Antibiotic Elution from Hip and Knee Acrylic Bone Cement Spacers: A Systematic Review

Antibiotic-loaded cement in total joint arthroplasty: a comprehensive review

This review evaluates the decision-making framework for using antibiotic-loaded cement (ALC) in the management of prosthetic joint infection (PJI). Drawing on available literature, we offer orthopaedic surgeons a guided discussion on several critical considerations. First, we explore the impact of antibiotic-loading on the mechanical properties of polymethylmethacrylate (PMMA) cement, assessing both strength and durability. We then explore the optimal antibiotic dosage to load into cement, aiming to achieve effective local concentrations for infection control without compromising mechanical stability. Furthermore, we explore how cement and antibiotic properties affect the overall antibiotic elution characteristics of ALC. Finally, we discuss risks of systemic toxicity, particularly acute kidney injury, when using ALC. The principal goal in this review is to provide a balanced approach based on best available evidence that optimises antibiotic elution from ALC whilst minimising potential harms associated with its use.

Impact of Antibiotic-Loaded PMMA Spacers on the Osteogenic Potential of hMSCs

Antibiotic-loaded PMMA bone cement is frequently used in modern trauma and orthopedic surgery. Although many of the antibiotics routinely applied are described to have cytotoxic effects in the literature, clinical experience shows no adverse effects for bone healing. To determine the effects of antibiotic-loaded PMMA spacers on osteogenesis in vitro, we cultivated human bone marrow mesenchymal stem cells (BM-hMSCs) in the presence of PMMA spacers containing Gentamicin, Vancomycin, Gentamicin + Clindamycin as well as Gentamicin + Vancomycin in addition to a blank control (agarose) and PMMA containing no antibiotics. The cell number was assessed with DAPI staining, and the osteogenic potential was evaluated by directly measuring the amount of hydroxyapatite synthesized using radioactive 99mTc-HDP labelling as well as measuring the concentration of calcium and phosphate in the cell culture medium supernatant. The results showed that Gentamicin and Vancomycin as well as their combination show a certain amount of cytotoxicity but no negative effect on osteogenic potential. The combination of Gentamicin and Clindamycin, on the other hand, led to a drastic reduction in both the cell count and the osteogenic potential.

The Practice Patterns of American Association of Hip and Knee Surgeons for the Management of Chronic Periprosthetic Joint Infection After Total Knee Arthroplasty

BACKGROUND

The management of periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) has considerable variation. In order to better capture current preferences for the management of PJI, this study sought to poll the current members of American Association of Hip and Knee Surgeons (AAHKS) first to characterize the distribution of practice patterns.

METHODS

There were 32 questions in an online survey distributed to members of AAHKS. The questions were multiple choice regarding the management of PJI for TKA. There were 844 out of 2,752 members who completed the survey (response rate of 31%).

RESULTS

Most of the members were in private practice (50%) compared to 28% being in an academic setting. On average, members were performing between 6 to 20 PJI cases per year. Two-stage exchange arthroplasty was performed in over 75% of the cases with either a cruciate retaining (CR) or posterior stabilized (PS) primary femoral component used in over 50% of the cases and 62% using an all-polyethylene tibial implant. Most of the members were using vancomycin and tobramycin. Typically, 2 to 3 grams of antibiotics were added per bag of cement regardless of the cement type. When indicated, amphotericin was the most often-used antifungal. Post-operative management had major variability with range of motion, brace use, and weight-bearing restrictions.

CONCLUSION

There was variability in the responses from the members of AAHKS, but there was a preference toward performing a two-stage exchange arthroplasty with an articulating spacer using a metal femoral component and an all-polyethylene liner.

The effectiveness and mechanical properties of chemotherapy-impregnated cement in Ewing sarcoma

Bone cement is often used in the surgical treatment of Ewing sarcoma (ES). Chemotherapy-impregnated cement (CIC) has never been tested in slowing ES growth. The purpose of the study is to determine if CIC can decrease cell proliferation, and to assess changes in the mechanical qualities of the cement. Chemotherapeutic agents including doxorubicin, cisplatin, etoposide, and SF2523 were mixed with bone cement. ES cells were plated and exposed to cell growth media that had contained CIC or regular bone cement (RBC) as a control, and cell proliferation assays were performed daily for 3 days. Mechanical testing on RBC and CIC was also performed. There was a significant decrease (p < 0.001) in cell proliferation among all cells treated with CIC compared to cells treated with RBC by 48 h postexposure. Additionally, there was a synergistic effectiveness of the CIC noted when multiple antineoplastic agents were combined. Three-point bending tests did not reveal substantial reductions in tolerated maximum bending load and maximal displacement at maximal bending load between CIC and RBC. Statement of Clinical Significance: CIC does appear to be effective at decreasing cell growth and does not appear to substantially alter the mechanical properties of the cement.

Enhanced antibiotic release from bone cement spacers utilizing dual antibiotic loading with elevated vancomycin concentrations in two-stage revision for periprosthetic joint infection

PURPOSE

Antibiotic loaded bone cement spacers provide high local antibiotic concentrations, preserve bone stock, and reduce soft tissue contractions. The objective of this in-vitro study was to compare antibiotic release from spacers, aiming to discover the most optimal preparation and identify modifiable factors that can further enhance antibiotic release.

METHODS

Six distinct spacer preparation were created using three different bone cements and manual incorporation of antibiotics. During a six-week period, the release of antibiotics from each spacer was measured individually at ten predetermined time points using a chemiluminescent immunoassay.

RESULTS

Manually adding 4 g of vancomycin to every 40 g of "Palacos R + G" yielded the most favorable release profile. Throughout all preparations, antibiotic release consistently and significantly decreased over the six-week period. When incorporating a higher concentration of vancomycin, a significantly higher cumulative release of vancomycin was observed, with varying effects on the release of gentamicin. The choice of bone cement had a significant impact on antibiotic release.

CONCLUSION

To enhance antibiotic release from spacers, surgeons should manually incorporate high antibiotic concentrations into the most appropriate bone cement and keep the interim period as short as possible. Specifically, we suggest manual incorporation of 4 g of vancomycin to every 40 g of gentamicin premixed "Palacos R + G" to create bone cement spacers.

Cyclic Stability of Locking Plate Augmented with Intramedullary Polymethyl Methacrylate (PMMA) Strut Fixation for Osteoporotic Humeral Fractures: A Biomechanical Study

The locking plate may provide improved fixation in osteoporotic bone; however, it has been reported to fail due to varus collapse or screw perforation of the articular surface, especially in osteoporotic bone with medial cortex comminution. Using bone graft as an intramedullary strut together with plate fixation may result in a stronger construct. However, the drawbacks of bone grafts include limited supply, high cost, and infection risk. PMMA (so-called bone cement) has been widely used for implant fixation due to its good mechanical properties, fabricability, and biocompatibility. The risk of donor-site infection and the drawbacks of allografting may be overcome by considering PMMA struts as alternatives to fibular grafts for humeral intramedullary grafting surgeries. However, the potential effects of intramedullary PMMA strut on the dynamic behaviour of osteoporotic humerus fractures remain unclear. This study aimed to investigate the influence of an intramedullary PMMA strut on the stability of unstable proximal humeral fractures in an osteoporotic synthetic model. Two fixation techniques, a locking plate alone (non-strut group) and the same fixation augmented with an intramedullary PMMA strut (with-strut group), were cyclically tested in 20 artificial humeral models. Axially cyclic testing was performed to 450 N for 10,000 cycles, intercyclic motion, cumulated fragment migration, and residual deformation of the constructs were determined at periodic cyclic intervals, and the groups were compared. Results showed that adding an intramedullary PMMA strut could decrease 1.6 times intercyclic motion, 2 times cumulated fracture gap migration, and 1.8 times residual deformation from non-strut fixation. During cycling, neither screw pull-out, cut-through, nor implant failure was observed in the strut-augmented group. We concluded that the plate-strut mechanism could enhance the cyclic stability of the fixation and minimize the residual displacement of the fragment in treating osteoporotic proximal humeral unstable fractures. The PMMA strut has the potential to substitute donor bone and serve as an intramedullary support when used in combination with locking plate fixation. The intramedullary support with bone cement can be considered a solution in the treatment of osteoporotic proximal humeral fractures, especially when there is medial comminution.

