Objectives. Vancomycin and fosfomycin are antibiotics commonly used to treat methicillin-resistant Staphylococcus aureus (MRSA) infection. This study compares the in vitro inhibitory effects against MRSA of articulating cement spacers impregnated with either vancomycin or fosfomycin. Methods. Vancomycin-impregnated articulating cement spacers and fosfomycin-impregnated articulating cement spacers were immersed in sterile phosphate-buffered saline (PBS) solutions and then incubated. Samples were collected for bioactivity evaluation. The aliquots were tested for MRSA inhibition with the disc diffusion method, and the inhibition zone diameters were measured. The inhibition zone differences were evaluated using the Wilcoxon Rank Sum Test. Results. The vancomycin group had significantly larger inhibition zones than the fosfomycin group from day three through to completion of the fourth week of incubation (p < 0.001). The vancomycin group exhibited a MRSA inhibition zone up to four weeks but the fosfomycin group showed an inhibition zone for only three days and after that did not show the the potential to inhibit MRSA. Conclusion. This in vitro study found that the inhibitory effect of vancomycin-impregnated articulating cement spacers against MRSA outperformed fosfomycin-impregnated articulating cement spacers. Further comparing our results to other published reports suggests there might be a limitation of the disc diffusion bioassay to show a large inhibitory zone in a high concentration of a highly soluble antibiotic. Cite this article: V. Yuenyongviwat, N. Ingviya, P. Pathaburee, B. Tangtrakulwanich. Inhibitory effects of vancomycin and fosfomycin on methicillin-resistant Staphylococcus aureus from antibiotic-impregnated articulating cement spacers. Bone Joint Res 2017;6:132–136. DOI: 10.1302/2046-3758.63.2000639

Objectives. The optimal protocol for antibiotic loading in the articulating cement spacers for the treatment of prosthetic joint infection (PJI) remains controversial. The objective of the present study was to investigate the effectiveness of articulating cement spacers loaded with a new combination of antibiotics. Methods. A retrospective cohort study involving 114 PJI cases treated with implantation of an articulating cement spacer between 2005 and 2016 was performed. The treatment outcomes of the conventional protocol (i.e. gentamicin and vancomycin (GV protocol)) were compared with those reported using the sophisticated antibiotic-loading protocol (i.e. vancomycin, meropenem, and amphotericin (VMA protocol)). Results. There were 62 and 52 PJI cases treated with the GV and VMA protocols, respectively. Antimicrobial susceptibility testing revealed that 22/78 of all isolates (28.2%) in this series were resistant to gentamicin, whereas there were no vancomycin-, meropenem-, or amphotericin-resistant strains. The overall infection recurrence rates were 17.7% (11/62) and 1.9% (1/52), respectively (p = 0.006). In patients with a negative preoperative culture, there was no infection recurrence reported in the VMA cohort (0/45 (0%) vs 10/54 (18.5%) in the GV cohort; p = 0.002). Multivariate analysis indicated that the VMA protocol correlated with a decreased risk of infection recurrence compared with the GV protocol (p = 0.025). Conclusion. The sophisticated VMA protocol for the loading of antibiotics in articulating cement spacers, as part of a two-stage exchange, was associated with a reduced rate of infection recurrence. This proposed protocol appears to be safe and effective, especially in patients with negative culture results prior to the first-stage operation. Cite this article: Bone Joint Res 2019;8:526–534

Objectives. The optimal protocol for antibiotic loading in the articulating cement spacers for the treatment of prosthetic joint infection (PJI) remains controversial. The objective of the present study was to investigate the effectiveness of articulating cement spacers loaded with a new combination of antibiotics. Methods. A retrospective cohort study involving 114 PJI cases treated with implantation of an articulating cement spacer between 2005 and 2016 was performed. The treatment outcomes of the conventional protocol (i.e. gentamicin and vancomycin (GV protocol)) were compared with those reported using the sophisticated antibiotic-loading protocol (i.e. vancomycin, meropenem, and amphotericin (VMA protocol)). Results. There were 62 and 52 PJI cases treated with the GV and VMA protocols, respectively. Antimicrobial susceptibility testing revealed that 22/78 of all isolates (28.2%) in this series were resistant to gentamicin, whereas there were no vancomycin-, meropenem-, or amphotericin-resistant strains. The overall infection recurrence rates were 17.7% (11/62) and 1.9% (1/52), respectively (p = 0.006). In patients with a negative preoperative culture, there was no infection recurrence reported in the VMA cohort (0/45 (0%) vs 10/54 (18.5%) in the GV cohort; p = 0.002). Multivariate analysis indicated that the VMA protocol correlated with a decreased risk of infection recurrence compared with the GV protocol (p = 0.025). Conclusion. The sophisticated VMA protocol for the loading of antibiotics in articulating cement spacers, as part of a two-stage exchange, was associated with a reduced rate of infection recurrence. This proposed protocol appears to be safe and effective, especially in patients with negative culture results prior to the first-stage operation. Cite this article: Bone Joint Res 2019;8:526–534

