Injectable Hydrogels for Nucleus Pulposus 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. CPG has spun this technology out into a new company, Hydrospine, Inc.

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 Rheology

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.

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.

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.

Mock Arteries

CPG is developing vascular analogs or mock arteries that mimick healthy and diseased blood vessels for equipment validation and procedure training. Go to our application notes page for more information.

ASTM Methods for Biomedical Testing

We perform testing in compliance with the following ASTM standards:

• F2459 Standard test method for extracting residue from metallic medical components and quantifying via gravimetric analysis
• F648 Standard specification for ultra-high molecular weight polyethylene powder and fabricated form for surgical implants
• F451 Standard specification for acrylic bone cement
• F2625 Measurement of enthalpy of fusion, percent crystallinity, and melting point of ultra-high molecular weight polyethylene by means of differential scanning calorimetry
• F2214 Standard test method for in situ determination of network parameters of crosslinked ultra high molecular weight polyethylene
• D2765 Standard test methods for determination of gel content and swell ratio of crosslinked ethylene plastics
• F2003 Standard practice for accelerated aging of ultra-high molecular weight polyethylene after gamma irradiation in air
• D3895 Standard test method for oxidative-induction time of polyolefins by differential scanning calorimetry