, silver can also exert toxic effects on eukaryotic cells both in the immediate vicinity of the coated implants and systemically. In most clinically-used implants, silver coatings are applied on bulk components that are not in direct contact with bone, such as in partial or total long bone arthroplasties used in tumour or complex revision surgery. These implants differ considerably in the coating method, total silver content, and silver release rates. Safety issues, such as the occurrence of argyria, have been a cause for concern, and the efficacy of silver coatings in terms of preventing PJI is also controversial. The application of silver coatings is uncommon on parts of implants intended for cementless fixation in host bone, but this option might be highly desirable since the modification of implant surfaces in order to improve osteoconductivity can also increase bacterial adhesion. Therefore, an optimal silver content that inhibits bacterial colonization while maintaining osteoconductivity is crucial if silver were to be applied as a coating on parts intended for bone contact. This review summarizes the different methods used to apply silver coatings to arthroplasty components, with a focus on the amount and duration of silver release from the different coatings; the available experience with silver-coated implants that are in clinical use today; and future strategies to balance the effects of silver on bacteria and eukaryotic cells, and to develop silver-coated titanium components suitable for bone ingrowth. Cite this article: Bone Joint J 2021;103-B(3):423-429.

Adjuvant antibiotic-loaded bone cement: Concerns with current use and research to make it work

Antibiotic-loaded bone cement (ALBC) is broadly used to treat orthopaedic infections based on the rationale that high-dose local delivery is essential to eradicate biofilm-associated bacteria. However, ALBC formulations are empirically based on drug susceptibility from routine laboratory testing, which is known to have limited clinical relevance for biofilms. There are also dosing concerns with nonstandardized, surgeon-directed, hand-mixed formulations, which have unknown release kinetics. On the basis of our knowledge of in vivo biofilms, pathogen virulence, safety issues with nonstandardized ALBC formulations, and questions about the cost-effectiveness of ALBC, there is a need to evaluate the evidence for this clinical practice. To this end, thought leaders in the field of musculoskeletal infection (MSKI) met on 1 August 2019 to review and debate published and anecdotal information, which highlighted four major concerns about current ALBC use: (a) substantial lack of level 1 evidence to demonstrate efficacy; (b) ALBC formulations become subtherapeutic following early release, which risks induction of antibiotic resistance, and exacerbated infection from microbial colonization of the carrier; (c) the absence of standardized formulation protocols, and Food and Drug Administration-approved high-dose ALBC products to use following resection in MSKI treatment; and (d) absence of a validated assay to determine the minimum biofilm eradication concentration to predict ALBC efficacy against patient specific micro-organisms. Here, we describe these concerns in detail, and propose areas in need of research.

Silver-coated megaprosthesis in prevention and treatment of peri-prosthetic infections: a systematic review and meta-analysis about efficacy and toxicity in primary and revision surgery

AIM

Prosthetic joint infection (PJI) is a common complication following orthopedic megaprosthetic implantations (EPR), estimated up to 50%. Silver coatings were introduced in order to reduce the incidence of PJI, by using the antibacterial activity of silver. Three different silver coatings are available: MUTARS^® (Implantcast), Agluna^® (Accentus Medical), PorAg^® (Waldemar Link). The aim of this review is to provide an overview on efficacy and safety of silver-coated EPR both in primary and revision surgery, comparing infection rate according to the type of implant.

METHODS

Through an electronic systematic search, we reviewed the articles concerning silver-coated EPRs. Infection rate, silver-related complications, local and blood concentrations of the silver were evaluated. Meta-analyses were performed to compare results from each study included.

RESULTS

Nineteen studies were included. The overall infection rate in patients with silver-coated implants was 17.6% (133/755). Overall infection rate in primary silver-coated EPR was been 9.2% (44/445), compared to 11.2% (57/507) of non-silver-coated implants. The overall infection rate after revisions was 13.7% (25/183) in patients with silver-coated EPR and 29.2% (47/161) when uncoated EPR were used, revealing a strength statistically significative utility of silver coatings in preventing infections in this group (p: 0.019). Generally, the use of MUTARS^® EPR had produced an almost constant decrease in the incidence of primary PJI but there are few data on the effectiveness in revisions. The results from the use of Agluna^® in both primary and revisions implants are inconstant. Conversely, PorAg^® had proven to be effective both in PJI prevention but, especially, when used in PJI revision settings. Local argyria was reported in 8 out of 357 patients (2.2%), while no systemic complications were described. Local and blood concentrations of silver were always reported very far to the threshold of toxicity, with the lowest concentration found using PorAg^®.

