Acetabular Socket Anti-Lock Mechanism for Hip Prosthesis
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Solution Overview
Problem
The acetabular socket insert tends to lock prematurely in the socket shell due to the conical/spherical interface, making it difficult for surgeons to achieve precise positioning and orientation during hip endoprosthesis implantation without additional instrumentation.
Innovation Solution
A moveable anti-lock mechanism is introduced between the socket shell and insert, which initially restrains the insert from seating, allowing for uncoupled orientation and rotation, and only engages to secure the insert when optimal positioning is achieved, preventing premature locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conical/spherical interface is used between socket insert and socket shell, then self-retaining clamping is achieved, but premature locking in position occurs making precise positioning difficult
Solution Approach 1:
The anti-lock means is designed to be movable between a first position (restraining the socket insert from seating) and a second position (allowing the socket insert to be pressed into the accommodating space). This dynamic mechanism resolves the contradiction by temporarily preventing the harmful locking effect during positioning, then enabling the beneficial self-retaining clamping when positioning is complete.
Solution Approach 2:
The anti-lock means performs a preliminary action by restraining the socket insert from seating within the accommodating space before the surgeon is ready to finalize the positioning. This preliminary restraint prevents the premature locking that would otherwise occur during the positioning process, allowing the surgeon to achieve precise alignment without additional instrumentation.
2Manufacturing precision
If the socket insert is pressed into the accommodating space to achieve precise positioning, then correct orientation is achieved, but the socket insert locks prematurely in an undesirable position
Solution Approach 1:
The movable anti-lock means allows the system to transition from a restrained state (preventing premature locking) to an engaged state (enabling precise positioning and self-retention). The anti-lock means moves from a first position that prevents seating to a second position that allows the socket insert to be pressed into the accommodating space, achieving correct orientation without premature locking.
Solution Approach 2:
The anti-lock means acts as an intermediary mechanism between the socket insert and the accommodating space. It mediates the interaction by initially preventing direct contact and locking, then allowing controlled engagement when positioning is complete. This intermediary function resolves the contradiction between achieving precise orientation and preventing premature locking.
Data Source
AI summary
An acetabular socket (1) for a hip endoprosthesis comprises a socket shell (7) and a socket insert (8). The socket shell (7) is configured for implantation in a pelvic bone (2) of a patient and has an inner surface (12) that defines an accommodating space (10) extending about an axis of rotation (11). The socket insert (8) is coupleable with the socket shell (7) and is configured to provide a bearing for a joint head (6) of a prosthesis stem (3). The socket insert (8) has an outer surface (14) configured to be seated in the accommodating space (10) of the socket shell (7). A moveable anti-lock means (17) is provided between the socket shell (7) and the socket insert (8). In a first position the anti-lock means (17) restrains the socket insert (8) from seating within die accommodating space (10) of the socket shell (7) but the anti-lock means (17) is moveable into a second position wherein the socket insert (7) is capable of seating within the socket shell (7) and of coupling therewith. The anti-lock means (17) preventing the socket insert (8) from prematurely locking into an undesirable position in the socket shell (7) prior to correct positioning and orientation by a surgeon during implantation.