Talar Implant Rotatable Stem Ball-and-Socket Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current total ankle replacement systems face challenges in achieving optimal alignment and stability of talar and tibial implants, particularly in accommodating variances in bone anatomy and ensuring secure fixation without additional drilling or reaming.
Innovation Solution
A talar implant design featuring a rotatable stem with a ball-and-socket mechanism, allowing adjustable angular positioning and secure locking, which includes anti-movement features like splines and friction coatings to prevent stem displacement, enabling flexible implantation and alignment with existing bone holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-angle stem is used in the talar implant, then the implantation process is simpler, but the ability to accommodate anatomical variances and achieve optimal alignment is reduced
Solution Approach 1:
The stem is designed with a ball-and-socket mechanism that allows dynamic adjustment of the stem angle relative to the implant body. The stem can be positioned at various angles within the cavity and locked in place, transforming a static fixed-angle design into a dynamic adjustable one, thereby accommodating anatomical variances while maintaining surgical simplicity
Solution Approach 2:
The stem is divided into separate components: a stem body and a head with ball mechanism. This segmentation allows independent positioning and angulation of the stem relative to the implant body, enabling customization of the implant alignment to match patient-specific anatomy without requiring a completely different implant design
2Reliability
If additional drilling or reaming is performed to ensure secure fixation, then the fixation stability is improved, but the surgical time and bone loss increase
Solution Approach 1:
The implant cavity is pre-designed with a ball-and-socket mechanism that inherently provides angular adjustment capability. This preliminary design feature eliminates the need for additional intraoperative drilling or reaming to achieve proper alignment, as the stem can be angled to match the pre-drilled hole orientation, thereby reducing surgical time and bone loss while maintaining fixation stability
Solution Approach 2:
The stem angle parameter is made variable through the ball-and-socket mechanism, allowing the surgeon to adjust the stem orientation to match the existing bone hole without modifying the bone further. This parameter change approach enables secure fixation using the originally drilled hole, avoiding additional bone removal and surgical time
3Ease of operation
If the stem angle is fixed relative to the implant body, then the manufacturing precision is easier to control, but the flexibility in implantation and alignment is reduced
Solution Approach 1:
The stem assembly transforms from a fixed rigid structure to a dynamic adjustable mechanism. The ball-and-socket joint allows the stem to be positioned at multiple angles relative to the implant body, providing surgical flexibility. The locking mechanism then secures the selected angle, achieving both ease of operation and acceptable manufacturing precision through a two-stage process
4Adaptability or versatility
If a rotatable stem mechanism is implemented, then the alignment flexibility is improved, but the device complexity and potential for movement increase
Solution Approach 1:
The stem mechanism provides dynamic adjustability during implantation through the ball-and-socket joint, allowing alignment flexibility. Once the optimal angle is achieved, the locking mechanism transitions the system to a static stable state, preventing further movement. This dynamic-to-static transformation resolves the contradiction between flexibility and stability
Solution Approach 2:
The stem is segmented into an adjustable head portion and a fixed shaft portion. The head with ball mechanism provides the rotatable alignment capability, while the shaft provides stable fixation in the bone. This segmentation isolates the movement capability to only where needed (at the joint) while maintaining stability in the fixation portion
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the flexibility and stability of the ankle joint replacement by allowing precise angular adjustment and secure fixation, accommodating anatomical variances without the need for extensive bone modification, thereby improving surgical efficiency and patient outcomes.
Implementation Method 1
friction coatings to prevent stem displacement
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A talar implant comprises a talar dome (110) including a bone contact surface (116) and an articulation surface (114) located opposite the bone contact surface, the talar dome defining a cavity (118) extending from the bone contact surface into the talar dome. The talar implant further comprises a stem (102; 202a; 202b; 202c) comprising a head (104) and a longitudinal shaft (106; 206) coupled at a predetermined angle to the head. The head (104) is sized and configured to be received within the cavity (118). The head (104) is rotatable about at least one axis with respect to the talar dome (110). The longitudinal shaft (106; 206) comprises one or more features (240) configured to interface with a wall of a hole formed in a bone to prevent movement of the stem with respect to the bone.