Feasibility evaluation of the induced membrane technique with structural autologous strip bone graft management of phalangeal and metacarpal segmental defects using radiography

PURPOSE

The purpose of this study was to explore the feasibility and evaluate the clinical outcomes of treatment for phalangeal and metacarpal segmental defects with the induced membrane technique and autologous structural bone grafting.

METHODS

Sixteen patients who sustained phalangeal or metacarpal bone segmental defects were treated by the induced membrane technique and autologous structural bone grafting from June 2020 to June 2021 at our center.

RESULTS

The average follow-up was 24 weeks (range, 12-40 weeks). Radiography demonstrated union of all bone grafts after an average of 8.6 weeks (range, 8-12 weeks). All incisions at donor and recipient sites demonstrated primary heal without infection complications. The mean visual analog scale score of the donor site was 1.8 (range, 0-5), with a good score in 13 cases and a fair score in 3. The mean total active motion of the fingers was 179.9°.

CONCLUSIONS

The feasibility of the induced membrane technique and structural treatment with a cylindrical bone graft for segmental bone defects of the metacarpal or phalanx is demonstrated by follow-up radiography results. The bone graft provided much more stability and structural support in the bone defects, and the bone healing time and bone union rate were ideal.

Enoxaparin sodium bone cement plays an anti-inflammatory immunomodulatory role by inducing the polarization of M2 macrophages

OBJECTIVE

The implantation of PMMA bone cement results in an immune response and the release of PMMA bone cement particles causes an inflammatory cascade. Our study discovered that ES-PMMA bone cement can induce M2 polarization of macrophages, which has an anti-inflammatory immunomodulatory effect. We also delved into the molecular mechanisms that underlie this process.

METHODS

In this study, we designed and prepared samples of bone cement. These included PMMA bone cement samples and ES-PMMA bone cement samples, which were implanted into the back muscles of rats. At 3, 7, and 14 days after the operation, we removed the bone cement and a small amount of surrounding tissue. We then performed immunohistochemistry and immunofluorescence to observe the polarization of macrophages and the expression of related inflammatory factors in the surrounding tissues. The RAW264.7 cells were exposed to lipopolysaccharide (LPS) for 24 h to establish the macrophage inflammation model. Then, each group was treated with enoxaparin sodium medium, PMMA bone cement extract medium, and ES-PMMA bone cement extract medium, respectively, and cultured for another 24 h. We collected cells from each group and used flow cytometry to detect the expressions of CD86 and CD206 in macrophages. Additionally, we performed RT-qPCR to determine the mRNA levels of three markers of M1 macrophages (TNF-α, IL-6, iNOS) and two M2 macrophage markers (Arg-1, IL-10). Furthermore, we analyzed the expression of TLR4, p-NF-κB p65, and NF-κB p65 through Western blotting.

RESULTS

The immunofluorescence results indicate that the ES-PMMA group exhibited an upregulation of CD206, an M2 marker, and a downregulation of CD86, an M1 marker, in comparison to the PMMA group. Additionally, the immunohistochemistry results revealed that the levels of IL-6 and TNF-α expression were lower in the ES-PMMA group than in the PMMA group, while the expression level of IL-10 was higher in the ES-PMMA group. Flow cytometry and RT-qPCR analyses revealed that the expression of M1-type macrophage marker CD86 was significantly elevated in the LPS group compared to the NC group. Additionally, M1-type macrophage-related cytokines TNF-α, IL-6, and iNOS were also found to be increased. However, in the LPS + ES group, the expression levels of CD86, TNF-α, IL-6, and iNOS were decreased, while the expression of M2-type macrophage markers CD206 and M2-type macrophage-related cytokines (IL-10, Arg-1) were increased compared to the LPS group. In comparison to the LPS + PMMA group, the LPS + ES-PMMA group demonstrated a down-regulation of CD86, TNF-α, IL-6, and iNOS expression levels, while increasing the expression levels of CD206, IL-10, and Arg-1. Western blotting results revealed a significant decrease in TLR4/GAPDH and p-NF-κB p65/NF-κB p65 in the LPS + ES group when compared to the LPS group. Additionally, the LPS + ES-PMMA group exhibited a decrease in TLR4/GAPDH and p-NF-κB p65/NF-κB p65 levels when compared to the LPS + PMMA group.

CONCLUSION

ES-PMMA bone cement is more effective than PMMA bone cement in down-regulating the expression of the TLR4/NF-κB signaling pathway. Additionally, it induces macrophages to polarize towards the M2 phenotype, making it a crucial player in anti-inflammatory immune regulation.

Local Antibiotic Delivery Options in Prosthetic Joint Infection

Prosthetic Joint Infection (PJI) causes significant morbidity and mortality for patients globally. Delivery of antibiotics to the site of infection has potential to improve the treatment outcomes and enhance biofilm eradication. These antibiotics can be delivered using an intra-articular catheter or combined with a carrier substance to enhance pharmacokinetic properties. Carrier options include non-resorbable polymethylmethacrylate (PMMA) bone cement and resorbable calcium sulphate, hydroxyapatite, bioactive glass, and hydrogels. PMMA allows for creation of structural spacers used in multi-stage revision procedures, however it requires subsequent removal and antibiotic compatibility and the levels delivered are variable. Calcium sulphate is the most researched resorbable carrier in PJI, but is associated with wound leakage and hypercalcaemia, and clinical evidence for its effectiveness remains at the early stage. Hydrogels provide a versatile combability with antibiotics and adjustable elution profiles, but clinical usage is currently limited. Novel anti-biofilm therapies include bacteriophages which have been used successfully in small case series.

Two-stage revision of infected hip prosthesis after post-operative antibiotic therapy: An observational study

Infection is a major threatening side effect after total hip arthroplasty (THA) that its management is so difficult and is accompanied by different complications. The aim of this study was to determine the outcomes of patients underwent 2-staged THA after a course of antibiotic therapy. It was an observational prospective study performed during 2009 and 2019. We managed 51 patients with infected THA using a method in which antibiotic prophylaxis was performed after THA. We followed the same protocol for treatment of patients included 2-staged revision: in first stage, removal of infected instruments were performed and insertion of a hand-made antibiotic-cement spacer was done until erythrocyte sedimentation rate and CRP were normalized. In second stage, an un-cemented prosthesis was re-implanted in femoral side and post-operative IV antibiotic were administered for a week. Patients were monitored for about 15 months. Data were analyzed. There were 3 patients developed recurrent infection required girdlestone due to the aging. One of them needed to remove implant and 2 other with 3 times of re-infection were treated by antibiotic therapy. Other 10 cases were treated first by re-changing the cement. The rate of successful treatment was 78.4% (40 of 51) after the primary surgery and antibiotic therapy. This rose to 92.1% (47 of 51) following more debridement and antibiotic therapy. The merging of staged surgical debridement, using spacer of cement-antibiotic and re-implant beside 1-week intravenous antibiotic therapy, leaded to appropriate early outcomes in this series.

High Rate of Intramedullary Canal Culture Positivity in Total Knee Arthroplasty Resection for Prosthetic Joint Infection

BACKGROUND

Periprosthetic infection is a devastating complication following total knee arthroplasty. A 2-stage protocol often includes an interim antibiotic spacer with intramedullary (IM) dowels. However, the necessity of IM dowels has recently been challenged. Specifically, the data supporting bacterial colonization of the IM canal are limited and controversial. The purpose of this study was to identify the rate of positive IM cultures during resection arthroplasty in periprosthetic knee infection.

