Modular Spacer Mold Inserts for Precise Fit and Easy Extraction
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Solution Overview
Problem
Existing molds for forming spacer devices for joint prostheses often fail to adapt to the anatomical and dimensional variations of patients, leading to imperfect fits and requiring additional processing, and are either deformable, resulting in defects, or rigid, making extraction difficult.
Innovation Solution
A modular mold with interchangeable inserts and rigid half-shells that allow for precise adaptation to patient needs, enabling single-step formation of spacer devices without further processing, using a biocompatible material like PMMA bone cement with antibiotics, and allowing manual filling without injection systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible molds are used for forming spacer devices, then the molds can be easily deformed for extraction, but the resulting spacer devices may not have the desired configuration or may have defects
Solution Approach 1:
The mold is divided into two separate half-shells that can be detached from each other. This segmentation allows the spacer device to be extracted by separating the mold halves rather than deforming the entire mold structure, thereby maintaining both ease of operation and manufacturing precision.
Solution Approach 2:
The inner surface of each half-shell is equipped with a forming surface that provides the precise configuration for the spacer device. This localized precision surface ensures accurate geometry is transferred to the spacer while the overall mold structure remains rigid for easy extraction.
2Manufacturing precision
If rigid molds are used for forming spacer devices, then the desired configuration can be achieved, but it is often difficult to extract the spacers from these molds after the bone cement has hardened
Solution Approach 1:
The rigid mold is segmented into two detachable half-shells. This allows the mold to maintain rigidity for precise configuration transfer during forming, while enabling easy extraction by simply separating the two halves after the spacer device hardens.
3Device complexity
If molds are made in a single size or few sizes to reduce costs and storage, then manufacturing and storage are simplified, but the surgeon has to adapt the joint device to the real anatomical situation during surgery, lengthening the surgical time
Solution Approach 1:
The mold system provides different half-shell combinations that can be selected based on patient-specific anatomical requirements. Each half-shell pair is designed with specific forming surfaces for different spacer configurations, allowing the surgeon to choose the optimal mold set before surgery and eliminate intraoperative adaptation time.
Solution Approach 2:
Multiple mold half-shell sets are prepared in advance with different configurations. The surgeon selects the appropriate pre-configured mold set before surgery based on preoperative planning, allowing the spacer device to be formed immediately without intraoperative adaptation.
4Manufacturing precision
If custom-sized molds are made for each patient to achieve perfect anatomical fit, then the anatomical precision is improved, but the manufacturing cost and warehouse storage requirements increase
Solution Approach 1:
The mold is segmented into standardized half-shells that can be combined in different ways to create custom configurations. This allows a limited inventory of half-shells to generate multiple spacer device sizes and shapes, achieving patient-specific anatomical fit without requiring a unique mold for each patient.
Solution Approach 2:
Each half-shell is designed with universal features that allow it to be paired with different opposing half-shells to create various spacer configurations. This multi-functionality enables a small set of half-shells to serve multiple purposes, reducing inventory requirements while maintaining the ability to produce custom-fit spacers.
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
The mold provides customizable, defect-free spacer devices that fit anatomically, reducing surgical time and ensuring safety by avoiding toxic additives, while being cost-effective and easy to use.
Implementation Method 1
The material with which the spacer devices for the replacement of a joint prosthesis are usually made is a material known, for example, as bone cement, which initially appears in a fluid state and hardens after a certain period of time.
Data Source
AI summary
A mold for forming a spacer device for the replacement of a joint prosthesis. In particular, a mold that has at least two removable inserts.