Objectives. Preclinical data showed poly(methyl methacrylate) (PMMA) loaded with microsilver to be effective against a variety of bacteria. The purpose of this study was to assess patient safety of PMMA spacers with microsilver in prosthetic hip infections in a prospective cohort study. Methods. A total of 12 patients with prosthetic hip infections were included for a three-stage revision procedure. All patients received either a gentamicin-PMMA spacer (80 g to 160 g PMMA depending on hip joint dimension) with additional loading of 1% (w/w) of microsilver (0.8 g to 1.6 g per spacer) at surgery 1 followed by a gentamicin-PMMA spacer without microsilver at surgery 2 or vice versa. Implantation of the revision prosthesis was carried out at surgery 3. Results. In total, 11 of the 12 patients completed the study. No argyria or considerable differences in laboratory parameters were detected. Silver blood concentrations were below or around the detection limit of 1 ppb in ten of the 11 patients. A maximum of 5.6 ppb at 48 hours after implantation of the silver spacer, which is below the recommended maximum level of 10 ppb, was found in one patient. No silver was detected in the urine. Drainage fluids showed concentrations between 16.1 ppb and 23.3 ppb at 12 hours after implantation of the silver spacers, and between 16.8 ppb to 25.1 ppb at 48 hours after implantation. Pathohistological assessment of the periprosthetic membrane did not reveal any differences between the two groups. Conclusion. Microsilver-loaded gentamicin-PMMA spacers showed good biocompatibility and the broad antimicrobial activity warrants further clinical research to assess its effectivity in reducing infection rates in prosthetic joint infection. Cite this article: V. Alt, M. Rupp, K. Lemberger, T. Bechert, T. Konradt, P. Steinrücke, R. Schnettler, S. Söder, R. Ascherl. Safety assessment of microsilver-loaded poly(methyl methacrylate) (PMMA) cement spacers in patients with prosthetic hip infections: Results of a prospective cohort study. Bone Joint Res 2019;8:387–396. DOI: 10.1302/2046-3758.88.BJR-2018-0270.R1

Aims

This study was designed to characterize the recurrence incidence and risk factors of antibiotic-loaded cement spacer (ALCS) for definitive bone defect treatment in limb osteomyelitis.

Aims. To explore the clinical efficacy of using two different types of articulating spacers in two-stage revision for chronic knee periprosthetic joint infection (kPJI). Methods. A retrospective cohort study of 50 chronic kPJI patients treated with two types of articulating spacers between January 2014 and March 2022 was conducted. The clinical outcomes and functional status of the different articulating spacers were compared. Overall, 17 patients were treated with prosthetic spacers (prosthetic group (PG)), and 33 patients were treated with cement spacers (cement group (CG)). The CG had a longer mean follow-up period (46.67 months (SD 26.61)) than the PG (24.82 months (SD 16.46); p = 0.001). Results. Infection was eradicated in 45 patients overall (90%). The PG had a better knee range of motion (ROM) and Knee Society Score (KSS) after the first-stage revision (p = 0.004; p = 0.002), while both groups had similar ROMs and KSSs at the last follow-up (p = 0.136; p = 0.895). The KSS in the CG was significantly better at the last follow-up (p = 0.013), while a larger percentage (10 in 17, 58.82%) of patients in the PG chose to retain the spacer (p = 0.008). Conclusion. Prosthetic spacers and cement spacers are both effective at treating chronic kPJI because they encourage infection control, and the former improved knee function status between stages. For some patients, prosthetic spacers may not require reimplantation. Cite this article: Bone Joint Res 2024;13(6):306–314

