MWCNT Used in Orthopaedic Bone Cements

Abstract

implant procedures. In 2005, cement was used for the fixation of 73% of femoral stems and 53% of acetabular cups, in England and Wales (NJR 2006). 2.3 Acrylic bone cement Poly (methylmethacrylate) (PMMA) has been used in orthopaedics since the early 1960s (Charnley 1960). It was first introduced by Sir John Charnley and Dr Dennis Smith. Also known as acrylic bone cement, it acts as a grouting agent for the fixation of artificial joints as well as the treatment of spinal compression fractures (vertebroplasty). In TJR, bone cement fills the space between prosthesis and bone and acts as an elastic buffer, therefore transferring mechanical load on the implant to the bone. This function of distributing stresses is critical for implant longevity. If the external stresses exceed the ability of the cement to transfer the load, a fracture results (Kuehn et al., 2005). Acrylic bone cement is a two phase system, consisting of a polymer powder and monomer liquid. The powder phase primarily consists of spherical PMMA beads (82-89 wt. %), in addition to an inorganic radiopacifying agent, usually barium sulphate or zirconium dioxide (10-15 wt. %). The powder component also contains benzoyl peroxide (BPO; 0.5-2.6 wt. %), which catalyses polymerisation. The liquid phase is largely MMA monomer (98 wt. %), with 2 wt. % N, N-Dimethyl-p-toluidene (DmpT) which accelerates the polymerisation. From a chemical point of view, MMA is an ester of methacrylic acid with a polymerisable double bond. When the liquid and powder phases are mixed, the initiator (BPO) reacts with the accelerator (DmpT) to form free radicals in what is known as the 'initiation reaction'. These free radicals initiate polymerisation of MMA into PMMA by adding to the polymerisable double-bond of the monomer molecule. Temperatures during this reaction can reach up to 110ºC. During polymerisation, the bone cement is worked into a 'dough' phase that can be moulded or injected. In a relatively short amount of time (10-15 minutes) the bone cement hardens to ca. 90% of its final mechanical properties (Kuehn et al., 2005). Although current revision rates of cemented TJR are low, improved mechanical and thermal properties are required to further reduce subsequent surgeries of cemented arthroplasties, and increase the longevity of the implant. With 88.7% of current cemented implants expected to last at least 14 years (Karrholm et al. 2008), this would mean that more physically active patients would have to undergo a number of revision surgeries in their lifetime. Furthermore, younger patient populations are more likely to impose heavier, more complex loadings on the implant, as they would wish to continue pursuing an active lifestyle. 3. Composition and polymerisation reaction 3.1 Composition Acrylic bone cement, as mentioned is primarily composed of poly methylmethacrylate (PMMA). Most commercial acrylic bone cements comprise of a two part self-curing acrylic polymer, usually formulated as a 2:1 powder to liquid ratio. These components are mixed immediately prior to implantati...

Polymethyl Methacrylate-Based Bone Cements Containing Carbon Nanotubes and Graphene Oxide: An Overview of Physical, Mechanical, and Biological Properties

“…Diseases like osteoporosis, osteoarthritis, and rheumatoid arthritis can degenerate the joint. Osteoarthritis, a degenerative joint disease that can lead to the breakdown of the cartilage in the joints [ 1 , 2 ], is known as the most typical reason to have a hip or knee replaced as shown in Figure 1 [ 2 ]. Total joint replacement (TJR) is a field of treatment for reducing pain and enhancing life quality, and is remarkably used for treating these debilitating illnesses.…”

“…Total joint replacement (TJR) is a field of treatment for reducing pain and enhancing life quality, and is remarkably used for treating these debilitating illnesses. It is expected that the number of joint replacements is widely increased, due to the escalation of the elderly population as well as associated trauma and disease [ 1 , 2 ]. TJR is known as one of the most usual tasks in orthopedic surgery, considering an appropriate prognosis.…”

“…The achievement and wide-spreading utilization of joint substitutions in the management of arthritic states along with trauma has caused an essential influence in modern healthcare. The successful results in the cases of total knee/hip joint replacements have provided active lives and also good life quality for us [ 1 , 2 , 3 ]. In this relation, polymethyl methacrylate (PMMA)-based bone cements (BCs) has been utilized as a fixation agent between the bone and the implant.…”

“…In this relation, polymethyl methacrylate (PMMA)-based bone cements (BCs) has been utilized as a fixation agent between the bone and the implant. The PMMA-based BCs are located between the implant and the bone, and the BCs with specific structure can enable the cement for impressive transferring of the body weight and other loads from the prosthesis to the bone [ 1 , 2 , 3 , 4 ]. The success of cemented prosthesis is strongly dependent on the reliable interface between the prosthesis and the cement as well as the mechanical bond between the bone and the cement; therefore, a robust bond at the interface between prostheses–cement–bone is essential.…”

Investigation of the microstructure, mechanical properties and cell viability of zirconia-toughened alumina composites reinforced with carbon nanotubes

“…This is due to their remarkable properties originating from their unique one-dimensional character. A combination of outstanding mechanical (elastic modulus ³1.28 TPa, tensile strength ³30 GPa), 1), 2) thermal (conductivity >2000 W/mK) and electrical (conductivity >1.5 © 10 4 S/m) 3) properties makes CNTs suitable reinforcing materials for different systems. The very high aspect ratio of CNTs enhances load transfer with the matrix and provides effective reinforcement.…”