Patient-Specific Hip Alignment Instrument with Tangential Sighting Edges
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Solution Overview
Problem
The implantation of acetabulum hip joint endoprosthesis is challenging, especially in obese patients, due to error-prone palpation of landmarks and the time-consuming use of navigation systems, which can lead to inaccurate positioning of the implant.
Innovation Solution
A medical alignment instrument with a shell-shaped body featuring a patient-specific bone contact surface and visible edges that allow for both tactile and visual confirmation of correct positioning, enabling precise alignment of the acetabulum using a combination of tactile instruments and navigation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large bone contact surface is used to ensure complete contact with the acetabulum, then the alignment accuracy is improved, but the surgeon's view into the acetabulum is blocked and manual feeling becomes difficult
Solution Approach 1:
The bone contact surface is segmented into multiple regions with different functions: a large area for stable contact with the acetabulum and a specific region with visible edges that allows optical access. This segmentation enables the instrument to maintain both large contact area for accuracy and visible edges for surgeon orientation.
Solution Approach 2:
Different regions of the bone contact surface are given different properties. The overall surface provides large-area contact for stability, while specific local regions incorporate visible edges with tangentially discontinuous transitions that allow optical access without compromising the overall contact quality.
2Measurement precision
If the bone contact surface is made large to use the entire acetabulum as reference, then the alignment reference is improved, but the risk of inaccuracies from surface irregularities or foreign bodies increases
Solution Approach 1:
The bone contact surface is divided into multiple independent contact regions rather than a single large continuous surface. This segmentation allows the instrument to distribute contact points across different areas of the acetabulum, reducing the impact of local irregularities or foreign bodies on overall alignment accuracy.
3Strength
If the shaped body is made thick to provide structural stability, then the mechanical strength is improved, but the weight and volume increase
Solution Approach 1:
The shaped body is designed as a shell structure with constant thickness that provides structural stability while minimizing weight and volume. The shell geometry distributes mechanical loads efficiently, maintaining strength without requiring excessive material thickness.
4Illumination intensity
If the visible edge width is made large to improve visibility, then the optical access is improved, but the transition between the edge and bone contact surface becomes difficult to detect
Solution Approach 1:
The visible edge is designed with specific local geometric properties including tangentially discontinuous transitions that create distinct visual and tactile signatures. This local quality enhancement allows the edge to provide visibility while maintaining detectable transition zones for precise positioning.
5Measurement precision
If a navigation system is used to achieve precise acetabulum positioning, then the alignment accuracy is improved, but the procedure time increases significantly
Solution Approach 1:
The alignment instrument is designed to be self-aligning through its patient-specific bone contact surface that automatically conforms to the unique geometry of the patient's acetabulum. This self-service alignment mechanism eliminates the need for time-consuming navigation system setup and operation, providing rapid and accurate positioning.
Data Source
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AI summary
The invention relates to a medical instrument, in particular for implanting a hip joint cup, comprising a medical alignment instrument having a molding, which molding has a bone support surface which is individual to a patient, points away from the molding and differs from a section of a spherical surface, which surface s shaped so as to correspond to a bone surface of the patient. In order to improve said medical instrument such that the implantation, in particular of a hip joint cup of a hip joint prosthesis, is simplified, the molding according to the invention has at least one sighting edge having a sighting elevation, the sighting edge adjoins the patient-individual bone support surface, and tat a transition between the sighting edge and the patient-individual bone support surface is tangentially discontinuous.