Abstract: A method is disclosed for analysis of the impedance behavior of electrochemical impedance circuits or the Transfer Function for input-output systems, utilizing the symmetry of the phase angle response with the Log of the frequency to allow for determination of the lower frequency half of the impedance response over Log frequency based only on information from the upper half response. The underlying analytical basis for the symmetry of the phase angle and the methods for applying this analysis are applicable to simple R-C circuits, Randle circuits, Constant Phase Element (CPE)-Randles and coating model circuits. Symmetric functions describing the derivative of the phase angle, ?, with respect to the Log of the frequency can be used to determine the circuit elements requiring only the high frequency information. Only knowledge of the high frequency-based response is needed to know how the low frequency range behaves.

Abstract: The use of lipids in the taper junction or other metal on metal interface of a modular orthopedic implant to prevent fretting corrosion and increase the pull off load. The incorporation of lipids or a lipid-like substrate within the taper junction increases the onset load and decreases the amount of corrosion. The incorporation of lipids also increases the pull-off load necessary to separate the head from the neck. As a result, the use of lipids in the taper junction of an orthopedic implant should reduce the need for revisions of implants, such as such as knee and hip replacements, which are often needed because of fretting corrosion.

Abstract: A method is disclosed for analysis of the impedance behavior of electrochemical impedance circuits or the Transfer Function for input-output systems, utilizing the symmetry of the phase angle response with the Log of the frequency to allow for determination of the lower frequency half of the impedance response over Log frequency based only on information from the upper half response. The underlying analytical basis for the symmetry of the phase angle and the methods for applying this analysis are applicable to simple R-C circuits, Randle circuits, Constant Phase Element (CPE)-Randles and coating model circuits. Symmetric functions describing the derivative of the phase angle, ?, with respect to the Log of the frequency can be used to determine the circuit elements requiring only the high frequency information. Only knowledge of the high frequency-based response is needed to know how the low frequency range behaves.

Abstract: The use of lipids in the taper junction or other metal on metal interface of a modular orthopedic implant to prevent fretting corrosion and increase the pull off load. The incorporation of lipids or a lipid-like substrate within the taper junction increases the onset load and decreases the amount of corrosion. The incorporation of lipids also increases the pull-off load necessary to separate the head from the neck. As a result, the use of lipids in the taper junction of an orthopedic implant should reduce the need for revisions of implants, such as such as knee and hip replacements, which are often needed because of fretting corrosion.

Abstract: The present invention relates to bone cements and, more particularly, to acrylic-based orthopedic bone cements, their use in spinal applications, and methods for making the same. An embodiment of the present invention provides multi-solution bone cements which include cross-linked PMMA beads, a linear polymer, and a monomer with various polymer to monomer ratios, and polymer bead to linear polymer ratios. The bone cement can include a polymer to monomer (P:M) ratio of between about 1:1 and 1.4:1, and can also include a polymer bead to linear polymer ratio of between about 1:1 and 2:1. Another embodiment of the present invention provides the use of a radiopacifier in the bone cement composition, such as ZrO2, in increasing concentrations.

Abstract: The invention discloses a novel method of controlling the open circuit potential (OCP) of a medical implant by coupling it with small amounts of metals having a lower OCP than the implant. Coupling of Mg to less than 1% of the surface area of a titanium implant is shown to induce cathodic polarization of the titanium that inhibits cell proliferation at the surface of the implant. Mg—Ti coupling in medical devices promises to attenuate or eliminate potential complications of surgery such as peri-implantitis and bacterial infections at the site of implantation.

Abstract: The present invention relates to bone cements and, more particularly, to multi-solution bone cements and methods for making the same. An embodiment of the present invention provides multi-solution bone cements which include cross-linked PMMA beads, thereby providing for a significant increase in the polymer-to-monomer (P:M) ratio. Another embodiment of the present invention provides cross-linked PMMA beads which are surface modified with unsaturated carbon double bonds. A further embodiment of the present invention provides multi-solution bone cements made with PMMA-PMMA spherical brush polymers.