Aims. Treatment outcomes for methicillin-resistant Staphylococcus aureus (MRSA) periprosthetic joint infection (PJI) using systemic vancomycin and antibacterial cement spacers during two-stage revision arthroplasty remain unsatisfactory. This study explored the efficacy and safety of intra-articular vancomycin injections for PJI control after debridement and cement spacer implantation in a rat model. Methods. Total knee arthroplasty (TKA), MRSA inoculation, debridement, and vancomycin-spacer implantation were performed successively in rats to mimic first-stage PJI during the two-stage revision arthroplasty procedure. Vancomycin was administered intraperitoneally or intra-articularly for two weeks to control the infection after debridement and spacer implantation. Results. Rats receiving intra-articular vancomycin showed the best outcomes among the four treatment groups, with negative bacterial cultures, increased weight gain, increased capacity for weightbearing activities, increased residual bone volume preservation, and reduced inflammatory reactions in the joint tissues, indicating MRSA eradication in the knee. The vancomycin-spacer and/or systemic vancomycin failed to eliminate the MRSA infections following a two-week antibiotic course. Serum vancomycin levels did not reach nephrotoxic levels in any group. Mild renal histopathological changes, without changes in serum creatinine levels, were observed in the intraperitoneal vancomycin group compared with the intra-articular vancomycin group, but no changes in hepatic structure or serum alanine aminotransferase or aspartate aminotransferase levels were observed. No local complications were observed, such as sinus tract or non-healing surgical incisions. Conclusion. Intra-articular vancomycin injection was effective and safe for PJI control following debridement and spacer implantation in a rat model during two-stage revision arthroplasties, with better outcomes than systemic vancomycin administration. Cite this article: Bone Joint Res 2022;11(6):371–385

Introduction. The surgical management of late PJI was usually done in two stages with the placement of a temporary cement spacer. The development of one-stage surgical care raises questions about the two-stage strategy. The objectives of this study are to identify the complications related to the presence of the cement spacer within a two-stage strategy. The septic recurrence rate is also evaluated after a minimum follow-up of two years. Material and methods. Medical files of 208 patients (101 knees and 107 hips) who underwent a two-stage revision for late PJI prosthesis infection were retrospectively reviewed. Antibiotic loaded articulated homemade cement spacers were used. Second stage was usually planned on average 4 to 6 weeks after the first stage. Patients were allowed to walk without loading. The success rate was defined as the absence of septic recurrence after a minimum follow-up of two years. Descriptive statistics and uni- and multivariate analysis were conducted. Results. The spacers were left in place for an average of 42 days for the knees and 30 days for the hips. Six patients (3%) died before performing the second stage. Hip spacers were associated with 8 fractures for only one observed in the knee (4%). Spacer dislocation (11%) was observed in 23 cases (13 for the hip and 10 for the knee respectively). Treatment failure with recurrence of the infection within 2 years was observed in 26 patients (12%). Resistance to the antibiotic present in the cement was found in one third of infectious failures. The presence of a prior cemented prosthesis was significantly associated with the presence of a germ resistant to gentamicin and the persistence of the germ at the second stage. However, it was not associated with failure at two years. Discussion. the two-stage management of PJI is associated with a non-negligible mortality rate before the second stage, rarely reported in studies. The presence of an initially cemented prosthesis is associated with the presence of germs resistant to the antibiotic contained in the cement and exposes to the persistence of the resistant germ at the second stage. Spacer fractures are observed more at the hip, but less frequently than in previous reports, while dislocations are observed at both the hip and the knee, particularly due to loss of tibial fixation in this area. These observations are all arguments for further consideration of revision surgery in 1 stage

Aim. The aim of this study is to evaluate if the gentamycin elution from bone cement is influenced by the timing of application of the antibiotic powder. Method. This was an experimental in vitro study that compared the elution properties of different formulation of gentamycin from a commercially available hip, knee and shoulder cement spacers. Four different experimental models were prepared. Five different spacers were prepared for each experimental mode and for each joint. We compared four different formulation of cement spacers: spacer #1, in which the spacer was prepared with a premixed bone-cement antibiotic mixture; spacer #2, in which the spacer was prepared by adding antibiotic powder to the bone cement at the time of spacer preparation; spacer #3, in which the spacer was prepared as spacer #2 but was stored for two months before starting the experiment; spacer #4, in addition to the gentamycin, other two antibiotics (tobramycin and vancomycin) were added to the bone cement. Gentamycin concentration was documented at seven intervals of time: T0 = 0h, T1 = 1h, T2 = 24h, T3 = 1W, T4 = 2W, T5 = 1M, T6 = 3M and T7 = 6M. The gentamycin elution at each interval of time was evaluated by using a T-student test. Results. Spacer #2, in which the gentamycin powder was added to the bone cement at the time of spacer preparation showed the higher gentamycin elution at each interval of time observed. In addition, Spacer #1, in which gentamycin powder was premixed with the bone cement showed a higher gentamycin elution when compared with spacer #3, in which the spacers were stored for two months to simulate the preformed spacers. Lastly, the addition of different antibiotic to the bone cement increases the gentamycin elution from the spacers (as demonstrated by spacer #4 model). Conclusions. a higher gentamycin elution was observed if spacer was prepared at the time of surgery when compared with preformed spacer. Lastly, our study confirmed the synergistic effect of adding one or more antibiotics with the aims to increase gentamycin elution