CONCLUSIONS

Silver-coated EPRs are safe and effective in reduction in PJI and re-infection rate, in particular when used in higher risk patients and after two-stage revisions to fight PJI.

Outcome of repeated multi-stage arthroplasty with custom-made acetabular implants in patients with severe acetabular bone loss: a case series

BACKGROUND

Failed reconstruction in cases of severe acetabular bone loss, with or without pelvic discontinuity, in revision total hip arthroplasty (rTHA) remains a great challenge in orthopaedic surgery. The aim of this study was to describe the outcome of a "second" rTHA with "custom-made acetabular components (CMACs)" after a previously failed reconstruction with CMACs.

METHODS

4 patients with severe acetabular bone loss (Paprosky Type IIIB), who required a second rTHA after a previously failed reconstruction with CMAC, due to prosthetic joint infection (PJI), were included in our retrospective study. All prostheses had been constructed on the basis of thin-layer computed-tomography scans of the pelvis. The second rTHA was considered unsuccessful in the event of PJI or aseptic loosening (AL) with need for renewed CMAC explantation.

RESULTS

The treatment success rate after second rTHA with a CMAC was 50% (2 of 4). In the successful cases, the visual analogue scale (VAS) score and Harris Hip Score (HHS) after the second rTHA (VAS range 2-4; HHS range 45-58 points) did not differ from those after the first rTHA, before onset of symptoms (VAS: range 2-4; HHS: range 47-55 points). In the failed cases, the second CMACs needed to be explanted due to PJI, with renewed detection of previous pathogens. Patients with treatment failure of the second CMAC had required a higher number of revision surgeries after explantation of the first CMAC than patients with a successful outcome.

CONCLUSIONS

In patients with severe acetabular bone loss and previously failed rTHA with CMACs, repeat rTHA with a CMAC may be a solid treatment option for patients with an "uncomplicated" multi-stage procedure, i.e., without persisting infection after explantation of the original CMAC. While the outcome in terms of clinical function does not appear negatively affected by such a "second attempt," the complication rate and risk of reinfection, nonetheless, is high.

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.

Antimicrobial silver-coating for locking plates shows uneventful osteotomy healing and good biocompatibility results of an experimental study in rabbits

Infections after internal fixation of fractures remain a challenge. Silver is known for its antimicrobial activity, including activity against multi-resistant strains. The aim of the current study was to analyze the biocompatibility and potential influence on the osteotomy healing process of a silver-coating technology for locking plates compared to silver-free locking plates in an established rabbit model. The implants used in this study were 7-hole titanium locking plates, and plasma electrolytic oxidation (PEO) silver-coated equivalents. A total of 24 rabbits were used in this study (12 coated, 12 non-coated). An osteotomy of the midshaft of the humerus was created and the humerus stabilized with the 7-hole locking plates with a total of 6 screws. Radiographs were taken on day 0, week 2, 4, 6, 8, and 10 for continuous radiographical evaluation. All animals were euthanized after 10 weeks and further assessment was performed using X-rays, micro-CT, non-destructive four-point bending biomechanical testing and semi-quantitative histopathological evaluation. Furthermore, silver concentration was measured in the blood, kidney, liver, spleen, brain, feces and soft tissue around the plate. Radiographs showed normal undisturbed and completed healing of the osteotomy in all animals without any differences between the two groups over the entire observation period. Micro-CT analysis revealed overall tissue volume as well as tissue density to be comparable between the two groups. Mechanical testing showed comparable stiffness with an average stiffness relative to contralateral bones of 75.7 ± 16.1% in the silver-free control group compared to 69.7 ± 18.5% (p-value: 0.46). Semi-quantitative histopathological evaluation showed no remarkable difference in the analysis of the osteotomy gap healing or in the surrounding soft tissue area. There were detectable silver concentrations in the soft tissue around the plate after 10 weeks. Silver in the blood was only found in 3 animals within the first two weeks and all animals were free of silver afterwards. There were no detectable silver concentrations in the brain, liver, spleen, axillary lymph nodes and kidney. This study shows undisturbed osteotomy healing of the presented antimicrobial silver surface coating and a good biocompatibility in this rabbit model.