METHODS

A total of 66 IM diaphyseal cultures were taken during resection arthroplasty from 34 patients diagnosed with periprosthetic knee infection. These IM cultures were taken from the femoral and tibial canals using separate sterile instruments. All patients had infected primary total knee arthroplasty implants at the time of resection.

RESULTS

Thirty one percent (n = 21) of IM canal cultures in this study were positive from either the tibial or the femoral diaphysis at the time of resection arthroplasty. There were 18 of 21 (86%) of the positive IM canal cultures with concordant intraoperative joint cultures where the IM cultures matched the intraarticular cultures.

CONCLUSION

With a 31% positive IM canal culture rate, this study confirms the logic of using IM dowels with an antibiotic spacer to treat periprosthetic knee infection. Since the failure of a 2-stage reimplantation is catastrophic, any attempt to provide additional local antibiotic delivery seems warranted. Since nearly one-third of our patients had positive IM cultures, this simple addition to an antibiotic spacer has the potential to improve 2-stage results. Claims supporting the elimination of IM dowels during resection arthroplasty seem ill-advised.

Is the routine use of local antibiotics in the management of periprosthetic joint infections justified?

Periprosthetic joint infection (PJI) following total hip and total knee arthroplasty continues to be a leading cause of re-operation and revision arthroplasty. Not only is the treatment of PJI notoriously challenging, but success rates are variable. Regardless of the surgical strategy used, successful management of PJI requires a comprehensive surgical debridement focused at eradicating the underlying biofilm followed by appropriate antimicrobial therapy. Although systemic antimicrobial delivery continues to be a cornerstone in the treatment of PJI, many surgeons have started using local antibiotics to deliver higher concentrations of antibiotics directly into the vulnerable joint and adjacent soft tissues, which often have compromised vascularity. Available evidence on the use of topical powder, bone cement, and calcium sulphate carriers for local delivery of antibiotics during the initial treatment of PJI is limited to studies that are extremely heterogeneous. There is currently no level-1 evidence to support routinely using these products. Further, appropriately powered, prospective studies are needed to quantify the safety and efficacy of antibiotic-located calcium-sulphate carriers to justify their added costs. These products should not encourage surgeons to deviate from best practice guidelines, such as those recommended during the International Consensus Meeting on Musculoskeletal Infections.

Wound fluid ceftriaxone concentrations after local application with calcium sulphate as carrier material in the treatment of orthopaedic device-associated hip infections

Aims

There is a considerable challenge in treating bone infections and orthopaedic device-associated infection (ODAI), partly due to impaired penetration of systemically administrated antibiotics at the site of infection. This may be circumvented by local drug administration. Knowledge of the release kinetics from any carrier material is essential for proper application. Ceftriaxone shows a particular constant release from calcium sulphate (CaSO4) in vitro, and is particularly effective against streptococci and a large portion of Gram-negative bacteria. We present the clinical release kinetics of ceftriaxone-loaded CaSO4 applied locally to treat ODAI.

Methods

A total of 30 operations with ceftriaxone-loaded CaSO4 had been performed in 28 patients. Ceftriaxone was applied as a single local antibiotic in 21 operations and combined with vancomycin in eight operations, and in an additional operation with vancomycin and amphotericin B. Sampling of wound fluid was performed from drains or aspirations. Ceftriaxone concentrations were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS).

Results

A total of 37 wound fluid concentrations from 16 operations performed in 14 patients were collected. The ceftriaxone concentrations remained approximately within a range of 100 to 200 mg/l up to three weeks. The median concentration was 108.9 mg/l (interquartile range 98.8 to 142.5) within the first ten days. No systemic adverse reactions were observed.

Conclusion

Our study highlights new clinical data of locally administered ceftriaxone with CaSO4 as carrier material. The near-constant release of ceftriaxone from CaSO4 observed in vitro could be confirmed in vivo. The concentrations remained below known local toxicity thresholds. Cite this article: Bone Joint Res 2022;11(11):835–842.

Mechanical strength of antibiotic-loaded PMMA spacers in two-stage revision surgery

Background

Antibiotic-loaded polymethylmethacrylate (PMMA) bone cement spacers provide high local antibiotic concentrations and patient mobility during the interim period of two-stage revision for periprosthetic joint infection (PJI). This study compares mechanical characteristics of six dual antibiotic-loaded bone cement (dALBC) preparations made from three different PMMA bone cements. The study`s main objective was to determine the effect of time and antibiotic concentration on mechanical strength of dALBCs frequently used for spacer fabrication in the setting of two-stage revision for PJI.

Methods

A total of 84 dual antibiotic-loaded bone cement specimens made of either Copal spacem, Copal G + V or Palacos R + G were fabricated. Each specimen contained 0.5 g of gentamicin and either 2 g (low concentration) or 4 g (high concentration) of vancomycin powder per 40 g bone cement. The bending strength was determined at two different timepoints, 24 h and six weeks after spacer fabrication, using the four-point bending test.

Results

Preparations made from Copal G + V showed the highest bending strength after incubation for 24 h with a mean of 57.6 ± 1.2 MPa (low concentration) and 50.4 ± 4.4 MPa (high concentration). After incubation for six weeks the bending strength had decreased in all six preparations and Palacos R + G showed the highest bending strength in the high concentration group (39.4 ± 1.6 MPa). All low concentration preparations showed superior mechanical strength compared to their high concentration (4 g of vancomycin) counterpart. This difference was statistically significant for Copal spacem and Copal G + V (both p < 0.001), but not for Palacos R + G (p = 0.09).

Conclusions

This study suggests that mechanical strength of antibiotic-loaded PMMA bone cement critically decreases even over the short time period of six weeks, which is the recommended interim period in the setting of two-stage revision. This potentially results in an increased risk for PMMA spacer fracture at the end of the interim period and especially in patients with prolonged interim periods. Finally, we conclude that intraoperative addition of 4 g of vancomycin powder per 40 g of gentamicin-premixed Palacos R + G (Group D) is mechanically the preparation of choice if a dual antibiotic-loaded bone cement spacer with high antibiotic concentrations and good stability is warranted. In any case the written and signed informed consent including the off-label use of custom-made antibiotic-loaded PMMA bone cement spacers must be obtained before surgery.

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

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

A study of bioactive glass-ceramic's mechanical properties, apatite formation, and medical applications

Apparently, bioactive glass-ceramics are made by doing a number of steps, such as creating a microstructure from dispersed crystals within the residual glass, which provides high bending strength, and apatite crystallizes on surfaces of glass-ceramics when calcium ions are present in the blood. Apatite crystals grow on the glass and ceramic surfaces due to the hydrated silica. These materials are biocompatible with living bone in a matter of weeks, don't weaken mechanically or histologically, and exhibit good osteointegration as well as mechanical properties that are therapeutically relevant, such as fracture toughness and flexural strength. As part of this study, we examined mechanical properties, process mechanisms involved in apatite formation, and potential applications for bioactive glass-ceramic in orthopedic surgery, including load-bearing devices.

Is debridement really the best we can do for periprosthetic joint infections following total ankle replacements? A systematic review and meta-analysis

BACKGROUND

Ankle periprosthetic joint infections are rising in number, but an evidence-based gold standard treatment has not been defined yet.

METHODS

We made a systematic review about the operative treatment of infections following total ankle arthroplasty. Proportional meta-analysis was used to summarize effects of the surgical techniques included. Primary outcome of this study was infection eradication, followed by complications, re-interventions, amputation rates and functions.

RESULTS

We included six studies(113 patients) reporting 6 types of surgical interventions, mostly irrigation and debridement (35.4%) and two-stage revisions (24.8%). No differences among all analyzed techniques were found in the infection eradication outcome as well as in the secondary outcomes. Patients receiving a permanent spacer are most likely to end up with amputation.