Abstract: The present invention relates to bone cements and, more particularly, to acrylic-based orthopedic bone cements, their use in spinal applications, and methods for making the same. An embodiment of the present invention provides a method of grafting PMMA brushes on cross-linked PMMA nanospheres comprising at least one of the following steps: performing a hydrolysis reaction of surface methyl ester groups of said cross-linked PMMA nanospheres to form surface carboxylic acid groups of said cross-linked PMMA nanospheres; forming a 2-aminoethyl acrylate compound; coupling said surface carboxylic acid groups of said cross-linked PMMA nanospheres with said 2-aminoethyl acrylate compound to form a coupled compound with an initiating site; and grafting said PMMA brushes onto said initiating site.

Abstract: The invention discloses a novel method of controlling the open circuit potential (OCP) of a medical implant by coupling it with small amounts of metals having a lower OCP than the implant. Coupling of Mg to less than 1% of the surface area of a titanium implant is shown to induce cathodic polarization of the titanium that inhibits cell proliferation at the surface of the implant. Mg—Ti coupling in medical devices promises to attenuate or eliminate potential complications of surgery such as peri-implantitis and bacterial infections at the site of implantation.

Abstract: The present invention relates to bone cements and, more particularly, to acrylic-based orthopedic bone cements, their use in spinal applications, and methods for making the same. An embodiment of the present invention provides a method of grafting PMMA brushes on cross-linked PMMA nanospheres comprising at least one of the following steps: performing a hydrolysis reaction of surface methyl ester groups of said cross-linked PMMA nanospheres to form surface carboxylic acid groups of said cross-linked PMMA nanospheres; forming a 2-aminoethyl acrylate compound; coupling said surface carboxylic acid groups of said cross-linked PMMA nanospheres with said 2-aminoethyl acrylate compound to form a coupled compound with an initiating site; and grafting said PMMA brushes onto said initiating site.

Abstract: The present invention relates to bone cements and, more particularly, to acrylic-based orthopedic bone cements, their use in spinal applications, and methods for making the same. An embodiment of the present invention provides multi-solution bone cements which include cross-linked PMMA beads, a linear polymer, and a monomer with various polymer to monomer ratios, and polymer bead to linear polymer ratios. The bone cement can include a polymer to monomer (P:M) ratio of between about 1:1 and 1.4:1, and can also include a polymer bead to linear polymer ratio of between about 1:1 and 2:1. Another embodiment of the present invention provides the use of a radiopacifier in the bone cement composition, such as ZrO2, in increasing concentrations.

Abstract: Orthopedic bone cements of low porosity, prepared by mixing together at least two liquid components under conditions that allow only minimal exposure to air, are disclosed. In a preferred system, each liquid component consists essentially of a solution of a linear (non-crosslinked) polymer or copolymer of methyl methacrylate (PMMA) dissolved in a non-crosslinking methyl methacrylate (MMA) monomer, with one such solution also containing an activator and a polymerization inhibitor and a second solution containing an initiator as well as a polymerization inhibitor. No reinforcing fillers are present, although a small amount (no more than 12% by weight of the total cement composition) of a radiopacifier may be included in the composition.

Abstract: Self-reinforced composites of amorphous thermoplastic materials such as poly(methylmethacrylate), polycarbonate and polysulfone are made by melt-extruding and simultaneously drawing and cooling the material to produce fibers with longitudinally-oriented molecular chains, then arranging the fibers in a preform, such as a mat, rod, plate or other useful shape, in which adjacent fibers are in contact with each other, and thereafter heating the preform with fiber constraint to a temperature above the glass transition temperature and below the degradation temperature of the thermoplastic, and applying pressure, to soften and fuse together the outer surfaces of the fibers without completely eliminating the longitudinal orientation of the molecules within the fibers. Where the amorphous thermoplastic is poly(methylmethacrylate), the preform may be wrapped about the bone-implantable element of a joint prosthesis to provide a high-strength integrated mantle of connected, contracted, and oriented fibers.

Abstract: An orthopedic implant, such as the bone-implantable portion of a joint prosthesis, in which a rigid stem is dimensioned to be received in the intramedullary canal of a bone, and in which the stem has at least a portion of its length encased in a preformed mantle consisting of a self-reinforced poly(methylmethacrylate) fiber composition where the fibers are oriented in predetermined directions with respect to the axis of the stem, are of a diameter within the range of about 5 to 500 microns (.mu.m), and have aligned molecular chains that provide such fibers with longitudinal heat relaxation ratios of no less than about 6 to 1 is disclosed. Also disclosed are the methods for making such an implant and for securing it in an intramedullary canal.