PyroCarbon CMC Implants

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Raw Graphite Material Radiolucent Carbon Coating FIGURE 1. Manufacturing Process CVD Reaction Chamber Precision Machining Surface Polishing Radiopaque Graphite Substrate Substrate Coating Finished Implant FIGURE 2. Elastic modulus of metal and ceramic are much greater than that of bone or PyroCarbon. PyroCarbon Material PyroCarbon is a specific form of carbon that has been tailored for durability and compatibility. PyroCarbon has portions of 2-D and 3-D crystalline structures, resulting in excellent strength and wear properties between those of graphite and diamond. PyroCarbon should not be confused with carbon fibers, which are minute particles used to strengthen other materials. Manufacturing a PyroCarbon implant begins with a precision-machined graphite substrate that contains 1 atomic percent tungsten to make the core visible on X-ray. Using patented steady-state process controls, a thick layer of radiolucent On-X ® pure carbon is deposited onto the graphite core, maximizing strength and durability. FIGURE 1. The elastic modulus of PyroCarbon is very similar to cortical bone resulting in biomechanical compatibility with bone. Unlike surgical grade metals, PyroCarbon transfers load from implant to bone more effectively, thus reducing stress shielding and potential bone resorption. 1 FIGURE 2. PyroCarbon exhibits exceptional wear performance against bone compared to ceramic and metals. After cyclical testing to 5,000,000 cycles, PyroCarbon demonstrated minimal wear into cortical bone. It was not possible to test the other materials past 375,000 cycles with Cobalt Chrome, 50,000 cycles with Titanium and 25,000 cycles with Zirconia because the bone specimens had worn away. 2 FIGURE 3. Cortical Bone 23 PyroCarbon 29.4 Titanium 105 Zirconia 210 CoCr Alloy 230 FIGURE 3. Cyclic Wear Test Against Bone FIGURE 4. Photomicrograph shows appositional bone growth on material. FIGURE 5. Left – PyroCarbon after 18 months; shows healthy cartilage and surrounding tissue. Right – metal alloy after 18 months; shows damaged cartilage and tissue. Wear Penetration Rate into Bone (nanometer/cycle) 0 10 20 30 40 5,000,000 cycles 0.2 375,000 cycles 4.3 50,000 cycles 30.4 25,000 cycles 34.7 PyroCarbon CoCr Titanium Zirconia Fixation Pyrocarbon has a micro-porous structure that enhances bone fixation without the need for cement. This unique fixation is achieved initially through a press fit design using precise instrumentation. Long term fixation is achieved via appositional bone growth as bone remodels up to the biologically active surface of PyroCarbon. 3 FIGURE 4. Cartilage Friendly A study of cartilage wear in 45 canine acetabula was performed using both PyroCarbon and metal alloy hip prostheses. PyroCarbon showed remarkably less wear damage to cartilage. After 18 months, cartilage articulating with PyroCarbon exhibited a 92% survivorship probability compared to 20% survivorship with metal alloys. 4 FIGURE 5.
Ascension PyroCarbon CMC implants are designed for high demand patients undergoing joint replacement who: • Have healthy, strong bones • Show no signs of joint infection • Have muscles and tendons which are repairable Ascension CMC Implants • Do not have other devices that block implant insertion or normal motion • Do not have concerns with cuts healing or other skin problems • Do not have numbness or tingling in hands or fingers The NuGrip CMC Implant is our most recent thumb arthroplasty design, bringing together viewpoints and years of expertise from surgeons around the world. We continue to market multiple CMC options, and our challenge is explaining for whom each implant should be used. Each design allows minimal bone resection and requires no use of cement – providing an open pathway for revision. All Ascension PyroCarbon CMC implants require healthy and stable soft tissues for sucessful outcomes. Stemmed Designs CMC Saddle: STAGES 1 OR 2 Use of this implant requires the full shape of the trapezium to be intact. Minimal lateral erosion of the trapezium is integral to the functionality of this implant, allowing a secure fit and permitting the head of the implant to articulate on the trapezium without potentially dislocating radially. No bone removal on the trapezium is required when using the CMC Saddle. The anatomical stem provides a press fit within the metacarpal for additional stability. Stages of Arthritis Based on radiological features, clinical stages of arthritis were first described by Eaton and Littler, and further defined in an article by Dr. Sam Anand of the Horton NHS Treatment Centre and Horton Hospital. These images and descriptions help identify the proper implant for patient indication. NUGRIP CMC: STAGES 2 OR 3 The NuGrip CMC Implant is a redesigned version of the original PyroHemiSphere, which is still available. New design features include a neck collar and an anatomical stem specifically designed for the 1st metacarpal to allow press fit and additional stability. The creation of a cup in the trapezium holds the spherical head in place. This head provides generous range of motion and additional height – minimizing bone-on-bone impingement. Interpositional Designs PYROSPHERE: STAGES 2 OR 3 This device may be used when there is evidence of joint space narrowing and/or sclerosis in the trapeziometacarpal joint. Shallow cups are made in the metacarpal and trapezium using soft tissues to stabilize and hold the implant in place. This spherical, interpositional spacer design provides height to the joint space minimizing potential for impingement and restoring natural range of motion. PYRODISK: STAGES 2 OR 3 (not available for distribution in the U.S.) The PyroDisk is a biarticular disk design which incorporates the patient’s own anatomy to restore joint space and minimize pain. It re-establishes proper alignment of the thumb using the patient’s tendon for stabilization and preserves trapezial bone stock – only requiring minimal bone resection on the trapezium and metacarpal – thereby limiting the risk of thumb shortening and weakness. Stage 1: Synovitis as evidenced by increased joint space in X-ray Stage 3: Sclerosis in the trapeziometacarpal joint Stage 2: Joint space narrowing Stage 4: Pan trapezial osteoarthritis as evidenced by radiological changes in the scapho-trapezialtrapezoidal (STT) joint.
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PyroCarbon CMC Implants

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