Adjustable Intramedullary Nail Targeting for Bent Bone Fixation
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Solution Overview
Problem
Intramedullary nails often bend during implantation, causing misalignment of screw holes at the distal end with respect to the proximal end, making it difficult to achieve precise drilling alignment for anchoring screws.
Innovation Solution
A targeting system with a distal targeting arm and an adjusting device that includes a nail follower and an adjusting element, allowing for the adjustment of targeting holes to align with bent locking holes, using mechanisms like screws with different threads, cam mechanisms, or pivot axes to ensure accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the intramedullary nail is implanted in the bone, then the nail provides reinforcement for the fractured bone, but the nail may bend during implantation causing misalignment of the screw holes at distal and proximal ends
Solution Approach 1:
The targeting device incorporates adjustable components that allow dynamic adaptation to the bent nail configuration. The device can be adjusted after nail implantation to compensate for bending, enabling realignment of targeting holes with the actual positions of screw holes at both distal and proximal ends despite the nail's deformation.
Solution Approach 2:
The targeting device allows modification of geometric parameters (angles, positions) to match the actual bent configuration of the implanted nail. By adjusting these parameters, the device compensates for nail bending and maintains accurate alignment for screw insertion.
2Adaptability or versatility
If the nail bends after implantation, then the nail adapts to the bone canal shape, but the relative positions of screw holes at distal and proximal ends change from their original alignment
Solution Approach 1:
The targeting device incorporates adjustment mechanisms that allow the operator to observe the actual positions of screw holes (potentially using imaging feedback) and mechanically adjust the device to compensate for nail bending. This feedback loop ensures accurate alignment despite the nail's adaptation to the bone canal.
Solution Approach 2:
The device transitions from a fixed configuration to a dynamically adjustable one, allowing real-time compensation for nail bending. The adjustable components enable the targeting holes to be repositioned to match the actual deformed geometry of the implanted nail.
3Device complexity
If a fixed targeting device is used, then the device structure is simple, but the device cannot compensate for nail bending and maintain alignment accuracy
Solution Approach 1:
The targeting device incorporates adjustable components that allow dynamic adaptation to the bent nail configuration. The device can be adjusted after nail implantation to compensate for bending, enabling realignment of targeting holes with the actual positions of screw holes at both distal and proximal ends despite the nail's deformation.
Data Source
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Figure 3a~3b
AI summary
A targeting system for aligning an axis of a targeting sleeve and a bore in a distal end portion of an intramedullary nail is proposed, the targeting device comprising a distal targeting arm with a first end being configured to be coupled to a trailing end of an intramedullary nail, an adjusting device, the adjusting device being configured to be coupled to the distal targeting arm. The adjusting device comprises an adjusting element and a nail follower including two targeting holes each being configured to receive a sleeve assembly. The adjusting element is configured to cooperate with the nail follower such that the positions of the two targeting holes are adjustable so as to correspond to respective locking holes at a leading end of the intramedullary nail, even when the nail is bent.