Our Nitinol Technology
Nitinol is an alloy comprised of approximately 50% nickel and 50% titanium. It can exist in two phases, or states: martensite and austenite. These phases are similar to the phases in which other substances can exist (in the case of water, for instance, liquid and solid ice). Nitinol’s martensitic phase is associated with lower temperatures and a molecular arrangement that allows the metal to be softer and more malleable. Its austenitic phase is associated with higher temperatures and a cubic, more stable and rigid molecular arrangement.
Though a manufacturing process, Nitinol can be programmed to transform from martensite to austenite through a designated temperature range. Heating Nitinol though this transformation temperature range causes it to change from a softer metal to a stronger metal.
In addition to change in the molecular arrangement, Nitinol also possesses two characteristics that are displayed as the material is heated through its transformation temperature range: shape recovery (or shape memory) and superelasticity. Shape recovery occurs when a Nitinol device, when heated though its transformation temperatures, returns to a predetermined shape. Superelasticity refers to the characteristic of the metal to store heat energy and use that energy to exhibit a spring-like behavior. Both of these characteristics can work hand-in-hand. For instance, a Nitinol device in martensite that is heated through its transformation temperature will exhibit a shape recovery effect as it transforms to austenite. If that device is physically prevented from fully returning to its predetermined shape, it is said to be in a constrained martensite state. As long as a heat source is available, the device will continually attempt to return to its austenitic phase and its predetermined shape and thus it will exhibit a spring-like behavior.
Biocompatibility
Nitinol possesses additional characteristics that make it a beneficial material for orthopaedic use. It is highly biocompatible when properly surface treated and has been used in orthodontic wires and cardiac stents for decades. BME employs a sophisticated manufacturing process that creates a protective corrosion resistant surface and minimizes nickel on the surface.
Strength
With comparable treatments, Nitinol has a higher breaking strength than 316L stainless steel when in austenite. This allows for the development of low-profile fixation devices that provide excellent strength and construct stability.
Continuous Compression™ Technology
BME’s OSStaple™ lines (smooth, barbed, step and arc) are heat-activated Nitinol devices. They remain in martensite (soft and malleable) at room temperature and transform into austenite as they approach 56°C. As they are heated through their transformation temperature range, their shape recovery properties compress the bone fragments to which they are fixated. The surrounding bone tissue constrains the implants, preventing them from fully reaching their predetermined shape and austenite phase. As long as these implants are exposed to heat energy, they will remain in a constrained martensite state, behaving like springs and maintaining a compressive force on the bone fragments (although heated to 56°C, they are programmed to
maintain a significant amount of force as they cool down to normal body temperature). Our implant lines thus produce immediate compression at the time of surgery and continuous compression throughout the healing process.
Controllable Compression™ Technology
BME’s Nitinol implant are the only controllable heat-activated implants on the market. Unlike superelastic and body temperature-activated Nitinol staples, the OSStaple™ lines (smooth, barbed, step and arc) are heated using the patented OSSforce™ Implant Controller. The OSSforce™ is a bipolar electrical resistance unit that safely warms each implant to non-necrotic temperatures using implant-specific time and power settings. With the OSSforce™, the surgeon can adjust the amount of compressive force our implants exert, making this Nitinol fixation system the only one suitable for cases involving questionable bone quality. Other methods of heating heat-activated staples, such as the application of electrocautery, are unsafe for the patient and may damage hospital equipment. Through design innovations and sophisticated manufacturing techniques, BME has become the world leader in shape memory implant development and production.