Introduction. Periprosthetic joint infection (PJI) is a serious problem and requires great effort and cost for its treatment. Treatment options may vary from resection arthroplasty, retention of prosthesis with debridement, one stage revision and two stage revision with handmade antibiotic impregnated cement spacer or with prefabricated antibiotic loaded cement spacer. Two stage revision remains the gold standard for the treatment of periprosthetic joint infection after Total Hip Arthroplasty (THA). This study was aimed to find the efficacy and cost effectiveness of handmade antibiotic impregnated articulating cement spacer over commercially available prefabricated antibiotic loaded cement spacer for the treatment of deep PJI of hip prosthesis and to evaluate its functional outcome. Material and methods. A total of 23 PJI patients were enrolled in this prospective cohort study. In the two stages of revision, the first stage consisted of thorough debridement, implant removal and implantation of handmade articulating antibiotic impregnated cement spacer. The second stage surgery consisted of removal of cement spacer, thorough debridement and implantation of new prosthesis. All patients were followed for a period of 24 months. Results. A total of 23 patients (15 males and 8 females) underwent two stage revision arthroplasty for chronic periprosthetic joint infection. The mean age of the patient was 57 years. The handmade antibiotic impregnated cement spacer was retained for 16– 20 weeks. Common organism observed was coagulase negative staphylococci followed by Staphylococcus aureus. After an average follow up of 2 years, 20 patients with PJI remained clinically free of infection. In 2 patients there was recurrence of infection. Conclusion. We conclude that two stage revision by hand made cement spacer is successful in eradication of infection with satisfactory functional outcome. Furthermore, these handmade cement spacer are cost effective and their efficacy may be comparable to commercially available prefabricated spacer

Aim. Studies have shown that retention of antibiotic cement spacer in selected elderly patients with low functional demand represents a viable option for periprosthetic joint infections (PJI) treatment. 1,2. . The aim of this study is to compare the efficacy in infection treating among modular taylored preformed and hand-made antibiotic spacers. Our hypothesis is that modular tailored preformed spacer provides a better rate of infection resolution, better radiological and functional outcomes compared to hand-made spacers. Materials and methods. We identified 48 patients treated with antibiotic cement spacer for shoulder chronic infection between 2015 and 2021 in our institution; (13 hand-made spacers and 35 modular tailored preformed spacers). We collected data about comorbidities, associated microorganism, infection resolution, clinical and radiographic evaluation. Results. The mean age at surgery was 63.2 years, (45.8% female − 54.2% male), mean BMI 28.3. The mean time of infection diagnosis after first surgery was 30 months; (31.2% infection after ORIF in proximal humeral fractures, 68.8% PJI after shoulder arthroplasty). The main pathogens were Propionibacterium Acnes (37.5%), Staphylococcus Epidermidis (29.2%), Staphylococcus Aureus (16.7%), negative intraoperative coltures (14.6%), Enterococcus (4.17%), Pseudomonas Aeruginosa (4.17%). The mean time of antibiotic spacer retention was 18 months: 23 patients (47.9%) underwent second stage surgery for prosthesis implantation; 2 removed the spacer because of spacer dislocation, 2 died during follow up; while 21 patients still hold the antibiotic spacer (17 patients in treatment with prefabricated spacers and 4 with self-constructed spacer). The mean value for clinical assessment for patients with modular tailored preformed spacer were: Constant Score 34 – QuickDASH 40 – SST 33 – ASES Score 66 – VAS 2. Patients treated with hand-made spacer registered the following scores: Constant Score 20 – QuickDASH 51 – SST 25 – ASES Score 38 – VAS 6. Two patients presented fracture of the spacer (one hand-made spacer and one tailored preformed). Conclusions. According to our data patients treated with modular tailored preformed antibiotic spacer show better functional outcomes. Patients are more likely to retain the spacer as a permanent implant, avoiding the risks of a second stage surgery in those low-demanding patients, achieving a reasonable satisfying quality of shoulder motion without pain

