Polyaxial Reaming Apparatus for Orthopedic Implants
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Solution Overview
Problem
Current bone preparation methods for orthopedic implants lack flexibility and precision, particularly in orienting fixation members independently of the implant, leading to suboptimal attachment and potential instability of orthopedic devices like pedicle screws.
Innovation Solution
A polyaxial reaming apparatus that allows the bone bed to be formed at an angle independent of the guide wire, enabling optimal orientation of the fixation member and implant, with a design featuring a cutting component and base component that can rotate around a guide wire, facilitating secure attachment and adjustable orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a guide wire is implanted to guide reaming or screw implantation, then the orientation of the resulting resection surface or pedicle screw is determined, but it is difficult to implant the guide wire at a precise angle with respect to the vertebra
Solution Approach 1:
A polyaxial reaming apparatus is introduced as an intermediary device between the guide wire and the final implant. The apparatus includes a reaming head that can be positioned at multiple angles relative to the guide wire axis, allowing the surgeon to first implant the guide wire along a safe trajectory and then use the reaming apparatus to create a bone bed at the optimal angle for the implant, thus decoupling the guide wire placement from the final implant orientation
Solution Approach 2:
The reaming head of the apparatus is designed with polyaxial capability, allowing it to rotate and be positioned at various angles relative to the guide wire axis. This dynamic positioning capability enables the surgeon to adjust the reaming angle to match the optimal implant orientation while maintaining the guide wire in its original position, thereby achieving precise angle control without difficulty in guide wire implantation
2Reliability
If the fixation member is implanted along the axis of the guide member, then the fixation member and resection have the same axis, but this is not optimal because the axis optimal for the fixation member does not reflect the best placement of the implant
Solution Approach 1:
The procedure is segmented into distinct steps: first, the guide wire is implanted to establish a safe trajectory; second, the polyaxial reaming apparatus is attached to the guide wire and the reaming head is positioned at the optimal angle for the implant; third, the bone bed is created at this optimal angle. This segmentation allows the guide wire to serve its guiding function while the reaming head independently establishes the optimal implant orientation, separating the constraints of guide wire placement from the requirements of optimal implant placement
Solution Approach 2:
The reaming head is designed to operate in an additional degree of freedom by allowing angular adjustment relative to the guide wire axis. This polyaxial capability adds a rotational dimension to the procedure, enabling the bone bed to be created at any angle within a range of motion, thus allowing the implant to be oriented optimally independent of the guide wire direction
3Adaptability or versatility
If traditional reaming apparatus is used, then the reaming head is fixed relative to the drive shaft, but this limits the ability to form bone beds at angles independent of the guide wire
Solution Approach 1:
The reaming head is designed with a polyaxial mechanism that allows it to rotate and be positioned at various angles relative to the drive shaft and guide wire. This dynamic positioning system includes mechanical elements such as a ball and socket joint or similar articulation that enables angular adjustment while maintaining a secure connection, providing orientation flexibility without excessive structural complexity
Solution Approach 2:
The apparatus is designed with nested components where the reaming head attaches to the drive shaft, which in turn attaches to the guide wire. This nested structure allows the guide wire to remain in place while the reaming head is positioned and oriented independently, achieving angular flexibility through a compact, integrated design that minimizes overall complexity
Data Source
AI summary
A reamer may be designed to engage a guide member, such as a guide wire, implanted in bone at any of a plurality of relative orientations such that the resulting resection of the bone does not depend on the relative orientation. The reamer may have a shaft that receives torque and a reaming head with a cavity into which a protruding portion of the guide wire is insertable. The cavity may have a generally conical shape capable of receiving the guide wire at a variety of relative orientations. The orientation of the reaming head is determined not by that of the guide wire, but by a stationary frame to which the reamer is coupled. The reamer may optionally have an offset assembly that causes the reaming head to rotate about an axis displaced from that of the shaft to reduce the size of the incision required to reaming head.