Introduction. Metaphyseal cones with cemented stems are frequently used in revision total knee arthroplasties (TKAs). However, if the diaphysis has been previously violated (as in revision of a failed stemmed implant), the resultant sclerotic canal can impair cemented stem fixation, which is vital for cone ingrowth and long-term fixation. We report the outcomes of our novel solution to this problem, in which impaction grafting and a cemented stem in the diaphysis was combined with an uncemented metaphyseal cone for revision TKAs with severely compromised bone. Methods. A metaphyseal cone was combined with diaphyseal impaction grafting and cemented stems in a novel fashion for 35 revision TKAs. Mean age at revision TKA was 70 years, with 63% being male. Patients had a mean of 4 prior knee arthroplasty procedures. Indications for the revision with this construct were aseptic loosening (80%) and two-stage re-implantation for periprosthetic infection (PJI; 20%). Mean follow-up was 3 years. Results. Survivorship free from revision of the cone/impaction grafting construct due to aseptic loosening was 100% at 5 years. Survivorships free from any revision of the cone/impaction grafting construct and free from any reoperation were 92% and 73% at 5 years, respectively. Six knees (17%) required a reoperation (4 for infection/wound issues and 2 for periprosthetic fractures). Radiographically, 97% of cones were ingrown (1 loose cone in setting of PJI). In all but one case, impacted diaphyseal bone graft appeared to have incorporated radiographically. Conclusions. When presented with a sclerotic diaphysis and substantial metaphyseal bone loss, this innovative technique combining diaphyseal impaction grafting with a metaphyseal cone provided near universal success in regards to implant fixation. Moreover, radiographs revealed incorporation of the bone graft, and ingrowth of the cones. While long-term follow-up is required, this novel technique provides an excellent option in the most difficult of revision TKAs. For figures, tables, or references, please contact authors directly

Introduction. Metaphyseal fixation during revision total knee arthroplasties (TKAs) is important, but potentially challenging with historical cone designs. Material and manufacturing innovations have improved the size and shape of cones available, and simplified requisite bone preparation. In a very large series, we assessed implant survivorship, radiographic results, and clinical outcomes of new porous 3-D printed titanium metaphyseal cones featuring a reamer-based system. Methods. We reviewed 142 revision TKAs using 202 cones (134 tibial and 68 femoral) from 2015 to 2016. Sixty cases involved tibial and femoral cones. Most cones (149 of 202; 74%) were used for Type 2B or 3 bone loss. Mean age was 66 years, with 54 % females. Mean BMI was 34 kg/m. 2. Patients had a mean of 2.4 prior surgeries and 48% had a history of periprosthetic infection. Mean follow-up was 2 years. Results. At 2 years, survivorship free of cone revision for aseptic loosening was 100% and free of cone revision for any reason was 98%. Survivorships free of any component revision and any reoperation were 90% and 83%. Five cones had been revised at latest follow-up: 3 for infection, 1 for periprosthetic fracture, and 1 for aseptic tibial loosening. Radiographically, three unrevised femoral cones appeared loose in the presence of hinged implants, while the remainder of cones appeared stable. All cases of cone loosening occurred in Type 2B or 3 defects. Mean Knee Society scores improved from 50 preoperatively to 87 at latest follow-up (p<0.001). Three intraoperative fractures with cone impaction (two femoral, one tibial) all healed uneventfully. Conclusion. Novel 3-D printed titanium cones, with an efficient mill system, yielded excellent early survivorship and few complications in difficult revision TKAs with severe bone loss. The diversity of cone options, relative ease of preparation, and outcomes rivaling prior cone designs support the continued use of these modern cones. For figures, tables, or references, please contact authors directly

Introduction. Periprosthetic joint infection (PJI) remains the main cause of failure in primary and revision total knee arthroplasties (TKAs). Local delivery of antibiotics, mainly antibiotic-loaded bone cement (ALBC), is commonly employed to prevent PJI. Over the past decade, tantalum and porous titanium have been successfully utilized as metaphyseal fixation devices to address bone loss and improve biologic fixation during revision TKA. However, no study has examined the antimicrobial properties compared to bone cement. The purpose of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement (ALBC) and smooth titanium alloy (STA) to inhibit Staphylococci bacterial agents in an in vitro medium environment, based on the evaluation of the zone of inhibition (ZOI) and the antibacterial activity duration. Our study hypothesis was that we will found no significant difference between groups to inhibit Methicillin-Sensitive or Methicillin-Resistant Staphylococcus aureus (MSSA/MRSA) agents. Methods. Thirty beads made of 3 different materials (tantalum/ 3D porous titanium/ STA) were bathed during 1hour inside of a solution made of 1g vancomycin with 20-mL of sterile water for injection (bath concentration: 50 mg/mL). Ten 1cm. 3. cylinders were also created mixing standard surgical cement with 1g of Vancomycin in standardized sterile molds (ALBC beads). Finally, thirty beads made of tantalum/ 3D porous titanium/ STA were bathed in phosphate buffered saline solution to act as a control group. Cylinders were then placed on agar plates inoculated with MSSA and MRSA. Inhibition zone diameters were measured each day and cylinders were transferred onto a new inoculated plate. Inhibition zones were measured with a manual Vernier caliper and with automated software. The mean inhibition zones between groups were compared using the Wilcoxon Test. Results. The inter-class coefficient correlation values indicated an optimal intra-observer and inter-observer reproducibility for ZOI measurement (ICC 0.96 and ICC 0.98). For MSSA and MRSA, no inhibitory effect was found in the control group and antibiotic-loaded STA beads exhibited a short inhibitory effect until day 2. For MSSA, both tantalum and 3D porous titanium beads exhibited larger inhibition zones than cement beads (all p<0.01) each day until day 7 for tantalum and until day 3 for 3D porous titanium. After 6 days, ALBC presented larger inhibition zone than the 3D porous titanium, but no difference was found with tantalum. For MRSA, both tantalum and 3D porous titanium beads had significantly larger inhibition zones than ALBC each day until day 6 for tantalum (all p<0.01) and until day 3 for 3D porous titanium (all p<0.04). ALBC presented larger inhibition zone than tantalum and 3D porous titanium from day 7 to 9 (all p<0.04). Conclusion. Our results demonstrate that porous metal implants can deliver local antibiotics over slightly varying time frames based on our in vitro analysis. Antibiotic-impregnated tantalum and 3D porous titanium constructs exhibited superior antimicrobial properties when compared to STA. Future goals include impregnating porous metals with antibiotics for intraoperative use during revision TKA. For figures, tables, or references, please contact authors directly

Aims

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.

Aims

Accumulated evidence indicates that local cell origins may ingrain differences in the phenotypic activity of human osteoblasts. We hypothesized that these differences may also exist in osteoblasts harvested from the same bone type at periarticular sites, including those adjacent to the fixation sites for total joint implant components.