Fighting Megaprosthetic Infections: What are the Chances of Winning?

BACKGROUND

Megaprosthetic infections continue to be a leading mode of failure after limb salvage surgery. Though challenging, amputations can be avoided with proper management in majority of the cases. This study aims to describe the spectrum of mega-endoprosthetic infections at our institute and assess the treatment efficacy in these patients.

MATERIALS AND METHODS

All patients treated for endoprosthetic infection at our institute between 2010 and 2018 were retrospectively analyzed for overall survival of reconstruction method, site and type of megaprosthesis, adjuvant therapy, microbial isolates, surgical and medical management and outcomes.

RESULTS

Thirty-five patients (22 males: 13 females) were analyzed following treatment for endoprosthetic infection. Majority were around the knee joint [most commonly with proximal tibia (n = 14) followed by distal femur (n = 12) megaprosthesis]. Ten patients had undergone primary surgical procedure at our institute, while 25 patients presented with infection after megaprosthesis implantation. In the 28 culture-positive infections, the most common micro-organism was Staphylococcus spp. (18 patients: methicillin-sensitive Staphylococcus aureus = 9, coagulase-negative Staphylococcus = 5, methicillin-resistant Staphylococcus aureus = 1, Staphylococcus epidermidis = 3) and poly-microbial infection was present in three patients. Nine patients underwent successful debridement and wound wash with insertion of antibiotic impregnated cement beads in 5/9 cases. Twenty-one patients required a two-stage revision. Of these 30 patients, all but one has completely resolved infections. One patient with resurfaced late infection after re-implantation is on chronic suppressive antimicrobial therapy and close follow-up. Amputation because of uncontrolled infection was performed in three patients (one death post-operatively due to systemic complications of septicemia), while two patients opted for amputation as opposed to stage revisions. Median antimicrobial therapy duration was 6 weeks (1-12 weeks). Reconstructive surgery for soft tissue cover was required in seven patients.

CONCLUSIONS

In patients with early or acute presentation without frank granulation or pus around the implant, debridement and insertion of antibiotic cement beads was adequate. Two-stage revisions with complete removal of the megaprosthesis showed best results in infections that could be controlled with antimicrobial therapy. More than one exchange of cement spacer was required for uncontrolled infections. Multidisciplinary approach in consultation with the infectious disease team is essential to determine choice of antibiotic cement for beads/spacer as well as appropriate adjuvant antimicrobial therapy to solve the challenging problem of endoprosthetic infections following bone tumor surgery. Adequate and healthy soft tissue cover of the implant should be achieved wherever indicated.

[Risk factors and management strategies for early and late infections following reconstruction with special tumour endoprostheses]

BACKGROUND

Periprosthetic joint infection (PJI) of megaprostheses occur in about 10% of all cases. The criteria for PJI are defined by the "Musculoskleletal Infection Society" (MSIS) and apply to both primary arthroplasty and megaprostheses.

MANAGEMENT

The management strategies of PJI in megaprostheses are dependent on the duration of infection and the maturity of the bacterial biofilm. Implant retention with an exchange of the mobile components is only possible in the presence of an immature biofilm. In the presence of a mature biofilm, a one- or two-stage exchange must be performed. A complete exchange of all endoprosthetic components should be performed, if possible, since a partial retention of isolated components results in inferior treatment success rates.

RESULTS

The highest success rates are achievable with two-stage exchanges. Multiple risk factors such as skin necrosis, postoperative haematoma, prolonged wound secretion and operative times ≥ 2.5 h are risk factors for the development of PJI in megaprostheses. Knowledge regarding these risk factors allows for an identification of high-risk patients and early management of PJI.