CONCLUSIONS

Literature dealing with infections after total ankle replacement is currently composed by few low-quality articles. The overlapping of confidence intervals related to all analyzed interventions showed no superiority of either technique.

LEVEL OF EVIDENCE

III.

PMMA Bone Cement: Antibiotic Elution and Mechanical Properties in the Context of Clinical Use

This literature review discusses the use of antibiotic loaded polymethylmethacrylate bone cements in arthroplasty. The clinically relevant differences that have to be considered when antibiotic loaded bone cements (ALBC) are used either for long-term implant fixation or as spacers for the treatment of periprosthetic joint infections are outlined. In this context, in vitro findings for antibiotic elution and material properties are summarized and transferred to clinical use.

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

Background

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

Methods

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

Results

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

Conclusion

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

Antifungal-Loaded Acrylic Bone Cement in the Treatment of Periprosthetic Hip and Knee Joint Infections: A Review

Little is known about the clinical use of antifungal-loaded acrylic bone cement in the treatment of periprosthetic hip and knee joint infections (PJIs). Hence, we performed a literature search using PubMed/MEDLINE from inception until December 2021. Search terms were “cement” in combination with 13 antifungal agents. A total of 10 published reports were identified, which described 11 patients and 12 joints in which antifungal-loaded cement was employed. All studies were case reports or case series, and no randomized controlled trials were identified. In 6 of 11 patients, predisposing comorbidities regarding the emergence of a fungal PJI were present. The majority of the studies reported on infections caused by Candida species. In six cases (seven joints), the cement was solely impregnated with an antifungal, but no antibiotic agent (amphotericin B, voriconazole, and fluconazole). In the other five joints, the cement was impregnated with both antibiotic(s) and antifungals. Great discrepancies were seen regarding the exact loading dose. Four studies investigated the local elution of antifungal agents in the early postoperative period and observed a local release of antifungals in vivo. We conclude that there is a paucity of data pertaining to the clinical use of antifungal-loaded bone cement, and no studies have assessed the clinical efficacy of such procedures. Future studies are urgently required to evaluate this use of antifungals in PJI.

Role of joint aspiration before re-implantation in patients with a cement spacer in place

BACKGROUND

The usefulness of a mandatory joint aspiration before re-implantation in patients with a cement spacer already in place is unclear.

AIM

To evaluate the role of culturing synovial fluid obtained by joint aspiration before re-implantation in patients who underwent a two-stage septic revision.

METHODS

A retrospective observational study was conducted, including patients that underwent a two-stage septic revision (hip or knee) from 2010 to 2017. After the first stage revision and according to intraoperative culture results, all patients were treated with an antibiotic protocol for 6-8 wk. Following 2 wk without antibiotics, a culture of synovial fluid was obtained. The results of these cultures were recorded and compared with cultures obtained during re-implantation surgery.

RESULTS

Forty-one patients (20 hip and 21 knee spacers) were included in the final analysis. In 39 cases, the culture of synovial fluid was negative, while in the remaining 2 cases (knee spacers) no analysis was possible due to dry tap. In 5 of the patients, two or more intraoperative cultures taken during the re-implantation surgery were positive.

CONCLUSION

We found no evidence to support mandatory joint aspiration before re-implantation in patients with a cement spacer in place.

Antibiotic Cement Utilization for the Prophylaxis and Treatment of Infections in Spine Surgery: Basic Science Principles and Rationale for Clinical Use

Antibiotic bone cement (ABC) is an effective tool for the prophylaxis and treatment of osteomyelitis due to the controlled, sustained release of local antibiotics. ABC has been proven to be effective in the orthopedic fields of arthroplasty and extremity trauma, but the adoption of ABC in spine surgery is limited. The characteristics of ABC make it an optimal solution for treating vertebral osteomyelitis (VO), a serious complication following spine surgery, typically caused by bacterial and sometimes fungal and parasitic pathogens. VO can be devastating, as infection can result in pathogenic biofilms on instrumentation that is dangerous to remove. New techniques, such as kyphoplasty and novel vertebroplasty methods, could amplify the potential of ABC in spine surgery. However, caution should be exercised when using ABC as there is some evidence of toxicity to patients and surgeons, antibiotic allergies, bone cement structural impairment, and possible development of antibiotic resistance. The purpose of this article is to describe the basic science of antibiotic cement utilization and review its usage in spine surgery.

Does Time to Reimplantation After Explant for Prosthetic Joint Infection Influence the Likelihood of Successful Outcomes at 2 Years?

BACKGROUND

Consensus recommendations are lacking regarding appropriate timing of reimplantation following 2-stage resection arthroplasty for prosthetic joint infections (PJIs). We investigated whether the time from resection arthroplasty to reimplantation was associated with treatment outcome at 2 years.

METHODS

Retrospective cohort review was conducted for 101 patients undergoing resection arthroplasty with an antibiotic spacer for PJI at a single tertiary academic referral institution. Time from explantation and spacer placement to reimplantation was categorized into 3 groups: <12, 12-18, and >18 weeks. Baseline patient and treatment course characteristics across these groups were obtained. Multivariate binary logistic regression was used to characterize association between treatment failure and time to reimplantation, controlling for American Society of Anesthesiologists (ASA) score and prior revision surgery.

RESULTS

Time to reimplantation (TTR) >18 weeks demonstrated statistically significant increased odds of treatment failure, after controlling for ASA score and prior revision surgery (odds ratio 7.00, confidence interval 2.14-25.42, P = .002). After excluding patients requiring second spacer or Girdlestone prior to replant, this increased odds of failure remained (odds ratio 4.12, confidence interval 1.18-15.37, P = .029). TTR groups were similar with respect to demographics, except for ASA (2.96 for time to reimplantation >18 weeks vs 2.55 for time to reimplantation <12 weeks; P = .011). Patients with TTR >18 weeks were more likely to have an unplanned readmission during the spacer period (48%, 19%, and 6% for time to reimplantation >18, 12-18, and 0-12 weeks, respectively; P < .002).

CONCLUSION

Although decision regarding TTR is largely patient specific, surgeons should be aware that TTR >18 weeks may be associated with higher rates of treatment failure at 2 years.

Outcomes After Use of the Induced Membrane Technique for Fractures of the Upper Extremity

PURPOSE

The purpose of this study was to review a series of cases in which the induced membrane technique was used for fractures with segmental bone loss in the upper extremity. We aimed to examine patient indications, outcomes based on union rates, and complications associated with this technique.

METHODS

An institutional review board-approved database at our institution was used to identify patients based on either diagnosis or procedure codes commonly used during the induced membrane treatment. The database was queried between 2003 and 2020 and included patients with segmental bone defects from acute trauma, nonunions, and infections. Demographic data, mechanism of injury, size and extent of the bone defect, treatment indication and methods along with intraoperative and postoperative complications were retrospectively reviewed.

RESULTS

We identified 23 patients who met our inclusion criteria, including 15 patients with traumatic segmental bone loss and 8 patients with chronic nonunions and/or infections. Fourteen cases involving the bones of the forearm, 8 cases involving the metacarpals and 3 cases involving the phalanges were identified. Radiographic union was ultimately demonstrated in 21/23 patients (91.3%) with a median time to union of 20 weeks (range 13-29 weeks). A total of 10 patients required unplanned reoperation, with 4 nonunions requiring repeat plating and grafting procedures, and 1 patient ultimately underwent amputation for persistent infection.

CONCLUSIONS

The induced membrane technique represents an effective treatment option for acute traumatic bone loss as well as chronic fracture nonunions. The technique has potential challenges, as 10 patients (43.5%) in our series required unplanned reoperations with 4 patients (17.4%) requiring a repeat intervention for persistent nonunion.

