We propose a state-of-the-art temporary spacer, consisting of a cobalt-chrome (CoCr) femoral component and a gentamicin-eluting ultra-high molecular weight polyethylene (UHMWPE) tibial insert, which can provide therapeutic delivery of gentamicin, while retaining excellent mechanical properties. The proposed implant is designed to replace conventional spacers made from bone cement. Gentamicin-loaded UHMWPE was prepared using phase-separated compression moulding, and its drug elution kinetics, antibacterial, mechanical, and wear properties were compared with those of conventional gentamicin-loaded bone cement.Aims
Methods
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 successfully 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 in to clinical use. One approach is to follow a stepwise strategy, with the first step of seeking clearance for a temporary UHMWPE spacer containing gentamicin sulfate. In this study, we explored the effect of gentamicin sulfate (GS) content in UHMWPE on GS elution rate and antimicrobial activity against methicillin-sensitive S. aureus(MSSA). We also assessed the effect of spacer fabrication on the activity of gentamicin sulfate. We prepared and consolidated UHMWPE/GS blends in varying concentrations. After consolidation, we fabricated test samples with surface area (350mm2) to volume (300mm3) ratio of 1.2 for elution in 1.5ml phosphate buffered saline at body temperature for up to six months and quantified eluted GS content using liquid chromatography – mass spectrometry (LCMS). We assessed the antibacterial activity of the obtained samples in vitro against various concentrations of MSSA (103–106 CFU/ml). Furthermore, we quantified the probability of bacterial colonization of UHMWPE impregnated with GS compared to GS containing bone cement. We assessed any detectable changes in activity of eluted GS caused by spacer fabrication by screening m/z peaks of GS isomers in mass spectra obtained from LC-MS. Gentamicin sulfate activity was not compromised by the elevated temperature and pressure used during spacer fabrication. Elution rate of GS increased with increasing GS content in the blends studied. At comparable elution rates, the GS-loaded UHMWPE was either equivalent or better in terms of antibacterial and anticolonization properties when compared with gentamicin containing bone cement. GS-impregnated UHMWPE is a promising material for temporary spacers.
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 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 Introduction
Methods
Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context. A retrospective analysis was conducted of 94 patients undergoing first-stage revision of an infected knee prosthesis between September 2007 and January 2020 at a single institution. Radiographs and clinical records were used to assess and classify the incidence and causes of static spacer failure. Of the 94 cases, there were 19 primary total knee arthroplasties (TKAs), ten revision TKAs (varus-valgus constraint), 20 hinged TKAs, one arthrodesis (nail), one failed spacer (performed elsewhere), 21 distal femoral endoprosthetic arthroplasties, and 22 proximal tibial arthroplasties.Aims
Methods
Endoprosthetic reconstruction with a distal femoral arthroplasty (DFA) can be used to treat distal femoral bone loss from oncological and non-oncological causes. This study reports the short-term implant survivorship, complications, and risk factors for patients who underwent DFA for non-neoplastic indications. We performed a retrospective review of 75 patients from a single institution who underwent DFA for non-neoplastic indications, including aseptic loosening or mechanical failure of a previous prosthesis (n = 25), periprosthetic joint infection (PJI) (n = 23), and native or periprosthetic distal femur fracture or nonunion (n = 27). Patients with less than 24 months’ follow-up were excluded. We collected patient demographic data, complications, and reoperations. Reoperation for implant failure was used to calculate implant survivorship.Aims
Methods
The aim of this study was to determine if a three-month course of microorganism-directed oral antibiotics reduces the rate of failure due to further infection following two-stage revision for chronic prosthetic joint infection (PJI) of the hip and knee. A total of 185 patients undergoing a two-stage revision in seven different centres were prospectively enrolled. Of these patients, 93 were randomized to receive microorganism-directed oral antibiotics for three months following reimplantation; 88 were randomized to receive no antibiotics, and four were withdrawn before randomization. Of the 181 randomized patients, 28 were lost to follow-up, six died before two years follow-up, and five with culture negative infections were excluded. The remaining 142 patients were followed for a mean of 3.3 years (2.0 to 7.6) with failure due to a further infection as the primary endpoint. Patients who were treated with antibiotics were also assessed for their adherence to the medication regime and for side effects to antibiotics.Aims
Methods
Two-stage exchange arthroplasty is the most common definitive treatment for prosthetic joint infection (PJI) in the USA. Complications that occur during treatment are often not considered. The purpose of this study was to analyze complications in patients undergoing two-stage exchange for infected total knee arthroplasty (TKA) and determine when they occur. We analyzed all patients that underwent two-stage exchange arthroplasty for treatment of PJI of the knee from January 2010 to December 2018 at a single institution. We categorized complications as medical versus surgical. The intervals for complications were divided into: interstage; early post-reimplantation (three months); and late post-reimplantation (three months to minimum one year). Minimum follow-up was one year. In total, 134 patients underwent a first stage of a two-stage exchange. There were 69 males and 65 females with an mean age at first stage surgery of 67 years (37 to 89). Success was based on the new Musculoskeletal Infection Society (MSIS) definition of success reporting.Aims
Methods
The integrity of the soft tissue envelope is crucial for successful treatment of infected total knee arthroplasty (TKA). The purpose of this study was to evaluate the rate of limb salvage, infection control, and clinical function following microvascular free flap coverage for salvage of the infected TKA. We retrospectively reviewed 23 microvascular free tissue transfers for management of soft tissue defects in infected TKA. There were 16 men and seven women with a mean age of 61.2 years (39 to 81). The median number of procedures performed prior to soft tissue coverage was five (2 to 9) and all patients had failed at least one two-stage reimplantation procedure. Clinical outcomes were measured using the Knee Society Scoring system for pain and function.Aims
Methods
Antibiotic impregnated articulating spacers are
used in two-stage revision total knee arthroplasty to deliver local antibiotic
therapy while preserving function. We have observed infection control
in greater than 95% of cases with functional outcomes approaching
those seen in revision for aseptic loosening. Higher failure has
been observed with methicillin resistant organisms.
