Modular Humeral Head with Adjustable Orientation and Secure Locking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current prosthetic devices for ball-and-socket joints, such as the shoulder and hip, lack the ability for quick and precise adjustment of the humeral head during trial reduction and fail to securely lock the prosthesis in an optimal position.
Innovation Solution
A modular humeral head system featuring a housing with a hemispherical socket and Morse taper, a cap with threaded holes for screw insertion, and an intermediate piece with a tapered shaft, allowing for angular adjustment and secure locking of the humeral head assembly using screws or bone cement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a classical one-piece NEER-type humeral component is used, then the implant structure is simple and reliable, but the orientation of the humeral head relative to the stem cannot be adjusted to match patient-specific anatomy
Solution Approach 1:
The humeral component is divided into separate modular segments: a stem portion and a head portion that can be assembled together. The head portion includes a spherical head, a collar, and a locking mechanism that can be independently positioned and locked relative to the stem, enabling adjustment of head orientation while maintaining structural reliability through the segmented design.
2Measurement precision
If an adjustable head portion with spherical socket and ball is used, then the orientation can be varied, but the adjustment process is time-consuming and lacks precise locking capability
Solution Approach 1:
The head portion is pre-assembled with the collar and locking mechanism before implantation. During surgery, the head portion can be quickly attached to the stem and locked into position using a pre-designed locking mechanism that requires minimal adjustment time, thereby achieving precise positioning without time-consuming intraoperative adjustments.
Solution Approach 2:
The complex mechanical adjustment system with spherical sockets and multiple locking points is replaced with a simplified locking mechanism featuring a single locking point and a cam- or screw-based lock that can be quickly secured, reducing the time required for precise positioning while maintaining accuracy.
3Reliability
If a conical push rod locking mechanism is used, then the head portion can be locked to the stem, but the locking process is complex and requires blocked lateral expansion of the ball
Solution Approach 1:
The complex conical push rod mechanism with blocked lateral expansion is extracted and replaced with a simplified locking mechanism. The new design uses a direct locking interface between the collar and stem, or a simple cam/screw lock that engages a single locking point, maintaining secure locking while eliminating the need for complex lateral expansion blocking features.
Data Source
AI summary
A modular humeral head system includes a housing having an outer surface and an inner surface. A hemispherical socket formed on one end of the inner surface and threads formed on the other end of the inner surface. A cap is attached at the threaded end of the housing. The cap has one or more threaded holes that run from the top surface to bottom surface of the cap. A screw may be inserted in each hole. The modular humeral head system also includes an intermediate piece having a hemispherical head at one end of a tapered shaft. The tapered shaft is inserted in a humeral stem. The hemispherical head and the hemispherical socket form a ball and socket coupling. A trial head may be impacted on the housing. The trial head has one or more holes that are aligned with the screws inserted in the cap.