Argenson, Jean‐Noël

Aims The aim of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement, and smooth titanium alloy to inhibit staphylococci in an in vitro environment, based on the evaluation of the zone of inhibition (ZOI). The hypothesis was that there would be no significant difference in the inhibition of methicillin-sensitive or methicillin-resistant Staphylococcus aureus (MSSA/MRSA) between the two groups. Methods A total of 30 beads made of three different materials (tantalum/3D porous titanium and smooth titanium alloy) were bathed for one hour in a solution of 1 g vancomycin in 20 ml of sterile water for injection (bath concentration: 50 mg/mL). Ten 1 cm3 cylinders of antibiotic-loaded cement were also created by mixing standard surgical cement with 1 g of vancomycin in standardized sterile moulds. The cylinders were then placed on agar plates inoculated with MSSA and MRSA. The ZOIs were measured each day and the cylinders were transferred onto a new inoculated plate. Results For MSSA and MRSA, no inhibitory effect was found in the control group, and antibiotic-loaded smooth titanium alloy beads showed a short inhibitory effect until day 2. For MSSA, both tantalum and 3D porous titanium beads showed significantly larger mean ZOIs than cement beads (all p < 0.01) each day until day 7 for tantalum and until day 3 for 3D porous titanium. After six days, antibiotic-loaded cement had significantly larger mean ZOIs than the 3D porous titanium (p = 0.027), but no significant difference was found with tantalum (p = 0.082). For MRSA, both tantalum and 3D porous titanium beads had significantly larger mean ZOIs than antibiotic-loaded cement each day until day 6 for tantalum (all p < 0.01) and until day 3 for 3D porous titanium (all p < 0.04). Antibiotic-loaded cement had significantly larger mean ZOIs than tantalum and 3D porous titanium from day 7 to 9 (all p < 0.042). Conclusion These results show that porous metal implants can deliver local antibiotics over slightly varying time frames based on in vitro analysis. Cite this article: Bone Joint J 2020;102-B(6 Supple A):158–162.

ABSTRACTRevisions TKAs are being completed with uncemented constructs more frequently. We hypothesized that tantalum cones could be an efficient carrier of antibiotics in uncemented procedures. We aimed to compare the release of vancomycin between (i) tantalum and smooth stainless cylinders; (ii) different concentrations of vancomycin; and (iii) different durations of bathing. Specifically designed tantalum cylinders were bathed in a vancomycin solution with various durations of baths. We investigated rinses between each interval as well as the dose of vancomycin. Vancomycin concentrations were determined in each group by fluorescence polarization immunoassay at different intervals (1 h, days 1, 2, 3, 5). At 1 h, the mean vancomycin concentration for the 1‐hour soaking group was 3,172 μg/ml, whereas mean concentration for the smooth stainless steel group was 39.37 μg/ml (p < 0.001). The rinsing group showed a significantly lower concentration at 1 h and 1 day (p < 0.05). The 2‐gram vancomycin group showed no difference at days 1, 2, and 3 compared to the 1‐hour group. The 5, 15, and 30‐minute bathing groups showed significantly lower vancomycin concentrations at all‐time points. All vancomycin concentrations at day 3 were superior to the minimal inhibitory concentration of Staphyloccocus aureus. The mean concentration of vancomycin depends on the material, duration of bathing, the rinsing effect, and the drug dose. Our in‐vitro study is the first to show that porous tantalum cylinders allow antibiotic carriage and progressive release. If appearing in vivo, in a similar extent, this intrinsic property might be useful to prevent and/or treat peri‐prosthetic joint infection. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:308–312, 2019.

Background: Osteonecrosis of the femoral head has a host of etiologies. However, in 30% of the cases, no underlying etiology is identified and the process is considered “idiopathic.” Our hypothesis was that osseous anatomical abnormalities might be frequently found in patients with femoral head osteonecrosis. Methods: A retrospective, 1:2 matched, case-control study was undertaken to compare ninety patients with idiopathic osteonecrosis who had undergone lower-limb computed tomography (CT) prior to undergoing total hip arthroplasty with 180 control patients matched for age, sex, and body mass index (BMI) who had undergone lower-limb computed tomography scanning at our radiology department for any reason except articular or bone disease. Preoperative CT scans were performed for all patients to evaluate femoral offset, femoral neck-shaft angle, femoral neck version, femoral head diameter, acetabular coverage estimated with use of the lateral center-edge angle, acetabular version, and acetabular diameter. The mean age was forty-five years, 69% of the patients were men, and the mean BMI was 26 kg/m 2 . Results: Anatomical “abnormalities” associated with osteonecrosis were determined to be a femoral neck-shaft angle of <129° (likelihood ratio [LR] = 3.6), femoral neck version of >17° (LR = 3.8), a lateral center-edge angle of <32° (LR = 5.7), and acetabular version of <19° (LR = 1.38). A combination of three of the four anatomical “abnormalities” was found in 73% of the patients with osteonecrosis but only 11% of the control cases (LR = 6). Conclusions: This 1:2 matched, anatomical study suggests that acetabular and femoral anatomical factors, in isolation or combination, can be found in a large percentage of cases of “idiopathic” osteonecrosis. Clinical Relevance: In this study, isolated or combined abnormalities of the hip were observed in the group of patients with osteonecrosis. Those elements may help surgeons to understand the process underlying idiopathic osteonecrosis and thus require further investigation.