Mid-term results after revision total hip arthroplasty with custom-made acetabular implants in patients with Paprosky III acetabular bone loss

INTRODUCTION

Severe acetabular bone loss, both with or without pelvic discontinuity, remains a challenge in revision total hip arthroplasty (RTHA). The goal of our study was to evaluate the mid-term results for consecutive patients with Paprosky III acetabular bone loss with or without pelvic discontinuity who needed RTHA with custom-made acetabular implants and to compare the results to those of other studies.

MATERIALS AND METHODS

Sixty-eight (68) patients with severe acetabular bone loss (Paprosky Type IIIa and IIIb), who required RTHA, were included in our study. All prostheses were constructed on the basis of thin-layer computed tomography (CT) scans of the pelvis. The visual analogue scale (VAS), Harrison hip score (HHS), and clinical and radiographic follow-up assessments were used to evaluate the outcome.

RESULTS

The average follow-up time was 43 months (range 1-120 months). Implant survival at last follow-up was 75% (51 of 68). Kaplan-Meier survival analysis, with explantation as the endpoint, revealed survival rates of 82.7% (3 years) and 77% (5 years). Patients with revision of the acetabular component only had a significant higher survival rate (p 0.012). Overall revision rate was 36.7%. Reinfection rate was 34.4%. Complications included 15 (22%) periprosthetic joint infections (PJI), 7 dislocations (10.2%), and 2 aseptic loosenings (2.9%). Mean VAS at last follow-up was 1.45 compared to 3.2 preoperatively, while mean HHS improved from 21.1 points preoperatively to 61 at last follow-up. The change in both scores was thus significant (p < 0.001).

CONCLUSION

Defect reconstruction with custom-made modular acetabular implants can be a good, nevertheless expensive, treatment option with clinically and radiologically satisfying results in comparison to recent studies in the literature. Nevertheless, high postoperative complication rates, especially in terms of PJI, remain a challenge.

Evidence-Based Recommendations for Local Antimicrobial Strategies and Dead Space Management in Fracture-Related Infection

Fracture-related infection (FRI) remains a challenging complication that imposes a heavy burden on orthopaedic trauma patients. The surgical management eradicates the local infectious focus and if necessary facilitates bone healing. Treatment success is associated with debridement of all dead and poorly vascularized tissue. However, debridement is often associated with the formation of a dead space, which provides an ideal environment for bacteria and is a potential site for recurrent infection. Dead space management is therefore of critical importance. For this reason, the use of locally delivered antimicrobials has gained attention not only for local antimicrobial activity but also for dead space management. Local antimicrobial therapy has been widely studied in periprosthetic joint infection, without addressing the specific problems of FRI. Furthermore, the literature presents a wide array of methods and guidelines with respect to the use of local antimicrobials. The present review describes the scientific evidence related to dead space management with a focus on the currently available local antimicrobial strategies in the management of FRI. LEVEL OF EVIDENCE:: Therapeutic Level V. See Instructions for Authors for a complete description of levels of evidence.

Antimicrobial Prophylaxis for the Prevention of Surgical Site Infections in Orthopaedic Oncology - A Narrative Review of Current Concepts

The incidence of surgical site infections (SSIs) after elective tumour orthopaedic surgery in adults is higher than non-oncologic orthopaedic surgery. Their causative microorganisms and antibiotic susceptibilities are also different from the non-oncologic cases; with no apparent predictable microbiological patterns. Clinicians continue to struggle to tailor the optimal prophylactic regimen for the very heterogeneous group of tumour patients. Many clinicians thus prolong the first-and second-generation cephalosporin agents, while a minority chooses to broaden the antimicrobial spectrum by combination prophylaxis. The variability in current practices and surgical techniques is enormous, even within the same setting. The scientific literature lacks adequate retrospective case-studies and there is currently only one prospective randomized trial. In this narrative review, we discuss various perioperative antibiotic concepts in oncologic orthopaedic surgery, including a summary of the state-to-the-art, opinions and difficulties related to the different prophylactic strategies.

[Non-cemented modular prosthetic reconstruction for bone defect after tumor resection in lower extremities]

OBJECTIVE

To report the preliminary clinical results and analyze the prognostic factors of prosthetic failures with non-cemented modular prosthetic reconstruction after tumor resection in lower extremities.

