Orthopedic Intramedullary Nail Screw Layout for Bone Fixation
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Solution Overview
Problem
Current orthopedic fixation devices, such as retrograde femoral and tibial IM nails, face challenges in screw placement and alignment, particularly in the medial-lateral direction, leading to difficulties in securing bone fragments and potential penetration of anatomical structures.
Innovation Solution
The retrograde femoral nail incorporates medial-lateral and anterior-posterior screw holes, with a medial-lateral slot for improved fixation, and the tibial IM nail features oblique and angled screw holes to avoid anatomical structures, while the SureShot targeting system ensures precise screw placement without fluoroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a retrograde femoral nail is used to stabilize femur fractures, then the nail can be inserted through the distal end of the femur, but screw placement in the medial-lateral direction at the proximal end becomes difficult or impossible due to fluoroscopic machine limitations
Solution Approach 1:
The patent introduces a medial-lateral screw hole oriented perpendicular to the anterior-posterior screw holes, enabling screw placement in a previously inaccessible direction. This dimensional addition to the screw hole configuration allows fluoroscopic machines to target and place screws in the medial-lateral direction at the proximal end, resolving the limitation of conventional retrograde femoral nails.
2Reliability
If screw holes are formed in the distal end portion of the retrograde femoral nail, then the nail can secure bone fragments, but the screw holes may not be properly aligned in situ to secure certain bone fragments and the nail lacks compression capability
Solution Approach 1:
The patent provides different screw hole configurations at different locations along the nail. The proximal end includes medial-lateral screw holes for specific bone fragment fixation, while the distal end includes oblique screw holes at specific angles for securing distal fragments. Each location has optimized screw hole orientation tailored to the specific bone anatomy and fixation requirements at that position.
Solution Approach 2:
The nail incorporates an elongated slot at the proximal end that is pre-configured to receive a compression device. This preliminary preparation enables compression of the proximal bone fragment before final fixation, ensuring proper alignment and securing of the fragment without requiring additional surgical steps.
3Ease of manufacture
If a tibial IM nail uses a single distal hole extending in the anterior-posterior direction, then the nail can be implanted, but it cannot provide increased fixation while avoiding anatomic structures such as nerves, vessels, and tendons
Solution Approach 1:
The patent divides the single distal hole into multiple separate screw holes positioned at different locations and orientations. This segmentation allows each screw hole to be optimally positioned to engage bone while avoiding specific anatomical structures. The distal end includes first and second screw holes at different angles, enabling selective engagement with bone fragments without compromising nearby nerves, vessels, or tendons.
4Device complexity
If the proximal most screws in the proximal end portion are positioned in holes perpendicular to the central longitudinal axis, then the nail can be manufactured simply, but the screws may not be parallel to the tibial plateau and may penetrate the tibial plateau
Solution Approach 1:
The patent introduces asymmetric angular orientation for the screw holes in the proximal end portion. Instead of all screw holes being perpendicular to the central longitudinal axis, the first and second screw holes are positioned at specific angles (e.g., ±15 to ±45 degrees) relative to the longitudinal axis. This asymmetric arrangement ensures that screws can be oriented parallel to the tibial plateau while avoiding penetration, accommodating the specific anatomical requirements of the proximal tibia.
Data Source
AI summary
An intramedullary (“IM”) nail for internal fixation of a bone is disclosed. In one embodiment, the IM nail may be a retrograde femoral nail. Alternatively, in another embodiment, the IM nail may be a tibial IM nail. In one or more embodiments, the screw holes are arranged and configured to optimize placement of one or more screws, fasteners, or the like. In addition, and/or alternatively, an IM nail may be arranged and configured to facilitate removal of a broken screw.