Resorptive intramedullary implant between two bones or two bone fragments
Patent No. US10383671 (titled "Resorptive intramedullary implant between two bones or two bone fragments") on Sep 18, 2015. The application was issued on Aug 20, 2019.
What is this patent about?
’671 is related to the field of orthopedic implants, specifically intramedullary devices used for arthrodesis and osteosynthesis in small bones like those found in the hand or foot. The invention addresses the mechanical challenges of using resorptive materials, such as lactic acid polymers, which must maintain structural integrity and bone compression during the healing process before being naturally absorbed by the body.
The underlying idea behind ’671 is to optimize bone fixation by using a hybrid geometry that compensates for the lower material stiffness of bioresorbable polymers compared to traditional metals. By combining a threaded cylindrical anchor on one end with a bifurcated flat anchor on the other, the implant achieves high primary stability through two different mechanical interfaces: a screw-in connection for one bone fragment and an elastic, press-fit expansion for the other.
The claims of ’671 focus on a method of bone fixation utilizing an implant with a specific tooth arrangement and an expandable distal geometry. The device features a longitudinal body where the second end includes a series of teeth spaced along its axis, with some teeth projecting in different directions to grip the bone. A critical aspect of the claimed method involves the use of spreadable arms defined by a central opening, which elastically engage the second bone part to maintain tension.
In practice, the surgeon prepares the site by tapping a thread into the first bone and rasping a flat channel into the second. The cylindrical end is screwed into the first bone until a central transition zone acts as a depth stop. The second bone fragment is then pressed onto the flat end, causing the internal arms to compress and then elastically expand, driving the external teeth into the cancellous bone to prevent rotation and pull-out.
This approach differs from prior art by specifically tailoring the implant's geometry to the behavior of resorptive polymers. While metal implants rely on rigid shapes, this design uses a dual-mechanism interface—threading for one side and elastic deformation for the other—to ensure the bones remain compressed even as the material begins its degradation phase, a combination not typically found in single-piece bioresorbable pins.
How does this patent fit in bigger picture?
Technical Landscape
In the late 2000s when ’671 was filed, orthopedic fixation for small bone arthrodesis was typically implemented using metallic intramedullary devices or K-wires. At a time when systems commonly relied on rigid stainless steel or titanium alloys to provide mechanical stability, the use of bioresorbable polymers was often limited by the material's inherent mechanical constraints, which made achieving both primary stability and long-term structural integrity non-trivial. During this era, hardware designs for small bone fragments were generally uniform in their anchoring mechanisms, often utilizing either symmetric threaded bodies or symmetric elastic legs, rather than hybrid geometries optimized for different bone morphologies.
Prosecution Position
The disclosed invention represents a technical advancement through an asymmetrical architectural shift in intramedullary implant design specifically optimized for resorbable materials. By integrating a tapered, threaded cylindrical anchor at one end with a flat, elastically deformable bifurcated anchor at the other, the implant overcomes the mechanical limitations of polymers like PLA or PGA. This hybrid structure enables a dual-mode fixation capability: the threaded zone provides high-torque rotational stability in one bone segment, while the opening in the flat zone allows for elastic expansion to accommodate the specific geometry of the opposing bone site. This configuration achieves a technical effect of improved primary stability and resistance to shear and flexion forces at the arthrodesis line, ensuring the implant maintains compression throughout the biological resorption window.
Claims
The patent contains 22 claims, with claims 1, 9, and 10 being independent. These independent claims focus on surgical methods for joining bone parts using an implant that features a specific arrangement of teeth on its second end, where teeth are spaced along a longitudinal axis and project in different directions to secure the device. The dependent claims serve to further define the procedure and the implant structure by specifying bone preparation steps, elastic deformation properties of the implant arms, the use of resorptive materials, and specific geometric configurations such as offset axes or coplanar tooth surfaces.
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US10383671
- Application Number
- US14858855A
- Filing Date
- Sep 18, 2015
- Publication Date
- Aug 20, 2019
- External Links
- Slate, USPTO , Google Patents