METHODS

A clinical data of 150 patients with lower extremity tumors treated with MEGASYSTEM-C non-cemented modular prosthetic reconstruction between October 2011 and September 2016 was retrospectively analyzed. There were 88 males and 62 females, aged from 12 to 81 years, with a median age of 24 years. According to World Health Organization (WHO) classification of bone tumors, 120 cases were primary malignant tumors, 27 cases were intermediate tumors, and 3 cases were metastatic tumors. Among them, 134 cases underwent primary operation and 16 cases underwent reoperation after recurrence. Eighty-seven patients with malignant tumors received chemotherapy before and after operation, and no patient received local radiotherapy during perioperative period. Proximal femur was reconstructed in 32 cases, distal femur in 83 cases, and proximal tibia in 35 cases. The postoperative follow-up time, the results of oncology (survival status and tumor recurrence), and prosthesis failure (prosthesis survival rate, reasons for failure, treatment plan after failure) were recorded. The reason of the prosthesis failure was classified into 5 types according to the classification defined by Henderson et al. Kaplan-Meier survival analysis and Log-Rank test were used to analyze patient and prosthesis survival. Lower extremity function was assessed by using the Musculoskeletal Tumor Society (MSTS) scoring system and MSTS scores were compared for patients with different reconstruction sites.

RESULTS

All patients were followed up 5-84 months, the median follow-up time was 39 months. During the follow-up period, there were 116 cases of tumor-free survival, 10 cases of tumor-bearing survival, and 24 died of lung metastasis or multiple metastases. The 3-year and 5-year survival rates of 120 patients with primary malignant tumors were 83.1% and 76.6%. There was no significant difference in survival rate between different reconstruction sites ( P=0.851). Seven cases (4.7%) had local recurrence at 7-21 months after operation. The 3-year and 5-year survival rates of the prosthesis in 150 patients were 94.4% and 92.5%. There was no significant difference in survival rate between different reconstruction sites ( P=0.765). There were 26 failures in 24 patients (16.0%) during the follow-up period. There were 9 cases of type 1 failure, 1 case of type 2 failure, 3 cases of type 3 failure, 5 cases of type 4 failure, and 8 cases of type 5 failure. At last follow-up, 120 of the 126 patients survived without prosthetic failure. Except that the influence of different parts of prosthesis on the incidence of type 4 failure ( P=0.029), the influence of chemotherapy on the incidence of type 5 failure ( P=0.002) were significant, the influence of other types of failure on different reconstructed parts of prosthesis, initial operation, and perioperative chemotherapy had no significant difference ( P>0.05). There were 5 cases of amputation (4 cases of type 5 failure, 1 case of type 4 failure), 3 cases of prosthesis removal (1 case of type 2 failure, 1 case of type 3 failure, 1 case of type 4 failure), 3 cases of revision while keeping the original prosthesis (2 cases of type 1 failure, 1 case of type 5 failure). The overall MSTS score was 24±3. The MSTS scores were 24±3, 25±3, and 23±3 in patients whose reconstruction sites located in proximal femur, distal femur, and proximal tibia, respectively, showing no significant difference ( F=3.014, P=0.052).

CONCLUSION

The short-term follow-up showed a lower incidence of complications and good function for MEGASYSTEM-C non-cement modular prosthesis system in treatment of bone defects after lower limb tumor resection. The main factors affecting the early survival of prosthesis were tumor progression and infection.

Is surface modification effective to prevent periprosthetic joint infection? A systematic review of preclinical and clinical studies

BACKGROUND

With increasing recognition of the importance of biofilm formation in the pathogenesis of periprosthetic joint infection (PJI), a push towards finding solutions to prevent PJI via surface modification of prostheses is occurring. Unlike the promising in vitro antimicrobial effects of these surface modifications, the preclinical and clinical prophylactic effects vary and are debated. Therefore, we performed this systematic review to answer: (1) what kinds of methods of surface modification are used in preclinical and clinical studies to prevent PJI, (2) whether these modifications are effective to prevent PJI.

METHODS

Electronic searches were performed using PubMed, Embase and the Cochrane library databases up to and including December 2017 with predetermined criteria: (1) in vivo studies with (2) surface modification for prophylactic effects against infection. Both animal studies and clinical trials were included. Data were extracted and presented systematically.