Polymethylmethacrylate (PMMA) bone cement is strong in compression, however it tends to fail under torsion. Sufficient pressurisation and subsequent interdigitation between cement and bone are critical for the mechanical interlock of cemented orthopaedic implants, and an irregular surface on the acetabular cup is necessary for reasonable fixation at the cup-cement interface. There is limited literature investigating discrepancies in the failure mechanisms of cemented all-polyethylene acetabular cups with and without cement spacers, under torsional loading. In vitro experimental comparison of three groups of polyethylene acetabular prosthesis (PAP) cemented into prepared sawbone hemipelvises:. * PAP without PMMA spacers maintaining an equal cement mantle circumferentially. (Group 1 n=3). * PAP without PMMA spacers cemented deliberately ‘bottoming-out’ the implant within the acetabulum. (Group 2 n=3). * PAP with PMMA spacers. (Group 3 n=3). The constructs were tested to torstional failure on a custom designed setup, and statistical analysis done by a one-way ANOVA and Tukey-Welsh test. Group 3 demonstrated superior torsional resistance with a statistically significant torque of 145Nm (SD±12Nm) at failure, compared to group 2 (109Nm, SD±7Nm) and group 1 (99Nm, SD±8Nm). Group 3 experienced failure predominantly at the bone-cement interface, in contrast, Groups 1 and 2 exhibited failure predominantly at the cup-cement interface. There was no significant difference between Group 1 and 2. Qualitative analysis of the failure mode indicates the efficient redistribution of stress throughout the cement mantle, consistent with the greater uniformity of cement. PMMA spacers increase the resistance to torsional failure at the implant-cement interface. Acetabular components without spacers (Groups 1 and 2) failed at the implant-cement interface before the cement-bone interface, at a statistically significantly lower level of torque to failure. Although the PMMA spacers may reduce cement interdigitation at the cement-bone interface the torsional forces required to fail are likely supraphysiological

Treatment of large bone defects represents a great challenge for orthopedic surgeons. The main causes are congenital abnormalities, traumas, osteomyelitis and bone resection due to cancer. Each surgical method for bone reconstruction leads its own burden of complications. The gold standard is considered the autologous bone graft, either of cancellous or cortical origin, but due to graft resorption and a limitation for large defect, allograft techniques have been identified. In the bone defect, these include the placement of cadaver bone or cement spacer to create the ‘Biological Chamber’ to restore bone regeneration, according to the Masquelet technique. We report eight patients, with large bone defect (for various etiologies and with an average size defect of 13.3 cm) in the lower and upper limbs, who underwent surgery at our Traumatology Department, between January 2019 and October 2020. Three patients were treated with both cortical and cancellous autologous bone grafts, while five received cortical or cement spacer allografts from donors. They underwent pre and postoperative radiographs and complete osseointegration was observed in all patients already undergoing monthly radiographic checks, with a restoration of length and range of motion. In our study, both the two stage-Masquelet and the cortical bone graft from a cadaver donor proved to be valid techniques in patients with very extensive defects to reconstruct the defect, restore the length, minimize implant left in situ and achieve complete functional recovery