TYPE OF STUDY/LEVEL OF EVIDENCE THERAPEUTIC

IV.

What Is the Most Effective Empirical Antibiotic Treatment for Early, Delayed, and Late Fracture-Related Infections?

Antibiotic treatment strategies for fracture-related infections (FRI) are often extrapolated from periprosthetic joint infections (PJI), although, in contrast to PJI, detailed analysis of pathogens and their antibiotic resistance is missing. Therefore, this study aimed to investigate antibiotic susceptibility profiles to identify effective empiric antibiotic treatment for early-, delayed-, and late-onset FRI. Patients treated for FRI from 2013 to 2020 were grouped into early (<2 weeks), delayed (3−10 weeks), and late (>10 weeks) onset of infection. Antibiotic susceptibility profiles were examined with respect to broadly used antibiotics and antibiotic combinations. In total, 117 patients (early n = 19, delayed n = 60, late n = 38) were enrolled. In early-onset FRI, 100.0% efficacy would be achieved by meropenem + vancomycin, gentamicin + vancomycin, co-amoxiclav + glycopeptide, ciprofloxacin + glycopeptide and piperacillin/tazobactam + glycopeptide. For patients with delayed FRI, the highest susceptibility was revealed for meropenem + vancomycin, gentamicin + vancomycin and ciprofloxacin + glycopeptide (96.7%). Meropenem + vancomycin was the most effective empiric antimicrobial in patients with late-onset of infection with 92.1% coverage. No subgroup differences in antibiotic sensitivity profiles were observed except for the combination ciprofloxacin + glycopeptide, which was significantly superior in early FRI (F = 3.304, p = 0.04). Across all subgroups meropenem + vancomycin was the most effective empiric treatment in 95.7% of patients with confirmed susceptibility. Meropenem + vancomycin, gentamicin + vancomycin, co-amoxiclav + glycopeptide are the best therapeutic options for FRI, regardless of the onset of infection. To avoid multidrug resistance, established antibiotic combinations such as co-amoxiclav with a glycopeptide seem to be reasonable as a systemic antibiotic therapy, while vancomycin + gentamicin could be implemented in local antibiotic therapy to reduce adverse events during treatment.

A Two-Stage Diabetic Foot Salvage Using Synthetic Bone Void Filler and Lesser Toe Fillet Flap: A Case Report

CASE

A 54-year-old type 2 diabetic man with a diabetic forefoot ulcer and osteomyelitis successfully underwent a staged reconstruction to salvage his foot. An antibiotic-carrying bone void filler was used to decrease the infection burden after initial debridement. The fifth toe fillet flap was performed to cover the large soft-tissue defect. The patient returned to baseline ambulation at the 1-year follow-up with a well-incorporated flap.

CONCLUSION

This case highlights the utility of combining an antibiotic-carrying bone void filler and a toe fillet flap in a two-stage approach to salvage complex diabetic foot ulcers.

Current Concepts on the Application, Pharmacokinetics and Complications of Antibiotic-Loaded Cement Spacers in the Treatment of Prosthetic Joint Infections

Prosthetic joint infection (PJI) is a devastating complication of total joint replacement surgery. It affects about 2% of primary total joint replacements. Treatment aims at infection eradication and restoration of patient's mobility. Two-stage revision arthroplasty with an interim application of an antibiotic-loaded cement spacer (ALCS) is the widely accepted treatment for PJI. Spacers are powerful local carriers of antibiotics at the site of infection, effective against biofilm-protected microbes. On the other hand, spacers permit some mobility of the patient and facilitate final prosthesis implantation. ALCS's are either commercially available or prepared intraoperatively on prefabricated or improvised molds. Antibiotic elution from the spacer depends on the amount of the antibiotic used for cement impregnation, at the expense of mechanical stiffness of the spacer. The antibiotic should not exceed 4g per 40g of bone cement to preserve the mechanical properties of the cement. Spacers are frequently accompanied by local or systemic complications. The spacer may break, dislocate and compress vessels or nerves of the limb. Systemic complications are the result of excess elution of antibiotic and include nephrotoxicity, hepatotoxicity, ototoxicity, allergic reactions or neutropenia. Elderly patients with comorbidities are at risk to present such complications. Microbial resistance is a potential risk of long-lasting spacer retention. Persisting infection may require multiple spacer replacements.

Impact of High-Dose Anti-Infective Agents on the Osteogenic Response of Mesenchymal Stem Cells

Treatment of infected nonunions and severe bone infections is a huge challenge in modern orthopedics. Their treatment routinely includes the use of anti-infective agents. Although frequently used, little is known about their impact on the osteogenesis of mesenchymal stem cells. In a high- and low-dose set-up, this study evaluates the effects of the antibiotics Gentamicin and Vancomycin as well as the antifungal agent Voriconazole on the ability of mesenchymal stem cells to differentiate into osteoblast-like cells and synthesize hydroxyapatite in a monolayer cell culture. The osteogenic activity was assessed by measuring calcium and phosphate concentrations as well as alkaline phosphatase activity and osteocalcin concentration in the cell culture medium supernatant. The amount of hydroxyapatite was measured directly by radioactive ^99mTechnetium-HDP labeling. Regarding the osteogenic markers, it could be concluded that the osteogenesis was successful within the groups treated with osteogenic cell culture media. The results revealed that all anti-infective agents have a cytotoxic effect on mesenchymal stem cells, especially in higher concentrations, whereas the measured absolute amount of hydroxyapatite was independent of the anti-infective agent used. Normed to the number of cells it can therefore be concluded that the above-mentioned anti-infective agents actually have a positive effect on osteogenesis while high-dose Gentamycin, in particular, is apparently capable of boosting the deposition of minerals.

Modular Total Femur Replacement for Staged Total Femur Replacement

As the numbers of arthroplasties performed worldwide increase, so do complications such as prosthetic joint infection. Cases that require a two-stage revision of a total femur replacement in the femur pose an ongoing challenge to the modern orthopedic surgeon. Unlike antibiotic spacers in hip and knee arthroplasty, there lacks a commercially available cement spacer for use in total femur replacements. We describe a novel technique for the intraoperative fabrication of a total femur spacer which uses modular components. As such, our technique is unique as it is modular and, therefore, highly customisable to each individual patient. Individual components can be made by different members of the team simultaneously and then assembled to make the final construct, thereby minimizing operative time. Furthermore, the inherent stability of the spacer allows immediate partial weightbearing and functional rehabilitation while patients are waiting for their second-stage procedure.

Novel lipophosphonoxin-loaded polycaprolactone electrospun nanofiber dressing reduces Staphylococcus aureus induced wound infection in mice

Active wound dressings are attracting extensive attention in soft tissue repair and regeneration, including bacteria-infected skin wound healing. As the wide use of antibiotics leads to drug resistance we present here a new concept of wound dressings based on the polycaprolactone nanofiber scaffold (NANO) releasing second generation lipophosphonoxin (LPPO) as antibacterial agent. Firstly, we demonstrated in vitro that LPPO released from NANO exerted antibacterial activity while not impairing proliferation/differentiation of fibroblasts and keratinocytes. Secondly, using a mouse model we showed that NANO loaded with LPPO significantly reduced the Staphylococcus aureus counts in infected wounds as evaluated 7 days post-surgery. Furthermore, the rate of degradation and subsequent LPPO release in infected wounds was also facilitated by lytic enzymes secreted by inoculated bacteria. Finally, LPPO displayed negligible to no systemic absorption. In conclusion, the composite antibacterial NANO-LPPO-based dressing reduces the bacterial load and promotes skin repair, with the potential to treat wounds in clinical settings.

