Papers by Keyword: Bone Cement

Abstract: Conventional calcium phosphate bone cements are self setting water based pastes. Recently pre-mixed calcium phosphate bone cements have been proposed that have non-aqueous fluid as liquid phase of the paste. Such cements thus only start setting reaction in contact with body fluids. In this work the properties (cohesion, compressive strength, phase composition) of pre-mixed calcium phosphate cements based on α-tricalcium phosphate and calcium dihydrogen phosphate monohydrate are described. Properties of several cement compositions are examined and compared to properties of β-tricalcium phosphate and calcium dihydrogen phosphate monohydrate based cements. It was found that α-tricalcium phosphate and calcium dihydrogen phosphate monohydrate based cements have higher compressive strength (10 - 15 MPa) than corresponding β-tricalcium phosphate and calcium dihydrogen phosphate monohydrate based cements (10 - 6 MPa). Out of examined cement paste liquids (glycerol, polyethylene glycol and polypropylene glycol) cements using glycerol as the liquid phase had higher compressive strength and are more cohesive.

Abstract: Conventional calcium phosphate bone cements are self setting water based pastes. Recently pre-mixed calcium phosphate bone cements have been proposed that have non-aqueous fluid as liquid phase of the paste. Such cements thus only start setting reaction in contact with body fluids. In this work the properties (cohesion, compressive strength, phase composition) of pre-mixed calcium phosphate cements based on α-tricalcium phosphate and calcium dihydrogen phosphate monohydrate are described. Properties of several cement compositions are examined and compared to properties of β-tricalcium phosphate and calcium dihydrogen phosphate monohydrate based cements. It was found that α-tricalcium phosphate and calcium dihydrogen phosphate monohydrate based cements have higher compressive strength (10 - 15 MPa) than corresponding β-tricalcium phosphate and calcium dihydrogen phosphate monohydrate based cements (10 - 6 MPa). Out of examined cement paste liquids (glycerol, polyethylene glycol and polypropylene glycol) cements using glycerol as the liquid phase had higher compressive strength and are more cohesive.

Abstract: Various bone cements with different compositions were prepared in several model configurations which differed in volume (i.e. setting temperature profile) and mode of mixing (manual and vacuum bowl). Local mechanical properties (nanohardness, elasticity modulus) of all experimental states were measured by nanoindentation technique and compared. Role of the preparation route as well as influence of composition, particularly of presence of antibiotics, on the measured properties was investigated.

Abstract: Clinical studies have proved that artificial joints may fail under prolonged gait load, which failure mechanism includes mechanical loosening and infectious loosening. Infectious loosening can be prevented by avoiding osteomyelitis, caused by bacterial infection arising from the marrow cavity, which affects the fixation function of the bone handle. As a result, use of bone cement containing various antibiotics has become an important method for prevention and treatment of infection after artificial joint replacement. This study was aimed to investigate the mechanical properties of bone cement after the addition of antibiotics through the mechanical tests. With the measurements we can then assessed the variations of mechanical strength with the dosage of antibiotics. The results showed that the dose of antibiotics directly affected the compression strength and elastic modulus of antibiotic bone cement. When the antibiotics was added more than 4.8 wt %, the cement strength was obviously affected and reduced, by 27%, indicating that during artificial hip joint replacement, the dose of antibiotics should be concerned, in order to avoid affecting the strength of bone cement and stability of the entire implant.

Abstract: The designs of cemented hip femoral stems have an influence on both the quality of the metalbone cement contact and the failure rate of the cement mantle. Finite element stress technique has been used to optimize both design and material selection in load-bearing components in artificial hip joints based on the static load analysis, by selecting the peak load during the patient activity. In this study, two stem shapes (Ceraver Osteal and Charnley stems) for total hip arthoplasty (THA) were modelled. Static behaviour of these designed stem shapes were analyzed using commercial finite element analysis code ABAQUS. Linear elastic analysis is adapted; Von Mises stress and shear stress are the criterions that are of concern. Results show that, the stresses distribution in the femoral arthroplasty components depends on the material and design of the stem. In addition, the cement-bone and cement-stem interfaces seem to be crucial for the success of the hip replacement, hip prosthesis with Charnely stem induces the more stresses on the interfaces cement.

