Materials – Knee Implants
Wireless data collected directly from patients during normal physical activities could enable the development of better knee implants
By: Joyce Laird
Metals and medical alloys
Stainless steel, titanium, and high-grade medical alloys are used for implants and instrumentation. Biodur medical alloys vary in strength, corrosion resistance, wear resistance, and fabrication potential to satisfy a range of applications. Previously, the alloys have been used for surgical and orthopedic implants such as bone plates, bone screws, and hip and knee replacements. Stainless-steel alloys have been used for surgical instruments designed for cutting and scraping. Cellular manufacturing enables quick response to customer needs, and stocking programs can be provided. Services offered include straightening, chamfering, heat-treating, and cut processing.
Boston Centerless, Woburn, MA
A line of rigid, moldable, acrylic-based multipolymer compounds is designed to deliver the same structural integrity as other transparent plastics, but at a thinner gauge, according to the company. Cyrolite Med 2, CG-97, GS-90, G-20, and G-20 Hiflo can be sterilized using the Sterrad sterilization system and are contact compatible with a variety of treatment drugs and carriers. Applications include filter housings, luers, IV connectors and accessories, spikes, cassettes, Y-sites, check valves, and pumps. The compound is intended for injection molding of disposable devices requiring maximum chemical resistance to isopropanols and lipids. GS-90, G-20, and G-20 Hiflo are intended for applications requiring clarity, toughness, and rigidity. The compounds withstand gamma, E-beam, and EtO sterilization, and resist most chemicals as well as fatty and oily products.
Cyro Industries, Parsippany, NJ
Nonplasticized urethane blend
Suitable for a diverse range of applications, particularly where a soft feel or touch is desired, the Neusoft urethane blend can be injection molded, extruded, or blow molded. Applications also include those requiring films. The urethane blend comes in Shore A hardnesses of 50, 60, and 70, and is designed to have the beneficial properties of rubber and to be an alternative to polymers and thermosets. The nonplasticized formulation is meant to help processing and performance. Small to medium orders are available, and can be shipped in clear-to-transparent pellets. Various additives or fillers can be incorporated for applications with special needs.
New England Urethane Inc., North Haven, CT
A line of color masterbatches for liquid silicone rubbers (LSRs) has been extended with the addition of a translucent color palette that meets USP and ISO biological testing requirements. The off-the-shelf pigmenting options provided by the restricted MED50-4800-X and unrestricted MED50-4900-X series consist of pigments dispersed in a vinyldimethyl-terminated polydimethylsiloxane polymer. The standard range of translucent colors available comprises black, white, red, orange, yellow, green, blue, and dark blue; custom colors obtainable through the blending of these base colors are available upon request. These translucent masterbatches are offered to enable molders to easily and precisely pigment LSRs and low-consistency materials to be injection-molded. They are available in 50-g, 1-lb, 8-lb, and 40-lb packages.
Nusil Technology, Carpinteria, CA
Polyether polyurethane film
A polyether polyurethane film is applicable for breathable wound dressings, blood pressure cuffs, hospital sheets and pads, surgical gloves, surgical drapes, and medical inflatables. The thermoplastic urethane offers antimicrobial properties and can withstand prolonged exposure to high-moisture environments. Polyether’s supple hand and conformability help it to function in contact with human skin. The film has a high moisture-vapor transmission rate, and is made from FDA-approved and USP Class VI–certified materials. Contract custom converting services, including adhesive coating, precision slitting, and die-cut and packaged films, are available.
American Polyfilm Inc. Branford, CT
Biocompatible hybrid metals
Developed for use in implantable medical devices, surgical instruments, and drug-delivery devices, a company’s biocompatible hybrid metals are designed to help with corrosion prevention, wear resistance, electrical or electronic interconnect reliability, joining by soldering and brazing, and thermal management. One application for the metals is an electronic interconnect used in an implantable device: A biocompatible refractory metal is joined with another metal to create a hybrid metal that offers unique properties and functions. The use of this hybrid as an interconnect ensures reliable communication between the sensor, logic, and active elements. Metals have also been developed in which a single strip can be comprised of differing grades of stainless steel and other metals, temper conditions, and thicknesses. These strips can be used to fabricate a variety of surgical instruments and components of medical devices. Also, refractory metal processing makes possible the use of roll-bond cladding, electroplating, electron beam welding, profile machining, and solder coating.
Technical Materials Inc., Lincoln, RI
Suited for single- or multiple-use medical devices, a line of silicone formulations can be overmolded onto such substrates as stainless steel, aluminum, PEEK, and Radel. The silicone can be used for applications requiring hundreds of sterilization cycles or for single-use procedures. A proprietary silicone bonding process also provided by the company creates a hermetic seal between the silicone and the overmolded instrument. The bonds are capable of withstanding repeated autoclaving and inhibit the migration of body fluids between sealed surfaces. Durometers, conductive or insulated silicone materials, and custom colorization components are offered to enhance the custom silicone overmolding formulations. Many of the company’s silicones are USP Class VI and ISO 10993 implantable-grade materials.
Minnesota Rubber and QMR Plastics, Minneapolis
Thermoplastic elastomer compounds
Thermoplastic elastomer (TPE) grades have been designed to yield medical tubing with high puncture and reseal performance, even after EtO sterilization. Featuring high tensile strength and tear resistance, the Monprene TPE grades enable tubing to be connected to other apparatuses. In addition, these materials are intended to provide greater clarity than comparable compounds, and a surface feel that is desirable in medical tubing applications. The TPEs are blends of styrenic triblock copolymer rubber and thermoplastic resins formulated to yield a broad array of hardnesses, textures, and physical properties. Their high levels of elasticity and tensile strength provide rubber-like characteristics. Formulations are available for injection molding, extrusion, and blow molding. The TPEs are FDA compliant.
Teknor Apex, Pawtucket, RI
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