Surgical Management of Charcot Spinal Arthropathy in the Face of Possible Infection

BACKGROUND

The design is a retrospective cohort study. Charcot spinal arthropathy (CSA) is a rare and poorly understood progressive destructive spine condition that usually affects patients with preexisting spinal cord injury. The complexity of this condition, especially when additionally burdened by superimposed infection in the CSA zone, can potentially lead to suboptimal management such as protracted antibiotic therapy, predisposition to hardware failure, and pseudarthrosis. While in noninfected CSA primary stabilization is the major goal, staged surgical management has not been stratified based upon presence of a superinfected CSA. We compare clinical and radiological outcomes of surgical treatment in CSA patients with and without concurrent spinal infections.

METHODS

Our single-institution database was reviewed for all patients diagnosed with CSA and surgically treated, who were subsequently divided into 2 cohorts: spinal arthropathy with superimposed infection and those without. Those were comparatively studied for complications and reoperation rate.

RESULTS

Fifteen patients with CSA underwent surgical intervention; mean follow up of 15.3 months (range, 0-43). Eleven patients received stabilization with a quadruple-rod thoracolumbopelvic construct, while 4 patients with superinfected CSA underwent a staged procedure. Patients treated with a staged approach experienced fewer intraoperative complications (0% versus 18%) and fewer revision surgeries (25% versus 36%). Both cohorts had the same eventual healing.

CONCLUSIONS

Surgical management in CSA patients with primary emphasis on stability and modified surgical treatment based on presence of an active infection in the zone of neuropathic destruction will lead to similar eventual successful results with relatively few and manageable complications in this challenging patient population.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

The proposed treatment algorithm including the use of a quadruple-rod construct with lumbopelivic fixation and a staged approach in patients with superinfected CSA represents a reasonable option in the surgical treatment of CSA.

Effect of Local Delivery of Vancomycin and Tobramycin on Bone Regeneration

OBJECTIVE

A bone defect rat model was established to investigate the osteogenic effect of local delivery two antibiotics (vancomycin and tobramycin powder) on bone regeneration.

METHODS

Twenty-four Sprague-Dawley (SD) male rats (6 to 8 weeks, 200 to 250 g) were used in this study. All these rats were randomly divided into four groups. Based on dose conversion between rat and human via body surface area, the rat dose of two antibiotics was 88μg/g and 176 μg/g for vancomycin and tobramycin, respectively. Con group (no antibiotic), Van group (vancomycin, 88 μg/g), Tob group (tobramycin 176 μg/g), and Van+Tob group (vancomycin 88μg/g combined with tobramycin 176 μg/g). A 5.0-mm full-thickness standardized mandibular bone defect was performed with a drill in each rat and different antibiotic powders were placed over the bone defect space, respectively. All these animals were sacrificed after 12 weeks post-operation. The mandible bones were harvested for further radiographic and histologic analysis. The bone volume/total volume (BV/TV) ratio, bone volume (BV), and bone fractional area (BFA) in the defect area via micro-computed tomography (μCT scanning) were further analyzed. Then, we performed a histological assessment via hematoxylin and eosin (H&E) and Masson's trichrome staining to analyze bone regeneration and also analyze the number of osteoblasts per filed.

RESULTS

There were no postoperative deaths, signs of vancomycin-related or tobramycin-related toxicity, or signs of systemic illness in any of the four groups. All wounds healed well, and no complications or surgical site infection were observed in all rats. From the μCT scans analyses, there was less bone regeneration in the Van group than in the Con group (BV/TV: F = 64.29, R²  = 0.9602; P = 0.0052; BFA: F = 76.17, R²  = 0.9662, P = 0.0007; BV: F = 194.4, R²  = 0.9865, P = 0.0022). However, when the tobramycin and vancomycin were combined, an increase in bone defect re-ossification was found in the Van+Tob group than in the Van group (BV/TV: F = 64.29, R²  = 0.9602, P = 0.0033; BFA: F = 76.17, R²  = 0.9662, P = 0.0006; BV: F = 194.4, R²  = 0.9865, P = 0.0033). Routine H&E and Masson staining supported the finding of μCT scanning. Quantitative indices confirmed that both the bone regeneration and the number of osteoblasts per filed in the defect area was higher in the Van+Tob group than in the Van group (percentage of bone tissue: F = 145.7, R²  = 0.9562, P = 0.0008; number of osteoblasts per file; F = 67.3, R²  = 0.9098, P < 0.0001). There was no significant difference between the Con group and the Van+Tob group on the number of osteoblasts each field (F = 145.7, R²  = 0.9562, P > 0.9999).

CONCLUSION

For bone defect, local application of vancomycin combined with tobramycin was recommended over vancomycin alone. This animal study presents data suggesting that the use of local delivery of vancomycin and tobramycin should be investigated further in clinical studies.

Nanotechnology as an Anti-Infection Strategy in Periprosthetic Joint Infections (PJI)

Background: Periprosthetic joint infection (PJI) represents a devastating consequence of total joint arthroplasty (TJA) because of its high morbidity and its high impact on patient quality of life. The lack of standardized preventive and treatment strategies is a major challenge for arthroplasty surgeons. The purpose of this article was to explore the potential and future uses of nanotechnology as a tool for the prevention and treatment of PJI. Methods: Multiple review articles from the PubMed, Scopus and Google Scholar databases were reviewed in order to establish the current efficacy of nanotechnology in PJI preventive or therapeutic scenarios. Results: As a prevention tool, anti-biofilm implants equipped with nanoparticles (silver, silk fibroin, poly nanofibers, nanophase selenium) have shown promising antibacterial functionality. As a therapeutic tool, drug-loaded nanomolecules have been created and a wide variety of carrier materials (chitosan, titanium, calcium phosphate) have shown precise drug targeting and efficient control of drug release. Other nanotechnology-based antibiotic carriers (lipid nanoparticles, silica, clay nanotubes), when added to common bone cements, enhanced prolonged drug delivery, making this technology promising for the creation of antibiotic-added cement joint spacers. Conclusion: Although still in its infancy, nanotechnology has the potential to revolutionize prevention and treatment protocols of PJI. Nevertheless, extensive basic science and clinical research will be needed to investigate the potential toxicities of nanoparticles.

Drug Reaction with Eosinophilia and Systemic Syndrome in Revision Arthroplasty for a Prosthetic Knee Infection: A Case Report

CASE

A 51-year-old woman underwent stage I of a 2-stage revision for a prosthetic knee infection with a vancomycin-impregnated articulating cement spacer followed by IV vancomycin and ceftriaxone. Four weeks later, she developed fevers, a diffuse cutaneous eruption, lymphadenopathy, transaminitis, and acute renal tubular necrosis before being diagnosed with drug reaction with eosinophilia and systemic syndrome (DRESS).

CONCLUSION

DRESS is a rare, potentially life-threatening adverse drug reaction with cutaneous manifestations and multiorgan involvement. Although rare, its incidence in orthopaedic patients is likely to increase with the aging population. It must be recognized early to minimize end-stage organ dysfunction and mortality.

Safety and tolerability of liquid amikacin in antibiotic-loaded bone cement - a case series

High-dose liquid antibiotics are uncommon in bone cement. We present a case series of patients in which up to 16 mL of liquid amikacin (250 mg mL-1) was successfully incorporated into bone cement to treat periprosthetic joint infections. We did not observe adverse drug reactions definitively attributed to its use.

Modified Cyclodextrin Microparticles to Improve PMMA Drug Delivery Without Mechanical Loss

Antibiotic-loaded poly(methyl methacrylate) (PMMA) cement is commonly used as a local delivery system to treat and prevent orthopedic infections associated with arthroplasties in load-bearing applications. However, these delivery systems are inefficient as release rate sharply declines to subinhibitory levels. Prior studies have shown that by adding in drug-filled cyclodextrin (CD) microparticles into PMMA cement, a more consistent release is observed, and antibiotic refilling through simulated implantation can be achieved. However, the mechanical strengths of PMMA is reduced. In order to decrease the mechanical loss, modified CD microparticles (PMMA-CD) are synthesized that contain covalently appended PMMA chains. The compressive strengths, handling characteristics, and refilling ability of PMMA cement with PMMA-CD are evaluated. Specifically, up to a 13.7% increase in compressive strength is observed when unmodified CD is substituted with PMMA-CD in PMMA samples with 10 wt% CD microparticles. Additionally, a 13.3% increase in working time, a 7.5% decrease in maximum polymerization temperature, and up to a 32.1% increase in amount of drug refilled are observed with the addition of 10 wt% CD PMMA-CD into PMMA in comparison to plain PMMA without CD microparticles.