RESULTS

Overall, 21 studies were included. Among these, fourteen were carried out in animal models and seven were clinical studies. In the animal studies, six used antibiotics and six silver modifications, while copper and Cationic Steroidal Antimicrobial-13 were each used for one study. In the seven clinical studies targeting patients with high infection risk, five of them focused on silver-coated prostheses and the remaining two studied iodine-coated implants. In all of the animal studies, when compared with the control group, the surface modified groups had a lower infection risk (RR ranging from 0 to 0.71). Clinical studies using silver-coated prostheses also demonstrated a lower infection risk (RR ranging from 0.24 to 0.70), while iodine-coated implants showed a 0% and 5% incidence of PJI in the two case series included.

DISCUSSION

The results from the publications included in this review indicate that surface modification, especially antibiotic and silver modifications, are helpful preventing PJI in both preclinical animal models and in clinical trials.

LEVEL OF EVIDENCE

III, systematic review of level III retrospective comparative studies and level IV case series and animal experiments.

High complication and revision rates after total femoral replacement: a retrospective single center analysis of indication, function, and complication

INTRODUCTION

Total femoral replacement (TFR) is a limb salvage procedure performed for large bony defects. However, it is often associated with major complications and reduced function. Data on limb preservation rates and functional outcomes after TFR are limited. The primary objective of this study is to assess indications, functional outcomes, and complications after TFR.

MATERIALS AND METHODS

We retrospectively analyzed all patients after TFR between 2006 and 2016. All patients received a modular mega endoprosthesis (MUTARS^®). Patients were grouped according to their initial indication for TFR: (1) fracture, (2) tumor, or (3) infection. We evaluated (i) patient survival, (ii) postoperative function with the Musculoskeletal Tumor Society Score (MSTS), knee strength, range of motion, and (iii) complications.

RESULTS

Between 2006 and 2016, TFR was performed in 22 patients with a mean age of 64 +/-17 years. Indications for TFR were tumor (n = 6), infection (n = 8) and fracture (n = 8). The mean follow-up (f/up) was 18 months. At final follow-up, mean MSTS was 24%. Mean knee flexion strength was reduced 63% compared to the contralateral leg (p = 0.004). At time of final f/up, 5 patients (22%) died, 5 (22%) underwent secondary hip exarticulation, and 12 (54%) suffered a major complication. At f/up, 11 patients had infections. Of these 11 patients, 5 died, 4 were treated with debridement, and 5 were treated with hip exarticulation. Fifteen patients survived with preserved limbs at f/up.

CONCLUSION

TFR is a salvage procedure with limited functional outcome and high complication rates. Nevertheless, the majority of our cohort could be treated successfully with limb salvage.

Current review of surgical management options for extremity bone sarcomas

Modern surgical management of extremity bone sarcomas is governed by limb-sparing surgery combined with adjuvant and neoadjuvant chemotherapy.

All the resection and reconstruction techniques have to achieve oncologic excision margins, with survival rates and functional results superior to amputation.

The main reconstruction techniques of bone defects resulted after resection are: modular endoprosthetic reconstruction; bone graft reconstruction; bone transport; resection arthrodesis; and rotationplasty.

Oncologic resection and modular endoprosthetic reconstruction are the generally approved surgical options adopted for the majority of cases in major specialized bone sarcoma centres.

Good basic principles, efficient multidisciplinary approach and sustained research in the field can provide a better future for the challenge posed by extremity bone sarcoma treatment.

Cite this article: EFORT Open Rev 2019;4:174-182. DOI: 10.1302/2058-5241.4.180048

[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.

The use of silver coating in hip megaprostheses: a systematic review

Retrospective studies of silver-coated hip implants have demonstrated promising results and safety profile, however, the potential benefits are so far unproven in prospective studies. Silver-coated implants may have a role in patients undergoing revision or primary surgery with a high risk of infection but as yet there are no human studies investigating silver in primary hip arthroplasty. Adequately powered robust prospective studies are needed in this area to determine if silver-coated implants would be efficacious and cost-effective. The purpose of this systematic review article is to review the current literature regarding the use of silver in hip arthroplasty. Our review showed that there is some encouraging evidence that silver coatings can reduce infection.

