Aim. The preparation of antibiotic-containing polymethyl methacrylate (PMMA), as spacers generates a high polymerization heat, which may affect their antibiotic activity; it is desirable to use bone cement with a low polymerization heat. Calcium phosphate cement (CPC) does not generate heat on polymerization, and comparative elution testings are reported that vancomycin (VCM)-containing CPC (VCM-CPC) exceeded the antibiotic elution volume and period of PMMA (VCM-PMMA). Although CPC alone is a weak of mechanical property spacer, the double-layered, PMMA-covered CPC spacer has been created and clinically used in our hospital. In this study, we prepared the double-layered spacers: CPC covered with PMMA and we evaluated its elution concentration, antimicrobial activity and antibacterial capability. Method. We prepared spherical, double-layered, PMMA-coated (CPC+PMMA; 24 g CPC coated with 16 g PMMA and 2 g VCM) and PMMA alone (40 g PMMA with 2 g VCM) spacers (5 each). In order to facilitate VCM elution from the central CPC, we drilled multiple holes into the CPC from the spacer surface. Each spacer was immersed in phosphate buffer (1.5 mL/g of the spacer), and the solvent was changed daily. VCM concentrations were measured on days 1, 3, 7, 14, 28, 56, and 84. Antimicrobial activity against MRSA and MSSA was evaluated by the broth microdilution method. After measuring all the concentration, the spacers were compressed at 5 mm/min and the maximum compressive load up to destruction was measured. Results. The VCM concentration of the CPC+PMMA spacer exceeded that of the PMMA spacer at all-time points; in particular, it was approximately 7.3 times (109.30 vs. 15.03 μg/mL) and approximately 9.1 times (54.47 vs. 6.50 μg/mL) greater on days 14 and 28, respectively. Using the broth microdilution method, we found that the CPC+PMMA spacer had higher antimicrobial activity than the PMMA model. On day 56, the PMMA spacer lost the capability to inhibit bacterial growth, but the CPC+PMMA spacer maintained this ability. The average maximum compressive load for the CPC+PMMA was 7.28 kN, and that of PMMA was 16.21 kN. Conclusions. The CPC+PMMA spacer was superior to PMMA alone in VCM elution volume and duration, so CP- C+PMMA may be effective for the treatment of MRSA and MSSA infection. The double-layered, antibiotic-loaded cement spacer may maintain antibacterial capability and sufficient strength

Introduction. Osteoporotic intertrochanteric fracture (ITF) is frequent injuries affecting elderly, osteoporotic patients leading to significant morbidity and mortality. Successful prognosis including union and alignment is challenging even though initial successful reduction with internal fixation. Although many factors are related to the patient's final prognosis. Well reduction with stable fracture fixation is still the goal of treatment to improve the quality of life and decrease morbidity in patients with hip fractures, but this in turn depends on the type of fracture and bone quality. Poor bone quality is responsible for common complications, such as failure of fixation, varus collapse and lag screw cut-out, in elderly patients. Kim et al. found that the complication rate when using conventional DHS in unstable ITFs can be as high as 50% because of screw cut-out. We used the dynamic hip screws (DHS) strengthened by calcium phosphate cement (CPC) for treatment femoral intertrochanteric fracture and review the prognosis of our patients. Materials and Methods. From January of 2011 to January of 2014, 42 patients with femoral intertrochanteric fracture underwent surgery with DHS strengthened by CPC. Comparisons were made between the DHS plus CPC group with the other patients with only DHS used in our department. All patients were followed up for an average time of 14.8(6 to 24) months. X-ray was reviewed for the conditions of union and implant failure. Results. In DHS group, fixation failure happened in 3 case, delayed union and coax varus deformity in 2 cases. IN DHS plus CPC group, all fractures healed uneventfully, there is no non-union or malunion in this group. There is only 1 fixation cut-out and 1 secondary lag screw sliding was noted, however, union was still well over fracture site in this case, the patient had no clinical symptoms. Discussion. Residual bony defects present after DHS fixation in intertrochanteric fracture may lead to postoperative complications, including nonunion or implant failure. DHS strengthened by CPC is reliable fixation for old patients with intertrochanteric fracture, We demonstrated that augmentation of the bony defect with dynamic hip screw by reinforced calcium phosphate cement significantly improved the strength of osteoporotic bone, prevent screw loosening, and promote early healing of fracture. The patients can be decreased the risk of refracture and allow early weight bearing, especially in elderly patients with osteoporotic bone

Background. Calcium phosphate cement (CPC) is a promising biomaterial which can be used in numerous medical procedures for bone tissue repairing because of its excellent osteoconductivity. An injectable preparation and relatively short consolidation time are particularly useful characteristics of CPC. However, the low strength of CPC and its brittleness restrict its use. One method for toughening brittle CPC is to incorporate fibrous materials into its matrix to create a composite structure. Fibers are widely used to reinforce matrix materials in a variety of areas. Objective. We hypothesized that there must be an optimal fiber length and structure which can balance these conflicting aspects of fiber reinforcement. The purpose of this study is to prove our conjectures that adding a small amount of short fibers significantly improves the hardness and the toughness of CPC while maintaining its injectability with a syringe and that fiber morphologies that have crimps and surface roughness are favorable for reinforcing. Material and Methods. We used 3 types of short fibers of approximately 20–50 micrometer in diameter and 2 mm in length in this study: crimpy wool, crimpy polyethylene and straight polyethylene fibers. All of the materials were prepared by mixing a solvent with CPC powder with or without fiber. We grouped as follow, the control group, the wool group, the crimpy polyethylene group, the straight polyethylene group. After soaking in 37 degrees Celsius Simulated Body Fluid∗∗∗∗∗ for 1, 3, or 7 days, they were tested for each period. Impact strength test by the falling weight and compression test were performed. Result. In the impact strength test, after soaking for 1 day, impact resistance in the wool group was approximately 180 times greater than in the control group. When soaking for 3 days or more, impact resistance of wool group improve better than control group. The impact resistance of the wool group was the greatest among the four groups in soaking for 3 days. In the compression test, the yield strength and ultimate strength of the wool group were significantly higher than ultimate strength of the control group. The wool group has stress–strain curves that are typical of those of ductile materials, whereas the stress–strain curves of the control group resemble those of brittle materials. This indicates that fiber reinforcement drastically alters the physical properties of CPC converting it from brittle to ductile. Conclusion. In the present study, we sought to develop a method for producing injectable fiber-reinforced CPC. We focused on morphology and surface roughness of fiber in the reinforcement of CPC. This study clearly showed that CPC was substantially strengthened and toughened by crimpy short fiber reinforcement. CPC reinforced with short fibers which have morphology similar to wool should be a promising tool for orthopedic surgeons