Hip Stem Centralizer Datum Guide for Precise Positioning
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Solution Overview
Problem
In total hip arthroplasty, accurately positioning the hip stem component within the bone cement in the intramedullary canal is challenging due to the need for precise orientation and uniform cement mantle distribution, which affects long-term stability and biomechanical functioning.
Innovation Solution
A hip stem centralizer datum guide system that includes a base positionable adjacent to the intramedullary canal and a cut guide to create a datum on the femur, allowing for precise positioning of the hip stem component by referencing alignment marks on the femur and the component itself, ensuring correct medial/lateral, anterior/posterior, and proximal/distal placement within the cement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual positioning methods are used to place the hip stem component in the intramedullary canal, then the surgeon has flexibility in positioning, but the positioning precision and uniformity of the cement mantle are compromised
Solution Approach 1:
The datum guide is positioned and secured to the femur before cement injection, establishing precise reference marks (datums) on the bone surface that guide subsequent hip stem placement. This preliminary positioning action ensures that the correct orientation and depth are predetermined, allowing for accurate reproduction of the desired position without requiring complex real-time adjustment mechanisms during cementation.
Solution Approach 2:
The datum guide acts as an intermediary device between the surgeon's positioning intent and the actual hip stem placement. It includes reference marks, alignment features, and guide structures that translate the desired stem orientation into precise physical references on the bone, eliminating the need for direct manual positioning of the stem itself and ensuring uniform cement mantle distribution.
2Manufacturing precision
If no datum reference system is used, then the implantation process is simpler, but the uniformity and strength of the cement mantle cannot be ensured
Solution Approach 1:
The datum guide establishes reference marks and alignment features on the femur before cement injection, predetermined the correct hip stem position and orientation. This preliminary action creates a permanent reference system that ensures uniform cement mantle distribution without requiring complex real-time adjustments during the implantation process.
Solution Approach 2:
The datum guide creates a physical copy or replica of the desired hip stem position through reference marks and alignment features on the bone surface. These datums serve as a template that can be referenced during stem insertion, ensuring that the cement mantle is distributed uniformly without requiring the surgeon to repeatedly measure or adjust the position manually.
3Reliability
If the hip stem component is positioned without a predetermined datum, then the surgical procedure is faster, but the long-term stability and biomechanical functioning are compromised
Solution Approach 1:
The datum guide is positioned and reference marks are established on the femur before cement injection, predetermined the optimal hip stem position and orientation based on preoperative planning and intraoperative assessment. This preliminary action ensures that when the stem is inserted, it automatically achieves the correct position for long-term stability, eliminating the need for time-consuming adjustments or revisions later.
Solution Approach 2:
The datum guide provides visual and physical feedback through reference marks, alignment features, and guide structures that indicate when the hip stem is correctly positioned. This feedback mechanism allows the surgeon to verify proper placement immediately during the procedure, ensuring long-term stability without requiring additional time for postoperative adjustments or revision surgeries.
Data Source
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AI summary
A hip stem centralizer datum guide (40, 100, 200, 300) and method are provided for positioning a proximal portion of a hip stem component (44) within bone cement in an intramedullary canal of a femur. The datum guide is positionable in a predetermined position relative to the intramedullary canal and is able to create a datum (70, 72, 74, 76, 120, 220, 302) that records the predetermined hip stem component position relative to the intramedullary canal. The datum is able to be referenced to position the hip stem component in the predetermined hip stem component position in the bone cement in the intramedullary canal.