Vitamin E Characterization

Vitamin E has become a preferred antioxidant for stabilizing thermoplastics such as ultra high molecular weight polyethylene (UHMWPE). CPG scientists have developed several testing assays to quantify Vitamin E in thermoplastics, and characterize the transformation products of Vitamin E after thermal and radiation exposure.

Injectable Hydrogels for Nucleus Augmentation

CPG scientists have developed a formulation of hydrogel that can be injected as a liquid into the nuclear cavity of the spine to restore biomechanical function of a collapsed spinal unit. The liquid hydrogel will fully gel into a permanent hydrogel in vivo without chemical reaction or heat generation. Go to the presentations page for more information.

Injectable Hydrogels for Tissue Augmentation

CPG scientists have developed a formulation of hydrogel that can be used to reinforce human tissue, acting as a bulking agent. In collaboration with the Massachusetts General Hospital, this hydrogel has been used to treat animals showing mitral valve regurgitation. Additionally, CPG is investigating the use of this formulation for urinary incontinence and gastroesophageal reflux disease (GERD). The formulation can be injected through a long, narrow gauge catheter, and will gel up in vivo without a chemical reaction. Contact us for more information.

FTIR Analysis of Crosslinked Polyethylene

Radiation-crosslinking of ultra-high molecular weight polyethylene components has been shown to increase the wear properties of these materials when used in total hip and knee replacements. It is essential to know the uniformity of the dose across the thickness of an irradiated component, and useful to know the dose received by the component. CPG has developed a technique using Fourier-transform infra-red spectroscopy to measure these parameters in in vivo and shelf-aged components. This technique also yields the degree of oxidation in aged component. See application note #002 for more details.

Accelerated Aging of Polymers

CPG performs accelerated aging protocols for assessment of long-term storage conditions of polymeric devices. We use standardized oxygen bomb or convection oven protocols, or develop custom protocols for individual projects, and often work with Q10 development according to ASTM standard F1980-02. CPG can also measure oxygen content in packaging.

Biomedical Product Recalls

Scientists at CPG have been involved with several product recalls, including catheters and orthopedic components. We help to identify the cause of failure, and assist in improving processing conditions or material properties to avoid future failures. Our testing facilities provide data needed for FDA compliance and re-entry into the marketplace. Contact one of our scientists for more details.

Cleanliness of Biomedical Components

CPG is active in research activities involving issues of cleanliness in biomedical devices. Our scientists worked with Sulzer Orthopedics on the InterOp voluntary recall in 2000 in an attempt to determine the root cause of failure in the devices. We consult with several medical device companies on cleanliness issues, and are involved with ASTM activities involving cleanliness of biomedical devices

Bone Cement Characterization

We routinely characterize PMMA-based bone cement for clients for product development as well as 510(k) applicaitons. We have developed a quantitative analysis technique to monitor the cure properties of acrylic bone cement. Through the use of multi-harmonic oscillatory rheometry, the viscosity, dynamic modulus, temperature, volumetric shrinkage, and relaxation behavior is measured as a function of cure time. Portions of this technique are now included in ASTM F451. We have also developed a new titration assay to assess benzoyl peroxide content in acrylic bone cements.

Crosslink Density in Irradiated Polyethylene

Using the SRT-1™, swell ratio measurements were performed on cross-linked ultra high molecular weight polyethylene samples to determine the relationship between crosslink density and molecular weight distribution.

Rheology of Biofluids

CPG’s custom designed CaBER® has been used to examine the properties of biologically relevant fluids, such as synovial fluid and bovine serum. The small quantities of fluid required (<0.1 ml) and the flow conditions experienced by these materials, which are often extensional in nature, makes the CaBER® an ideal instrument platform for this process.

Radiopacity Measurements

CPG performs quantitative radiopacity measurements of medical devices in accordance with ASTM F640. Go to CPG's blog for more details on this technique.

Hydrogel Formulations

CPG has developed hydrogel formulations for use in many biomedical applications. Gels can be formed in vivo or externally with a variety of properties.

Synthetic Tissue

CPG is developing arterial analogs that mimick healthy and diseased blood vessels for product development, equipment validation and procedure training. We design custom tissue models based on client specifications, incorporating mechanical properties and geometry. Go to our application notes page for more information.

ASTM Methods for Biomedical Testing

We perform testing in compliance with the following ASTM standards:

• D638 Standard Test Method for Tensile Properties of Plastics
• D695 Standard Test Method for Compressive Properties of Rigid Plastics
• D792 Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
• D1505 Standard Test Method for Density of Plastics by the Density-Gradient Technique
• D2765 Standard test methods for determination of gel content and swell ratio of crosslinked ethylene plastics
• D3895 Standard Test Method for Oxidative-Induction Time of Polyolefins by Differential Scanning Calorimetry
• D5946 Standard Test Method for Corona-Treated Polymer Films Using Water Contact Angle Measurements
• D6068 Standard Test Method for Determining J-R Curves of Plastic Materials
• E647 Standard Test Method for Measurement of Fatigue Crack Growth Rates
• F451 Standard specification for acrylic bone cement
• F640 Standard Test Methods for Determining the Radiopacity for Medical use
• F648 Standard specification for ultra-high molecular weight polyethylene powder and fabricated form for surgical implants
• F1980 Standard Guide for Accelerated Aging of Sterile Medical Device Packages
• F2003 Standard Practice for Accelerated Aging of Ultra-High Molecular Weight Polyethylene after Gamma Irradiation in Air
• F2102 Standard Guide for Evaluating the Extent of Oxidation in Ultra-High-Molecular-Weight Polyethylene Fabricated Forms Intended for Surgical Implants
• F2183 Standard Test Method for Small Punch Testing of Ultra-High Molecular Weight Polyethylene Used in Surgical Implants
• F2214 Standard test method for in situ determination of network parameters of crosslinked ultra high molecular weight polyethylene
• F2381 Standard test method for evaluating trans-vinylene yield in irradiated Ultra-High-Molecular-Weight Polyethylene fabricated forms intended for surgical implants by infrared spectroscopy
• F2459 Standard test method for extracting residue from metallic medical components and quantifying via gravimetric analysis
• F2565 Standard guide for extensively irradiation-crosslinked Ultra-High Molecular Weight Polyethylene fabricated forms for surgical implant applications
• F2625 Measurement of enthalpy of fusion, percent crystallinity, and melting point of ultra-high molecular weight polyethylene by means of differential scanning calorimetry
• F2759 Standard guide for to Ultra-High Molecular Weight Polyethylene in orthopedic and spinal applications