In vitro elution characteristics of gentamicin- and teicoplanin-loaded CMW1 and Palacos R bone cement

Purpose

To compare the in vitro elution characteristics of CMW1 and Palacos R bone cement loaded with gentamicin, teicoplanin, or in combination.

Methods

Four bone cement discs were prepared for each cement type. Disc 1 contained no antibiotics; disc 2 contained 0.5 g gentamicin; disc 3 contained 2 g teicoplanin; disc 4 contained 0.5 g gentamicin and 2 g teicoplanin. Elution studies were conducted using a fluorescence polarisation immunoassay technique and performed at intervals of 6 weeks.

Results

For CMW1, gentamicin and teicoplanin elution levels in combination discs were higher than those in the single antibiotic discs (p < 0.001 & p < 0.06). For Palacos R, gentamicin elution levels in combination discs were higher than those in the single antibiotic discs (p < 0.001), but teicoplanin elution levels in combination discs were lesser than that from the single antibiotic discs (p < 0.02). In single and combination discs, gentamicin elution levels in Palacos R were higher than those in CMW1 (p < 0.001 & p < 0.001). Palacos R eluted more teicoplanin than CMW1, except in combined disc with gentamicin, when less teicoplanin was eluted.

Conclusion

Antibiotic elution is higher in Palacos R than CMW1. Antibiotic combination in both cement types has the synergistic effect of increasing antibiotic elution, except for teicoplanin from Palacos R. When high elution of gentamicin is required, Palacos R is preferable. When high elution of teicoplanin is required, Palacos R with only teicoplanin is superior to CMW1.

A meta-analysis of bone cement mediated antibiotic release: Overkill, but a viable approach to eradicate osteomyelitis and other infections tied to open procedures

A number of clinical studies have highlighted the success of antibiotics formulated at concentrations between 0 and 6% w/w into bone cements to address localized infections. Separately, some commercial manufacturers have produced gentamycin-infused bone cement mixtures as a countermeasure to infection. The anecdotal evidence suggests that antibiotic infused cements can help eradicate or delay the onset of infections. Quantifying the functionality of that response is more challenging. We have surveyed the literature to identify studies in which controlled drug release or mechanical behavioral assessments have been conducted on drug-infused cements. The focus here is on vancomycin (VAN) in part due to its higher potency relative to gentamycin and its more common usage for staph infections. Takeaways from the limited pool of research studies indicate that large fractions (>99%) of the infused vancomycin remain sequestered in the cement and aren't bioavailable after solidification. Antibiotic fluence ranged from 1 to 283 μg/cm²hr. The initial strength of the various antibiotic loaded samples as produced were 52-96 MPa. Simulated exposures in a fluid environment by submersion reduced the antibiotic loaded strengths between 3 and 29%. Some strength measurements were noted below the ASTM F451 standard for acrylic bone cement although drug releasing spacers likely have different requirements. The glassy behavior of the cured cement led to both vancomycin and gentamicin having low permeability and a burst response. Smaller drug molecules and more gel-like immobilization matrices with lower glass transition temperatures offer higher potential for larger and more comprehensive drug bioavailability.

Elution Kinetics from Antibiotic-Loaded Calcium Sulfate Beads, Antibiotic-Loaded Polymethacrylate Spacers, and a Powdered Antibiotic Bolus for Surgical Site Infections in a Novel In Vitro Draining Knee Model

Antibiotic-tolerant bacterial biofilms are notorious in causing PJI. Antibiotic loaded calcium sulfate bead (CSB) bone void fillers and PMMA cement and powdered vancomycin (VP) have been used to achieve high local antibiotic concentrations; however, the effect of drainage on concentration is poorly understood. We designed an in vitro flow reactor which provides post-surgical drainage rates after knee revision surgery to determine antibiotic concentration profiles. Tobramycin and vancomycin concentrations were determined using LCMS, zones of inhibition confirmed potency and the area under the concentration-time curve (AUC) at various time points was used to compare applications. Concentrations of antibiotcs from the PMMA and CSB initially increased then decreased before increasing after 2 to 3 h, correlating with decreased drainage, demonstrating that concentration was controlled by both release and flow rates. VP achieved the greatest AUC after 2 h, but rapidly dropped below inhibitory levels. CSB combined with PMMA achieved the greatest AUC after 2 h. The combination of PMMA and CSB may present an effective combination for killing biofilm bacteria; however, cytotoxicity and appropriate antibiotic stewardship should be considered. The model may be useful in comparing antibiotic concentration profiles when varying fluid exchange is important. However, further studies are required to assess its utility for predicting clinical efficacy.

Controlling Antibiotic Release from Polymethylmethacrylate Bone Cement

Bone cement is used as a mortar for securing bone implants, as bone void fillers or as spacers in orthopaedic surgery. Antibiotic-loaded bone cements (ALBCs) have been used to prevent and treat prosthetic joint infections by providing a high antibiotic concentration around the implanted prosthesis. High antibiotic concentrations are, on the other hand, often associated with tissue toxicity. Controlling antibiotic release from ALBCS is key to achieving effective infection control and promoting prosthesis integration with the surrounding bone tissue. However, current ALBCs still need significant improvement in regulating antibiotic release. In this review, we first provide a brief introduction to prosthetic joint infections, and the background concepts of therapeutic efficacy and toxicity in antibiotics. We then review the current state of ALBCs and their release characteristics before focusing on the research and development in controlling the antibiotic release and osteo-conductivity/inductivity. We then conclude by a discussion on the need for better in vitro experiment designs such that the release results can be extrapolated to predict better the local antibiotic concentrations in vivo.

Material modifications enhancing the antibacterial properties of two biodegradable poly(3-hydroxybutyrate) implants

The aim of this study was to evaluate the antimicrobial efficacy of adding a gentamicin palmitate (GP) coating and zirconium dioxide (ZrO₂) to biodegradable poly(3-hydroxybutyrate) (PHB) to reduce biofilm formation. Cylindrical pins with and without a coating were incubated in Müller-Hinton broth inoculated with 2 × 10⁵ colony-forming units (CFU) ml-1 of Staphylococcus aureus for 2 d or 7 d, then sonicated to disrupt biofilms. Pure PHB (PHB + GP) and PHB pins with ZrO₂ added (PHBzr + GP) were coated with GP and compared with PHB pins lacking a coating (PHB). Cells (CFU) were counted to quantify the number of bacteria in the biofilm and a cell proliferation assay was employed to evaluate metabolic activity, and scanning electron microscopy (SEM) was performed to visualize the structure of the biofilm. After 2 d of incubation there were significantly more cells in biofilms on PHB pins than PHB + GP and PHBzr + GP pins (p < 0.0001), and cells in the sonication fluid obtained from GP-coated pins exhibited significantly lower metabolic activity than cells from uncoated PHB pins (p < 0.0001). After 7 d of incubation metabolic activity was lowest for PHBzr + GP, with significant differences between PHB and PHBzr + GP (p = 0.001). SEM revealed more cells attached to the surface, and more structured biofilms, on pins without a coating. Coating pins with GP significantly reduced early biofilm formation on PHB implants. This could lower the potential risk of surgical site infections when using PHB implants. Addition of ZrO₂ might further enhance the antibacterial properties. Such modification of the implant material should therefore be considered when developing new biodegradable PHB implants.