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.

Silver-coated modular Megaendoprostheses in salvage revision arthroplasty after periimplant infection with extensive bone loss - a pilot study of 34 patients

Background

Hip and knee replacements in patients with bone defects after infection correlates with high rates of reinfection. In this vulnerable patient population, the prevention of reinfection is to be considered superordinate to the functionality and defect bridging. The use of silver coating of aseptic implants as an infection prophylaxis is already proven; however, the significance of these coatings in septic reimplantation of large implants is still not sufficiently investigated.

Methods

In a retrospective analysis, 34 patients who have been treated with a modular mega-endoprosthesis after a cured bone infection of the lower limb (femur or tibia) have been evaluated. One group with 14 patients (NSCG: non silver- coated group) was supplied with the non silver- coated implants: MML München- Lübeck™ modular endoprosthesis system (AQ Implants, Ahrensburg, Germany) or MUTARS® Modular Universal Tumor And Revision System (Implantcast GmbH, Buxtehude, Germany). The other group with 20 patients (SCG: silver- coated group) was supplied with the silver- coated system of MUTARS®. In addition to the clinical findings and the patients’ histories, specifically the reinfection rates, the patients’ mobility was assessed using the New Mobility Score (NMS, by Parker and Palmer).

Results

The median follow-up period was 72 months, ranging from 6 to 267 months. The dropout rate was 5.8%. The reinfection rate after healed reinfection in SCG was 40% (8/20), in NSCG 57% (8/14), p = 0.34; α =0.05. The time for reinfection was, on average, 14 months (1–72 months) in SCG and 8 months (1–48 months) in the NSCG (p = 0.61; α =0.05). The two groups showed no differences in the NMS.

Conclusion

With this retrospective analysis, it can be determined that the rate of reinfection of modular mega-endoprostheses on the hip and knee joint after healed periprosthetic joint infection (PJI) can be reduced by the use of silver coated implants. The time until reinfection can also be delayed by utilizing silver coated implants. Due to the low number of cases of this highly specific patient population, no statistical significance could be determined. A positive effect, however, can be assumed through the use of silver coatings in mega-endoprostheses after an infectious situation.

Megaprosthesis of the knee in tumor and revision surgery

The introduction of multidisciplinary approach with chemo and radiotherapy, the advances in surgical and the improvements of diagnostic techniques allowed limb salvage surgery in most cases of bone sarcomas instead of amputation. Modular megaprostheses are the most common method of reconstruction after segmental resection of the long bones in the extremities for their availability, immediate fixation, early weight bearing, good function. Despite the advances in materials and implant designs, these systems have an high incidence of complications. Aim of this study was to report the experience on mega-prostheses implanted around the knee in tumor and revision surgery to analyze: the most frequent used current systems, the problems of stems fixation, extensor mechanism reconstructions in proximal tibia resections and the preservation of growth of the lower extremity in children.

Megaprosthesis of the knee in tumor and revision surgery

The introduction of multidisciplinary approach with chemo and radiotherapy, the advances in surgical and the improvements of diagnostic techniques allowed limb salvage surgery in most cases of bone sarcomas instead of amputation. Modular megaprostheses are the most common method of reconstruction after segmental resection of the long bones in the extremities for their availability, immediate fixation, early weight bearing, good function. Despite the advances in materials and implant designs, these systems have an high incidence of complications. Aim of this study was to report the experience on mega-prostheses implanted around the knee in tumor and revision surgery to analyze: the most frequent used current systems, the problems of stems fixation, extensor mechanism reconstructions in proximal tibia resections and the preservation of growth of the lower extremity in children. (www.actabiomedica.it)

Surgical Innovation in Sarcoma Surgery

The field of orthopaedic oncology relies on innovative techniques to resect and reconstruct a bone or soft tissue tumour. This article reviews some of the most recent and important innovations in the field, including biological and implant reconstructions, together with computer-assisted surgery. It also looks at innovations in other fields of oncology to assess the impact and change that has been required by surgeons; topics including surgical margins, preoperative radiotherapy and future advances are discussed.