Introduction. Infection remains as one of the major challenges of total joint surgery. One-stage irrigation, debridement and reimplantation, or two-stage revision surgery with a temporary implantation of antibiotic eluting bone cement spacer followed by reimplantation are two methods often used to treat infected patients with mixed outcomes. Like bone cement, ultra-high molecular weight polyethylene (UHMWPE) can also be used as a carrier for antibiotics. Recently, we demonstrated that vancomycin and rifampin can be delivered from UHMWPE implants at therapeutic levels to eradicate Staphylococcus aureus biofilm in a lupine animal model. There are regulatory challenges in translating these types of combination devices to clinical use. Last year, at this meeting, we presented the preliminary pre-clinical testing for a temporary UHMWPE spacer containing gentamicin sulfate as a first step towards clinical use. Since then, we carried out a survey among the Knee Society membership about their preference for spacer use in two-stage revision surgery and found that 43% prefer to use a CoCr femoral component on an all-poly cemented tibial insert, 22% prefer bone cement spacers molded in the OR, 20% prefer static bone cement spacers, and 14% prefer pre-formed bone cement spacers. We modified our implant design based on the majority's preference for a total knee system, rather than bone cement spacers, in the temporary two-stage approach. In this study, we explored the effect of gentamicin sulfate (GS) elution from UHMWPE/GS tibial inserts on bacterial colonization on CoCr surfaces. Methods. We characterized the gentamicin sulfate (GS) particles with scanning electron microscopy (SEM). We molded UHMWPE/GS powder blends and characterized the morphology using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). We submerged samples of molded UHMWPE/GS in buffered phosphate solution (PBS) at 37°C and quantified the extent of GS elution into PBS with a method described by Gubernator et al. using o-phthaladehyde (OPA) [1]. Under basic conditions, OPA reacts with primary amino groups to form fluorescent complexes. Since gentamicin is the only source of such amino acids in our elution samples, the number of fluorescent complexes formed is directly proportional to the amount of gentamicin in the sample. Using this method, we could quantify gentamicin elution by measuring sample fluorescence post OPA-reaction. We used a plate reader to excite the fluorescent complexes formed in the OPA reaction and measured the resulting emission at wavelengths of 340 nm and 455 nm, respectively. We also quantified the effect of the standard cleaning protocol (heated sonication in alkaline water and alcohol) used to clean UHMWPE implants on subsequent GS elution from UHMWPE/GS samples using the OPA method. We used agar diffusion tests to characterize antibacterial properties of UHMWPE/GS samples after cleaning. For these tests, we collected eluents collected from UHMWPE/GS and gentamicin-impregnated bone cement (BC/GS) following 1, 2, 3, and 4 weeks of elution, and tested against S. aureus (ATCC 12600). We used the “daughter cells” method developed by Bechert et al. to assess anticolonizing properties of UHMWPE/GS [2,3]. We also characterized the colonization of bacteria on CoCr surfaces in the presence of GS eluting from UHMWPE/GS test samples. For this we modified a Pin-on-Disc (PoD) wear tester: An UHMWPE/GS pin and UHMWPE pin (control) articulated against an implant-finish CoCr disc with Tryptic Soy Broth containing S. Aureus as the lubricant. After 18 hrs, we rinsed the articular surfaces of the pin and disc and stamped them onto Agar gel to transfer any adherent bacteria. We incubated the Agar plate overnight such that adherent bacteria proliferated and became visible. Results. SEM characterized the GS particles as hollow spheres (Fig 1a). These formed small groups of agglomerated domains at the virgin resin boundaries of UHMWPE after molding (Fig 1b). Sulfur signature from the EDS analysis identified the agglomerated domains as GS particles (Fig 2). Elution of GS started with an initial burst and was followed by steady elution up to 12 weeks (Fig 3). Cleaning reduced the initial burst GS elution; and the elution remained unchanged after 2 days (Fig 4). The agar diffusion test showed simmilar inhibition zones for the eluents collected from UHMWPE/GS and BC/GS, suggesting that these samples yield similar antibacterial activity against S. aureus (Fig 5). UHMWPE/GS demonstrated pronounced anticolonizing properties, effectively mitigating the proliferation of S. aureus “daughter” cells. Anticolonizing activity of Palacos R+G was not significantly different when compared with UHMWPE/GS. The PoD test showed little-to-no colonization of CoCr surfaces in the presence of UHMWPE/GS pins, indicative of excellent antibacterial properties of UHMWPE/GS against S. aureus. Conclusion. SEM and EDS has allowed us to visualize domains of gentamicin sulfate particles in UHMWPE. Our OPA method has greater precision than traditional agar-well diffusion methods of measuring gentamicin concentration and showed that gentamicin sulfate-loaded UHMWPE elutes at the same rate as Palacos R+G. Pin-on-disc experiments and the daughter cell method both confirmed that these two materials have similar anticolonization abilities. We also found that using the standard cleaning protocol for UHMWPE orthopedic implants decreased the burst of gentamicin eluting from UHMWPE, but after 2 days, it had no effect compared to uncleaned UHMWPE/GS. Finally, we found that UHMWPE/GS can reduce the colonization of bacteria on CoCr. UHMWPE/GS continues to be a promising material for treating PJI. For figures, tables, or references, please contact authors directly