The Role of Chitosan and Graphene Oxide in Bioactive and Antibacterial Properties of Acrylic Bone Cements

Acrylic bone cements (ABC) are widely used in orthopedics for joint fixation, antibiotic release, and bone defect filling, among others. However, most commercially available ABCs exhibit a lack of bioactivity and are susceptible to infection after implantation. These disadvantages generate long-term loosening of the prosthesis, high morbidity, and prolonged and expensive treatments. Due to the great importance of acrylic bone cements in orthopedics, the scientific community has advanced several efforts to develop bioactive ABCs with antibacterial activity through several strategies, including the use of biodegradable materials such as chitosan (CS) and nanostructures such as graphene oxide (GO), with promising results. This paper reviews several studies reporting advantages in bioactivity and antibacterial properties after incorporating CS and GO in bone cements. Detailed information on the possible mechanisms by which these fillers confer bioactive and antibacterial properties to cements, resulting in formulations with great potential for use in orthopedics, are also a focus in the manuscript. To the best of our knowledge, this is the first systematic review that presents the improvement in biological properties with CS and GO addition in cements that we believe will contribute to the biomedical field.

Progress of antibiotic-loaded bone cement in joint arthroplasty

Bone cement, consisting of polymethyl methacrylate, is a bioinert material used for prothesis fixation in joint arthroplasty. To treat orthopedic infections, such as periprosthetic joint infection, antibiotic-loaded bone cement (ALBC) was introduced into clinical practice. Recent studies have revealed the limitations of the antibacterial effect of ALBC. Moreover, with the increase in high infection risk patients and highly resistant microbes, more researches and modification of ALBC are required. This paper reviewed latest findings about ALBC for most popular and destructive pathogens, summarized the influence of antibiotic kind, drug dosage, application method, and environment towards characteristic of ALBC. Subsequently, new cement additives and clinical applications of ALBC in joint arthroplasty were also discussed.

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

BACKGROUND

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

THERAPEUTIC PROCEDURES

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

The Osteogenic Effect of Local Delivery of Vancomycin and Tobramycin on Bone Marrow Stromal Cells

Purpose

Bone tissue infections are a difficult problem in orthopedic surgery. Topical application of vancomycin and tobramycin powder has been proved to significantly reduce infection rates. However, the osteogenic effect of the topical application of these two antibiotics is unclear. In this study, the osteogenic effect of local delivery antibiotics on bone regeneration was investigated in vitro.

Methods

Bone marrow stromal cells (BMSCs) were incubated in the presence of vancomycin (14.28μg/mL), tobramycin (28.57μg/mL), or vancomycin combined with tobramycin (vancomycin 14.28μg/mL and tobramycin 28.57μg/mL). Cell viability, proliferation, and migration were analyzed. The alizarin red staining as well as the alkaline phosphatase staining was investigated. Then, the quantitative real-time (qRT)-PCR of osteogenic mRNA expression levels were also evaluated.

Results

The results showed that vancomycin combined with tobramycin has no adverse effect on the viability and proliferation of BMSCs. The topical application of vancomycin alone may interfere with the bone regenerative processes. However, the tobramycin can promote the osteogenic differentiation of BMSCs and also rescue the osteogenic potential of BMSCs inhibited by vancomycin both in vitro.

Conclusion

From this in vitro study, local application of vancomycin combined with tobramycin does not affect the osteogenic potential of BMSCs.

Prevention of Prosthetic Joint Infection: From Traditional Approaches towards Quality Improvement and Data Mining

A projected increased use of total joint arthroplasties will naturally result in a related increase in the number of prosthetic joint infections (PJIs). Suppression of the local peri-implant immune response counters efforts to eradicate bacteria, allowing the formation of biofilms and compromising preventive measures taken in the operating room. For these reasons, the prevention of PJI should focus concurrently on the following targets: (i) identifying at-risk patients; (ii) reducing “bacterial load” perioperatively; (iii) creating an antibacterial/antibiofilm environment at the site of surgery; and (iv) stimulating the local immune response. Despite considerable recent progress made in experimental and clinical research, a large discrepancy persists between proposed and clinically implemented preventative strategies. The ultimate anti-infective strategy lies in an optimal combination of all preventative approaches into a single “clinical pack”, applied rigorously in all settings involving prosthetic joint implantation. In addition, “anti-infective” implants might be a choice in patients who have an increased risk for PJI. However, further progress in the prevention of PJI is not imaginable without a close commitment to using quality improvement tools in combination with continual data mining, reflecting the efficacy of the preventative strategy in a particular clinical setting.

Research into biocompatibility and cytotoxicity of daptomycin, gentamicin, vancomycin and teicoplanin antibiotics at common doses added to bone cement

OBJECTIVES

This study aims to investigate the biocompatibility and cytotoxicity of daptomycin, gentamicin, vancomycin and teicoplanin at commonly-used dose intervals added to polymethylmethacrylate (PMMA) in vitro.

MATERIALS AND METHODS

This prospective study was conducted between February 2016 and June 2016. Antibiotics were added to PMMA at doses frequently used in clinical practice. The antibiotic doses added were teicoplanin (2 g, 3 g, 4 g), gentamicin (0.5 g, 0.75 g, 1 g), daptomycin (0.5 g.) and vancomycin (2 g, 3 g, 4 g). Standard cement balls (10 mm) were created. Activated L929 mouse fibroblast cell culture was used for incubation. Agar diffusion, Cell Proliferation Kit II (XTT) test and electron microscope investigations were performed to examine biocompatibility and cytotoxicity.

RESULTS

In the cytotoxicity test, teicoplanin at 4 g and daptomycin at 0.5 g doses were observed to cause reductions in viability percentages. The same doses caused 20% and 20-40% cell lysis indices during the agar diffusion test. On electron microscope images, cytotoxic effects in fibroblast cells and involvement with the surface of cement balls were observed.

CONCLUSION

Gentamicin, vancomycin and teicoplanin were observed to be non-toxic and biocompatible at commonly-used dose intervals. Teicoplanin at 4 g and daptomycin at 0.5 g doses were identified to be cytotoxic and not biocompatible. When selecting antibiotics to be added to bone cement, care should be taken that the antibiotic is non-toxic and biocompatible.

Is Treatment of Periprosthetic Joint Infection Improving Over Time?

BACKGROUND

It is unknown whether the outcomes of treatment for periprosthetic joint infection (PJI) are improving with time. This study evaluated trends in PJI treatment outcomes in the hip and knee following 2-stage exchange arthroplasty and irrigation and debridement (I&D) over the last 17 years.

METHODS

We reviewed 550 two-stage exchange arthroplasties and 194 I&Ds between 2000 and 2016 at our institution. Treatment success was defined according to the Delphi consensus criteria and Kaplan-Meier survivorship curves were generated. A multivariate Cox proportional hazards regression model was generated to determine time trends in the outcome of PJI treatment with the year of surgery included as both a continuous covariate (per 1-year increase) and a categorical covariate (2000-2010 or 2011-2016).

RESULTS

The survivorship of I&D, 2-stage revision, and the total combined cohort were comparable between 2000-2010 and 2011-2016 groups. Multivariate Cox regression analysis showed that the year of surgery was not associated with treatment failure following an I&D or 2-stage exchange arthroplasty, and neither did it increase the risk of non-reimplantation. When year of surgery was considered as a categorical variable, there remained no significant difference in treatment failure following an I&D or 2-stage exchange arthroplasty between the 2000-2010 cohort and 2011-2016 cohort.

CONCLUSION

Despite the increasing clinical focus, research advances, and growing literature relating to PJI, we were unable to detect any substantial improvement in the treatment success rates of PJI at our institution over the 17 years examined in this study. Novel treatments and techniques are certainly needed as current and prior strategies remain far from optimal.