Abstract: In orthopedic surgery and particularly in the total hip arthroplasty, the stem fixation is performed in general using a surgical cement which consists essentially of polymer (PMMA). Fracture of cement and prosthesis loosening appears after a high-stress level. This phenomenon origin is due to the presence of micro-cavities in the PMMA volume. The focus of our study is the modeling using the finite-element method of the cement damage around these cavities, the cavities' sizes and shapes effect on the damage risk, and the crack length estimation due to this damage. A small Fortran schedule was incorporated with the Abaqus code to calculate the damage zone. Results show that the presence of a cavity in the cement increases the damage parameter. The damage appears when the cavity is located in cement on the loading axis. If the cavity changes its shape from circular to elliptical, the size of the damage zone increases. One can predict the initiation of a crack in cement with a maximal length of 70μm.Keywords: total hip prosthesis, crack, bone cement, biomechanics, damage.

Abstract: In situ monitoring of structural changes, taking place upon calcium phosphate bone cements hardening process was carried out by means of the Energy Dispersive X-Ray Diffraction method. Two different cement systems were studied, one of them based on the octacalcium phosphate and another - on the dicalcium phosphate dehydrate. Both systems contained natural biopolymer chitosan and were soaked in Simulated Body Fluid. The obtained experimental results evidence that during the hardening of the cement containing octacalcium phosphate its partial transformation into hydroxyapatite takes place, whereas no significant changes were detected during the hardening process of cement containing the dicalcium phosphate dehydrate.

Abstract: The rationale behind failure of cemented total hip replacement is still far from being well understood in a mechanical and molecular perspective. In the present study, the integrity of the stem–cement interface was investigated through an in vitro experiment monitoring fluid flow along this interface. The results indicated that a good mechanical bonding formed at the stem–cement interface before debonding of this interface was induced by physiological loadings during the in vivo service of the hip prosthesis.

Abstract: To explore a new type of injectable composite cements similar to the natural bone in both composition and hierarchical structure, the mineralized collagen and calcium sulphate dihydrate（CSD）were incorporated into α-calcium sulphate hemihydrate (α-CSH).The mineralized collagen was synthesized biomimetically by nanohydroxyapatite/collagen. We investigated the injectability, the setting time and the biomechanics properties to find an ideal combination of them to prepare the composite cements. SEM analysis showed biphasic cements consisting of an entanglement of calcium sulfate dihydrate and calcium-deficient hydroxyapatite crystals. We prepared porcine thoracolumbar burst fracture models and made the vertebroplasty for them by the composite cements. Imaging analysis showed the composite cements distributed uniformly and solidified well. Biomechanical test showed the ability of composite cements to repair spinal burst fractures was significant.

Abstract: To improve the fixation of bone and bone cement in THA we used Interface Bioactive Bone Cement technique (IBBC) since 1982. For prostheses 28 mm-alumina head with polyethylene socket (Kyocera Co.) were used. In IBBC not-resorbable pure crystalline HA granules (0.3– 0.5 mm) were smeared on the bone surface in one to three layers just before packing bone cement. Group 1: IBBC was used in six joints in 1982. Group 2: In 25 patients, conventional bone cement technique (non-IBBC) in the one hip (in 1985 to 1986) and IBBC technique in the other hip (in 1986) were performed in the same patients. Group 3: In 65 patients (71 joints) IBBC were performed. Neither radiolucent line nor osteolysis appeared in all case in group 1. In group 2 in Non-IBBC the appearance rate of radiolucent line and osteolysis were rather high, however in IBBC they were extremely low. In Non-IBBC loosening were seen in 5 joints in the acetabulum and in 2 joints in the femur. However, in IBBC there was no loosening. In group 3 the radiolucent line and the osteolysis appeared extremely low. There was no loosening. In Non-IBBC the appearance rate of radiolucent line and the osteolysis was very high and the rate of loosening was 20%. However, in IBBC, radiolucent line and osteolysis will be prevented eternally.