At first-stage revision surgery for infection of total knee arthroplasties, antibiotic-impregnated cement spacers are frequently implanted. Two types of cement spacers are commonly used, “static” and “articulating” cement spacers. Advocates of cement spacers state that they deliver high doses of antibiotics locally, increase patient comfort, allow mobility and provide joint stability. They also minimize contracture of collateral ligaments, thereby facilitating re-implantation of a definitive prosthesis at a later stage. The use of these cement spacers, however, are not without significant complications, including patella tendon injuries. We describe a series of three patients who sustained patella tendon injuries in infected total knee arthroplasties following the use of a static cement spacer at first-stage knee revision. The patella tendon injuries resulted in significant compromise to wound healing and knee stability requiring multiple surgeries. The mid-term function was poor with an Oxford score at 24 months ranging from 12–20. Based on our experience, we advise caution in the use of static cement spacer blocks. If they are to be used, we recommend that they should be keyed in the bone to prevent patella tendon injuries

Aims. In contrast to operations performed for other fractures, there is a high incidence rate of surgical site infection (SSI) post-open reduction and internal fixation (ORIF) done for tibial plateau fractures (TPFs). This study investigates the effect of induced membrane technique combined with internal fixation for managing SSI in TPF patients who underwent ORIF. Methods. From April 2013 to May 2017, 46 consecutive patients with SSI post-ORIF for TPFs were managed in our centre with an induced membrane technique. Of these, 35 patients were included for this study, with data analyzed in a retrospective manner. Results. All participants were monitored for a mean of 36 months (24 to 62). None were subjected to amputations. A total of 21 patients underwent two-stage surgeries (Group A), with 14 patients who did not receive second-stage surgery (Group B). Group A did not experience infection recurrence, and no implant or cement spacer loosening was noted in Group B for at least 24 months of follow-up. No significant difference was noted in the Lower Extremity Functional Scale (LEFS) and the Hospital for Special Surgery Knee Score (HSS) between the two groups. The clinical healing time was significantly shorter in Group B (p＜0.001). Those with longer duration of infection had poorer functional status (p＜0.001). Conclusion. Management of SSI post-ORIF for TPF with induced membrane technique combined with internal fixation represents a feasible mode of treatment with satisfactory outcomes in terms of infection control and functional recovery. Cite this article: Bone Joint Res 2021;10(7):380–387

BACKGROUND. High-dose antibiotic cement spacers are commonly used to treat prosthetic joint infections following knee arthroplasties. Several clinical studies have shown a high success rate with antibiotic cement spacers, however there is little data on the systemic complications of high-dose antibiotic spacers, particularly acute kidney injury (AKI). This study aims to determine the incidence of AKI and identify risk factors predisposing patients undergoing staged revision arthroplasty with antibiotic cement spacers. METHODS. A single-institution, retrospective review was used to collect and analyze clinical and demographic data for patients who underwent staged revision total knee arthroplasty with placement of an antibiotic-impregnated cement spacer from 2006 to 2016. A search was made through specific procedure (DRG) and diagnostic (CD) codes. Baseline descriptive data were collected for all patients including age, sex, medical comorbidities, type and quantity of antibiotics used in the cement spacer, pre- and postoperative hemoglobin (Hg), BMI, smoking status, peak creatinine levels, and random vancomycin levels. Acute kidney injury was defined as a more than 50% rise in serum creatinine from a preoperative baseline within 90 days postoperatively. RESULTS. A total of 54 staged revision TKA surgeries performed by 5 different surgeons between 2006 and 2016. The total incidence of AKI was 31% (n=17). There was a significant positive association between change in creatinine level and use of oral/intravenous antibiotics (p=0.03, Spearman's rho=0.33) and a significant positive association between AKI and the use of tobramycin cement (p=0.01, Spearman's rho=0.38). Factors that were not significantly associated with AKI include presence of preexisting hypertension (p = 0.26), hyperlipidemia (p = 0.83), coronary artery disease (p = 0.86), chronic kidney disease (p=0.56), and smoking status (p=.35). There was a trend towards increased risk of AKI in patients with diabetes mellitus (p= 0.12), however this was not significant. CONCLUSION. In single staged revision knee arthroplasty there is a significant association between acute kidney injury and type of oral/intravenous antibiotic used in the treatment. Both the use of intravenous vancomycin and tobramycin cement are independently associated with higher rates of AKI. Preexisting medical comorbidities are not independent risk factors for development of AKI. Serum creatinine and measurement of serum aminoglycoside and vancomycin levels should be performed after placement of an aminoglycoside-containing antibiotic cement spacer in a staged revision arthroplasty

Recent researches indicate that both M1 and M2 macrophages play vital roles in tissue repair and foreign body reaction processes. In this study, we investigated the dynamics of M1 macrophages in the induced membrane using a mouse femur critical-sized bone defect model. The Masquelet method (M) and control (C) groups were established using C57BL/6J male mice (n=24). A 3mm-bone defect was created in the right femoral diaphysis followed by a Kirschner wire fixation, and a cement spacer was inserted into the defect in group M. In group C, the bone defect was left uninserted. Tissues around the defect were harvested at 1, 2, 4, and 6 weeks after surgery (n=3 in each group at each time point). Following Hematoxylin and eosin (HE) staining, immunohistochemical staining (IHC) was used to evaluate the CD68 expression as a marker of M1 macrophage. Iron staining was performed additionally to distinguish them from hemosiderin-phagocytosed macrophages. In group M, HE staining revealed a hematoma-like structure, and CD68-positive cells were observed between the spacer and fibroblast layer at 1 week. The number of CD68-positive cells decreased at 2 weeks, while they were observed around the new bone at 4 and 6 weeks. In group C, fibroblast infiltration and fewer CD68-positive cells were observed in the bone defect without hematoma-like structure until 2 weeks, and no CD68-positive cells were observed at 4 and 6 weeks. Iron staining showed hemosiderin deposition in the surrounding area of the new bone in both groups at 4 and 6 weeks. The location of hemosiderin deposition was different from that of macrophage aggregation. This study suggests that M1 macrophage aggregation is involved in the formation of induced membranes and osteogenesis and may be facilitated by the presence of spacers

Treatment of bone infection often includes a burdensome two-stage revision. After debridement, contaminated implants are removed and replaced with a non-absorbable cement spacer loaded with antibiotics. Weeks later, the spacer is exchanged with a bone graft aiding bone healing. However, even with this two-stage approach infection persists. In this study, we investigated whether a novel 3D-printed, antibiotic-loaded, osteoinductive calcium phosphate scaffold (CPS) is effective in single-stage revision of an infected non-union with segmental bone loss in rabbits. A 5 mm defect was created in the radius of female New Zealand White rabbits. The bone fragment was replaced, stabilized with cerclage wire and inoculated with Staphylococcus aureus (MSSA). After 4 weeks, the infected bone fragment was removed, the site debrided and a spacer implanted. Depending on group allocation, rabbits received: 1) PMMA spacer with gentamycin; 2) CPS loaded with rifampin and vancomycin and 3) Non-loaded CPS. These groups received systemic cefazolin for 4 weeks after revision. Group 4 received a loaded CPS without any adjunctive systemic therapy (n=12 group1-3, n=11 group 4). All animals were euthanized 8 weeks after revision and assessed by quantitative bacteriology or histology. Covariance analysis (ANCOVA) and multiple regression were performed. All animals were culture positive at revision surgery. Half of the animals in all groups had eliminated the infection by end of study. In a historical control group with empty defect and no systemic antibiotic treatment, all animals were infected at euthanasia. There was no significant difference in CFU counts between groups at euthanasia. Our results show that treating an osteomyelitis with segmental bone loss either with CPS or PMMA has a similar cure rate of infection. However, by not requiring a second surgery, the use of CPS may offer advantages over non-resorbable equivalents such as PMMA

Background. Vancomycin and fosfomycin are antibiotic commonly used in Methicillin-resistant Staphylococcus aureus (MRSA) infection. This study compares the efficacy of articulating cement spacer implegnated with vancomycin and articulating cement spacer implegnated with fosfomycin to inhibit MRSA. Methods. Vancomycin implegnated articulating cement spacers and Fosfomycin implegnated articulating cement spacers were immersed in sterile phosphate buffered saline(PBS) and then incubated at 37 C. The samples were collected and change daily. Aliquots were tested for MRSA inhibition by disc diffusion method. The inhibition zones diameters were measured. Results. Vancomycin group showed an MRSA inhibition zone up to four weeks. However, Fosfomycin group showed inhibition zone in day 3 in some samples but after that no sample had the potential to inhibit MRSA. Conclusion. In this experiment. Vancomycin impregnated articulating cement spacers showed longer efficacy to inhibit MRSA when compared to Fosfomycin